Predation on cephalopods by Weddell seals, Leptonychotes weddellii, at Hope Bay, Antarctic Peninsula

摘要

Cephalopods play a key role in marine environ ments as food resources for top predators such as marine mammals and seabirds. However, detailed information on their trophic relationships with Antarctic seals is scarce. The aim of the present study was to examine the cephalo pod portion of the diet of adult and subadult Weddell seals, Leptonychotes weddellii, at Hope Bay, Antarctic Peninsula, through the analysis of scats collected during three consec utive summers (2003, 2004 and 2005). Cephalopods occurred in almost 45% of the 217 samples collected during the whole period of study. A total of 662 beaks (358 upper and 304 lower) were removed from scats containing cepha lopod remains (n = 93). Octopods were largely dominant in comparison with teuthoids constituting in numerical abun dance over 95% of the cephalopod prey. The octopod Par eledone turqueti was the most frequent and dominant prey species representing, respectively, 57.9 and 71.1% in num bers and biomass of cephalopods consumed. Species belonging to the group of papillated Pareledone were sec ond in importance. The results were compared with infor mation from previous dietary studies of L. weddellii at other localities of Antarctica. Based on the examination of the cephalopod prey taxa identified in this study, it is sug gested that during the study period Weddell seal individuals foraged mainly on benthic prey resources close to the coast, in inshore waters where octopods were dominant in com parison with pelagic squid.