Meeting Abstract

S1-5  Saturday, Jan. 4 10:00 - 10:30  New Insights Into Patterns of Zooplankton Abundance Along the Rapidly Changing Western Antarctic Peninsula STEINBERG, DK*; CONROY, JA; THIBODEAU, PS; Virginia Institute of Marine Science, College of William & Mary; Virginia Institute of Marine Science, College of William & Mary; Virginia Institute of Marine Science, College of William & Mary

During the last two decades the rapid regional warming and sea ice decline in the western Antarctic Peninsula (WAP) region observed since the mid-twentieth century has plateaued. While the long-term trend in warming and sea ice loss is still significant, there has been a notable increase in sea ice extent and duration, and its interannual variability, since the late 2000s in the coastal WAP. The Palmer, Antarctica Long-Term Ecological Research (PAL LTER) program is investigating marine ecosystem response to both long-term regional warming and shorter-term reversals along the peninsula’s marine continental shelf. Changes in the distribution and relative abundance of Antarctic krill (Euphausia superba) and other zooplankton that play a central role in the food web in many cases can be tied to warming and sea ice trends, and to the atmospheric circulation patterns that underlie these trends. For example, episodic recruitment sustains the Antarctic krill population along the WAP, and strong recruitment since 2011 is coincident with enhanced phytoplankton productivity and recent sea ice increases. A long-term increase in another krill species in the southern part of the study region is also attributed to increased phytoplankton production or more favorable timing of ice-retreat leading to subsequent blooms. Abundance of gelatinous salps and pteropods (pelagic snails) were significantly affected by sub-decadal climate oscillations (e.g., El Niño Southern Oscillation). We discuss the importance, and challenges, of understanding the effects of this environmental variability on the WAP food web, and some potential effects on regional carbon cycling.