Covering behavior of deep-water echinoids in Antarctica: possible response to predatory king crabs
Marine Ecology Progress Series
© The authors 2016. Open Access under Creative Commons by Attribution Licence. Use, distribution and reproduction are unrestricted. Authors and original publication must be credited. Publisher: Inter-Research · www.int-res.com
Covering behavior refers to the propensity of echinoids (Echinoidea) to lift materials from the surrounding environment onto their aboral surfaces using their tube feet and spines. This behavior has been widely documented in regular echinoids from a variety of well-lit, shallow-marine habitats. Covering behavior in the deep sea, however, is rarely observed, and the functional significance of covering when it does occur remains speculative. During a photographic survey of the seafloor off Anvers Island and Marguerite Bay along the western Antarctic Peninsula, we imaged 11 benthic transects at depths ranging from 390 to 2100 m. We recorded the number of echinoid species, incidence of covering behavior, types of materials used for covering, potential predators of echinoids, and potential prey items for predators. The echinoid Sterechinus spp. was found at all depths, and the percentage of individuals exhibiting covering behavior increased with depth between 390 and 1500 m. There was a significant positive correlation between the incidence of covering behavior in Sterechinus spp. and the density of king crabs (Anomura: Lithodidae), crushing predators that may be expanding their bathymetric range up the Antarctic continental slope as a consequence of ongoing climatic warming. In contrast, covering behavior was not positively correlated with the densities of non-crab predators, the total densities of predators, or the availability of prey. Our results document rarely observed covering behavior in echinoids living in the deep sea and suggest that covering could be a behavioral response to predation pressure by king crabs.
We thank the crew of the RV ‘Nathaniel B. Palmer’ during the NBP13-10 cruise for logistical help, as well as J. S. Anderson, A. Brown, C. Easson, D. Ellis, S. Thatje, and S. C. Vos. Thanks also to Paul Dayton as well as 2 anonymous reviewers who offered constructive comments and suggestions. Funding was provided by grants from the US National Science Foundation to R.B.A. (ANT- 1141877) and J.B.M. (ANT-1141896). This paper is contribution no. 160 from the Institute for Research on Global Climate Change at the Florida Institute of Technology.
This is the final version of the article. Available from Inter Research via the DOI in this record.
Vol. 553, pp. 155 - 162