Meeting Abstract
For millions of years king crabs and other durophagous (skeleton-breaking) predators have been fundamentally absent from benthic communities on the Antarctic shelf. In their absence, the resident faunas have evolved in isolation, with limited defenses against durophagy. However, rapidly rising sea-temperatures off the western Antarctic Peninsula (WAP) appear to be facilitating range expansion of bathyal king crabs (Lithodidae) up the continental slope. Expansion of durophagous crabs onto the Antarctic shelf could drastically impact the vulnerable, endemic fauna and restructure benthic food webs. Between 2010 and 2013, we established two 100-km2 study sites off the WAP. We conducted photographic surveys to investigate the current population status of king crabs and abundant endemic benthic fauna on the slope and shelf environment. At our first study site off Marguerite Bay, we observed lithodids at depths ranging 841–2266 m. We measured a maximum density of more than 5500 individuals per km-2. At our second study site off Anvers Island, approximately 380 km northeast of Marguerite Bay, we observed lithodids at 924–1941 m depth. We measured a maximum density of ~ 2500 individuals per km-2. Here, we examine the current densities of elements of the endemic benthic fauna and compare their depth distributions in relation to populations of lithodids on the slope and shelf environment across the WAP.
