Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem

SAHADE R; LAGGER C.; TORRE L; MOMO F; MONIEN P; SCHLOSS I; BARNES DKA; SERVETTO N; TARANTELLI, S.; TATIÁN M; ZAMBONI N; ABELE, D

Science Advances

AAAS

Lugar: Nueva York; Año: 2015 vol. 1 p. 1 - 8

2375-2548

The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largestice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasinglypredicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species beingbenthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblagelevel are unknown. This is probably due to the scarcity of baselines against which to assess change. Weperformed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure andenvironmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic communitythat can be linked to ongoing climate change. However, rather than temperature as the primary factor, wehighlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. Thesudden shift from a ?filter feeders?ascidian domination? to a ?mixed assemblage? suggests that thresholds (forexample, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of thechanges, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the currentscenario of glacier retreat, and attention needs to be paid to its effects along the AP.