Nonlinear effects of body size and optical attenuation on Diel Vertical Migration by zooplankton

Type Article
Date 2016-03
Language English
Author(s) Ohman Mark D.1, Romagnan Jean-Baptiste2
Affiliation(s) 1 : California Current Ecosystem LTER SiteScripps Institution of Oceanography, University of CaliforniaSan Diego La Jolla California
2 : Sorbonne Universités, UPMC Université Paris 06, UMR 7093, and CNRS, Observatoire océanologiqueF‐06230Villefranche‐sur‐mer France
Source Limnology and Oceanography (0024-3590) (Wiley), 2016-03 , Vol. 61 , N. 2 , P. 765-770
DOI 10.1002/lno.10251
WOS© Times Cited 68
Abstract

We adopt a trait-based approach to explain Diel Vertical Migration (DVM) across a diverse assemblage of planktonic copepods, utilizing body size as a master trait. We find a reproducible pattern of body size-dependence of day and night depths occupied, and of DVM. Both the smallest surface-dwelling and the largest deeper-dwelling copepods refrain from migrations, while intermediate-sized individuals show pronounced DVM. This pattern apparently arises as a consequence of size-dependent predation risk. In the size classes of migratory copepods the amplitude of DVM is further modulated by optical attenuation in the ocean water column because increased turbidity decreases encounter rates with visually hunting predators. Long-term changes in the ocean optical environment are expected to alter the vertical distributions of many copepods and thus to affect predator-prey encounters as well as oceanic carbon export.

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