The Response of Antarctic Bivalves to Environmental Change in the Southern Ocean

The Southern Ocean is considered to be a highly impacted by climate change. TheWestern Antarctic, Scotia Island Arc and South Georgia have experienced some of the greatest regional warming in the past 50 years (Gutt et al. 2015).The SO is predicted to reach aragonite undersaturation during winter season within the next decades and all-year-round from the middle of the century (McNeil & Matear, 2008). The biotic response to these changes though is unclear. Many organisms are too long lived to assess their adaptive capacity in the lab. Using differences in the regional oceanography and biogeochemistry though provides insights into mechanism to acclimate to lower saturation and warmer climates. Available data of mainly nonpolar species suggest a considerable variation in their ability to calcify and respond to changing environmental conditions (Pfister et al. 2016). Here we assess the morphological, geochemical and shell preservation differences in deep water Antarctic bivalve species to their environment by comparing shells from different depths and regions of the SO. As shells of bivalves are crucial for their survival, we useµ-CT scanning and electron microbe analysisto quantify dissolution patterns, density differences and material properties of the shells of Cyclocardia astoartoides and Limopsis knudseni. Using Raman spectroscopy, we quantify aragonite and calcite amounts in the shells as altering the amounts of the minerals with different dissolution behaviour might be a means to retain shell growth. Our findings may provide insights into future environmental changes in the Southern Ocean.