Using short-term measures of behaviour to estimate long-term fitness of southern elephant seals

• Published in: Marine Ecology Progress Series
• Main Authors: New, LF, Clark, JS, Costa, DP, Fleishman, E, Hindell, MA, Klanjscek, T, Lusseau, D, Kraus, S, McMahon, CR, Robinson, PW, Schick, RS, Schwarz, LK, Simmons, SE, Thomas, L, Tyack, P, Harwood, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Inter-Research 2014
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Southern Ocean; Elephant Seals; Macquarie Island; Mirounga leonina; Southern Elephant Seals
• Online Access: https://doi.org/10.3354/meps10547; http://ecite.utas.edu.au/92724

Environmental changes (a type of disturbance) are altering the habitat of southern elephantseals Mirounga leonina , an apex marine predator in the Southern Ocean. As a result, individualsmay shift their behaviour, spending more time in transit and less time foraging. The effects ofthese sublethal changes in behaviour can accumulate, indirectly impacting lifetime fitness throughchanges in individual survival and reproduction. If a sufficient proportion of the population is affected,the probability of population persistence will be altered. We used data from long-termtelemetry studies of female elephant seals at Macquarie Island, Australia, to model the effect of behaviouron the seals health (i.e. all internal factors that affect homeostasis). Through simulation, weinvestigated the effect of increasing periods of behavioural shifts, quantifying how the exclusion ofmaternal southern elephant seals from foraging habitat may affect their health, offspring survival,individual fitness and population growth rate. A long period of altered behaviour (>50% of an averageforaging trip at sea) in 1 yr resulted in a small (0.4%) decline in population size the followingyear. However, a persistent disruption (e.g. 30 yr), caused for example by the long-term effects ofclimate change, could result in a 0.3% decline in individual fitness and a 10% decline in populationsize. Our approach to estimating the long-term population effects of short-term changes in individualbehaviour can be generalised to include physiological effects and other causes of behaviouraland physiological disruption, such as anthropogenic disturbance, for any species.