Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C flux

Crustacean zooplankton, often dominated by copepods and euphausiids, are the major phytoplankton grazers in coastal upwelling systems. It has been argued that zooplankton grazing is a size-dependent process, such that models incorporating the size structure of zooplankton are appropriate for describ...

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Autores principales:	Valdés,Valentina, Escribano,Rubén, Vergara,Odette
Lenguaje:	English
Publicado:	Pontificia Universidad Católica de Valparaíso. Facultad de Recursos Naturales. Escuela de Ciencias del Mar 2017
Materias:	copepods grazing ingestion rate body size upwelling Chile
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000100005
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spelling	oai:scielo:S0718-560X20170001000052017-04-21Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C fluxValdés,ValentinaEscribano,RubénVergara,Odette copepods grazing ingestion rate body size upwelling Chile Crustacean zooplankton, often dominated by copepods and euphausiids, are the major phytoplankton grazers in coastal upwelling systems. It has been argued that zooplankton grazing is a size-dependent process, such that models incorporating the size structure of zooplankton are appropriate for describing herbivore C-transfer. Here, based on the size-spectrum theory and on gut-fluorescence experiments, conducted with numerically dominant copepods from two upwelling sites off the Chilean coast, we show that C-specific ingestion rates of copepods are size-dependent. We further show that the size structure of the copepod community, synthesized by the slope of the normalized size spectrum, determines the impact of grazing on phytoplankton. C-specific ingestion rates, depending on species size, were in the range of 0.14-353.97 (ng C μg C-1 h-1). A modelled normalized biomass-spectra of a copepod community in the size range of 0.5 to 74.0 μg C showed that C-specific grazing impact can increase by a factor of 4 when small-sized species (0.1-10 μg C ind-1), such as Paracalanus cf. indicus, Acartia tonsa, Oncaea spp. and Corycaeus spp., dominate the community in terms of biomass. By contrast, when larger-sized copepods dominate (10-100 μg C ind-1), such as Calanus chilensis, Calanoidespatagoniensis and Rhyncalanus nasutus, total zooplankton biomass may increase, but with a sharp decrease in the efficiency of C transfer via herbivores. Our findings indicate that processes affecting the size structure of zooplankton communities can substantially impact the phytoplankton C flux through the pelagic food web, thus controlling production of higher trophic levels.info:eu-repo/semantics/openAccessPontificia Universidad Católica de Valparaíso. Facultad de Recursos Naturales. Escuela de Ciencias del MarLatin american journal of aquatic research v.45 n.1 20172017-03-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000100005en10.3856/vol45-issue1-fulltext-5
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	copepods grazing ingestion rate body size upwelling Chile
spellingShingle	copepods grazing ingestion rate body size upwelling Chile Valdés,Valentina Escribano,Rubén Vergara,Odette Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C flux
description	Crustacean zooplankton, often dominated by copepods and euphausiids, are the major phytoplankton grazers in coastal upwelling systems. It has been argued that zooplankton grazing is a size-dependent process, such that models incorporating the size structure of zooplankton are appropriate for describing herbivore C-transfer. Here, based on the size-spectrum theory and on gut-fluorescence experiments, conducted with numerically dominant copepods from two upwelling sites off the Chilean coast, we show that C-specific ingestion rates of copepods are size-dependent. We further show that the size structure of the copepod community, synthesized by the slope of the normalized size spectrum, determines the impact of grazing on phytoplankton. C-specific ingestion rates, depending on species size, were in the range of 0.14-353.97 (ng C μg C-1 h-1). A modelled normalized biomass-spectra of a copepod community in the size range of 0.5 to 74.0 μg C showed that C-specific grazing impact can increase by a factor of 4 when small-sized species (0.1-10 μg C ind-1), such as Paracalanus cf. indicus, Acartia tonsa, Oncaea spp. and Corycaeus spp., dominate the community in terms of biomass. By contrast, when larger-sized copepods dominate (10-100 μg C ind-1), such as Calanus chilensis, Calanoidespatagoniensis and Rhyncalanus nasutus, total zooplankton biomass may increase, but with a sharp decrease in the efficiency of C transfer via herbivores. Our findings indicate that processes affecting the size structure of zooplankton communities can substantially impact the phytoplankton C flux through the pelagic food web, thus controlling production of higher trophic levels.
author	Valdés,Valentina Escribano,Rubén Vergara,Odette
author_facet	Valdés,Valentina Escribano,Rubén Vergara,Odette
author_sort	Valdés,Valentina
title	Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C flux
title_short	Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C flux
title_full	Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C flux
title_fullStr	Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C flux
title_full_unstemmed	Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C flux
title_sort	scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton c flux
publisher	Pontificia Universidad Católica de Valparaíso. Facultad de Recursos Naturales. Escuela de Ciencias del Mar
publishDate	2017
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2017000100005
work_keys_str_mv	AT valdesvalentina scalingcopepodgrazinginacoastalupwellingsystemtheimportanceofcommunitysizestructureforphytoplanktoncflux AT escribanoruben scalingcopepodgrazinginacoastalupwellingsystemtheimportanceofcommunitysizestructureforphytoplanktoncflux AT vergaraodette scalingcopepodgrazinginacoastalupwellingsystemtheimportanceofcommunitysizestructureforphytoplanktoncflux
_version_	1714205175221059584

Scaling copepod grazing in a coastal upwelling system: the importance of community size structure for phytoplankton C flux

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