Unravelling the relative roles of top-down and bottom-up forces driving population change in an oceanic predator

Horswill, C. , Ratcliffe, N., Green, J.A., Phillips, R.A., Trathan, P.N. and Matthiopoulos, J. (2016) Unravelling the relative roles of top-down and bottom-up forces driving population change in an oceanic predator. Ecology, 97(8), pp. 1919-1928. (doi: 10.1002/ecy.1452) (PMID:27859185) (PMCID:PMC5008121)

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Abstract

In the open ocean ecosystem, climate and anthropogenic changes have driven biological change at both ends of the food chain. Understanding how the population dynamics of pelagic predators are simultaneously influenced by nutrient-driven processes acting from the “bottom-up” and predator-driven processes acting from the “top-down” is therefore considered an urgent task. Using a state-space demographic model, we evaluated the population trajectory of an oceanic predator, the Macaroni Penguin (Eudyptes chrysolophus), and numerically assessed the relative importance of bottom-up and top-down drivers acting through different demographic rates. The population trajectory was considerably more sensitive to changes in top-down control of survival compared to bottom-up control of survival or productivity. This study integrates a unique set of demographic and covariate data and highlights the benefits of using a single estimation framework to examine the links between covariates, demographic rates and population dynamics.

Item Type:Articles
Additional Information:This analysis was funded by a NERC PhD studentship grant number NE/I52797/X.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Horswill, Dr Catharine and Matthiopoulos, Professor Jason
Authors: Horswill, C., Ratcliffe, N., Green, J.A., Phillips, R.A., Trathan, P.N., and Matthiopoulos, J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Ecology
Publisher:Ecological Society of America
ISSN:0012-9658
Published Online:05 May 2016
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Ecology 97(8): 1919-1928
Publisher Policy:Reproduced under a Creative Commons License

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