SUPPLEMENTARY INFORMATION

Transcription

1 SUPPLEMENTARY INFORMATION Supplementary Information for Survival of mussels in extremely acidic waters on a submarine volcano Verena Tunnicliffe *, Kimberley T.A. Davies, David A. Butterfield, Robert W. Embley, Jonathan M. Rose and William W. Chadwick, Jr. nature geoscience 1

2 supplementary information Supplementary Field Description Setting on NW Eifuku Volcano - The sharply incised ridge and gully terrain around the summit area of NW Eifuku reflects construction from its most recent eruptions and subsequent masswasting on steep slopes. On the summit of NW Eifuku, areas of low-temperature diffuse venting are characterized by thick accumulations of orange-tan microbial mats [1]. Other diffuse fluids issue from fractures and permeable horizons in subsea slide headwall scarps that appear to have removed a large amount of the southern half of the summit. The Champagne Vent site is located in the headwall of a slide scarp at 1610 m depth. It is the only known focused flow site on the volcano. Milky plumes debouching from Champagne Vent drift up and around the summit area. The main mussel bed extended about 150 x 75 m around and above the chimneys where mussels attached to bare rock. Mussels avoided crevices and clustered on promontories and high points, often many individuals deep. There was little evidence of venting within these mussels either visible shimmering or temperature anomalies. We believe that the mussels use the dense clouds of fluid rising up from the Champagne vent wafted there by the circulating (counter-clockwise at time of observation) flow around the top of the volcano summit (Supplementary Figure 1. Such clouds were observed in this area on several dives. Mussels below the depth of Champagne may receive a down-wafted plume or use very low flux fluid from the substratum. Setting in Lau/Monowai - During the MANGO cruise aboard RV Sonne in May 2007, we located mussels around scattered low temperature vents on the western wall of the caldera on Monowai Volcano (northern Kermadec Arc). We also collected the same species further north at the previously known Hine Hina site in Lau Backarc Basin. At both these sites, numerous vent species included abundant brachyuran crabs (mostly Paralomis hirtella de St Laurent & Macpherson) that are predators of mussels (Supplementary Video 2). Shells of Bathymodiolus 2 nature geoscience

3 supplementary information brevior were donated by R. Vrijenhoek collected from several other locations in the Lau and Fiji Backarc basins (Supplementary Table 1). Because no water information was available for these specimens, analyses were restricted to morphometrics only. nature geoscience 3

4 supplementary information Supplementary Methods Water sampling -Water samples were collected on NW Eifuku using the Hydrothermal Fluid and Particle Sampler, which pumps water through a titanium/teflon manifold and into individual sample containers. To minimize the chance of entrainment of residual high-co 2 fluids into the mussel water samples, mussel bed fluid samples were taken first during the dive in 2004 and after other low-temperature fluids in The manifold is thoroughly flushed with background seawater between samples to ensure small dead volumes in the sample inlets do not contaminate the next sample. To consider the worst case scenario, a 750m background seawater sample taken above NW Eifuku after high-temperature, high-co 2 (>2500 mmol/kg) samples in 2004 had a ph of 7.22 (approximately 0.6 units less than normal background) and alkalinity of 2419 µmol/kg (within the range of expected values for this region from WOCE section P10 data, However, the mussel bed fluid samples were taken before the high-co 2 samples, and have ph values lower than the background sample taken at the end of the dive. Based on the sampling procedures used and the magnitude of the diffuse chemical signal, there is almost (but not zero) no chance that the results can be attributed to any kind of sampling artefact. On Monowai/Lau, water was pulled into unconnected evacuated cylinders very slowly to draw only water from the immediate mussel vicinity. Prior to sampling, the cylinders were acid washed, flushed with helium to remove air and water residues, and evacuated. Water Analyses - Water samples were refrigerated until processed. Fluid was removed from the sample containers into plastic syringes with no exposure to air, and ph was measured while preventing gas exchange. ph electrodes were standardized with commercial ph buffers (3, 4, 7, 8) and recorded to the nearest 0.1mV. To calculate the degree of saturation with respect to calcite and aragonite, we used the CO2Sys program in Excel macro form, adapted from the 4 nature geoscience

5 supplementary information CO2SYS program [2]. The program requires input of salinity, temperature, pressure, dissolved silica and phosphate, and two carbonate system parameters, namely ph and total alkalinity. We used the seawater scale for ph, K1 and K2 from Dickson et al. [3]. The program assumes that Ca is proportional to seawater salinity, not generally true in hydrothermal fluids, but closely approximated in these seawater-like diffuse fluids. We used a constant value of 34 salinity, 1 µmol/kg phosphate, and the measured or estimated dissolved silica concentration. The effects of phosphate and silicate on the calculated saturation state are negligible for these samples and do not affect the conclusions. We used lab conditions for input temperature and pressure and in-situ conditions for the output temperature and pressure. nature geoscience 5

6 supplementary information Supplementary References 1. Davis, R.E. & Moyer, C.L. Extreme spatial and temporal variability of hydrothermal microbial mat communities along the Mariana Island Arc and southern Mariana back-arc system In situ feeding with a remotely operated submersible. J Geophys Res Sol-Ear. 113, B08S15; doi: /2007jb (2008). 2. Lewis, E. & Wallace, D. W. R., Program Developed for CO 2 System Calculations from Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, (1998). 3. Dickson, A. G. & Millero, F. J. A comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media Deep-Sea Res. Pt. 1 34, (1987). 6 nature geoscience

7 supplementary information Supplementary Table 1. Location information for study sites in the western Pacific. R collected by ROPOS; J collected by Jason-II. No water information is available for the 2005 samples. Site Location Year ROV dive- Latitude Longitude sampled sample Mariana Arc NW Eifuku, Fouling 2004 R ' N 'E Mariana Arc NW Eifuku, Where 2006 J ' N ' E Mariana Arc NW Eifuku, Champagne 2006 J ' N ' E Mariana Arc NW Eifuku, Rippling 2006 J ' N ' E Kermadec Arc Monowai 2007 R ' S ' W Lau Basin Hine Hina 2007 R ' S ' W Lau Basin Hine Hina 2005 J145-unk ' S ' W Lau Basin Kilo Moana 2005 J141-A ' S ' W Lau Basin Tow Cam 2005 J142-A ' S ' W Lau Basin Tui Malila 2005 J144-A ' S ' W nature geoscience 7

8 supplementary information Supplementary Video 1 Champagne Vent on NW Eifuku Volcano, Mariana Volcanic Arc. Hydrothermal fluids over 100 o C emerge at 1610 m depth forming deposits of sulphur. Droplets of liquid carbon dioxide emerge from the rubble and sediment around the chimneys. Video from NOAA Ocean Exploration Program's Submarine Ring of Fire 2004 expedition: using ROV ROPOS. Supplementary Video 2 Crabs and mussels on Monowai Volcano, Kermadec Arc. Lithodid crabs are abundant in the mussel beds. Numerous crabs dislodge and attack a mussel. Video from NOAA Ocean Exploration Program's New Zealand American Submarine Ring of Fire 2005 expedition: using DSV Pisces IV. 8 nature geoscience

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