‘Hitchhiker’ polynoid polychaetes in cold deep waters and their potential influence on benthic soft bottom food webs

Abstract

AbstractWe describe a new association for Antarctica, involving an holothuroid host,Bathyplotes bongrainiVaney, 1914, and a parasitic polynoid polychaete,Eunoe opalinaMcIntosh, 1885, which lives on the host body. Both species have never been recorded in the study area, the Ross Sea. The ecological definition of this partnership is difficult to assess, being a mix of phoresis, protective association, parasitism and, possibly, kleptocommensalism.Eunoe opalinaemerges also as a true predator, ingesting several food items that do not belong to the diet ofBathyplotes. We compare this association with analogous examples known from shallow tropical environments as well as bathyal and abyssal depths. Given the conspicuous similarities between the deep water and high latitude examples of this kind of association, a possible common origin is hypothesized. Although the role of such a kind of parasitic relationships in Antarctic communities remains to be fully evaluated, it seems evident that, at high latitudes, where trophic levels are simplified and food webs do not have much redundancy, the impact of such a ‘multitasking’ predator-parasite asE. opalinamight be of a greater magnitude than its shallow water tropical counterpart.