Effects of copepod size on fish growth: a model based on data for North Sea sandeel

M van Deurs,C Jørgensen,Ø Fiksen

doi:10.3354/meps11092

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 520:235-243 (2015) - DOI: https://doi.org/10.3354/meps11092 Effects of copepod size on fish growth: a model based on data for North Sea sandeel Mikael van Deurs1,3,*, Christian Jørgensen2, Øyvind Fiksen2 1DTU Aqua National Institute of Aquatic Resources, Technical University of Denmark (DTU), Jægersborg Alle 1, Charlottenlund Castle, 2920 Charlottenlund, Denmark 2Thormøhlensgate 53B 3rd floor, Department of Biology, University of Bergen, PO Box 7803, 5020 Bergen, Norway 3Present address: Lund University, Sölvegatan 37, International Postal Code 50, Lund, Sweden *Corresponding author: mvd@aqua.dtu.dk ABSTRACT: In productive marine off-shore ecosystems, the flow of energy from zooplankton to large predators is channeled through a few species of short-lived, highly abundant schooling planktivorous fish. There are indications that these species respond to qualitative and phenological changes in the zooplankton. If so, the climate-induced alterations of the local copepod communities that we see in temperate and arctic regions may influence the energy flux in marine food chains. In order to investigate how different processes contribute to the relationship between copepod size and fish growth, we merged 2 mechanistic models from relevant data: (1) a model of the bioenergetics and stomach filling/evacuation dynamics, and (2) a Holling type II functional response model that encompasses visual range from basic principles. The model predicts that going from a situation where large Calanus copepods (2 mm) dominate the prey field of lesser sandeel Ammodytes marinus in the central North Sea to a situation where only relatively small (1 mm) and less energy-rich copepods are available roughly halves the energy intake of sandeels even if prey biomass concentration remains constant. Visual constraint on foraging was the most important factor, followed by handling time limitation and prey energy content. These limitations became stronger with increasing fish length, showing that copepod size and energy content have a strong effect on the specific growth potential of these fish. KEY WORDS: Prey preference · Bioenergetics · Optimal foraging · North Sea regime-shift · Climate change · Ammodytes · Holling disc · Calanus · Handling time limitation · Food quality Full text in pdf format PreviousNextCite this article as: van Deurs M, Jørgensen C, Fiksen Ø (2015) Effects of copepod size on fish growth: a model based on data for North Sea sandeel. Mar Ecol Prog Ser 520:235-243. https://doi.org/10.3354/meps11092 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 520. Online publication date: February 03, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Highlights

IntroductionIn marine productive off-shore ecosystems, the flow of energy from zooplankton to large predators (fish, birds, and mammals) is often channeled through a few species of short-lived, highly abundant schooling planktivorous fish ( known as the small pelagics, forage fish, or short-lived industrial species)
In marine productive off-shore ecosystems, the flow of energy from zooplankton to large predators is often channeled through a few species of short-lived, highly abundant schooling planktivorous fish
The model predicts that going from a situation where large Calanus copepods (2 mm) dominate the prey field of lesser sandeel Ammodytes marinus in the central North Sea to a situation where only relatively small (1 mm) and less energy-rich copepods are available roughly halves the energy intake of sandeels even if prey biomass concentration remains constant

Summary

Introduction

In marine productive off-shore ecosystems, the flow of energy from zooplankton to large predators (fish, birds, and mammals) is often channeled through a few species of short-lived, highly abundant schooling planktivorous fish ( known as the small pelagics, forage fish, or short-lived industrial species). While most zooplankton in the North Sea reaches sizes up to 1.3 mm (prosome length), Calanus finmarchicus and C. helgolandicus are the only abundant copepods that become bigger (adults reach lengths of 2 to 3 mm; Pitois et al 2009). The abundance of C. finmarchicus has declined all over the northeastern Atlantic, whereas C. helgolandicus has increased, but only in the southern North Sea (Planque & Taylor 1998). Little attention has been dedicated to the long-term changes in abundance and biomass of smaller calanoids such as the genera Temora, Pseudocalanus, Centropages, Paracalanus, Oithona, Microsetella, and Oncaea, (Nielsen et al 1993), but the combined biomass of all calanoid species has seemingly remained unchanged in the northeastern Atlantic (including the North Sea) (Planque & Batten 2000, Beaugrand 2004)

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