Unravelling the relative roles of top‐down and bottom‐up forces driving population change in an oceanic predator. Issue 8 (August 2016)

• Record Type: Journal Article
• Authors: Horswill, C.; Ratcliffe, N.; Green, J. A.; Phillips, R. A.; Trathan, P. N.; Matthiopoulos, J.
• Is Part Of: Ecology. Volume 97:Issue 8(2016)
• Page Start: 1919
• Page End: 1928
• Publication Date: 2016-08
• Subjects: density dependence -- El Niño Southern Oscillation -- Macaroni Penguin (Eudyptes chrysolophus) -- Monte Carlo Markov chain -- population model -- predation -- sea surface temperature -- seabird -- stochastic variable selection; Ecology -- Periodicals; Ecology -- Periodicals; Écologie -- Périodiques; Ecologie; Écologie; Écologie animale; Écologie végétale; Ecology; Periodicals; 577.05
• DOI: 10.1002/ecy.1452
• Languages: English
• ISSNs: 0012-9658

Abstract

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.