Seawater carbonate chemistry and Antarctic macroalgal biochemical composition and amphipod grazer feeding preferences

• Main Authors: Schram, Julie B, Schoenrock, Kathryn M, McClintock, James B, Amsler, Charles D, Angus, Robert A
• Format: Dataset
• Language: English
• Published: PANGAEA 2017
• Subjects: Alkalinity; total; standard deviation; Animalia; Antarctic; Aragonite saturation state; Arthropoda; Behaviour; Benthic animals; Benthos; Bicarbonate ion; Biomass/Abundance/Elemental composition; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chromista; Coast and continental shelf; Containers and aquaria (20-1000 L or < 1 m**2); Date; Desmarestia anceps; Desmarestia menziesii; EXP; Experiment; Experiment duration; Feeding rate; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gondogeneia antarctica; Identification; Laboratory experiment; Lipids; Macroalgae; Mass; Mass change; OA-ICC; Ocean Acidification International Coordination Centre; Antarctic Peninsula; Antarc*; Antarctica; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.892654; https://doi.org/10.1594/PANGAEA.892654

Increased anthropogenic atmospheric CO2 concentrations have resulted in ocean warming and alterations in ocean carbonate chemistry, decreasing seawater pH (ocean acidification). The combination of ocean warming and acidification (OWA) may alter trophic interactions in marine benthic communities along the western Antarctic Peninsula (WAP). Abundant and diverse macroalgae–grazer assemblages, dominated by macroalgae (e.g. chemically defended Desmarestia anceps and D. menziesii) and gammarid amphipods (e.g. Gondogeneia antarctica), occur on the nearshore benthos along the WAP. In the present study, the amphipod G. antarctica and macroalgae D. anceps and D. menziesii were exposed for 39 and 79 d, respectively, to combinations of current and predicted near-future temperature (1.5 and 3.5°C, respectively) and pH (8.0 and 7.6, respectively). Protein and lipid levels of macroalgal tissues were quantified, and 5-way choice amphipod feeding assays were performed with lyophilized macroalgal tissues collected at time zero and following exposure to the 4 temperature-pH treatments. For D. anceps, we found a significant interactive temperature-pH effect on lipid levels and significantly lower protein levels at reduced pH. In contrast, tissues of D. menziesii exhibited significantly greater lipid levels after exposure to reduced pH, but there was no temperature effect on lipid or protein levels. Despite shifts in macroalgal biochemical composition, there were no changes in amphipod feeding preferences. Our results indicate that despite altered macroalgal nutritional quality under OWA, both macroalgae retained their ability to deter amphipod feeding. This deterrent capacity could become an important contributor to net community resistance of macroalgae-mesograzer assemblages of the WAP to predicted OWA.