november, 2019

14nov1:00 pm2:00 pmSeals and Killers in the Roaring Forties: Subantarctic Marion Island's Marine Mammal ProgrammeP.J.N. (Nico) de Bruyn1:00 pm - 2:00 pm SOI Lecture Theatre Speaker organisation: University of Pretoria

Event Details

Following exploratory research done during the early 1950’s, Mammal research at Subantarctic Marion Island (MI) became a priority scientific endeavour in 1973. Baseline southern elephant seal research was conducted intermittently until 1983, when the present Marion Island Marine Mammal Programme (MIMMP) was born. Precipitous global declines in elephant seal numbers (e.g. >50% at MI between 1951 and 1983) prompted the inception of an intensive mark-recapture programme to better understand the demographics of the MI population in an effort to identify causal mechanisms for the declines there. Unparalleled longitudinal data over an almost 40-year timespan has highlighted both juvenile and adult female elephant seal mortality as proximate drivers of the declines. Food limitation has been suggested as the ultimate driver of the population decline, although various other hypotheses persist. In light of these hypotheses and the evidenced recent stabilisation of the population, intensive research on other mammalian top-predators within the Marion Island ecosystem commenced during recent decades. Investigation of possible top-down control of the elephant seal population by a resident killer whale population has received intensive recent attention. Novel characteristics of killer whales here have stimulated parallel investigations into the basic biology of this species there, with consequent global implication. Foraging ecology studies of otariid seals have furthermore assisted in disentangling questions pertaining to environmental change, interspecific interactions and important oceanographic features of importance to top-predators from this locality in general. This talk provides a whirl-wind tour of the research that has driven almost four decades of scientific inquiry into the population dynamics of mammalian marine top-predators and how this research has helped to answer questions of global significance from a region experiencing increased environmental change.


(Thursday) 1:00 pm - 2:00 pm


SOI Lecture Theatre

Gatty Marine Laboratory, St Andrews

Speaker organisation

University of Pretoria



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