Decadal changes in habitat characteristics influence population trajectories of southern elephant seals

Abstract

Understanding divergent biological responses to climate change is important for predicting ecosystem level consequences. We use species habitat models to predict the winter foraging habitats of female southern elephant seals and investigate how changes in environmental variables within these habitats may be related to observed decreases in the Macquarie Island population. There were three main groups of seals that specialized in different ocean realms (the sub-Antarctic, the Ross Sea and the Victoria Land Coast). The physical and climate attributes (e.g. wind strength, sea surface height, ocean current strength) varied amongst the realms and also displayed different temporal trends over the last two to four decades. Most notably, sea ice extent increased on average in the Victoria Land realm while it decreased overall in the Ross Sea realm. Using a species distribution model relating mean residence times (time spent in each 50 × 50 km grid cell) to 9 climate and physical co-variates, we developed spatial predictions of residence time to identify the core regions used by the seals across the Southern Ocean from 120°E to 120°W. Population size at Macquarie Island was negatively correlated with ice concentration within the core habitat of seals using the Victoria Land Coast and the Ross Sea. Sea ice extent and concentration is predicted to continue to change in the Southern Ocean, having unknown consequences for the biota of the region. The proportion of Macquarie Island females (40%) utilizing the relatively stable sub-Antarctic region, may buffer this population against longer-term regional changes in habitat quality, but the Macquarie Island population has persistently decreased (-1.45% per annum) over seven decades indicating that environmental changes in the Antarctic are acting on the remaining 60% of the population to impose a long-term population decline in a top Southern Ocean predator.

Colony‐specific differences in decadal longitudinal body composition of a capital‐breeding marine top predator

“…pup production, and which may also be linked to changes in environmental conditions impacting foraging success, similar to that described for southern elephant seals (e.g. Hindell et al, 2017).…”

“…Adult female grey seals around Britain are most likely to forage in the region containing their breeding colony (Russell et al, 2013 pup production, and which may also be linked to changes in environmental conditions impacting foraging success, similar to that described for southern elephant seals (e.g. Hindell et al, 2017).…”

Temporal changes in Weddell seal dive behavior over winter: Are females increasing foraging effort to support gestation?

“…This is because the timing of reproduction is often constrained by environmental conditions and must be short in duration. After depleting energetic capital to support critical life history events, animals must recuperate mass and condition efficiently, for the next year's reproductive efforts (Carlini, Daneri, Marquez, Soave, & Poljak, ), and short‐ and long‐term climate regime shifts that impact local productivity exhibit strong linkages with population pupping rates (Chambert, Rotella, & Garrott, ; Hindell et al, ; Paterson, Rotella, Arrigo, & Garrott, ). Therefore, greater investment of resources or inadequate recovery of energy stores is likely to influence the balance between current and future reproductive success, in which the energy and time devoted to the current reproductive event can impact expected future fecundity due to carry‐over costs (Boggs, ; Desprez et al, ; McMahon, Harcourt, Burton, Daniel, & Hindell, ; Stearns, ).…”

“…This is because the timing of reproduction is often constrained by environmental conditions and must be short in duration. After depleting energetic capital to support critical life history events, animals must recuperate mass and condition efficiently, for the next year's reproductive efforts (Carlini, Daneri, Marquez, Soave, & Poljak, 1997), and short-and long-term climate regime shifts that impact local productivity exhibit strong linkages with population pupping rates (Chambert, Rotella, & Garrott, 2012;Hindell et al, 2017;Paterson, Rotella, Arrigo, & Garrott, 2015).…”

Corrigendum

“…In the paper by Hindell et al. () entitled “Decadal changes in habitat characteristics influence population trajectories of southern elephant seals” error was discovered in Figure and it should be corrected.…”