Appendix D Sediment Profile and Plan View Imaging Report

Transcription

1 Appendix D Sediment Profile and Plan View Imaging Report

2 April 2010 Sediment Profile & Plan View Imaging Report Evaluation of Sediment and Benthos Characteristics Along Potential Cable Routes and Turbine Locations for the Proposed Block Island W Farm Prepared for: Ecology and Environment, Inc. 368 Pleasant View Drive Lancaster N.Y Contract Number DW06.01 Prepared by: CoastalVision 215 Eustis Avenue Newport, RI Germano & Associates, Inc SE 46th Place Bellevue, WA 98006

3 Sediment Profile & Plan View Imaging Report EVALUATION OF SEDIMENT AND BENTHOS CHARACTERISTICS ALONG POTENTIAL CABLE ROUTES AND TURBINE LOCATIONS FOR THE PROPOSED BLOCK ISLAND WIND FARM Prepared for Ecology and Environment, Inc. 368 Pleasant View Drive Lancaster, New York Contract Number DW06.01 Prepared by CoastalVision 215 Eustis Avenue Newport, RI and Germano & Associates, Inc SE 46 th Place Bellevue, WA April 2010

4 Table of Contents 1.0 INTRODUCTION MATERIALS AND METHODS Station Locations Vessel Navigation Sampling Equipment Measuring, Interpreting, and Mapping SPI and PUC Parameters Sediment Grain Size Prism Penetration Depth Small-Scale Surface Boundary Roughness Thickness of Depositional Layers Mud Clasts Apparent Redox Potential Discontinuity Depth Sedimentary Methane Infaunal Successional Stage Presence of Organisms Using SPI and PUC Data to Assess Benthic Quality & Habitat Conditions RESULTS Sediment Grain Size Habitat Classification Surface Boundary Roughness Prism Penetration Depth Apparent Redox Potential Discontinuity Depth Infaunal Successional Stage DISCUSSION CONCLUSIONS REFERENCES List of Tables Table 1. Udden-Wentworth size classes (adapted) Table 2. Coding matrix for presence of organisms Table 3. Modified Major Grain Size Groups and Folk Classes... 30

5 List of Figures Figure 1. Overview map of the stations sampled during the October 2009 survey. Figure 2 (a, b, c, d). Station locations in relation to potential cable routes, turbine locations, and bottom topography. Figure 3. Operation of the combined Ocean Imaging Model 3731 sediment profile and Model DSC-6000 plan view camera. Figure 4. Soft-bottom benthic community response to physical disturbance (top panel) or organic enrichment (bottom panel). From Rhoads and Germano, Figure 5 (a, b, c, d). Spatial distribution of sediment grain-size major mode (phi units). Figure 6. Profile image illustrating soft, muddy sediment (silt-clay with a major mode of >4 phi) at station NC-8. Figure 7. Profile image showing very fine sand (grain size major mode of 4 to 3 phi) at station BI-12. Figure 8. Profile images illustrating variability in sediment grain size at Point Judith Shoal stations. Figure 9. Close-up of sidescan sonar results at station PJ-20 showing a band of high backscatter (darker color) icative of coarser sediments. Figure 10. Profile images showing homogenous rippled fine sand at station T-4 (left) and fine sand mixed with small gravel (granules and pebbles) at station T-1 (right). Figure 11. Profile images from stations at the top of the Southeast Shoal providing examples of medium to coarse sand covered with varying amounts of gravel. Figure 12. Profile images showing examples of medium sand at station AS-35, very coarse sand at station AS-11, and small gravel (granules and pebbles) at station AS-9. Figure 13 (a,b,c). Planview and corresponding profile image illustrating undisturbed cobble habitat. Figure 14 (a,b,c,d). Planview and corresponding profile image illustrating washed gravel habitat. Figure 15 (a,b,c). Planview and corresponding profile image illustrating mobile sand habitat.

6 Figure 16 (a,b,c). Planview and corresponding profile image illustrating silty sand habitat. Figure 17 (a,b,c). Planview and corresponding profile image illustrating soft silt habitat. Figure 18 (a,b,c,d). Habitat type observed at each station based on analysis of both planview and profile images. Figure 19. Planview images from stations L1-8 and PJ-71 showing clusters of white squid eggs (insets) protruding from the sand among cobbles. Figure 20. Profile image from station AS-18 showing a cluster of white squid eggs at the sediment surface. Figure 21 (a,b,c,d). Spatial distribution of average station boundary roughness values (cm). Figure 22. Images from station NC-24 illustrating biogenic surface roughness Figure 23. Profile image from station PJ-44 showing coarse sand/gravel with a highly sloped surface (i.e., high small-scale boundary roughness). Figure 24. Profile and associated planview image showing rippled very fine sand at station T-4. Figure 25. Profile and associated planview image from station A2-12 showing rippled sediment consisting of mixed coarse sand and gravel. Figure 26 (a,b,c,d). Spatial distribution of average prism penetration depth (cm). Figure 27 (a,b,c,d). Spatial distribution of average arpd depths (cm). Figure 28. The profile image from Narragansett Connection station NC-6 near the Rhode Island mainland shows a relatively thin arpd of 1.2 cm and patches of dark, sulfidic sediment at depth. Figure 29 (a,b,c,d). Spatial distribution of infaunal successional stages. Figure 30. Profile image from station NC-10 showing soft mud with small tubes at the sediment surface (Stage 1) and a feeding void and several larger-bodied polychaetes at depth (Stage 3), resulting in a Stage 1 on 3 infaunal successional stage designation for this image.

7 Figure 31. Profile image from station BI-8 showing soft silt and minor amounts of very fine sand with a few surface tubes, extensive small burrows just below the sediment surface, and a larger burrow/void at depth (Stage 1 on 3). Figure 32. Stage 2 amphipod tubes are visible at the surface of very fine sand in this profile image from station BI-14. Figure 33. Representative planview image from Point Judith Shoal showing washed gravel lacking of any visible organisms at station PJ-54. Figure 34. Representative planview images of cobble habitat at Point Judith Shoal showing the cobbles encrusted with small muddy tubes, hydroids, and anemones. Figure 35. Profile image from station PJ-28 providing an example of Stage 2 on 3: dense amphipod and polychaete tubes at the sediment surface (Stage 2) and a Stage 3 feeding void/burrow at depth (lower right corner). Figure 36. Profile and associated planview image from station PJ-42 showing a dense aggregation of ampeliscid amphipod tubes covering the surface of fine sand. Figure 37. Representative planview images showing a general absence of visible biological activity at the sediment surface on washed gravel habitat Figure 38. Representative planview images from stations near each end of the Turbine Alternative 2 transect showing rippled, mobile sand with sand dollars and/or sea stars. Figure 39. Planview images from stations AS-20 and AS-22 on Southeast Shoal showing both sparse and dense cobbles covered with a variety of encrusting epifauna and algae. Figure 40. Location of areas of RI Sound near Block Island with greatest likelihood of cobble habitat. Figure 41. Distribution of sediment types from usseabed data (Reid et al. 2005) in Rhode Island Sound. Figure 42. Cable routes and turbine locations selected to avoid Undisturbed cobble habitat. Appendix A. Sediment Profile Results Appendix B. Station Locations Appendix C. Plan-View Camera Results

8 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm 1.0 INTRODUCTION Deepwater W LLC is conducting an array of environmental studies on and around Block Island, Rhode Island, as part of preparations for a proposed Block Island offshore w farm. One of the studies involved an assessment of seafloor conditions and benthic habitats in and around proposed locations of the w turbines in the waters immediately south of Block Island, as well as along potential routes that a power-transmission cable might take from the w farm to mainland Rhode Island. To assess seafloor conditions and characterize benthic habitats in these locations, a team of scientists representing Germano & Associates, Inc. (G&A), CR Environmental (CR), and CoastalVision (CV) performed a combined Sediment Profile Imaging (SPI) and Plan-View Underwater Camera (PUC) survey in October The survey was performed under the direction of Ecology and Environment, Inc. (ENE) for Deep Water LLC of Rhode Island. The survey results were used to provide reconnaissance and analysis of potential turbine sites and cable installation routes from the general area south of Block Island to a landfall on Block Island and from Block Island to the mainland near Narragansett, Rhode Island. Based on results of this survey and parallel studies of archaeology, w resources, geophysical properties and effects of cables and turbines on human and biological resources in Rhode Island Sound turbine locations and cable routes will continue to evolve. This survey provides a baseline of benthic habitats and seafloor conditions in the areas initially proposed for installation of a demonstration scale w farm (eight turbines) located within Rhode Island state waters. 1 P age

9 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm 2.0 MATERIALS AND METHODS 2.1 STATION LOCATIONS Between October 6 and 14, 2009, scientists from G&A (responsible for SPI/PUC operation), CR (responsible for navigation/vessel support), and CV (project oversight and real-time review of results) worked on-board the vessel Shanna Rose operating out of Hull, MA to perform the combined SPI/PUC survey in Rhode Island Sound. The field team collected sediment profile and plan-view images at each of 282 stations located in potential turbine locations and/or along potential power-transmission cable routes in and around Block Island and extending to the Rhode Island mainland (Figure 1). For clarity in presenting the results, the surveyed area has been divided into four finerscale maps, with the following distribution of stations: Figure 2a: Fifteen (15) stations (labeled NC-1 to NC-24) located along the potential cable route called the Narragansett connection and 20 stations (labeled BI-3 to BI-27 and PJ-24) located along the potential cable route called the Block Island connection. Figure 2b: Eighty-one (81) stations (labeled PJ-1 to PJ-91 and BI-2) located in and around potential cable routes over or around Point Judith Shoal. Figure 2c: Three (3) stations at the southern end of the Block Island Connection (labeled BI-28 to BI-30), 19 stations along the Alt 1 connection (labeled A1-1a to A1-14), 6 stations along the Alt 2 connection (labeled A2-1 to A2-6), 9 stations in the turbine alternative 1 location (labeled T-1 to T-9), and 24 stations in the turbine alternative 2 location (labeled AT-7 to AT-30). Figure 2d: A total of 105 stations located on and around the shoal located to the southeast of Block Island (Southeast Shoal). These 105 stations included several different groups, as follows: 7 stations in the turbine alternative 1 location (labeled T-10 to T-16), 16 stations along the Alt 2 connection (labeled A2-7 to A2-22), 6 stations in the turbine alternative 2 location (labeled AT-1 to AT-6), and the remaining 76 stations located on top of and to either side of the Southeast Shoal (labeled as either AS-1 to AS-37 or with the label prefixes L or Line in Figure 2d). Because the 2009 survey represented a reconnaissance sampling effort, it included both fixed and ad-hoc stations. The fixed stations were selected prior to the survey operations and were spaced at regular intervals along the potential cable routes and 2 P age

10 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm alternative turbine locations. The locations of the ad-hoc stations were determined in the field, based on existing knowledge of bottom topography and broad-scale features (from prior bathymetric and side scan sonar surveys) combined with real-time review of the images downloaded from the sediment-profile and plan-view cameras. The ad-hoc stations often were positioned as transects perpendicular to the lines of fixed stations to determine the spatial extent of certain habitat features, such as the hard-bottom conditions associated with the Southeast and Point Judith Shoals. 2.2 VESSEL NAVIGATION Navigation for the sampling effort was accomplished using a Trimble AgGPS 132 twelve-channel Trimble Differential Global Positioning System (DGPS) system capable of receiving the U.S. Coast Guard (USCG) beacon corrections. The system is capable of sub-meter (i.e., less than one-meter) horizontal position accuracy. The DGPS system was interfaced to a laptop computer running HYPACK hydrographic survey software. HYPACK provided the vessel captain with distance and direction to each sample station. The radius of sampling operations for each target location was 9 meters; if the boat drifted outside this 9-meter radial boundary before the camera hit bottom, the image was not used for analysis. HYPACK was also used to digitize the shot location at each SPI drop event. These digitized points were saved as a delimited ASCII text file and included the following fields: Time; Date; Northing; Easting; Latitude; Longitude; and fields describing satellite geometry, signal quality and differential correction status. 2.3 SAMPLING EQUIPMENT SPI was developed almost two decades ago as a rapid reconnaissance tool for characterizing physical, chemical, and biological seafloor processes and has been used in numerous seafloor surveys throughout North America, Asia, Europe, and Africa (Rhoads and Germano 1982, 1986, 1990; Revelas et al. 1987; Diaz and Schaffner, 1988; Valente et al. 1992). The sediment profile camera works like an inverted periscope. An Ocean Imaging Systems Model 3731 sediment profile camera with a Nikon D megapixel SLR camera and an 8-gigabyte compact flash card was used for this survey; the Nikon DSLR was mounted horizontally inside a watertight housing on top of a wedge-shaped prism. The prism has a Plexiglas faceplate at the front with a mirror placed at a 45 angle at the back. The camera lens looks down at the mirror, which is reflecting the image from the faceplate. The prism has an internal strobe mounted inside at the back of the wedge to provide illumination for the image; this chamber is filled with distilled water, so the camera always has an optically clear path. This wedge assembly is mounted on a moveable carriage within a stainless steel frame. The frame is lowered to the seafloor on a winch wire while the vessel maintains a stationary position at the water s 3 P age

11 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm surface, and the tension on the wire keeps the prism in its up position. When the frame comes to rest on the seafloor, the winch wire goes slack and the camera prism descends into the sediment at a slow, controlled rate by the dampening action of a hydraulic piston so as not to disturb the sediment-water interface. On the way down, it trips a trigger that activates a time-delay circuit of variable length (operator-selected) to allow the camera to penetrate the seafloor before any image is taken (Figure 3). The knife-sharp edge of the prism transects the sediment, and the prism penetrates the bottom. The strobe is discharged after an appropriate time delay to obtain a cross-sectional image of the upper 20 cm of the sediment column. The resulting images give the viewer the same perspective as looking through the side of an aquarium half-filled with sediment. After the first image is obtained at a given sampling location (i.e., station), the camera is then raised up about 2 to 3 meters off the bottom to allow the strobe to recharge; a wiper blade mounted on the frame removes any mud adhering to the faceplate. The strobe recharges within 5 seconds, and the camera is ready to be lowered again for a replicate image at that station. The entire process of raising and lowering the camera is repeated for additional replicates (typically three replicates per station in about 2 or 3 minutes time) while the vessel maintains a stationary position at the water s surface. The camera swings slightly on the winch wire between replicate drops, such that the replicate images are separated by a short distance (typically a few meters) on the seafloor. In this way, the SPI/PUC system can provide a measure of both small-scale (i.e., within station ) spatial variability as well as larger-scale (i.e., among station ) variability across a given area Surveys can be accomplished rapidly by pogo-sticking the camera among stations distributed across an area of seafloor while recording positional fixes on the surface vessel. Two types of adjustments to the SPI system were made in the field during the survey: physical adjustments to the chassis stop collars or adding/subtracting lead weights to the chassis to control penetration in harder or softer sediments, and electronic software adjustments to the Nikon D200 to control camera settings. Camera settings (f-stop, shutter speed, ISO equivalents, digital file format, color balance, etc.) were selected through a water-tight USB port on the camera housing and Nikon Capture software. At the beginning of the survey, the time on the sediment profile camera's internal data logger was synchronized with the internal clock on the computerized navigation system to local time. Details of the camera settings for each digital image are available in the associated parameters file embedded in the electronic image file. For this survey, the ISOequivalent was set at 640. The additional camera settings used were as follows: shutter speed was 1/250, f8, white balance set to flash, color mode to Adobe RGB, sharpening to none, noise reduction off, and storage in compressed raw Nikon Electronic Format (NEF) files (approximately 9 MB each). Electronic files were converted to high-resolution jpeg (8-bit) format files (2592 x 3872 pixels) using Nikon Capture NX2 software (Version 2.2.4). 4 P age

12 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm From one to three replicate images were obtained at each station; each SPI replicate is identified by the time recorded on the digital image file in the camera and on disk along with vessel position on the navigation computer. The unique time stamp on the digital image was then cross-checked with the time stamp in the navigational system s computer data file. The field crew kept redundant written sample logs. Images were downloaded periodically (sometimes after each station) to verify successful sample acquisition or to assess what type of sediment/depositional layer was present at a particular station. Digital image files were re-named with the appropriate station name immediately after downloading on deck as a further quality assurance step. Test exposures of the Kodak Color Separation Guide (Publication No. Q-13) were made on deck at the beginning and end of the survey to verify that all internal electronic systems were working to design specifications and to provide a color standard against which final images could be checked for proper color balance. A spare camera and charged battery were carried in the field at all times to insure uninterrupted sample acquisition. After deployment of the camera at each station, the frame counter was checked to make sure that the requisite number of replicates had been taken. In addition, a prism penetration depth icator on the camera frame was checked to verify that the optical prism had actually penetrated the bottom to a sufficient depth. If images were missed (frame counter icator or verification from digital download) or the penetration depth was insufficient (penetration icator), chassis stops were adjusted and/or weights were added or removed, and additional replicate images were taken. Changes in prism weight amounts and chassis stop positions were recorded for each replicate image. Images were inspected at high magnification to determine whether any stations needed re-sampling with different stop collar or weight settings. An Ocean Imaging Model DSC6000 plan-view underwater camera system equipped with Ocean Imaging Model Deep Sea Scaling lasers was attached to the sediment profile camera frame and used to collect plan-view photographs of the seafloor surface; both SPI and PUC images were collected during each drop of the system. The PUC system consisted of a 12-megapixel Nikon D-90 DSLR encased in a titanium housing, a 24 VDC autonomous power pack, a 500W strobe, and a bounce trigger. A weight was attached to the bounce trigger with a stainless steel cable so that the weight hung below the camera frame; the scaling lasers project 2 red dots that are separated by a constant distance (26 cm) regardless of the field of view of the PUC, which can be varied by increasing or decreasing the length of the trigger wire. As the camera apparatus was lowered to the seafloor, the weight attached to the bounce trigger contacted the seafloor prior to the camera frame hitting the bottom and triggered the PUC (Figure 3). Details of the camera settings for each digital image are available in the associated parameters file embedded in each electronic image file. For this survey, the ISO-equivalent was set at 800. The additional camera settings used were as follows: shutter speed was 1/25, f10 and f14, white balance set to flash, color mode to Adobe RGB, sharpening to none, noise 5 P age

13 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm reduction off, and storage in compressed raw Nikon Electronic Format (NEF) files (approximately 10 MB each). Electronic files were converted to high-resolution jpeg (8- bit) format files (2848 x 4288 pixels) using Nikon Capture NX2 software (Version 2.2.4). Prior to field operations, the internal clock in the digital PUC was synchronized with the GPS navigation system and the SPI camera. Each PUC image acquired was assigned a time stamp in the digital file and redundant notations in the field and navigation logs. Throughout the survey, PUC images were downloaded at the same time as the sediment profile images after collection and evaluated for successful image acquisition and image clarity. The ability of the PUC to collect usable images was dependent on the clarity of the water column. Water clarity varied over the course of the October 2009 survey, necessitating the use of both 3 and 5 foot bounce trigger cable lengths on different days. Using the shorter length cable limited the amount of water the camera had to see through, resulting in improved picture clarity. One drawback to the short trigger cable length and close distance between the PUC and the seafloor was that the field of view of the PUC system was decreased so that a smaller area of the seafloor was photographed. Following completion of the field operations, the raw NEF image files were converted to high-resolution Joint Photographic Experts Group (jpeg) format files using the minimal amount of image file compression. Once converted to jpeg format, the intensity histogram (RGB channel) for each image was adjusted in Adobe Photoshop to maximize contrast without distortion. Each image was reviewed by Dr. Drew Carey of CoastalVision and information about sediment and habitat type was recorded on a Microsoft Excel spreadsheet. 2.4 MEASURING, INTERPRETING, AND MAPPING SPI AND PUC PARAMETERS Sediment Grain Size The sediment grain size results presented in this report are based on the Udden- Wentworth scale, with grain size major mode expressed in terms of phi (φ) units (Table 1). The sediment grain-size major mode and range were visually estimated from the color profile images by overlaying a grain-size comparator that was at the same scale. This comparator was prepared by photographing a series of Udden-Wentworth size classes (equal to or less than coarse silt up to granule and larger sizes) with the SPI camera. Seven grain-size classes were on this comparator: >4 φ (silt-clay), 4 to 3 φ (very fine sand), 3 to 2 φ (fine sand), 2 to 1 φ (medium sand), 1 to 0 φ (coarse sand), 0 to -1 φ (very coarse sand), < -1 φ (granule and larger,see Table 1). The lower limit of 6 P age

14 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm optical resolution of the photographic system was about 62 microns, allowing recognition of grain sizes equal to or greater than coarse silt (> 4 φ). The accuracy of this method has been documented by comparing SPI estimates with grain-size statistics determined from laboratory sieve analyses. The comparison of the SPI images with Udden-Wentworth sediment standards photographed through the SPI optical system was also used to map near-surface stratigraphy such as sand-over-mud and mud-over-sand. When mapped on a local scale, this stratigraphy can provide information on relative sediment transport magnitude and frequency. PUC images were classified into a wider range of sediment grain sizes based on visual inspection of ividual images. The PUC images permitted measurement of large sediment grains and assessment of sediment texture and bedforms over a wider field of view than SPI images. PUC classes were determined based on the largest grain size present rather than major mode to permit mapping of isolated cobbles and gravel beds. Grains larger than 4 mm were measured directly on images utilizing a scalar derived from a laser scaling device on the PUC camera (Appendix 2). Finer grain sizes were estimated based on surface texture and the near surface characteristics of paired SPI images. More general habitat classes were derived from classification of the PUC and SPI results (see Table 1). Table 1. Udden-Wentworth size classes (adapted). SPI images are classified from > 4 Φ to <-1 Φ (shaded cells). PUC results were classified from > 8 Φ to < -8 Φ. phi (Φ) Wentworth Size Habitat class class 8 12 Boulder > 25 cm Boulder 6 8 Cobble cm Cobble 4 6 L. pebble mm Gravel 2 4 Pebble 4 16 mm Gravel 1 2 Granule 2 4 mm Gravel 0 1 V. coarse sand 1 2 mm Sand 1 0 Coarse sand.5 1 mm Sand 2 1 Medium sand.25.5 mm Sand 3 2 Fine sand mm Sand 4 3 V. fine sand mm Silty sand 5 4 Coarse silt microns Silty sand 8 5 Silt 4 31 microns Silt Shaded cells are those classified with SPI images. 7 P age

15 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm Prism Penetration Depth The SPI prism penetration depth was measured from the bottom of the image to the sediment-water interface. The area of the entire cross-sectional sedimentary portion of the image was digitized, and this number was divided by the calibrated linear width of the image to determine the average penetration depth. Linear maximum and minimum depths of penetration were also measured. All three measurements (maximum, minimum, and average penetration depths) were recorded in the data file. Prism penetration is a noteworthy parameter; if the number of weights used in the camera is held constant throughout a survey, the camera functions as a static-load penetrometer. Comparative penetration values from sites of similar grain size give an ication of the relative water content of the sediment. Highly bioturbated sediments and rapidly accumulating sediments tend to have the highest water contents and greatest prism penetration depths. The depth of penetration also reflects the bearing capacity and shear strength of the sediments. Overconsolidated or relic sediments and shell-bearing sands resist camera penetration. Highly bioturbated, sulfitic, or methanogenic muds are the least consolidated, and deep penetration is typical. Seasonal changes in camera prism penetration have been observed at the same station in other studies and are related to the control of sediment geotechnical properties by bioturbation (Rhoads and Boyer 1982). The effect of water temperature on bioturbation rates appears to be important in controlling both biogenic surface relief and prism penetration depth (Rhoads and Germano 1982) Small-Scale Surface Boundary Roughness Surface boundary roughness was determined by measuring the vertical distance between the highest and lowest points of the sediment-water interface. The surface boundary roughness (sediment surface relief) measured over the width of sediment profile images typically ranges from 0.02 to 3.8 cm, and may be related to either physical structures (ripples, rip-up structures, mud clasts) or biogenic features (burrow openings, fecal mounds, foraging depressions). Biogenic roughness typically changes seasonally and is related to the interaction of bottom turbulence and bioturbational activities. The camera must be level in order to take accurate boundary roughness measurements. In sandy sediments, boundary roughness can be a measure of sand wave height. On siltclay bottoms, boundary roughness values often reflect biogenic features such as fecal mounds or surface burrows. The size and scale of boundary roughness values can have dramatic effects on both sediment erodibility and localized oxygen penetration into the bottom (Huettel et al., 1996). 8 P age

16 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm The availability of the PUC images allows for measurement and observation of the wavelength and form of current and wave ripples, lag deposits, shell and gravel wrows, epifaunal tracks and infaunal burrows. Images were classified into five types of bedforms: ripples (wavelength cm); tracks or burrows (cones, pits, tracks of biological origin); megaripples (bedforms visible on sidescan); wrows (distinct ribbons of two sediment types); and pavement (>50% coverage by cobbles)(appendix C) Thickness of Depositional Layers Because of the camera's unique design, SPI can be used to detect the thickness of depositional and dredged material layers. SPI is effective in measuring layers ranging in thickness from 1 mm to 20 cm (the height of the SPI optical wow). During image analysis, the thickness of the newly deposited sedimentary layers can be determined by measuring the distance between the pre- and post-disposal sediment-water interface. Recently deposited material is usually evident because of its unique optical reflectance and/or color relative to the underlying material representing the pre-disposal surface. Also, in most cases, the point of contact between the two layers is clearly visible as a textural change in sediment composition, facilitating measurement of the thickness of the newly deposited layer Mud Clasts When fine-grained, cohesive sediments are disturbed, either by physical bottom scour or faunal activity, e.g., decapod foraging, intact clumps of sediment are often scattered about the seafloor. These mud clasts can be seen at the sediment-water interface in SPI images. During analysis, the number of clasts was counted, the diameter of a typical clast was measured, and their oxidation state was assessed. The abundance, distribution, oxidation state, and angularity of mud clasts can be used to make inferences about the recent pattern of seafloor disturbance in an area. Depending on their place of origin and the depth of disturbance of the sediment column, mud clasts can be reduced or oxidized. In SPI images, the oxidation state is apparent from the reflectance; see Section Also, once at the sediment-water interface, these mud clasts are subject to bottom-water oxygen concentrations and currents. Evidence from laboratory microcosm observations of reduced sediments placed within an aerobic environment icates that oxidation of reduced surface layers by diffusion alone is quite rapid, occurring within 6 to 12 hours (Germano 1983). Consequently, the detection of reduced mud clasts in an obviously aerobic setting suggests a recent origin. The size and shape of the mud clasts are also revealing; some clasts seen in the profile images are artifacts caused by the camera deployment (mud clots falling off the back of the prism or the wiper blade). Naturally-occurring mud clasts may be moved and broken by bottom 9 P age

17 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm currents and animals (macro- or meiofauna; Germano 1983). Over time, these naturallyoccurring, large angular clasts become small and rounded Apparent Redox Potential Discontinuity Depth Aerobic near-surface marine sediments typically have higher reflectance relative to underlying hypoxic or anoxic sediments. Surface sands washed free of mud also have higher optical reflectance than underlying muddy sands. These differences in optical reflectance are readily apparent in SPI images; the oxidized surface sediment contains particles coated with ferric hydroxide (an olive or tan color when associated with particles), while reduced and muddy sediments below this oxygenated layer are darker, generally gray to black (Fenchel 1969; Lyle 1983). The boundary between the colored ferric hydroxide surface sediment and underlying gray to black sediment is called the apparent redox potential discontinuity (arpd). The depth of the apparent RPD in the sediment column is an important time-integrator of dissolved oxygen conditions within sediment porewaters. In the absence of bioturbating organisms, this high reflectance layer (in muds) will typically reach a thickness of 2 mm below the sediment-water interface (Rhoads 1974). This depth is related to the supply rate of molecular oxygen by diffusion into the bottom and the consumption of that oxygen by the sediment and associated microflora. In sediments that have very high sediment oxygen demand (SOD), the sediment may lack a high reflectance layer even when the overlying water column is aerobic. In the presence of bioturbating macrofauna, the thickness of the high reflectance layer may be several centimeters. The relationship between the thickness of this high reflectance layer and the presence or absence of free molecular oxygen in the associated porewaters must be considered with caution. The actual RPD is the boundary or horizon that separates the positive Eh region of the sediment column from the underlying negative Eh region. The exact location of this Eh = 0 boundary can be determined accurately only with microelectrodes; hence, the relationship between the change in optical reflectance, as imaged with the SPI camera, and the actual RPD can be determined only by making the appropriate in situ Eh measurements. For this reason, the optical reflectance boundary, as imaged, was described in this study as the apparent RPD and it was mapped as a mean value. In general, the depth of the actual Eh = 0 horizon will be either equal to or slightly shallower than the depth of the optical reflectance boundary. This is because bioturbating organisms can mix ferric hydroxidecoated particles downward into the bottom below the Eh = 0 horizon. As a result, the mean arpd depth can be used as an estimate of the depth of porewater exchange, usually through porewater irrigation (bioturbation). Biogenic particle mixing depths can be estimated by measuring the maximum and minimum depths of imaged feeding voids in 10 P age

18 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm the sediment column. This parameter represents the particle mixing depths of head-down feeders, mainly polychaetes. The rate of depression of the arpd within the sediment is relatively slow in organic-rich muds, on the order of 200 to 300 micrometers per day; therefore this parameter has a long time constant (Germano and Rhoads 1984). The rebound in the arpd is also slow (Germano 1983). Measurable changes in the apparent RPD depth using the SPI optical technique can be detected over periods of 1 or 2 months. This parameter is used effectively to document changes (or gradients) that develop over a seasonal or yearly cycle related to water temperature effects on bioturbation rates, seasonal hypoxia, SOD, and infaunal recruitment. Time-series arpd measurements following a disturbance can be a critical diagnostic element in monitoring the degree of recolonization in an area by the ambient benthos (Rhoads and Germano 1986). The mean arpd depth also can be affected by local erosion. The peaks of disposal mounds commonly are scoured by divergent flow over the mound. This scouring can wash away fines and shell or gravel lag deposits, and can result in very thin surface oxidized layer. During storm periods, erosion may completely remove any evidence of the arpd (Fredette et al. 1988). Another important characteristic of the arpd is the contrast in reflectance at this boundary. This contrast is related to the interactions among the degree of organic loading, the bioturbation activity in the sediment, and the concentrations of bottom-water dissolved oxygen in an area. High inputs of labile organic material increase SOD and, subsequently, sulfate reduction rates and the associated abundance of sulfide end products. This results in more highly reduced, lower-reflectance sediments at depth and higher arpd contrasts. In a region of generally low arpd contrasts, images with high arpd contrasts icate localized sites of relatively large inputs of organic-rich material such as phytoplankton, other naturally-occurring organic detritus, dredged material, or sewage sludge. Because the determination of the arpd requires discrimination of optical contrast between oxidized and reduced particles, it is difficult, if not impossible, to determine the depth of the arpd in well-sorted sands of any size that have little to no silt or organic matter in them (Painter et al., 2007). When using SPI technology on sand bottoms, little information other than grain-size, prism penetration depth, and boundary roughness values can be measured; while oxygen has no doubt penetrated the sand beneath the sediment-water interface just due to physical forcing factors acting on surface roughness elements (Ziebis et al., 1996; Huettel et al., 1998), estimates of the mean arpd depths in these types of sediments are eterminate with conventional white light photography. 11 P age

19 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm Sedimentary Methane If organic loading is extremely high, porewater sulfate is depleted and methanogenesis occurs. The process of methanogenesis is icated by the appearance of methane bubbles in the sediment column, and the number and total area covered by all methane pockets is measured. These gas-filled voids are readily discernable in SPI images because of their irregular, generally circular aspect and glassy texture (due to the reflection of the strobe off the gas bubble) Infaunal Successional Stage The mapping of infaunal successional stages is readily accomplished with SPI technology. These stages are recognized in SPI images by the presence of dense assemblages of near-surface polychaetes and/or the presence of subsurface feeding voids; both may be present in the same image. Mapping of successional stages is based on the theory that organism-sediment interactions in fine-grained sediments follow a predictable sequence after a major seafloor perturbation. This theory states that primary succession results in the predictable appearance of macrobenthic invertebrates belonging to specific functional types following a benthic disturbance. These invertebrates interact with sediment in specific ways. Because functional types are the biological units of interest..., our definition does not demand a sequential appearance of particular invertebrate species or genera (Rhoads and Boyer 1982). This theory is presented in Pearson and Rosenberg (1978) and further developed in Rhoads and Germano (1982) and Rhoads and Boyer (1982). This continuum of change in animal communities after a disturbance (primary succession) has been divided subjectively into four stages: Stage 0, icative of a sediment column that is largely devoid of macrofauna, occurs immediately following a physical disturbance or in close proximity to an organic enrichment source; Stage 1 is the initial community of tiny, densely populated polychaete assemblages; Stage 2 is the start of the transition to head-down deposit feeders; and Stage 3 is the mature, equilibrium community of deep-dwelling, head-down deposit feeders (Figure 4). After an area of bottom is disturbed by natural or anthropogenic events, the first invertebrate assemblage (Stage 1) appears within days after the disturbance. Stage 1 consists of assemblages of tiny tube-dwelling marine polychaetes that reach population densities of 10 4 to 10 6 ividuals per m². These animals feed at or near the sedimentwater interface and physically stabilize or b the sediment surface by producing a mucous glue that they use to build their tubes. Sometimes deposited dredged material layers contain Stage 1 tubes still attached to mud clasts from their location of origin; these transported ividuals are considered as part of the in situ fauna in our assignment of successional stages. 12 P age

20 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm If there are no repeated disturbances to the newly colonized area, then these initial tubedwelling suspension or surface-deposit feeding taxa are followed by burrowing, headdown deposit-feeders that rework the sediment deeper and deeper over time and mix oxygen from the overlying water into the sediment. The animals in these later-appearing communities (Stage 2 or 3) are larger, have lower overall population densities (10 to 100 ividuals per m²), and can rework the sediments to depths of 3 to 20 cm or more. These animals loosen the sedimentary fabric, increase the water content in the sediment, thereby lowering the sediment shear strength, and actively recycle nutrients because of the high exchange rate with the overlying waters resulting from their burrowing and feeding activities. In dynamic estuarine and coastal environments, it is simplistic to assume that benthic communities always progress completely and sequentially through all four stages in accordance with the idealized conceptual model depicted in Figure 4. Various combinations of these basic successional stages are possible. For example, secondary succession can occur (Horn, 1974) in response to additional labile carbon input to surface sediments, with surface-dwelling Stage 1 or 2 organisms co-existing at the same time and place with Stage 3, resulting in the assignment of a Stage 1 on 3 or Stage 2 on 3 designation. Additional evidence of successional seres can be gathered from plan view images when they are taken at the same time as the sediment profile images; both surface tubicolous fauna (Stage 1 or 2) as well as burrow openings from infaunal deposit feeders (Stage 3) can be seen over a much larger surface area of the seafloor in the plan view images than the surface area available for investigation from the profile photos. While the successional dynamics of invertebrate communities in fine-grained sediments have been well-documented, the successional dynamics of invertebrate communities in sand and coarser sediments are not well-known. Subsequently, the insights gained from sediment profile imaging technology regarding biological community structure and dynamics in sandy and coarse-grained bottoms are fairly limited Presence of Organisms SPI and PUC images were examined for the presence of epifaunal or epiphytic organisms (those present and visible on the sediment surface) and evidence of their presence (shell hash). Three primary modes of presence were noted: Attached (hydroids, bryozoans, algae, squid eggs) on cobbles, and Mobile or Burrowing epifauna. Based on a review of images, a simple coding matrix was established to inventory observed presence (Table 2 and Appendix C). The dominant biological organism was coded as bio_notes and next most dominant was coded as bio_second (see Appendix C). 13 P age

21 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm Table 2. Coding matrix for presence of organisms. bio_notes Specifics Tubes 1 Polychaete tubes Amphipod tubes 2 Sea stars 3 Anemones 4 Epiphytes 5 Encrusting or attached algae Hydroids or bryozoans 6 Attached epifauna Squid eggs 7 Skate eggs 8 Fish 9 Crustacean 10 Crabs, shrimp, lobster Shells 11 Intact shells Shell hash 12 Small, broken pieces Sponges 13 Sand dollars USING SPI AND PUC DATA TO ASSESS BENTHIC QUALITY & HABITAT CONDITIONS While various measurements of water quality such as dissolved oxygen, contaminants, or nutrients are often used to assess regional ecological quality or health, interpretation is difficult because of the transient nature of water-column phenomena. Measurement of a particular value of any water-column variable represents an instantaneous snapshot that can change within minutes after the measurement is taken. By the time an adverse signal in the water column such as a low dissolved oxygen concentration is persistent, the system may have degraded to the point where resource managers can do little but map the spatial extent of the phenomenon while gaining a minimal understanding of factors contributing to the overall degradation. The seafloor, on the other hand, is a long-term time integrator of sediment and overlying water quality; values for any variable measured are the result of physical, chemical, and biological interactions on time scales much longer than those present in a rapidly moving fluid. The seafloor is thus an excellent icator of environmental health, both in terms of historical impacts and of future trends for any particular variable. 14 P age

22 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm Physical measurements made with the SPI system from profile images provide background information about gradients in physical disturbance (caused by dredging, disposal, oil platform cuttings and drilling muds discharge, trawling, or storm resuspension and transport) in the form of maps of sediment grain size, boundary roughness, sediment textural fabrics, and structures. The concentration of organic matter and the SOD can be inferred from the optical reflectance of the sediment column and the arpd depth. Organic matter is an important icator of the relative value of the sediment as a carbon source for both bacteria and infaunal deposit feeders. SOD is an important measure of ecological health; oxygen can be depleted quickly in sediment by the accumulation of organic matter and by bacterial respiration, both of which place an oxygen demand on the porewater and compete with animals for a potentially limited oxygen resource (Kennish 1986). The arpd depth is useful in assessing the quality of a habitat for epifauna and infauna from both physical and biological points of view. The arpd depth in profile images has been shown to be directly correlated to the quality of the benthic habitat in polyhaline and mesohaline estuarine zones (Rhoads and Germano 1986; Revelas et al. 1987; Valente et al. 1992). Controlling for differences in sediment type and physical disturbance factors, arpd depths < 1 cm can icate chronic benthic environmental stress or recent catastrophic disturbance. The distribution of successional stages in the context of the mapped disturbance gradients is one of the most sensitive icators of the ecological health of the seafloor (Rhoads and Germano 1986). The presence of Stage 3 equilibrium taxa (mapped from subsurface feeding voids as observed in profile images) can be a good ication of high benthic habitat stability and relative health. A Stage 3 assemblage icates that the sediment surrounding these organisms has not been disturbed severely in the recent past and that the inventory of bioavailable contaminants is relatively small. These inferences are based on past work, primarily in temperate latitudes, showing that Stage 3 species are relatively intolerant to sediment disturbance, organic enrichment, and sediment contamination. Stage 3 species expend metabolic energy on sediment bioturbation (both particle advection and porewater irrigation) to control sediment properties, including porewater profiles of sulfate, nitrate, and RPD depth in the sedimentary matrix near their burrows or tubes (Aller and Stupakoff 1996; Rice and Rhoads 1989). This bioturbation results in an enhanced rate of decomposition of polymerized organic matter by stimulating microbial decomposition ( microbial gardening ). Stage 3 benthic assemblages are very stable and are also called climax or equilibrium seres. The metabolic energy expended in bioturbation is rewarded by creating a sedimentary environment where refractory organic matter is converted to usable food. Stage 3 bioturbation has been likened to processes such as stirring and aeration used in tertiary sewage treatment plants to accelerate organic decomposition (these processes can be 15 P age

23 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm interpreted as a form of human bioturbation). Physical disturbance, contaminant loading, and/or over-enrichment result in habitat destruction and in local extinction of the climax seres. Loss of Stage 3 species results in the loss of sediment stirring and aeration and may be followed by a buildup of organic matter (sediment eutrophication). Because Stage 3 species tend to have relatively conservative rates of recruitment, intrinsic population increase, and ontogenetic growth, they may not reappear for several years once they are excluded from an area. The presence of Stage 1 seres (in the absence of Stage 3 seres) can icate that the bottom is an advanced state of organic enrichment, has received high contaminant loading, or experienced a substantial physical disturbance. Unlike Stage 3 communities, Stage 1 seres have a relatively high tolerance for organic enrichment and contaminants. These opportunistic species have high rates of recruitment, high ontogenetic growth rates, and live and feed near the sediment-water interface, typically in high densities. Stage 1 seres often co-occur with Stage 3 seres in marginally enriched areas. In this case, Stage 1 seres feed on labile organic detritus settling onto the sediment surface, while the subsurface Stage 3 seres tend to specialize on the more refractory buried organic reservoir of detritus. Stage 1 and 3 seres have dramatically different effects on the geotechnical properties of the sediment (Rhoads and Boyer 1982). With their high population densities and their feeding efforts concentrated at or near the sediment-water interface, Stage 1 communities tend to b fine-grained sediments physically, making them less susceptible to resuspension and transport. Just as a thick cover of grass will prevent erosion on a terrestrial hillside, so too will these dense assemblages of tiny polychaetes serve to stabilize the sediment surface. Conversely, Stage 3 taxa increase the water content of the sediment and lower its shear strength through their deep burrowing and pumping activities, rendering the bottom more susceptible to erosion and resuspension. In shallow areas of fine-grained sediments that are susceptible to storm-uced or wave orbital energy, it is quite possible for Stage 3 taxa to be carried along in the water column in suspension with fluid muds. When redeposition occurs, these Stage 3 taxa can become quickly re-established in an otherwise physically disturbed surface sedimentary fabric. The presence or absence of bedforms and encrusting organisms are suitable proxies for information on the relative mobility of seafloor sediments (Greene et al., 1999; Velegrakis et al. 2007). While these icators are not diagnostic predictors of the full range of bottom stress that may be encountered at any given site, they do represent an integration of the recent sediment transport history. For instance, well-sorted coarse sands at the surface generally icate a level of bottom stress high enough to remove finer grains; a silty surface layer covered with epifaunal tracks and burrows suggests a level of bottom stress low enough to allow deposition of finer grains. Both sediments 16 P age

24 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm might be classified as medium sand due to an underlying horizon of predominantly medium sand, but the recent history of surface conditions would be quite different. SPI in combination with PUC imagery has been shown to be a powerful reconnaissance tool that can efficiently map gradients in sediment type, biological communities, benthic habitat or disturbances from physical forces or organic enrichment. The conclusions reached at the end of this report are about dynamic processes that have been deduced from imaged structures; as such, they should be considered hypotheses available for further testing/confirmation. By employing Occam s Razor, we feel reasonably assured that the most parsimonious explanation provided by our interpretation of the profile images has been the one usually borne out by subsequent data confirmation. 17 P age

25 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm 3.0 RESULTS In this section, the SPI/PUC results are presented in a series of maps that also show the broad-scale topography of the surveyed area, based on existing National Oceanic and Atmospheric Administration (NOAA) bathymetric data (e.g., Figure 2a-d). Sidescan sonar (backscatter) data also were available from the U.S. Geological Survey for a relatively small portion of the surveyed area near Point Judith Shoal (Figure 2b, McMullen et al. 2009). A complete set of all the data measured from each profile image is presented in Appendix A. The recorded navigational fixes for all camera images acquired during the field operations are presented in Appendix B; while the results of the review of plan view images are presented in Appendix C. Results for some of the SPI parameters are icated as being eterminate in the maps presented in this section. This is a result of the sediments being too hard for the profile camera to penetrate, preventing observation of all subsurface sediment features. The sediment/water interface and the apparent RPD must be visible to measure most of the key SPI parameters (e.g., arpd depth, penetration depth, infaunal successional stage, etc.). Parameters such as boundary roughness, bedforms, and mud clast data (number, size) provide supplemental information pertaining to the physical regime and bottom sediment transport activity at a site. Even though mud clasts are definitive characteristics whose presence can icate physical disturbance of some form, the mud clasts noted in the images from this survey were either biogenic in origin or artifacts due to sampling (mud clumps clinging to the frame base or camera wiper blade) and not icative of physical disturbance or sediment transport activities. Therefore, mud clast data were not mapped separately as ividual SPI parameters for interpretation. There was no evidence detected in any of the sediment profile images collected in this survey of either subsurface methane or low dissolved oxygen in the benthic boundary layer due to either hypoxic water column conditions or excess organic loading to the sediments. In addition, there were no discrete depositional layers observed in any of the profile images collected during in this survey. 3.1 SEDIMENT GRAIN SIZE The estimated sediment grain size at each station, based on analysis of the profile images, is shown in Figure 5a to d. The majority of stations along the Narragansett and Block Island Connections (Figure 5a) were characterized by fine-grained sediments, either silt- 18 P age

26 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm clay (major mode of >4 phi) or very fine sand (major mode of 4 to 3 phi; Figures 6 and 7). These finer-grained sediments coincided with the deeper water depths over most of the Narragansett and Block Island Connection routes. In general, depths below 90 feet were characterized by very fine sand or silt. In the shallower water at the distal ends of these two routes (close to the shoreline on both the mainland and on Block Island), sandier sediments predominated (Figure 5a). At stations BI-9 and BI-10, the replicate profile images showed that both silt-clay and very fine sand were present, icating small-scale spatial variability at these locations (Figure 5a). In contrast to the Narragansett and Block Island connection stations, there was significant variability in grain size in the Point Judith shoal area (Figure 5b). This variability was observed both among different stations and, at a significant number of stations, among the replicate images (Figure 5b). Surface sediments in this area consisted of a heterogeneous mixture ranging from fine or medium sand, coarse sand, and small gravel having a phi size ranging from -1 to -6 (Figure 8). The sidescan sonar results in Figure 5b shows alternating bands of high and low backscatter, icative of the variability in sediment texture observed in the profile images. The backscatter and imaging results together suggest that the area is characterized by sandy sediments interspersed with patches and/or broad elongated ribbons of coarse sand and gravel. The results from station PJ-20 serve to illustrate the point: the backscatter results at this station show a distinct line or ribbon of high relative backscatter (Figure 9). Two of the profile images at this station showed fine sand (corresponding to the lower backscatter), while one of the images showed very coarse sand (corresponding to the dark band of high backscatter; Figure 9). Grain size could not be determined at a number of the Point Judith Shoal stations because the profile camera did not penetrate sufficiently into the harder, coarser-grained sediments in this area. While there were patches of larger gravel (cobbles and boulders) in this area, most of the coarser-grained sediment appeared to consist of smaller gravel (granules and pebbles). Moving off the shoal into deeper water, softer, finer-grained sediments (silt-clay or silty very fine sand) were observed at stations PJ-25 to PJ-30, PJ- 1, PJ-50, and BI-2 (Figure 5b). The cluster of stations near the east shoreline of Block Island, where the Block Island and Alt 1 connections converge, were characterized by sandy sediments, ranging from very fine sand (4 to 3 phi) to very coarse sand (0 to -1 phi)(figure 5c). Moving away from Block Island along the Alt 1 connection, three stations located in deeper water (stations A1-6, A1-7 and A2-1) were characterized by either soft silt-clay or silty very fine sand (Figure 5c). The remaer of the Alt 1 connection stations, as well as the nearby stations on the upper end of the Alt 2 connection, had either sandy sediments (ranging from very fine to coarse sand) or small gravel. Along the station transect corresponding to Turbine 19 P age

27 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm Alternative 1, stations T-1 to T-9 had either homogenous fine sand or mixtures of fine sand and small gravel (Figures 5c and 10). Along the station transect corresponding to Turbine Alternative 2, stations AT-7 to AT-30 likewise were characterized predominantly by clean, homogenous, rippled fine to medium sand, with some stations exhibiting coarse to very coarse sand (Figure 5c). Most of the stations on the western end of the Turbine Alternative 1 transect (stations T- 10 to T-16) exhibited coarse sand or small gravel (Figure 5d). On the eastern end of the Turbine Alternative 2 transect (stations AT-2 to AT-6), station AT-2 had coarse sand while the rest had fine sand mixed with minor amounts of coarse sand (Figure 5d). The area defined as Alt 2 SE Shoal included a cluster of stations on the nominal top of the shoal, where water depths ranged from about 50 to 70 feet, as well as stations aligned along the potential cable route on the broad flanks of the shoal to the east and west (Figure 5d). On top of the shoal, there were many stations where the grain size was eterminate because pebbles and cobbles prevented the profile camera from penetrating sufficiently. At other stations, the profile images revealed that the sediments in this area consisted mostly of medium to coarse sand, covered with varying amounts of gravel (i.e., pebbles and cobbles; Figure 11). This was confirmed by the PUC images discussed in the next section. On the station transect lines to the east and west of Southeast Shoal, sediments consisted of sand having various grain sizes, including ranging from medium to very coarse (Figures 5d and 12). Granules and pebbles also occurred at a few of the stations on these transects (Figures 5d and 12). 3.2 HABITAT CLASSIFICATION The combined profile and PUC images were used to devise a simple, geologically-based habitat classification scheme for the surveyed area. Five basic habitat types were identified, as follows: Undisturbed cobble: Larger-sized gravel (i.e., cobbles and boulders with ividual diameters ranging from 64 to >256 millimeters as shown in Table 1) occurring over most of the sediment surface (Figure 13a-c). The cobble/boulders were either very dense (i.e., forming a continuous pavement over the sediment surface as shown in Figure 13a), or more typically were dispersed within an underlying sandy substratum (e.g., Figure 13b and c). The cobble/boulders typically were covered with both epifauna (e.g., hydroids and bryozoans) and encrusting algae ranging in color from pink to dark burgundy. Washed gravel: Smaller-sized gravel (i.e., granules and pebbles with ividuals diameters ranging from 2 to 64 millimeters as shown in Table 1) occurring at varying 20 P age

28 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm densities over the sediment surface (Figure 14a-d). This gravel, which was free of any encrusting epifauna, typically occurred as concentrated accumulations in the troughs between mobile sand waves (e.g., Figure 14c-d). Mobile sand: Sand ranging in size from fine to coarse (ividual particle diameters ranging from to 2.0 millimeters as shown in Table 1), with notable sand waves (symmetrical or assymetrical ripples; Figure 15a-c). Mobile epifauna like sea stars and sand dollars were observed occasionally and burrows and feeding pits were visible in some PUC images. Silty sand: Fine to very fine sand (ividual particle diameters ranging from to 0.25 millimeters as shown in Table 1), with a significant proportion of silt present (Figure 16a-c). The penetration depth of the profile camera was variable, as this habitat type ranged from moderately firm to soft depending on the relative amount of silt present. The sediment surface appeared pockmarked in the PUC images, due to the presence of small worm tubes, burrow openings and feeding pits, and sea stars were frequently observed. Soft silt: Soft, homogenous, muddy sediment comprised of silt and clay particles having ividual diameters less than millimeters (Table 1 and Figure 17a-c). The profile camera typically achieved relatively high penetration in this soft material (i.e., penetration depths on the order of 15 to 20 cm). In the PUC images, the sediment surface appeared pockmarked by numerous small biogenic pits, mounds, tubes and burrow openings (Figure 17a-c). The profile images revealed evidence of extensive infaunal activity below the sediment surface in the form of feeding voids, burrows, and organisms (principally polychaetes). The distribution of these five habitat types across the surveyed area is depicted in a series of maps (Figure 18a-d). Not surprisingly, the maps of habitat type and grain size (previous section) are very similar, since the habitat classification scheme is based largely on sediment texture. Along the deeper waters of the Narragansett and Block Island Connections, soft silt and silty sand habitats were predominant (Figure 18a). In the slightly shallower water over Point Judith Shoal, habitats were more variable and included mobile sand, washed gravel, and undisturbed cobble (Figure 18b). With the exception of stations A1-6, A1-7, and A2-1 located in deeper water, stations along the Alt 1 and Alt 2 connections had either mobile sand or washed gravel habitats (Figure 18c). Most of the Turbine Alternative 1 stations had washed gravel habitat, while most of the Turbine Alternative 2 stations had mobile sand (Figure 18c). Over the shallowest section of Southeast Shoal, undisturbed cobble habitat was most common (Figure 18d). In a number of the PUC images showing cobble habitat at Southeast and Point Judith Shoals, concentrated clusters of white, finger-like objects were visible. These have been 21 P age

29 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm identified as clusters of squid eggs, likely of the long-finned squid Loligo sp. (Figures 19 and 20). Squid eggs were observed in association with cobble habitat at 12 of the Southeast Shoal stations (Figure 18d) and with washed gravel at one of the Turbine Alternative 1 stations (Figure 18c), as well as both habitats at 3 of the Point Judith Shoal stations (Figure 18b). 3.3 SURFACE BOUNDARY ROUGHNESS At the stations along the Narragansett and Block Island Connections, where sediments consisted of either mud or silty sand, there was relatively low surface boundary roughness (Figure 21a). Most this small-scale roughness was due to the presence of biogenic structures at the sediment surface, including pits, burrows, and mounds created by infaunal, mobile epifauna, and foraging fish (Figure 22). There was high variability in boundary roughness among the Point Judith Shoal stations, reflecting the variability in sediment texture (Figure 21b). Relatively high boundary roughness in this area was often associated with the washed gravel habitat type. It is likely that most of the gravel beds and sheets of coarse sand comprising this shoal have rippled surfaces as a result of being subject to wave and current energy (Figure 23). Most of the boundary roughness at the Point Judith Shoal stations therefore was judged to be of physical rather than biological origin. Most of the stations comprising the Alt 1 and upper Alt 2 Connections, as well as the two Turbine Alternative transects, had low to moderate boundary roughness in the range of 0 to 3.0 cm (Figure 21c). Similar to the Point Judith Shoal stations, the boundary roughness at many stations in this area was of physical origin, reflecting the presence of ripples comprised of sand ranging from very fine to very coarse (Figure 24). Relatively high boundary roughness (>3.0 cm) occurred at many of the stations along the lower half of the Alt 2 Connection (Figure 21d), reflecting the presence of larger ripples comprised of coarse sand and gravel (Figure 25). In general, the small scale roughness at the stations in and around Southeast Shoal was due primarily to the presence of ripples or cobbles, which in turn are the result of waves and currents acting on the coarse sediments in this area. 3.4 PRISM PENETRATION DEPTH With the exception of 6 stations, the entire survey was performed without changing the number of weights or the stop collars settings of the sediment-profile camera. Almost all of the sampling took place with the stop collar setting at 15 inches and the maximum number of lead bricks (5) added to each side of the camera chassis. At stations BI-4 to BI-8, the stop collars settings were changed to 14 inches and the number of lead bricks 22 P age

30 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm was reduced to 2 per side. Difference in the penetration depth among station, therefore, accurately reflect differences in the shear strength of the sediments. Not surprisingly, prism penetration depth was influenced strongly by sediment type, with the relatively deep penetration achieved at the stations with highly bioturbated, soft mud or silty fine sand along the Narragansett and Block Island Connections (Figure 26a). The group of stations BI-4 to BI-8 had very soft sediments, necessitating the aforementioned adjustment to the profile camera. Otherwise, the average penetration depths at these stations shown in Figure 26a easily would have been >15 cm. At stations BI-9, BI-12 and BI-14 in the middle of the Block Island Connection, penetration was relatively low due to the presence of fine and very fine sand. At Point Judith Shoal, average penetration was relatively low, reflecting the widespread presence of firm, fine-to-coarse sand and gravel. In this area, moderately deep penetration (10 to 15 cm) was achieved only at the stations with muddy sediment located in the deeper water to the east, north and south of the shoal. Average penetration likewise was relatively low in the areas sampled around Block Island (Figure 26c and d), due to the predominance of firm sand and gravel in this area. The profile camera either failed to penetrate (0 cm) or did not penetrate more than 4 cm in the very firm sediment (coarse sand and cobble) comprising the shallow spine of the Southeast Shoal (Figure 26d). 3.5 APPARENT REDOX POTENTIAL DISCONTINUITY DEPTH Most of the stations along Narragansett Connection had average arpd values in the range 1.1 to 2.0 cm, while most of the stations along the Block Island Connection had values in the range 2.1 to 4.0 cm (Figure 27a). The shallower arpd depths at the nearshore Narragansett Connection stations may reflect a higher amount of organic loading from Narragansett Bay and from mainland sources (e.g., runoff and sewage outfalls) compared to sediments at the Block Island Connection stations, located offshore in Rhode Island Sound (Figure 28). At most of the Point Judith Shoal stations, the arpd could not be measured adequately because of low penetration of the profile camera and the widespread presence of firm sand and gravel lacking any distinct color contrast (Figure 27b). At the stations with fine-grained sediments located in deeper water surrounding the shoal, arpd depths were generally deep, ranging from 2.1 to 4.0 cm (Figure 27b). The average arpd depths at many of the stations to the east and south of Block Island (Figures 27c and d) likewise could not be determined because of low penetration into the firm sand and gravel sediments that were dominant in this area. At those stations where the arpd could be measured, the majority of values were in the range 1.1 to 3.0 cm; these are intermediate values icating a moderate degree of surface sediment aeration (Figure 27c and d). 23 P age

31 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm None of the stations sampled during the October 2009 survey showed any evidence of unduly elevated sediment organic loading or low dissolved oxygen conditions in nearbottom waters. 3.6 INFAUNAL SUCCESSIONAL STAGE As explained in section 2.4.8, the infaunal successional stage can be readily determined in profile images of fine-grained sediments (i.e., silt-clay or silty sand), but the successional dynamics of invertebrate communities in sand and coarser sediments is not well-documented. Because these latter sediments characterized much of the survey area, the infaunal successional stage was deemed eterminate at a high percentage of stations (Figure 29a-d). Silt-clay and silty sand were observed most consistently at the stations comprising the Narragansett and Block Island Connections, and these soft sediments were found to be inhabited by mature, infaunal deposit-feeding communities. The majority of stations on these transects had Stage 1 on 3, based on the presence of both small opportunistic organisms at the sediment surface and abundant evidence of larger-bodied organisms below the sediment surface (Figures 30 and 31). At a cluster of stations in the middle of the Block Island Connection transect (stations BI-10 to BI-16), the sediment consisted of silty, very fine sand that was somewhat firmer than the soft mud observed at the surrounding stations to the north and south. Many of the images from these stations showed amphipod tubes (Stage 2) at the sediment surface; these ampeliscid amphipods are common on sandy sediments throughout Rhode Island Sound (Figure 32). At Point Judith Shoal, low penetration of the profile camera in coarse sand and gravel prevented the successional stage from being determined at most stations (Figure 29b). At the stations in this area with washed gravel habitat, the PUC images generally showed a lack of visible organisms at the sediment surface (Figure 33). At the stations with cobble habitat, the cobbles generally were covered with encrusting epifauna such as hydroids, bryozoans and small tubes, as well as the occasional anemone (Figure 34). In contrast to the cobble on the Southeast Shoal, the cobble at Point Judith Shoal tended not to be covered with red encrusting algae, perhaps due to deeper water depths. At the stations with soft muddy sediment in the deeper water around the Point Judith Shoal, mature infaunal communities (Stages 1 on 3 or 2 on 3) were observed (Figures 29b and 35). Many stations on the south side of the shoal had silty, very fine to fine sand that permitted moderate penetration of the profile camera. A number of these stations had ampeliscid amphipod tubes present at the sediment surface (classified as Stage 2), often in dense aggregations (Figures 29b and 36). 24 P age

32 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm Along the Alt 1 Connection, mature Stage 2 and 3 communities characterized the finegrained sediments observed at stations A1-5 to A2-1 (Figure 29c). At all the other stations located east and south of Block Island, the infaunal successional stage could not be determined in the profile images because of low penetration of the SPI camera in the sand and gravel that dominated these areas (Figure 29c and d). The PUC images from these areas, however, help provide insights on infaunal community dynamics. In the areas east and south of Block Island, many of the stations with washed gravel were characterized by a general lack of visible biological activity at the sediment surface (Figure 37). Stations with mobile sand habitat typically had sand dollars and/or sea stars occurring in relatively low densities at the sediment surface (Figure 38). At stations with undisturbed cobble habitat on the spine of Southeast Shoal, the cobbles typically were covered with both epifauna (e.g., hydroids and bryozoans) and encrusting or attached filamentous algae ranging in color from pink to dark burgundy (Figure 39). 25 P age

33 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm 4.0 DISCUSSION The key physical and biological characteristics of the five broad habitat types identified in the study area were consistently found in both the SPI and PUC results. Not surprisingly, water depth, wave exposure and geological substrate appear to be the controlling factors in benthic habitat distribution. Finer-grained sediments (i.e., silt and clay) tend to accumulate preferentially within the broad topographic depressions, such that soft silt and silty sand habitats were observed predominantly in water depths greater than 90 feet. These habitats were characterized by relatively deep penetration of the profile camera, low surface roughness attributed mainly to biological activity (bioturbation), and high infaunal densities. In contrast, the washed gravel and mobile sand habitats observed in the shallower/nearshore areas were characterized by low to moderate penetration of the profile camera (icating relative firmness), low apparent infaunal densities, abundant mobile epifauna (seastars, crabs, shrimp), and surface roughness due to the presence of bedforms. The presence of ripples icates that these habitats are subject to frequent physical disturbance from bottom currents and waves. Of the five broad habitat types identified in our survey, undisturbed cobble is the least suitable for turbine placement or cable installation. Cobble habitats in Southern New England are typically remnant deposits of glacial moraines (boulders and cobbles that are more or less fixed in place on eroded moraines) or gravels composed of large gravel to cobble sized rounded rocks that only move during very large storms. As a result, most cobble habitats in deeper water (>30 feet) are very stable and contain high habitat complexity (microhabitats between cobbles and within matrix of sediments). This stability and complexity is very difficult to restore after physical disturbance (e.g., dredging, cable emplacement, trawling, and foundation installation), and complex cobble habitat is not easy to create for mitigation of loss or disturbance. Because of strong evidence that cobble habitats are potentially a limiting factor for lobster populations (Wahle and Steneck 1991; see below), we paid particular attention to mapping and describing this habitat. The minimal rock size for provision of shelter is 5 phi (large pebble 32 mm; Wahle 1990). We defined undisturbed cobble habitat as any substratum with at least one cobble-sized rock with some epiphytic or epifaunal growth. The growth of encrusting algae or attachment of hydroids or bryozoans is a clear ication that large pebbles or cobbles (even if buried under sand) are sufficiently resistant to scour or movement to provide long-term (months) shelter for juvenile early benthic phase lobsters. We did not encounter cobble-sized rocks without epiphytic growth but defined washed gravel as a habitat with gravel-sized rounded rocks with little or no epiphytic growth. In areas with more wave energy (e.g., beachface and shallow subtidal), mobile cobble habitats might be more prevalent. 26 P age

34 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm Early benthic phase (EBP) juvenile lobsters seek shelter in mixed substrata with flat cobbles overlying sand or silt (Cobb 1971; Palma et al. 1998) or cobble pavements (Lawton and Lavalli 1995). In one study in coastal Maine, EBP lobsters were virtually absent from ledge and sedimentary substrata devoid of vegetation; these habitats instead were dominated by adult lobsters (Wahle and Steneck 1991). EBP lobsters (carapace length of 5-40 mm; Incze and Wahle 1991) are very dependent on shelter during this period of growth (MacKenzie and Moring 1985). This phase lasts for approximately two years: after reaching a carapace length of 45 mm, the lobsters then may begin nocturnal foraging, returning to shelter during the day (Cooper and Uzmann 1980, Lawton and Lavalli 1995). As lobsters finally reach reproductive age (females reach maturity in southern New England at 65 mm carapace length; Aiken and Waddy 1980), they become much more mobile and move from shallow coastal habitats to deeper coastal or offshore waters (Uzmann et al. 1977). As a result, the presence of undisturbed cobble habitat is critical for maintenance of inshore lobster populations in New England waters (Wahle and Steneck 1991). Compared to undisturbed cobble; washed gravel and mobile sand are considered more suitable for turbine placement or cable installation because these habitats already experience relatively high levels of natural physical disturbance. The bedforms observed in the SPI and PUC images icate that both types of habitats are characterized by frequent displacement of the substrata by waves and currents. Resident biota are adapted to this natural disturbance regime and therefore are expected to be quite resilient to the temporary man-made seafloor disturbance (i.e., substratum displacement) associated with cable or turbine installation. Assuming no appreciable changes in bottom type, washed gravel and mobile sand habitats affected by installation activities should be rapidly recolonized by benthic communities comparable to those that characterized these two habitats prior to installation. Silty sand and silt habitats exist within seafloor environments that are not subject to the same degree of natural physical disturbance as the washed gravel and mobile sand habitats. Rather, these two habitats types are found within broad topographic depressions which are not as readily affected by elevated waves and currents during storm events and which therefore favor the long-term accumulation of fine-grained sediments. These relatively quiescent muddy environments are ideal for the establishment of mature infaunal communities dominated by larger-bodied, deposit-feeding organisms. The feeding and burrowing activities of these organisms serve to mix and aerate the surface sediments, and there was abundant evidence of this bioturbation in the form of burrow openings, mounds, pits, and subsurface feeding voids in both the SPI and PUC images in these areas. Installation of a subsurface power cable in such habitats would involve fluidization and mixing of surface sediments with jet plow technology, representing a temporary physical 27 P age

35 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm disturbance that is somewhat comparable ecologically to the effects of open-water dredged material disposal (which involves displacement and burial of existing muddy sediments with exogenous but similar muddy sediments). In general, long-term monitoring studies conducted in New England and similar coastal areas throughout the world serve to demonstrate that benthic infaunal communities in muddy offshore environments successfully recolonize dredged material deposits in timeframes ranging from several months to several years, in a manner consistent with the successional model depicted in Figure 4. In New England, the U.S. Army Corps of Engineers DAMOS program has conducted intensive monitoring of invertebrate recolonization and benthic ecosystem recovery at 11 different open-water dredged material disposal site for over two decades (Fredette and French, 2004). This monitoring demonstrates that a temporary physical disruption to muddy seafloor habitats results in a change in benthic community structure which, over time, becomes similar to benthic communities on the ambient seafloor through the normal successional process (see DAMOS contributions 100, 113, 116, 134, 147, and 162 at Similar results are found in the literature at other dredging and disposal sites (Bolam and Rees 2003; Newell et al. 1998; Simonini et al. 2007). In 2008, a gas pipeline was installed in Massachusetts Bay as part of the Neptune Deepwater Port Location. Post-construction SPI and PUC monitoring conducted in September 2009, one year following completion of pipeline backfilling, demonstrated successful infaunal recolonization of the pipeline route and an absence of any adverse ecological effects (Germano and Associates, 2010). In particular, all stations which had experienced physical disturbance related to the installation were well on the way to recovery one year later, with all locations showing transitional (Stage 2) or advanced (Stage 3) successional taxa present. If anything, there appeared to be enhanced secondary production as a result of the construction activities (Rhoads et al., 1978; Bolam and Fernandes, 2002), with more frequent occurrence and higher densities of surface tubicolous fauna and a substantially higher occurrence of epifaunal and demersal fish foraging traces than were found in the pre-construction survey of 2008 (Germano and Associates 2005; 2008; 2010). Based on these past studies, it is reasonable to predict that silty sand and silt habitats affected by cable installation activities would be successfully recolonized by comparable infaunal communities within six to eighteen months following installation. Within southern New England, cobble habitat is limited in distribution compared to sandy and silty substrata. Wahle and Steneck (1991) found that cobble habitat comprised about 8% of the outer coast in their study area in Maine, a notably rockier coastline than Rhode Island, although the presence of glacial moraines is the primary contributor of cobble habitat in RI Sound not rocky substrata. In order for cobble habitat to support 28 P age

36 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm lobster populations by providing shelter for EBP lobsters, the cobble areas need to be located in inshore waters of sufficient depth to avoid constant disturbance from storms and shallow enough to provide epiphytic growth and avoid sedimentation. We found in this study that near Block Island and Point Judith Shoal any areas deeper than feet were soft silt, even if the underlying substratum was mapped as moraine (Figure 40). The areas identified in this survey as undisturbed cobble habitat appear to be optimum habitat for EBP lobsters and represent an important resource for support of the overall population. While the exact amount of cobble habitat in RI Sound is unknown, sediment distribution maps suggest that the cobble habitats south of Block Island and on Point Judith Shoal are undersampled and should be carefully investigated when planning cable or turbine installations. The maps used for examination of seafloor sediments in the vicinity of Block Island were developed from usseabed data (Reid et al. 2005). This data was compiled from published sources and consists of samples with laboratory testing of grain size as well as visual descriptions based on videos, still cameras, grabs, cores and dredges. In order to compare different approaches to estimation of sediment types and simplify the results to search for cobble deposits, we modified the USGS approach (Reid et al. 2005). When percent gravel, sand, silt, clay is available, the Folk sediment classification can be used directly (Reid et al. 2005, Poppe et al. 2005). When sediments are described visually it usually includes the mean or major mode grain size and these don t fit the Folk or Shepard triangle (Folk 1954, Shepard 1954) but are generally expressed in ranges of Wentworth phi sizes (Krumbein 1936). To permit a more generalized data presentation consistent with SPI results, major grain size was clumped into groups and in order to use laboratory analytical results, the Folk Classification was clumped into five groups as modified from UKSeaMap (Long 2006, Table 3). These two approaches are not directly comparable because one focuses on the relative abundance of grain size by weight (Modified Folk) while the other focuses on the dominant grain size by weight (Major Grain Size). However, they allow visualization of a wider range of samples and provide some utility in descriptive mapping of sediments (Poppe et al. 2005). The Modified Folk Classification adopted by UKSeaMap does not include cobble sizes (neither does Folk) although these are often best surveyed with visual descriptions. The sampling conducted for grain size measurement with sieves and pipette analysis is usually conducted with surface grabs or cores. These sampling devices are inefficient in cobble substrata and likely underrepresent those habitats. However, the visual results presented in usseabed contain results classified as hard (Folk) or solid (Shepard) that do not contain grain size breakdowns; these results are interpreted as either bedrock or boulder/cobble fields. As a result maps generated with the datasets contained in 29 P age

37 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm usseabed can provide some ication of the distribution of cobble habitat but do not distinguish cobble habitat from bedrock (Figure 41). Bedrock habitats that are shallow enough to support algal growth have been identified as suitable for EBP lobsters (Wahle and Steneck 1991). Table 3. Modified Major Grain Size Groups and Folk Classes. Visual sediment descriptions Sieve and pipette analysis descriptions Major Grain Size Wentworth Modified Folk (Long 2006) Folk Classes Groups phi size Hard unknown N/A H (Hard) Cobble -6-8 N/A Gravel Coarse sediments Gravel, sandy Gravel, gravelly Sand Very coarse to Coarse sand Mixed sediments (also called Gravelly sediment by Poppe et al and Shepard 1954) muddy Gravel, muddy sandy Gravel, gravelly Mud, gravelly muddy Sand Medium to Fine Sand Sand sand Very fine sand muddy Sand muddy Sand Mud Mud and sandy Mud Mud, sandymud It is clear that silt and sand dominates the areas of RI Sound deeper than 100 feet with dynamic deposits of sand and gravel concentrated on moraines and areas shallower than 100 feet. Where there is gravel below 100 feet it is usually mixed with mud. Areas classified as Hard (Major Grain Size) are most likely to be Cobble habitat as very little bedrock exists in RI Sound but additional visual surveys (sidescan, video or still camera) would be required to verify this. Preliminary cable routes have been defined that avoid the Undisturbed cobble habitat (Figure 42). No cable route could be identified to connect the Alternative 2 Turbine site to Old Harbor, Block Island. The Southeast Shoal extends from Southeast Light to at least five miles offshore. The results of our survey were very consistent, cobble habitats were observed along any part of the shoal shallower than 70 feet. Point Judith Shoal is also unsuitable for cable installation due to the patchy presence of Undisturbed cobble habitat (Figure 18b). The preliminary cable route has been located along the margin of the shoal in sediments characterized as silty sand habitat and moderate backscatter with predominantly silt major mode grain size (Figure 5b and McMullen et al. 2009). 30 P age

38 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm 5.0 CONCLUSIONS Five benthic habitat types were mapped in the vicinity of proposed underwater cable installation routes. Habitat types were based on presence of the largest grain size and surface features visible in Plan view Underwater Camera (PUC) images and Sediment Profile Imaging results. Of these habitat types, four appeared suitable for cable installation: Washed gravel, Mobile sand, Silty sand and Soft silt. These habitat types are either frequently subject to physical disturbance (Washed gravel and Mobile sand) or biologically mixed (Silty sand and Soft silt). In both cases, evidence from gas pipeline installation projects and dredged material disposal site investigations confirm that these habitats recover quickly from moderate physical disturbance such as caused by jetplow fluidization. The fifth habitat type, Undisturbed cobble, is not suitable for cable installation. The habitat is rarely disturbed physically and the biological mediation is primarily structural rather than mixing (algae and epifauna attached to cobbles). In similar coastal environments of New England, cobble habitats have been identified as critical habitat for Early Benthic Phase (EBP) juvenile lobsters. Restoration of disturbed cobble habitat is difficult and the substratum is hard to fluidize with a jetplow. In addition, this habitat was identified as a preferred habitat for attachment of Longfinned Squid eggs. The distribution of Undisturbed cobble habitat beyond the survey results is speculative but appears to be limited to shallow ridges underlain by glacial moraine in nearshore waters and isolated patches along the south shore of Rhode Island. With the apparent limited distribution of this critical habitat, cable installation routes and turbine locations should be located to avoid Undisturbed cobble habitat. Preliminary cable routes have been identified that avoid Undisturbed cobble habitat from Alternative 1 turbine site to Old Harbor, Block Island and from Old Harbor, Block Island to the mainland landfall in Narragansett. Both turbine alternatives are located in mixed habitats (Mobile sand and Washed gravel) that are suitable for construction activity and are likely to recover quickly from any benthic disturbance. The cable route from Alternative 1 to Block Island and the Mainland Connection both transit mixed habitats (Mobile sand, Silty sand and Soft silt) that are suitable for cable installation and are likely to recover quickly from cable installation activities. None of these habitats are characterized by rare occurrence in RI Sound or association with critical habitat for spawning, feeding or refuge for fish or shellfish species. The preliminary cable routes will need to be surveyed for archaeological evidence and engineering suitability studies before they are proposed as preferred alternatives. 31 P age

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42 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm Pearson, T.H. and R. Rosenberg Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanogr. Mar. Biol. Ann. Rev. 16: Poppe, L.J., Williams, S.J., and Paskevich, V.F., 2005, U.S. Geological Survey East- Coast sediment analysis: Procedures, database, and GIS data: U.S. Geological Survey Open-File Report , available online at Reid, J.M., Reid, J.A., Jenkins, C.J., Hastings, M.E., Williams, S.J., and Poppe, L.J, 2005, usseabed: Atlantic coast offshore surficial sediment data release: U.S. Geological Survey Data Series 118, version 1.0, available online at Revelas, E.C., J.D. Germano, and D.C. Rhoads REMOTS reconnaissance of benthic environments. pp In: Coastal Zone 87 Proceedings, ASCE, WW Division, May 26-29, Seattle, WA. Rhoads, D.C Organism-sediment relations on the muddy seafloor. Oceanogr. Mar. Biol. Ann. Rev. 12: Rhoads, D.C. and L.F. Boyer The effects of marine benthos on physical properties of sediments. pp In: Animal-Sediment Relations. McCall, P.L. and M.J.S. Tevesz (eds). Plenum Press, New York, NY. Rhoads, D.C. and J.D. Germano Characterization of benthic processes using sediment profile imaging: An efficient method of remote ecological monitoring of the seafloor (REMOTS System). Mar. Ecol. Prog. Ser. 8: Rhoads, D.C. and J.D. Germano Interpreting long-term changes in benthic community structure: A new protocol. Hydrobiologia. 142: Rhoads, D.C. and J.D. Germano The use of REMOTS imaging technology for disposal site selection and monitoring. pp In: Geotechnical Engineering of Ocean Waste Disposal, K. Demars and R. Chaney (eds). ASTM Symposium Volume, January, Orlando, FL. Rhoads, D.C., P.L. McCall, and J.Y. Yingst Disturbance and production on the estuarine seafloor. American Scientist 66: Rice, D.L. and D.C. Rhoads Early diagenesis of organic matter and the nutritional value of sediment. pp In: Ecology of Marine Deposit Feeders, Vol. 31, Lecture notes on coastal and estuarine deposit feeders. Lopez, G., G. Tagon, 35 P age

43 Benthic Habitat Assessment of Turbine and Cable Alternatives Block Island W Farm and J. Levinton, (eds.). Springer-Verlag, New York, NY. Shepard, F.P., 1954, Nomenclature based on sand-silt-clay ratios: Journal of Sedimentary Petrology, v. 24, p Simonini, R., I. Ansaloni, P. Boini, V. Grandi, F. Graziosi, M. Iotti, G. Massamba- N Siala, M. Mauri, G. Montanari, M. Preti, N. De Nigris, and D. Prevedelli Recolonization and recovery dynamics of the macrozoobenthos after sand extraction in relict sand bottoms of the Northern Adriatic Sea. Marine Environmental Research 64: Uzmann, J.R., R.A. Cooper, K.J. Pecci Migration and dispersion of tagged American lobsters, Homarus americanus, on the southern New England continental shelf. NOAA Tech. Rep. NMFS-SSRF 705, p Valente, R.M., D.C. Rhoads, J.D. Germano, and V.J. Cabelli Mapping of benthic enrichment patterns in Narragansett Bay, RI. Estuaries 15:1-17. Velegrakis, A.F. M.B. Collins, A.C. Bastos, D. Paphitis, A. Brampton Seabed sediment transport pathway investigations: review of scientific approach and methodologies. Geol. Soc. London, Spec. Publ. 274: Wahle, R.A Recruitment, habitat selection, and the impact of predators on the early benthic phase of the American lobster (Homarus americanus Milne Edwards). Ph. D. dissertation, University of Maine. Wahle, R.A. and R.S. Steneck Recruitment habitats and nursery grounds of the American lobster (Homerus americanus Milne Edwards). Mar. Ecol. Prog. Ser. 69: Ziebis, W., Huettel, M., and S. Forster Impact of biogenic sediment topography on oxygen fluxes in permeable seabeds. Mar. Ecol. Prog. Ser. 1409: P age

44 Cable Routes Alternative 3 Narragansett Connection Pt. Judith Shoal Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Overland Alt1_ N Miles Depth in feet Figure 1. Overview map of the stations sampled during the October 2009 SPI/PUC survey (color-coded bathymetry data from NOAA).

45 Cable Routes Alternative 3 Narragansett Connection Pt. Judith Shoal Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Overland Alt1_ NC-1 NC-2 NC-3 NC-4 NC-5 NC-6 NC-8 NC-10 NC-12 NC-14 NC-16 NC-18 NC-20 NC-22 NC Miles c N d BI-25 BI-26 BI-20 BI-23 BI-27 BI-18 BI-16 BI-9 BI-10 BI-12 BI-14 BI-22 BI-6 BI-7 BI-8 BI-3 BI-4 BI-5 b PJ-24 Depth in feet Figure 2a. Station locations in relation to potential cable routes, turbine locations, and bottom topography.

46 USGS Backscatter Moderate backscatter Rocks Trawlmks Cable Routes Alternative 3 Pt. Judith Shoal Block Island Connection Narragansett Connection N Miles PJ-21 PJ-19 PJ-20 PJ-46 PJ-18 PJ-17 PJ-45 PJ-10 PJ-1 PJ-2 PJ-3 PJ-4 PJ-5 PJ-6 PJ-7 PJ-29 PJ-30 PJ-31 PJ-32 PJ-33 PJ-34 PJ-35 PJ-11 PJ-62 PJ-36 PJ-12 PJ-37 PJ-61 PJ-65 PJ-66 PJ-67 PJ-13 PJ-60 PJ-68 PJ-38 PJ-69 PJ-14 PJ-74 PJ-73 PJ-72 PJ-59 PJ-71 PJ-75 PJ-70 PJ-76 PJ-58 PJ-39 PJ-57 PJ-77 PJ-80 PJ-40 PJ-78 PJ-79 PJ-56 PJ-15 PJ-16 PJ-44 PJ-52 PJ-8 PJ-9 PJ-43 PJ-42 PJ-53 PJ-41 PJ-55 PJ-54 PJ-64 PJ-63 Depth in feet -2 PJ-81 PJ PJ-28 PJ-22 PJ-23 PJ-49 PJ-48 PJ-47 PJ-51 PJ-25 PJ-26 BI-2 PJ-50 Figure 2b. Station locations in relation to potential cable routes, turbine locations, backscatter (sidescan sonar) records, and bottom topography.

47 Cable Routes Alternative 3 Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal BI-28 A1-H3 BI-29 A1-H2 BI-30 A1-H1 A1-1 A1-2 A1-3 A1-4 A1-1a A1-H4 A1-5 A1-6 A1-7 A2-1 A1-8 A1-9 A2-2 A1-10 A1-11 A2-3 A2-4 A2-5 A1-12 A1-13 A1-14 T-1 A2-6 T-2 d T-3 AT-30 AT-29 AT-27 AT-28 AT-25 AT-26 AT-23 AT-24 AT-21 AT-22 AT-19 AT-20 AT-17 AT-15 AT-18 AT-9 AT-13 AT-11 AT-7 AT-16 N AT-14 AT-12 AT Miles AT-8 T-9 T-8 T-6 T-7 T-4 T-5 Depth in feet Figure 2c. Station locations in relation to potential cable routes, turbine locations, and bottom topography.

48 Turbine Alternative 1 Turbine Alternative 2 Cable Routes Alt 2 Connection Alt 2 SE Shoal Line 0-1 A2-8 A2-9 A2-10 Line 2-1 A2-11 Line 3-1 A2-12 A2-13 A2-14 A2-15 L1-1 A2-16 A2-17 A2-18 L1-2 A2-19 AS-7 AS-5 AS-3 AS-1 A2-20 Line 3-3 A2-21 AS-9 L1-3 Line 2-2 AS-11 AS-8 AS-6 AS-4 AS-2 A2-22 Line 3-4 AS-13 AS-10 L1-4 Line 2-4 AS-12 AS-16 AS-14 L15-1 L1-5 Line 2-5 AS-18 AS-15 L15-2 Line 2-6 AS-20 AS-19 Line 3-6 L1-6 L15-3 Line 3-5 AS-17 AS-21 AS-22 Line 2-7 Line 3-7 AS-24 L15-4 AS-23 AS-25 Line 2-8 L15-5 L1-7 Line 3-8 L15-6 AS-26 L15-7 Line 2-9 L1-8 Line 3-9 L15-8 L15-12 L15-9 Line 2-10 L1-9 AS-28 L15-11 AS-29 L15-10 AS-30 AS-31 AS-32 AS-33 AS-34 N Miles L1-10 T-15 T-16 T-14 T-13 T-12 A2-7 T-11 T-10 Depth in feet AS AT-6 AT-5 AT-3 AT-2 AT-4 AS-36 AS-37 AT Figure 2d. Station locations in relation to potential cable routes, turbine locations, and bottom topography.

49 Acoustic Signal to the Surface Acoustic Signal Rate Doubles profile camera plan-view camera wow mirror flash 1-2 meters SPI image Plan-view image Deployed 1-2 meters from seafloor On the seafloor "Down" position transecting the sedimentwater interface Figure 3. Operation of the combined Ocean Imaging Model 3731 sediment profile and Model DSC-6000 plan view camera.

50 Stage 0 Stage 1 Stage 2 Stage 3 Water 0 A Reduced Sediment Oxidized Sediment 1 2 Depth (cm) 3 Physical Disturbance Time Normal Stage 0 Stage 1 Stage 2 Stage 3 Fiber Blanket Water 0 B Reduced Sediment Oxidized Sediment Depth (cm) Grossly Polluted Distance Normal Figure 4. Soft-bottom benthic community response to physical disturbance (top panel) or organic enrichment (bottom panel). From Rhoads and Germano, 1982.

51 Sediment grain-size major mode (phi) >4 (silt/clay) >4 to 3 (silty very fine sand) 4 to 3 (very fine sand) 3 to 2 (fine sand) 2 to 1 (medium sand) 1 to 0 (coarse sand) 0 to -1 (very coarse sand) -1 to -6 (small gravel: granules & pebbles) > -6 (cobbles and boulders) Indeterminate rep 1 rep 3 rep 1 rep 2 rep Miles c N d Cable Routes BI-25 BI-26 BI-20 BI-23 BI-27 Alternative 3 Narragansett Connection Pt. Judith Shoal Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Overland Alt1_ BI-18 BI-16 BI-9 BI-10 BI-12 BI-14 BI-22 BI-6 BI-7 BI-8 NC-1 NC-2 NC-3 NC-4 NC-8 NC-10 NC-12 NC-5 NC-6 NC-14 NC-16 NC-18 NC-20 NC-22 NC-24 BI-3 BI-4 BI-5 b PJ-24 Depth in feet Figure 5a. Spatial distribution of sediment grain-size major mode (phi units).

52 Sediment grain-size major mode (phi) >4 (silt/clay) >4 to 3 (silty very fine sand) 4 to 3 (very fine sand) 3 to 2 (fine sand) 2 to 1 (medium sand) 1 to 0 (coarse sand) 0 to -1 (very coarse sand) -1 to -6 (small gravel: granules & pebbles) > -6 (cobbles and boulders) Indeterminate rep 1 rep 3 rep 1 rep 2 rep 2 USGS Backscatter Moderate backscatter Rocks Trawlmks Cable Routes Alternative 3 Pt. Judith Shoal Block Island Connection Narragansett Connection PJ-21 PJ-19 PJ-20 PJ-46 PJ-18 PJ-17 PJ-45 PJ-10 PJ-1 PJ-2 PJ-3 PJ-4 PJ-5 PJ-6 PJ-7 PJ-29 PJ-30 PJ-31 PJ-32 PJ-33 PJ-34 PJ-35 PJ-11 PJ-62 PJ-36 PJ-12 PJ-37 PJ-61 PJ-65 PJ-66 PJ-67 PJ-13 PJ-60 PJ-68 PJ-38 PJ-69 PJ-14 PJ-74 PJ-73 PJ-72 PJ-59 PJ-71 PJ-75 PJ-70 PJ-76 PJ-58 PJ-39 PJ-57 PJ-77 PJ-80 PJ-40 PJ-78 PJ-79 PJ-56 PJ-15 PJ-16 PJ-44 PJ-52 PJ-8 PJ-9 PJ-43 PJ-42 PJ-53 PJ-41 PJ-55 PJ-54 PJ-64 PJ-63 Depth in feet -2 PJ-81 PJ PJ-28 BI-2 PJ-22 PJ-23 PJ-49 PJ-48 PJ-50 PJ-47 PJ-51 PJ-25 PJ-26 N Miles Figure 5b. Spatial distribution of sediment grain-size major mode (phi units).

53 Sediment grain-size major mode (phi) BI-28 A1-H3 BI-29 A1-H2 BI-30 A1-H1 A1-1 A1-2 A1-3 A1-4 A1-1a A1-H4 A1-5 >4 (silt/clay) >4 to 3 (silty very fine sand) 4 to 3 (very fine sand) 3 to 2 (fine sand) 2 to 1 (medium sand) 1 to 0 (coarse sand) 0 to -1 (very coarse sand) -1 to -6 (small gravel: granules & pebbles) > -6 (cobbles and boulders) Indeterminate rep 1 rep 3 rep 1 rep 2 rep 2 Cable Routes Alternative 3 Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal AT-30 AT-29 AT-27 AT-28 AT-25 AT-26 AT-23 AT-24 AT-21 AT-22 AT-19 AT-20 AT-17 AT-15 AT-18 AT-9 AT-13 AT-11 AT-7 AT-16 N AT-14 AT-12 AT Miles AT-8 d A1-6 A1-7 A2-1 A1-8 A2-5 A2-6 A1-9 A1-10 A2-2 A1-11 A2-3 A2-4 T-9 T-8 A1-12 T-6 T-7 A1-13 T-4 T-5 A1-14 T-2 T-3 T-1 Depth in feet Figure 5c. Spatial distribution of sediment grain-size major mode (phi units).

54 A2-7 Sediment grain-size major mode (phi) >4 (silt/clay) >4 to 3 (silty very fine sand) 4 to 3 (very fine sand) 3 to 2 (fine sand) 2 to 1 (medium sand) 1 to 0 (coarse sand) 0 to -1 (very coarse sand) -1 to -6 (small gravel: granules & pebbles) > -6 (cobbles and boulders) Indeterminate rep 1 rep 3 rep 1 rep 2 rep 2 Turbine Alternative 1 Turbine Alternative 2 Cable Routes Alt 2 Connection Alt 2 SE Shoal Line 0-1 A2-8 A2-9 A2-10 Line 2-1 A2-11 Line 3-1 A2-12 A2-13 A2-14 A2-15 L1-1 A2-16 A2-17 A2-18 L1-2 A2-19 AS-7 AS-5 AS-3 AS-1 A2-20 Line 3-3 A2-21 AS-9 L1-3 Line 2-2 AS-11 AS-8 AS-6 AS-4 AS-2 A2-22 Line 3-4 AS-13 AS-10 L1-4 Line 2-4 AS-12 AS-16 AS-14 L15-1 L1-5 Line 2-5 AS-18 AS-15 L15-2 Line 2-6 L15-3 AS-20 AS-19 Line 3-6 L1-6 Line 3-5 AS-17 AS-21 AS-22 Line 2-7 Line 3-7 AS-24 L15-4 AS-23 AS-25 Line 2-8 L15-5 L1-7 Line 3-8 L15-6 AS-26 L15-7 Line 2-9 L1-8 Line 3-9 L15-8 L15-12 L15-9 Line 2-10 L1-9 AS-28 L15-11 AS-29 L15-10 AS-30 AS-31 AS-32 AS-33 AS-34 N Miles L1-10 T-15 T-16 T-14 T-13 T-12 T-11 T-10 Depth in feet AS AT-6 AT-5 AT-3 AT-2 AT-4 AS-36 AS-37 AT Figure 5d. Spatial distribution of sediment grain-size major mode (phi units).

55 Figure 6. Profile image illustrating soft, muddy sediment (silt-clay with a major mode of >4 phi) at station NC-8. The profile camera had relatively deep penetration in this soft sediment, and a subsurface feeding void (upper arrow) and polychaete worm (lower arrow) also are visible. Scale: width of SPI image = 14.5 cm.

56 Figure 7. Profile image showing very fine sand (grain size major mode of 4 to 3 phi) at station BI-12. Scale: width of SPI image = 14.5 cm.

57 PJ-19_B PJ-38_B PJ-40_B PJ-63_B Figure 8. Profile images illustrating variability in sediment grain size at Point Judith Shoal stations. Clockwise from upper left: rippled fine sand (grain size major mode of 3 to 2 phi), medium sand (major mode of 2 to 1 phi), granules (major mode of -1 to -2), and pebbles (major mode of -2 to -6 phi). Scale: width of each SPI image = 14.5 cm.

58 PJ-20_C PJ-20_A Figure 9. Close-up of sidescan sonar results at station PJ-20 showing a band of high backscatter (darker color) icative of coarser sediments. The corresponding profile images at this station show that the area of high relative backscatter likely consisted of very coarse sand (left image), while the surrounding area with low relative backscatter (lighter color) was comprised of fine sand (right image). Scale: width of each SPI image = 14.5 cm.

59 T-4 T-1 Figure 10. Profile images showing homogenous rippled fine sand at station T-4 (left) and fine sand mixed with small gravel (granules and pebbles) at station T-1 (right). Scale: width of each SPI image = 14.5 cm.

60 AS-22 AS-26 AS-25 Line2-7 Figure 11. Profile images from stations at the top of the Southeast Shoal providing examples of medium to coarse sand covered with varying amounts of gravel. Scale: width of each SPI image = 14.5 cm.

61 AS-35 AS-11 AS-9 Figure 12. Profile images showing examples of medium sand at station AS-35, very coarse sand at station AS-11, and small gravel (granules and pebbles) at station AS-9. Scale: width of each SPI image = 14.5 cm.

62 Undisturbed cobble Figure 13a. Planview and corresponding profile image illustrating undisturbed cobble habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

63 Undisturbed cobble Figure 13b. Planview and corresponding profile image illustrating undisturbed cobble habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

64 Undisturbed cobble Figure 13c. Planview and corresponding profile image illustrating undisturbed cobble habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

65 Washed gravel Figure 14a. Planview and corresponding profile image illustrating washed gravel habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

66 Washed gravel Figure 14b. Planview and corresponding profile image illustrating washed gravel habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

67 Washed gravel Figure 14c. Planview and corresponding profile image illustrating washed gravel habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

68 Washed gravel Figure 14d. Planview and corresponding profile image illustrating washed gravel habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

69 Mobile Sand Figure 15a. Planview and corresponding profile image illustrating mobile sand habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

70 Mobile Sand Figure 15b. Planview and corresponding profile image illustrating mobile sand habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

71 Mobile Sand Figure 15c. Planview and corresponding profile image illustrating mobile sand habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

72 Silty Sand Figure 16a. Planview and corresponding profile image illustrating silty sand habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

73 Silty Sand Figure 16b. Planview and corresponding profile image illustrating silty sand habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

74 Silty Sand Figure 16c. Planview and corresponding profile image illustrating silty sand habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

75 Soft Silt Figure 17a. Planview and corresponding profile image illustrating soft silt habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

76 Soft Silt Figure 17b. Planview and corresponding profile image illustrating soft silt habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

77 Soft Silt Figure 17c. Planview and corresponding profile image illustrating soft silt habitat. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

78 Habitat Type Undisturbed cobble Washed gravel Mobile sand Silty sand Soft silt rep 1 rep 3 rep 2 NC-1 NC-2 NC-3 NC-4 NC-5 NC-6 NC-8 NC-10 NC-12 NC-14 NC-16 NC-18 NC-20 Cable Routes Alternative 3 Narragansett Connection Pt. Judith Shoal Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Overland Alt1_ Miles c N d BI-25 BI-26 BI-18 BI-20 BI-23 BI-27 BI-16 BI-9 BI-10 BI-12 BI-14 BI-22 BI-6 BI-7 BI-8 NC-22 NC-24 BI-3 BI-4 BI-5 b PJ-24 Depth in feet Figure 18a. Habitat type observed at each station based on analysis of both planview and profile images.

79 Habitat Type rep 3 Undisturbed cobble Washed gravel Mobile sand Silty sand Soft silt Squid eggs rep 1 rep 2 USGS Backscatter Moderate backscatter Rocks Trawlmks Cable Routes Alternative 3 Pt. Judith Shoal Block Island Connection Narragansett Connection PJ-21 PJ-19 PJ-20 PJ-46 PJ-18 PJ-17 PJ-45 PJ-10 PJ-1 PJ-2 PJ-3 PJ-4 PJ-5 PJ-6 PJ-7 PJ-29 PJ-30 PJ-31 PJ-32 PJ-33 PJ-34 PJ-35 PJ-11 PJ-62 PJ-36 PJ-12 PJ-37 PJ-61 PJ-65 PJ-66 PJ-67 PJ-13 PJ-60 PJ-68 PJ-38 PJ-69 PJ-14 PJ-74 PJ-73 PJ-72 PJ-59 PJ-71 PJ-75 PJ-70 PJ-76 PJ-58 PJ-39 PJ-57 PJ-77 PJ-80 PJ-40 PJ-78 PJ-79 PJ-56 PJ-15 PJ-16 PJ-44 PJ-52 PJ-8 PJ-9 PJ-43 PJ-42 PJ-53 PJ-41 PJ-55 PJ-54 PJ-64 PJ-63 Depth in feet PJ-81-2 PJ PJ-28 BI-2 PJ-22 PJ-23 PJ-49 PJ-48 PJ-50 PJ-47 PJ-51 PJ-25 PJ-26 N Miles Figure 18b. Habitat type observed at each station based on analysis of both planview and profile images.

80 Habitat Type Undisturbed cobble A1-1 BI-28 BI-29 BI-30 A1-2 A1-1a A1-3 A1-H4 A1-H3 A1-H2 A1-H1 A1-4 A1-5 Washed gravel Mobile sand A1-6 Silty sand A1-7 Soft silt Squid eggs A2-1 A1-8 A1-9 rep 3 rep 1 rep 2 A2-2 A1-10 A1-11 Cable Routes A2-3 A1-12 Alternative 3 Block Island Connection A2-4 A1-13 A1-14 Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal A2-5 A2-6 T-2 T-1 d T-3 T-4 T-5 T-7 T-6 Depth in feet -2 T-9 T AT-30 AT-29 AT-27 AT-28 AT-25 AT-26 AT-23 AT-24 AT-21 AT-22 AT-19 AT-20 AT-17 AT-15 AT-18 AT-9 AT-13 AT-11 AT-7 AT-16 N AT-14 AT-12 AT Miles AT Figure 18c. Habitat type observed at each station based on analysis of both planview and profile images.

81 Habitat Type A2-7 Undisturbed cobble Washed gravel Mobile sand N Miles A2-8 rep 3 Silty sand Soft silt Squid eggs rep 1 rep 2 Turbine Alternative 1 Turbine Alternative 2 Cable Routes Alt 2 Connection Alt 2 SE Shoal Line 0-1 L1-1 AS-27 AS-28 L1-2 AS-26 L1-3 L1-4 L1-5 L1-6 L1-9 L15-1 AS-24 AS-23 AS-25 L1-7 L1-8 Line 2-1 L15-2 L15-3 AS-21 AS-22 L15-4 L15-5 L15-6 L15-12 Line 2-2 Line 2-3 Line 3-4 Line 2-4 AS-16 Line 2-5 AS-18 Line 2-6 AS-20 AS-19 Line 3-6 Line 3-5 Line 2-7 Line 3-7 L15-7 L15-8 L15-9 L15-11 Line 2-8 Line 2-9 Line 3-1 Line 2-10 Line 3-2 Line 3-3 AS-14 AS-15 Line 3-8 Line 3-9 AS-13 AS-7 AS-5 AS-3 AS-1 AS-9 AS-11 AS-8 AS-6 AS-4 AS-2 AS-10 AS-12 AS-17 A2-9 A2-10 A2-11 A2-12 A2-13 A2-14 A2-15 A2-16 A2-17 A2-18 A2-19 A2-20 A2-21 A2-22 T-11 T-10 AS-29 L1-10 L15-10 AS-34 AS-33 AS-32 AS-31 AS-30 T-16 T-15 T-14 T-13 T-12 Depth in feet AS AS-36 AT-6 AT-5 AT-3 AT-2 AT-4 AT-1 AS Figure 18d. Habitat type observed at each station based on analysis of both planview and profile images.

82 L1-8A PJ-71_B Figure 19. Planview images from stations L1-8 and PJ-71 showing clusters of white squid eggs (insets) protruding from the sand among cobbles. Scale: distance between red laser dots in each planview image = 26 cm.

83 Figure 20. Profile image from station AS-18 showing a cluster of white squid eggs at the sediment surface. Scale: width of SPI image = 14.5 cm.

84 Average Station Boundary Roughness (cm) cm cm cm cm > 3.0 cm Origin of Boundary Roughness (cm) Biological Biological & Physical Physical 0.7 NC NC NC-3 NC-4 NC-5 NC NC NC NC NC NC NC NC NC Cable Routes Alternative 3 Narragansett Connection Pt. Judith Shoal Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Overland Alt1_ N Miles c d 1.2 BI BI BI BI-20 BI BI BI BI BI BI BI BI BI BI BI-9 BI BI-6 b NC BI-3 PJ Depth in feet Figure 21a. Spatial distribution of average station boundary roughness values (cm).

85 Average Station Boundary Roughness (cm) USGS Backscatter BI-2 Moderate backscatter Rocks Trawlmks Cable Routes cm cm cm cm > 3.0 cm Indeterminate Origin of Boundary Roughness (cm) Biological Biological & Physical Physical Alternative 3 Pt. Judith Shoal Block Island Connection Narragansett Connection PJ PJ-23 PJ PJ PJ-19 PJ-20 PJ PJ PJ PJ-18 PJ PJ-17 PJ-45 PJ-1 PJ-2 PJ-3 PJ-4 PJ-5 PJ-6 PJ-7 PJ-29 PJ-30 PJ-31 PJ-32 PJ-33 PJ-34 PJ-35 PJ PJ PJ PJ-12 PJ-37 PJ PJ-65 PJ PJ PJ PJ-60 PJ PJ-38 PJ-69 PJ-14 PJ-74 PJ PJ-72 PJ-59 PJ PJ-75 PJ PJ-76 PJ-58 PJ PJ-57 PJ-77 PJ-80 PJ-40 PJ PJ-79 PJ-56 PJ-44 PJ-52 PJ PJ-15 PJ PJ PJ PJ PJ PJ-42 PJ-53 PJ-41 PJ-55 PJ-54 PJ-25 PJ-64 PJ-63 Figure 21b. Spatial distribution of average station boundary roughness values (cm) PJ-26 PJ PJ-27 Depth in feet PJ N Miles

86 Average Station Boundary Roughness (cm) cm cm cm cm > 3.0 cm Indeterminate Cable Routes Alternative 3 Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Origin of Boundary Roughness (cm) Biological Biological & Physical Physical 1.5 BI-28 A1-H BI-29 A1-H BI-30 A1-H1 1.4 A1-1 A1-2 A1-3 A A1-1a A1-H4 A A A A2-1 A A A A A A A A A A A A T T-2 d T AT-30 AT AT-27 AT AT-25 AT AT-23 AT AT AT-22 AT AT-20 AT AT AT AT AT AT-11 AT-7 AT-16 N 2.0 AT AT AT Miles 1.3 AT T T T T T T Depth in feet Figure 21c. Spatial distribution of average station boundary roughness values (cm).

87 A Average Station Boundary Roughness (cm) cm cm cm cm > 3.0 cm Indeterminate Turbine Alternative 1 Turbine Alternative 2 Cable Routes Alt 2 Connection Alt 2 SE Shoal Origin of Boundary Roughness (cm) AS-30 AS-31 AS-32 AS-33 AS-34 T T T T-12 A2-8 Biological & Physical A Physical A Line 2-1 A Line 3-1 A A A A L1-1 A A A L1-2 A AS-7 AS-5 AS-3 AS-1 A Line A AS-9 L1-3 Line 2-2 AS-11 AS-8 AS-6 AS-4 AS A AS L1-4 Line 3-4 AS Line AS AS-16 AS L15-1 L1-5 Line 2-5 AS AS L Line 2-6 AS-20 AS-19 Line 3-6 L1-6 L15-3 AS Line 3-5 AS AS-22 Line 2-7 Line AS-24 L AS AS Line 2-8 L L1-7 Line 3-8 L15-6 T-10 AS L15-7 Line L Line 3-9 L L15-12 L Line 2-10 L1-9 T-11 AS L AS-29 L15-10 Line 0-1 Biological L N Miles 1.9 T Depth in feet AT-6 AT AT-3 AT-2 AT AS-36 AS AT AS Figure 21d. Spatial distribution of average station boundary roughness values (cm).

88 Figure 22. Images from station NC-24 illustrating biogenic surface roughness: the profile image (bottom) shows a vertical burrow (arrow) that terminates in a small mound at the sediment surface, while the planview image from this station (top) shows numerous burrow openings, small pits, mounds, and tracks of small organisms at the sediment surface. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

89 Figure 23. Profile image from station PJ-44 showing coarse sand/gravel with a highly sloped surface (i.e., high small-scale boundary roughness). This slope is the result of the profile camera transecting a large bedform (ripple or megaripple). Scale: width of SPI image = 14.5 cm.

90 Figure 24. Profile and associated planview image showing rippled very fine sand at station T-4. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

91 Figure 25. Profile and associated planview image from station A2-12 showing rippled sediment consisting of mixed coarse sand and gravel. The gravel has accumulated in the troughs between the sand waves. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

92 Average Station Prism Penetration Depth (cm) cm cm cm cm >15.0 cm 11.1 NC-3 NC NC-1 NC-2 NC NC NC NC NC NC NC NC NC Cable Routes Alternative 3 Narragansett Connection Pt. Judith Shoal Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Overland Alt1_ N Miles c d 4.0 BI BI BI BI-20 BI BI BI BI BI BI BI BI BI BI BI-18 BI BI-6 b NC NC BI-3 PJ Depth in feet Figure 26a. Spatial distribution of average prism penetration depth (cm).

93 Average Station Prism Penetration Depth (cm) cm cm cm cm >15.0 cm USGS Backscatter BI-2 Moderate backscatter Rocks Trawlmks Cable Routes N Miles 14.8 Alternative 3 Pt. Judith Shoal Block Island Connection Narragansett Connection PJ PJ-23 PJ PJ PJ-19 PJ-20 PJ PJ PJ PJ-18 PJ PJ-17 PJ-45 PJ-1 PJ-2 PJ-3 PJ-4 PJ-5 PJ-6 PJ-7 PJ-29 PJ-30 PJ-31 PJ-32 PJ-33 PJ-34 PJ PJ PJ PJ PJ PJ-37 PJ PJ-65 PJ PJ PJ PJ-60 PJ PJ PJ-69 PJ-14 PJ-74 PJ PJ-72 PJ-59 PJ PJ-75 PJ PJ-76 PJ-58 PJ PJ-57 PJ PJ-80 PJ-40 PJ PJ-79 PJ-56 PJ-44 PJ-52 PJ-51 PJ-15 PJ PJ PJ PJ PJ PJ-42 PJ-53 PJ-41 PJ-55 PJ-54 Figure 26b. Spatial distribution of average prism penetration depth (cm) PJ PJ PJ PJ PJ PJ-27 Depth in feet PJ

94 Average Station Prism Penetration Depth (cm) cm cm cm cm cm >20.0 cm (overpenetration) Cable Routes Alternative 3 Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal 4.7 BI-28 A1-H BI-29 A1-H BI-30 A1-H1 3.3 A1-1 A1-2 A1-3 A A1-1a A1-H4 A A A A2-1 A A A A A A A A A A A T A T AT-30 AT AT-27 AT AT-25 AT AT-23 AT AT AT-22 AT AT-20 AT AT AT AT AT AT-11 AT-7 AT-16 N 6.0 AT AT AT Miles 4.4 AT d T T T T T T T Depth in feet Figure 26c. Spatial distribution of average prism penetration depth (cm).

95 Average Station Prism Penetration Depth (cm) cm cm cm cm cm >20.0 cm (overpenetration) Turbine Alternative 1 Turbine Alternative 2 Cable Routes Alt 2 Connection Alt 2 SE Shoal Line AS-30 AS-31 AS-32 AS-33 AS-34 N Miles T T T T-12 A2-8 A2-7 A A Line A Line 3-1 A A A A L1-1 A A A L1-2 A AS-7 AS-5 AS-3 AS-1 A Line A AS-9 L1-3 Line 2-2 AS-11 AS-8 AS-6 AS-4 AS A AS L1-4 Line 3-4 AS Line 2-4 AS AS-16 AS L L1-5 Line 2-5 AS AS L Line AS-20 AS-19 Line 3-6 L1-6 L15-3 AS-17 Line AS AS-22 Line Line AS-24 L AS AS Line 2-8 L L1-7 Line L T-10 AS L Line L Line 3-9 L L15-12 L Line 2-10 L T-11 AS-28 L AS-29 L L T Depth in feet AT-6 AT AT-3 AT-2 AT AS-36 AS AT AS Figure 26d. Spatial distribution of average prism penetration depth (cm).

96 Station Averaged Mean Apparent RPD Depth (cm) cm cm cm cm cm >5.0 cm Indeterminate 1.1 NC NC NC-3 NC-4 NC-5 NC NC NC NC NC NC NC NC NC Cable Routes Alternative 3 Narragansett Connection Pt. Judith Shoal Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Overland Alt1_ N Miles c d BI-25 BI BI-20 BI BI BI BI BI BI BI BI BI BI BI BI-9 BI BI-6 b NC BI-3 PJ Depth in feet Figure 27a. Spatial distribution of average arpd depths (cm).

97 Map 2 Station Averaged Mean Apparent RPD Depth (cm) cm cm cm cm cm >5.0 cm Indeterminate USGS Backscatter Moderate backscatter Rocks Trawlmks Cable Routes Alternative 3 Pt. Judith Shoal Block Island Connection Narragansett Connection PJ PJ-19 PJ-20 PJ PJ-18 PJ-17 PJ-45 PJ-10 PJ-1 PJ-2 PJ-3 PJ-4 PJ-5 PJ-6 PJ-7 PJ-29 PJ-30 PJ-31 PJ-32 PJ-33 PJ-34 PJ-35 PJ-11 PJ-62 PJ-36 PJ-12 PJ-37 PJ-61 PJ-65 PJ-66 PJ-67 PJ-13 PJ-60 PJ-68 PJ-38 PJ-69 PJ-14 PJ-74 PJ-73 PJ-72 PJ-59 PJ-71 PJ-75 PJ-70 PJ-76 PJ-58 PJ-39 PJ-57 PJ-77 PJ-80 PJ-40 PJ-78 PJ-79 PJ-56 PJ-15 PJ PJ-44 PJ-52 PJ-8 PJ-9 PJ-43 PJ-42 PJ PJ-41 PJ-55 PJ PJ PJ-63 Depth in feet PJ PJ PJ BI PJ-23 PJ PJ PJ PJ PJ PJ PJ PJ N Miles Figure 27b. Spatial distribution of average arpd depths (cm).

98 Station Averaged Mean Apparent RPD Depth (cm) cm cm cm cm cm >5.0 cm Indeterminate Cable Routes Alternative 3 Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal BI-28 A1-H3 BI-29 A1-H2 BI-30 A1-H1 A1-1 A1-2 A1-3 A1-4 A1-1a A1-H4 A A A A2-1 A A A1-9 A1-10 A2-2 A A A A A A1-14 T-1 A2-6 T-2 d T-3 AT-30 AT-29 AT-27 AT-28 AT-25 AT AT-23 AT-24 AT AT-22 AT AT-20 AT-17 AT-15 AT-18 AT-9 AT-13 AT-11 AT-7 AT-16 N AT AT-12 AT Miles 2.9 AT-8 T-9 T-8 T-6 T-7 T-4 T-5 Depth in feet Figure 27c. Spatial distribution of average arpd depths (cm).

99 Station Averaged Mean Apparent RPD Depth (cm) cm cm cm cm cm >5.0 cm Indeterminate (IND) Turbine Alternative 1 Turbine Alternative 2 Cable Routes Alt 2 Connection Alt 2 SE Shoal Line 0-1 A2-8 A2-9 A2-10 Line 2-1 A2-11 Line 3-1 A2-12 A2-13 A2-14 A2-15 L1-1 A2-16 A2-17 A2-18 L1-2 A2-19 AS-7 AS-5 AS-3 AS-1 A2-20 Line 3-3 A2-21 AS-9 L1-3 Line 2-2 AS-11 AS-8 AS-6 AS-4 AS-2 A2-22 AS Line 3-4 AS-10 L1-4 Line 2-4 AS-12 AS-16 AS-14 L15-1 L1-5 Line 2-5 AS-18 AS-15 L15-2 Line 2-6 AS-20 AS-19 Line 3-6 L1-6 L15-3 Line 3-5 AS-17 AS-21 AS-22 Line 2-7 Line 3-7 AS-24 L15-4 AS-23 AS-25 Line 2-8 L15-5 L1-7 Line 3-8 L15-6 AS-26 L15-7 Line 2-9 L1-8 Line 3-9 L15-8 L15-12 L15-9 Line 2-10 L1-9 AS-28 L15-11 AS-29 L15-10 AS-30 AS-31 AS-32 AS-33 AS-34 N Miles L1-10 T-15 T-16 T-14 T-13 T-12 A T T-10 Depth in feet AS AT-6 AT-5 AT-3 AT-2 AT-4 AS-36 AS-37 AT Figure 27d. Spatial distribution of average arpd depths (cm).

100 NC-6_C BI-20_A Figure 28. The profile image from Narragansett Connection station NC-6 near the Rhode Island mainland shows a relatively thin arpd of 1.2 cm and patches of dark, sulfidic sediment at depth. The sediment at station BI-20 in the deeper water of Rhode Island Sound is both lighter-colored (i.e. less sulfidic) and has a deeper arpd depth of 3.4 cm. Scale: width of each SPI image = 14.5 cm.

101 Infaunal Successional Stages Stage I Stage I 2 rep 1 rep 3 Stage 2 rep 2 Stage 2 3 Stage 3 rep 1 rep 2 Stage I on 3 Stage 2 on 3 Indeterminate NC-1 NC-2 NC-3 NC-4 NC-5 NC-6 NC-8 NC-10 NC-12 NC-14 NC-16 NC-18 NC-20 NC-22 NC-24 Cable Routes Miles c Alternative 3 Narragansett Connection Pt. Judith Shoal Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal Overland Alt1_ N d BI-25 BI-26 BI-18 BI-20 BI-23 BI-27 BI-16 BI-9 BI-10 BI-12 BI-14 BI-22 BI-6 BI-7 BI-8 BI-3 BI-4 BI-5 b PJ-24 Depth in feet Figure 29a. Spatial distribution of infaunal successional stages.

102 Infaunal Successional Stages rep 3 rep 1 rep 2 rep 1 rep 2 USGS Backscatter Moderate backscatter Rocks Trawlmks Cable Routes Alternative 3 Pt. Judith Shoal PJ-21 Stage I Block Island Connection Stage I 2 Stage 2 Stage 2 3 Stage 3 Stage I on 3 Stage 2 on 3 Narragansett Connection Indeterminate PJ-19 PJ-20 PJ-46 PJ-18 PJ-17 PJ-45 PJ-10 PJ-1 PJ-2 PJ-3 PJ-4 PJ-5 PJ-6 PJ-7 PJ-29 PJ-30 PJ-31 PJ-32 PJ-33 PJ-34 PJ-35 PJ-11 PJ-62 PJ-36 PJ-12 PJ-37 PJ-61 PJ-65 PJ-66 PJ-67 PJ-13 PJ-60 PJ-68 PJ-38 PJ-69 PJ-14 PJ-74 PJ-73 PJ-72 PJ-59 PJ-71 PJ-75 PJ-70 PJ-76 PJ-58 PJ-39 PJ-57 PJ-77 PJ-80 PJ-40 PJ-78 PJ-79 PJ-56 PJ-15 PJ-16 PJ-44 PJ-52 PJ-8 PJ-9 PJ-43 PJ-42 PJ-53 PJ-41 PJ-55 PJ-54 PJ-64 PJ-63 Depth in feet PJ-81 PJ PJ-28 BI-2 PJ-23 PJ-22 PJ-49 PJ-48 PJ-50 PJ-47 PJ-51 PJ-25 PJ-26 N Miles Figure 29b. Spatial distribution of infaunal successional stages.

103 Infaunal Successional Stages Stage I Stage I 2 rep 1 rep 3 Stage 2 rep 2 Stage 2 3 rep 1 rep 2 Stage 3 Stage I on 3 Stage 2 on 3 Indeterminate Cable Routes Alternative 3 Block Island Connection Alt 1 Connection Alt 2 Connection Alt 2 SE Shoal BI-28 A1-H3 BI-29 A1-H2 BI-30 A1-H1 A1-1 A1-2 A1-3 A1-4 A1-1a A1-H4 A1-5 A1-6 A1-7 A2-1 A1-8 A2-5 A1-9 A1-10 A2-2 A1-11 A2-3 A2-4 A1-12 A1-13 A1-14 T-1 A2-6 T-2 d T-3 AT-30 AT-29 AT-27 AT-28 AT-25 AT-26 AT-23 AT-24 AT-21 AT-22 AT-19 AT-20 AT-17 AT-15 AT-18 AT-9 AT-13 AT-11 AT-7 AT-16 N AT-14 AT-12 AT Miles AT-8 T-9 T-8 T-6 T-7 T-4 T-5 Depth in feet Figure 29c. Spatial distribution of infaunal successional stages.

104 Infaunal Successional Stages rep 3 rep 1 rep 2 rep 1 rep 2 Turbine Alternative 1 Turbine Alternative 2 Cable Routes Alt 2 Connection Alt 2 SE Shoal Stage I Stage I 2 Stage 2 Stage 2 3 Stage 3 Stage I on 3 Stage 2 on 3 Indeterminate Line 0-1 A2-8 A2-9 A2-10 Line 2-1 A2-11 Line 3-1 A2-12 A2-13 A2-14 A2-15 L1-1 A2-16 A2-17 A2-18 L1-2 A2-19 AS-7 AS-5 AS-3 AS-1 A2-20 Line 3-3 A2-21 AS-9 L1-3 Line 2-2 AS-11 AS-8 AS-6 AS-4 AS-2 A2-22 Line 3-4 AS-13 AS-10 L1-4 Line 2-4 AS-12 AS-16 AS-14 L15-1 L1-5 Line 2-5 AS-18 AS-15 L15-2 Line 2-6 AS-20 AS-19 Line 3-6 L1-6 L15-3 Line 3-5 AS-17 AS-21 AS-22 Line 2-7 Line 3-7 AS-24 L15-4 AS-23 AS-25 Line 2-8 L15-5 L1-7 Line 3-8 L15-6 AS-26 L15-7 Line 2-9 L1-8 Line 3-9 L15-8 L15-12 L15-9 Line 2-10 L1-9 AS-28 L15-11 AS-29 L15-10 AS-30 AS-31 AS-32 AS-33 AS-34 N Miles L1-10 T-15 T-16 T-14 T-13 T-12 A2-7 T-11 T-10 Depth in feet AS AT-6 AT-5 AT-3 AT-2 AT-4 AS-36 AS-37 AT Figure 29d. Spatial distribution of infaunal successional stages.

105 Figure 30. Profile image from station NC-10 showing soft mud with small tubes at the sediment surface (Stage 1) and a feeding void and several larger-bodied polychaetes at depth (Stage 3), resulting in a Stage 1 on 3 infaunal successional stage designation for this image. The associated planview image shows numerous small depressions associated with burrow openings at the sediment surface (arrows). Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

106 Figure 31. Profile image from station BI-8 showing soft silt and minor amounts of very fine sand with a few surface tubes, extensive small burrows just below the sediment surface, and a larger burrow/void at depth (Stage 1 on 3). Scale: width of SPI image = 14.5 cm.

107 Figure 32. Stage 2 amphipod tubes are visible at the surface of very fine sand in this profile image from station BI-14. Scale: width of SPI image = 14.5 cm.

108 Figure 33. Representative planview image from Point Judith Shoal showing washed gravel lacking of any visible organisms at station PJ-54. Scale: distance between red laser dots in planview image = 26 cm.

109 PJ-57_A PJ-66_A Figure 34. Representative planview images of cobble habitat at Point Judith Shoal showing the cobbles encrusted with small muddy tubes, hydroids, and anemones. Scale: distance between red laser dots in each planview image = 26 cm.

110 Figure 35. Profile image from station PJ-28 providing an example of Stage 2 on 3: dense amphipod and polychaete tubes at the sediment surface (Stage 2) and a Stage 3 feeding void/burrow at depth (lower right corner). Scale: width of SPI image = 14.5 cm.

111 Figure 36. Profile and associated planview image from station PJ-42 showing a dense aggregation of ampeliscid amphipod tubes covering the surface of fine sand. Scale: distance between red laser dots in planview image = 26 cm and width of SPI image = 14.5 cm.

112 A2-12 T-13 AS-30 Figure 37. Representative planview images showing a general absence of visible biological activity at the sediment surface on washed gravel habitat: station A2-12 located along the Alt 2 Connection, station T-13 located along the Turbine Alternative 1 transect, and station AS-30 located along the Alt 2 Southeast Shoal transect. Scale: distance between red laser dots in each planview image = 26 cm.

113 AT-4 AT-29 Figure 38. Representative planview images from stations near each end of the Turbine Alternative 2 transect showing rippled, mobile sand with sand dollars and/or sea stars. Scale: distance between red laser dots in each planview image = 26 cm.

114 AS-20 AS-22 Figure 39. Planview images from stations AS-20 and AS-22 on Southeast Shoal showing both sparse and dense cobbles covered with a variety of encrusting epifauna and algae. Scale: distance between red laser dots in each planview image = 26 cm.

115 Point Judith Weekapaug Point Charlestown Block Island Figure 40. Location of areas of RI Sound near Block Island with greatest likelihood of cobble habitat. Glacial moraine is mapped from seismic data and may not reflect surface features. Sediments deeper than 100 feet are generally finer with some isolated gravel and coarse sand areas. Nearshore areas with sources of cobble can develop patchy cobble habitat (e.g. much of nearshore area between Point Judith and Weekapaug Point has important cobble habitat).

116 Charlestown Block Island Figure 41. Distribution of sediment types from usseabed data (Reid et al. 2005) in Rhode Island Sound. Sediment type groupings have been modified to provide comparison between primarily visual estimation (Major Grain Size) and grain size analysis (Modified Folk).

117 Figure 42. Cable routes and turbine locations selected to avoid Undisturbed cobble habitat.