Antarctic crustacean grazer assemblages exhibit resistance following exposure to decreased pH

• Main Authors: Schram, Julie B, Amsler, Margaret O, Amsler, Charles D, Schoenrock, Kathryn M, McClintock, James B, Angus, Robert A
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2016
• Subjects: Antarctic; Benthos; Biomass/Abundance/Elemental composition; Coast and continental shelf; Community composition and diversity; Entire community; Laboratory experiment; Mesocosm or benthocosm; Polar; Rocky-shore community; Type; Species; Identification; Treatment; Individuals; pH; pH, standard deviation; Alkalinity, total; Alkalinity, total, standard deviation; Temperature, water; Temperature, water, standard deviation; Salinity; Salinity, standard deviation; Partial pressure of carbon dioxide water at sea surface temperature wet air; Partial pressure of carbon dioxide, standard deviation; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Calcite saturation state; Calcite saturation state, standard deviation; Aragonite saturation state; Aragonite saturation state, standard deviation; Carbonate system computation flag; Carbon dioxide; Fugacity of carbon dioxide water at sea surface temperature wet air; Bicarbonate ion; Carbonate ion; Experiment; Spectrophotometric; Potentiometric titration; Calculated using CO2calc; Calculated using seacarb after Nisumaa et al. 2010; Ocean Acidification International Coordination Centre OA-ICC; Antarctic Peninsula; Palmer Station; Palmer-Station; Antarc*; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.862139; https://doi.pangaea.de/10.1594/PANGAEA.862139

Anthropogenic atmospheric CO2 concentrations are increasing rapidly, resulting in declining seawater pH (ocean acidification). The majority of ocean acidification research to date has focused on the effects of decreased pH in single-species experiments. To assess how decreased pH may influence natural macroalgal-grazer assemblages, we conducted a mesocosm experiment with the common, chemically defended Antarctic brown macroalga Desmarestia menziesii and natural densities of its associated grazer assemblage, predominantly amphipods. Grazer assemblages were collected from the immediate vicinity of Palmer Station (64°46'S, 64°03'W) in March 2013. Assemblages were exposed for 30 days to three levels of pH representing present-day mean summer ambient conditions (pH 8.0), predicted near-future conditions (2100, pH 7.7), and distant-future conditions (pH 7.3). A significant difference was observed in the composition of mesograzer assemblages in the lowest pH treatment (pH 7.3). The differences between assemblages exposed to pH 7.3 and those maintained in the other two treatments were driven primarily by decreases in the abundance of the amphipod Metaleptamphopus pectinatus with decreasing pH, reduced copepod abundance at pH 7.7, and elevated ostracod abundance at pH 7.7. Generally, the assemblages maintained at pH 7.7 were not significantly different from those at ambient pH, demonstrating resistance to short-term decreased pH. The relatively high prevalence of generalist amphipods may have contributed to a net stabilizing effect on the assemblages exposed to decreased pH. Overall, our results suggest that crustacean grazer assemblages associated with D. menziesii, the dominant brown macroalgal species of the western Antarctic Peninsula, may be resistant to short-term near-future decreases in seawater pH. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2015) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation is 2016-07-05.