Aquatic Plant Community of Crooked Lake: 2017 Anoka County, MN (# )

Transcription

1 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August Creekside Lane Osseo, MN 5569 (65) Aquatic Plant Community of Crooked Lake: 07 Anoka County, MN (#0-008) Surveyed August, 07 Surveying, Analysis, and Reporting by: James A. Johnson Freshwater Scientific Services, LLC Funded by: Crooked Lake Area Association 07 Freshwater Scientific Services, LLC Page of 9.

2 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August 07 Survey & Analysis Methods Point-Intercept Aquatic Plant Survey Freshwater Scientific Services conducted a lake-wide aquatic plant survey for Crooked Lake on August, 07 using the point-intercept method described by Madsen (999). This survey incorporated assessments at a total of 77 sample points (5 littoral; 5 ft) arranged in a uniform grid (5-m spacing; Figs and ). We generated these sample points using desktop GIS software to project a grid of points over an aerial image of the lake. We then loaded the selected sample locations onto a handheld GPS unit (Garmin GPSMAP-78) for navigation to each point while in the field. At each designated sample location, we collected plants using a double-headed, -tine rake on a on a rope. For each rake sample, we dragged the rake over the lake bottom for approximately 5 ft before retrieving. Retrieved plants were piled on top of the rake head and assigned density scores from to based upon rake head coverage (Table ) for each individual species and for all plants collectively. We calculated the littoral frequency ( 5 ft, % occurrence) and littoral mean density score (plant abundance) for each encountered plant species (Table ), as well as lake-wide and littoral plant community metrics (Table ). We also used desktop GIS software to map the distribution and abundance of plants in the lake (pages 5 9). Additional species that were observed floating or growing in the vicinity of a sample point but not retrieved on the rake were given a rating of zero for that location. These zero species were noted as being present on the plant distribution maps (shown as an X ), but zero ratings were excluded from calculations of plant community metrics and statistics (not treated as denoting presence). At each location, we also documented water depth and overall plant height. Figure. Designated sample locations for the 07 Crooked Lake plant survey. Darker shaded area >5 ft (based upon MDNR bathymetric map). Figure. Sampling effort (number of locations sampled) within successive -ft depth zones 07 Freshwater Scientific Services, LLC Page of 9

3 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August 07 Results Statistical Summary of Findings Table. Littoral frequency (% occurrence) and abundance (mean density score) of plant species found in Crooked Lake (Anoka Co., MN) during the Aug, 07 survey. and Mean Density (0- scale) were calculated using all littoral points (water depth 5 ft). Plant taxa that were observed growing in the lake but not retrieved in any rake samples are noted as being present (P). PLANT TAXA COMMON NAME % OCCURRENCE MEAN DENSITY ALL TAXA (combined) SUBMERSED TAXA Myriophyllum spicatum * Eurasian watermilfoil <0. Ceratophyllum demersum Coontail Chara sp. Muskgrass.0.0 Potamogeton illinoensis Illinois pondweed Stuckenia pectinata Sago pondweed Najas guadalupensis Southern naiad 6 0. <0. Eleocharis acicularis Needle spikerush <0. <0. Potamogeton crispus * Curly-leaf pondweed 6 <0. 0. Potamogeton pusillus Small pondweed 5 <0. <0. Zosterella dubia Water stargrass 5 <0. 0. Najas flexilis Slender naiad 6 0. Utricularia vulgaris Common bladderwort <0. Potamogeton gramineus Variable pondweed P Potamogeton zosteriformis Flat-stem pondweed <0. FLOATING TAXA Nymphaea odorata White waterlily Lemna minor Small duckweed Spirodela polyrhiza Large Duckweed 7 0. <0. Wolffia columbiana Common watermeal <0. <0. Nuphar variegata Spatterdock P <0. Lemna trisulca Star duckweed <0. EMERGENT TAXA Typha sp. Cattail <0. <0. Schoenoplectus acutus Hard-stem Bulrush P P * Invasive, non-native species 07 Freshwater Scientific Services, LLC Page of 9

4 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August 07 Table. Summary of Crooked Lake plant community metrics from the Aug, 07 survey. CROOKED LAKE WHOLE-LAKE METRICS Lake Area (acres) 6 6 Total Points Sampled Vegetated Area (acres) Area with Veg. to Surface (acres) 6 Max Depth of Growth (95%).0 ft.5 ft Native Submersed Taxa 0 Native Floating/Emergent Taxa 7 8 Non-Native Submersed Taxa LITTORAL METRICS Littoral Area ( 5 ft, acres) 8 85 Littoral Points Sampled 5 5 % Littoral Points Vegetated 95% 8% Mean Plant Height.7 ft. ft % of Max Littoral Biovolume 5% % Mean Native Taxa / Point.5.0 Simpson s Diversity Floristic Quality (FQI) AMCI Score (Nichols et al. 000) 7 5 Table. Overview of rake density scores used to document plant abundance 07 Freshwater Scientific Services, LLC Page of 9

5 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August 07 Croooked Lake Aquatic Plant Community All Vegetation Density (-) X No plants Darker shaded area >5ft N Native Plant Diversity Number of Native Species per point X None Surveyed: Aug, 07 Methods: Rake, Sonar, Depth Rod Surveyor: JA Johnson 07 Freshwater Scientific Services, LLC Page 5 of 9

6 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August 07 Crooked Lake Invasive Aquatic Plants Eurasian Watermilfoil Density (-) Darker shaded area >5ft Curlyleaf Density (-) Southern Naiad 07 Freshwater Scientific Services, LLC Page 6 of 9

7 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August 07 Crooked Lake Native Aquatic Plants Muskgrass (Chara) Density (-) Illinois Density (-) 07 Freshwater Scientific Services, LLC Page 7 of 9

8 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August 07 Crooked Lake Native Aquatic Plants Sago Density (-) Coontail Density (-) 07 Freshwater Scientific Services, LLC Page 8 of 9

9 Aquatic Plant Survey Crooked Lake (Anoka County, MN) August 07 Crooked Lake Native Aquatic Plants White Waterlily Water Stargrass Small Density (-) Southern Naiad Flat-Stem Hardstem Bulrush Density (-) 07 Freshwater Scientific Services, LLC Page 9 of 9