Meeting Abstract

52.3  Thursday, Jan. 6  Anchor Ice and Antarctic Benthis Ecology: The Role of Interspecific Variation in Ice Nucleation DENNY, Mark*; DORGAN, Kelly; EVANGELISTA, Dennis; HETTINGER, Annaliese; LEICHTER, James; RUDER, Warren; TUVAL, Idan; Stanford University; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Davis; Scripps Institution of Oceanography; Boston University; Mediterranean Institute for Advanced Studies mwdenny@stanford.edu

Sea ice typically forms at the ocean’s surface, but given a source of supercooled water, anchor ice can nucleate on objects in the water column or at the seafloor. Ecologists have long considered anchor ice to be an important agent of disturbance in the shallow-water benthic communities of Antarctica. Divers have documented anchor ice in these communities, and its presence coincides with reduced abundance of sponges, especially Homaxinella balfourensis, which provides habitat for a diverse community of benthic organisms. However, the mechanism of this disturbance has not been explored. Here we document interspecific differences in ice nucleation characteristics, a key step in both the formation of anchor ice and its impact on organisms. The sponges H. balfourensis and Suberites cuminatus show increased incidence of nucleation and accelerated spread of ice crystals compared to urchins and sea stars. Our results provide a potential first step toward explaining disturbance patterns observed in shallow polar benthic communities. Interspecific differences in ice nucleation raise questions about how surface tissue characteristics such as rugosity and mucus coating affect ice formation on invertebrates.