Regional, temporal and fine-scale spatial variation in Weddell seal diet at four coastal locations in east Antarctica
Lake, SE and Burton, H and van den Hoff, J, Regional, temporal and fine-scale spatial variation in Weddell seal diet at four coastal locations in east Antarctica, Marine Ecology Progress Series, 254 pp. 293-305. ISSN 0171-8630 (2003) [Refereed Article]
This description of 905 scats from 4 locations in east Antarctica almost doubles the observations of Weddell seal diet reported to date. Regional, temporal and fine-scale spatial variation in diet was evaluated using both randomisation and parametric statistics. Even within the Vestfold Hills (68° 33′ S, 78°15′ E) there were several different ecotypes. In the southern fjords the diet was benthic fish and prawns, whereas in the northern area the diet was dominated numerically by Pleuragramma antarcticum - a species of pelagic schooling fish. Along the Mawson coast (68°00′ S, 63° 00′ E) the diet was spatially homogeneous but varied over time. Squid Psychroteuthis glacialis was an important prey type for a short time in spring, and octopus was also abundant in the Mawson diet. As higher order predators, cephalopods represent another layer of complexity in the food web at Mawson. Both Vestfold Hills and Mawson seemed to be good foraging areas compared with Commonwealth Bay (67° 00′ S, 142° 30′ E) and Larsemann Hills (69° 24′ S, 76° 13′ E), where seals appeared to have eaten less during the summer haul-out period. This investigation described inshore diets using scats from coastal haul-out sites; it also showed that small crustaceae (mysids) were an important prey type, thus revealing the capacity for Weddell seals to join the krill-feeding communities north of the continental shelf. The variety in diet composition demonstrated both flexibility in the Weddell seals' foraging response and the range of different prey species available to Weddell seals over the Antarctic continental shelf and slope. In all but the most southerly area reported to date (McMurdo Sound), the seals take multiple prey species, which may minimise the coupling between Weddell seal population dynamics and the dynamics of their prey.