Effects of low salinity and low pH on behavioral aspects of Antarctic amphipod, Gondogeneia antarctica

초록

Rapid glacial retreat along with existing climate changes and anthropogenic CO2 induce declining trends of mean salinity and pH in Marian Cove, King George Island. Such seawater freshening and ocean acidification caused by meltwater intrusion near the glacier are inevitable, so the changes of the marine ecosystem and its members are expected. Gondogeneia antarctica, one of the abundant gammarid amphipod species in western Antarctic Peninsula, occupies important ecological niche in the cove. To predict the effects of the low salinity and pH on the population, we performed manipulation experiments for 38 days, raising G. antarctica in 4 different treatments combining two salinity (30 and 27 psu) and two pH (pH 8.0 and 7.6) levels. Low salinity increased cannibalism, while low pH reduced foraging behavior significantly. In low salinity conditions, swimming behavior during the daytime (= abnormality) was increased, whereas swimming behavior during the nighttime (= activity) was decreased significantly. Sheltering behavior during the daytime (= usual behavior) was decreased by low salinity and pH respectively. Although the interactions between low salinity and low pH were not observed during the experiments, the results suggest that each stressor due to glacier melting causes amphipods’ abnormal behavior and eventually may reduce survival in the cove.