Effects of glacier melting on the planktonic communities of two Antarctic coastal areas (Potter Cove and Hope Bay) in summer

Abstract

Climate change has contributed to the regional retreat and melting of glaciers in the Antarctic Peninsula. This phenomenon is expected to affect the composition of plankton communities. The aim of this study is to analyze the influence of glacier melting on the composition and structure of phytoplankton and micro- and mesozooplankton assemblages in two coastal areas located in the northwest (Potter Cove) and in the northern end (Hope Bay) of the Antarctic Peninsula during summer 2013. We expect differences in plankton assemblages between PC and HB related to the fact that these areas are subjected to different climatic and environmental conditions and that the glacier meltwater is accumulated in lakes in HB whereas the meltwater directly reaches the adjacent sea at PC. However, plankton communities differed according to their proximity to the glaciers in both areas investigated, with a transition from herbivorous to microbial plankton food webs towards the glacier. The microbial food web was favored under the effects of glacier meltwater due to the stratification of the water column that favors the development of small eukaryotic algae. These are potential prey for ciliates and heterotrophic dinoflagellates which, in turn, favors the development of small omnivorous copepods. Further away from the glaciers, the herbivorous food web consists of large phytoplankton and a greater representation of herbivorous mesozooplankton organisms. It can be inferred from this study that increases in atmospheric temperatures may favor the development of microbial plankton food webs in the Antarctic coastal seas during summer due to increased glacier meltwater.