Seasonal variability in temperature, oxygen, and conductivity on the nearshore benthos around McMurdo Sound, Antarctica

Abstract The nearshore marine benthos in McMurdo Sound is one of the best-studied high Antarctic marine ecosystems, yet multiparameter environmental datasets that describe both seasonal and geographic variation in key environmental parameters are lacking. We installed oxygen, temperature, and conductivity loggers at nearshore shallow benthic sites around McMurdo Sound to obtain a high-resolution year-long record of these parameters in 2021 and 2022. Our data showed that benthic organisms experienced a suite of seasonal changes, particularly in temperature and oxygen saturation, that had potential to significantly impact physiology. High summer temperatures were always accompanied by high oxygen saturations, which could provide a metabolic refuge for Antarctic benthic organisms whose oxygen demand increases strongly with temperature. Temperature and oxygen also fluctuated rapidly; on a timeframe of hours to days, these fluctuations sometimes spanned nearly the entire range of seasonal variability. Climate-driven changes to the Southern Ocean are likely to lead to increased seasonal warming, freshening, and potentially deoxygenation, and understanding the extent and rate of change that benthic organisms currently experience will be important to predicting their responses to future conditions.