Dear all,
On behalf of all my co-authors, we are happy to share our most recent publication on South Africa's southern right whales, entitled "Decadal shift in foraging strategy of a migratory southern ocean predator".
ABSTRACT:
Rapid anthropogenic climate change is expected to impact a host of ecological parameters in Southern Ocean ecosystems. Of critical concern are the consequences of these changes on the range of species that show fidelity to migratory destinations, as philopatry is hypothesised to help or hinder adaptation to climate change depending on the circumstances. Many baleen whales show philopatry to feeding grounds, and are also capital breeders that meet migratory and reproductive costs through seasonal energy intake. Southern right whales (Eubalaena australis, SRWs) are capital breeders that have a strong relationship between reproductive output and foraging success. The population dynamics of South Africa’s population of SRWs are characterised by two distinct periods: the 1990s, a period of high calving rates; and the late 2010s, a period associated with lowered calving rates. Here we use analyses of stable carbon (δ13C) and nitrogen (δ15N) isotope values from SRW biopsy samples (n = 122) collected during these two distinct periods to investigate foraging ecology of the South African population of SRWs over a time period coincident with the demographic shift. We show that South African SRWs underwent a dramatic northward shift, and diversification in foraging strategy between 1990s to 2010s. Bayesian mixing model results suggest that during the 1990s, South African SRWs foraged on prey with isotopic values similar to South Georgia krill. In contrast, in the 2010s, we infer that South African SRWs foraged on prey with isotopic values consistent with the waters of the Subtropical Convergence, Polar Front and Marion Island. This shift could represent a strategy to cope with changes in preferred prey or habitat. By linking reproductive decline to a shift in foraging strategy for the first time in SRWs, we show that altering foraging strategies may not be sufficient to adapt to a changing ocean.
Kind regards,