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Foraging strategy switch of a top marine predator according to seasonal resource differences

Citation

O'Toole, MD and Lea, MA and Guinet, C and Schick, R and Hindell, MA, Foraging strategy switch of a top marine predator according to seasonal resource differences, Frontiers in Marine Science, 2, (21) pp. 1-10. ISSN 2296-7745 (2015) [Refereed Article]


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Copyright Statement

2015 O'Toole, Lea, Guinet, Schick and Hindell. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) http://creativecommons.org/licenses/by/4.0/

DOI: doi:10.3389/fmars.2015.00021

Abstract

The spatio-temporal variability in marine resources influences the foraging behavior and success of top marine predators. However, little is known about the links between these animals and ocean productivity, specifically, how plankton density influences their foraging behavior. Southern elephant seals (Mirounga leonina) have two annual at-sea foraging trips: a 2 month post-breeding foraging trip (Nov–Jan) that coincides with elevated summer productivity; and an 8 month post-molting foraging trip (Feb–Oct) over winter, when productivity is low. Physical parameters are often used to describe seal habitat, whereas information about important biological parameters is lacking. We used electronic tags deployed on elephant seals during both trips to determine their movement and foraging behavior. The tags also recorded light, which measured the bio-optical properties of the water column, the bulk of which is presumably influenced by phytoplankton. We investigated the relationship between plankton density and seal foraging behavior; comparing trends between summer and winter trips. We found a positive relationship between plankton density and foraging behavior, which did not vary seasonally. We propose that profitable concentrations of seal prey are more likely to coincide with planktonic aggregations, but we also acknowledge that trophic dynamics may shift in response to seasonal trends in productivity. Seal prey (mid-trophic level) and plankton (lower-trophic level) are expected to overlap in space and time during summer trips when peak phytoplankton blooms occur. In contrast, aggregated patches of lower trophic levels are likely to be more dispersed during winter trips when plankton density is considerably lower and heterogeneous. These results show that southern elephant seals are able to exploit prey resources in different ways throughout the year as demonstrated by the variation observed between seal foraging behavior and trophic dynamics.

Item Details

Item Type:Refereed Article
Keywords:trophic link, lower-trophic distribution, foraging behavior, Mirounga leonina, Ross Sea, Antarctica, elephant seal
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Infectious Agents
Objective Division:Environment
Objective Group:Ecosystem Assessment and Management
Objective Field:Ecosystem Assessment and Management of Antarctic and Sub-Antarctic Environments
Author:O'Toole, MD (Dr Malcolm O'Toole)
Author:Lea, MA (Associate Professor Mary-Anne Lea)
Author:Hindell, MA (Professor Mark Hindell)
ID Code:100676
Year Published:2015
Deposited By:IMAS Research and Education Centre
Deposited On:2015-05-25
Last Modified:2016-04-18
Downloads:262 View Download Statistics

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