Combined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effects

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dc.contributor.authorTravers-Trolet, Morganeen_ZA
dc.contributor.authorShin, Yunne-Jaien_ZA
dc.contributor.authorShannon, Lynne Jen_ZA
dc.contributor.authorMoloney, Coleen Len_ZA
dc.contributor.authorField, John Gen_ZA
dc.date.accessioned2016-01-02T05:06:45Z
dc.date.available2016-01-02T05:06:45Z
dc.date.issued2014en_ZA
dc.description.abstractThe effects of climate and fishing on marine ecosystems have usually been studied separately, but their interactions make ecosystem dynamics difficult to understand and predict. Of particular interest to management, the potential synergism or antagonism between fishing pressure and climate forcing is analysed in this paper, using an end-to-end ecosystem model of the southern Benguela ecosystem, built from coupling hydrodynamic, biogeochemical and multispecies fish models (ROMS-N 2 P 2 Z 2 D 2 -OSMOSE). Scenarios of different intensities of upwelling-favourable wind stress combined with scenarios of fishing top-predator fish were tested. Analyses of isolated drivers show that the bottom-up effect of the climate forcing propagates up the food chain whereas the top-down effect of fishing cascades down to zooplankton in unfavourable environmental conditions but dampens before it reaches phytoplankton. When considering both climate and fishing drivers together, it appears that top-down control dominates the link between top-predator fish and forage fish, whereas interactions between the lower trophic levels are dominated by bottom-up control. The forage fish functional group appears to be a central component of this ecosystem, being the meeting point of two opposite trophic controls. The set of combined scenarios shows that fishing pressure and upwelling-favourable wind stress have mostly dampened effects on fish populations, compared to predictions from the separate effects of the stressors. Dampened effects result in biomass accumulation at the top predator fish level but a depletion of biomass at the forage fish level. This should draw our attention to the evolution of this functional group, which appears as both structurally important in the trophic functioning of the ecosystem, and very sensitive to climate and fishing pressures. In particular, diagnoses considering fishing pressure only might be more optimistic than those that consider combined effects of fishing and environmental variability.en_ZA
dc.identifier.apacitationTravers-Trolet, M., Shin, Y., Shannon, L. J., Moloney, C. L., & Field, J. G. (2014). Combined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effects. <i>PLoS One</i>, http://hdl.handle.net/11427/16170en_ZA
dc.identifier.chicagocitationTravers-Trolet, Morgane, Yunne-Jai Shin, Lynne J Shannon, Coleen L Moloney, and John G Field "Combined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effects." <i>PLoS One</i> (2014) http://hdl.handle.net/11427/16170en_ZA
dc.identifier.citationTravers-Trolet, M., Shin, Y. J., Shannon, L. J., Moloney, C. L., & Field, J. G. (2014). Combined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effects. PloS one, 9(4), e94286. doi:10.1371/journal.pone.0094286en_ZA
dc.identifier.ris TY - Journal Article AU - Travers-Trolet, Morgane AU - Shin, Yunne-Jai AU - Shannon, Lynne J AU - Moloney, Coleen L AU - Field, John G AB - The effects of climate and fishing on marine ecosystems have usually been studied separately, but their interactions make ecosystem dynamics difficult to understand and predict. Of particular interest to management, the potential synergism or antagonism between fishing pressure and climate forcing is analysed in this paper, using an end-to-end ecosystem model of the southern Benguela ecosystem, built from coupling hydrodynamic, biogeochemical and multispecies fish models (ROMS-N 2 P 2 Z 2 D 2 -OSMOSE). Scenarios of different intensities of upwelling-favourable wind stress combined with scenarios of fishing top-predator fish were tested. Analyses of isolated drivers show that the bottom-up effect of the climate forcing propagates up the food chain whereas the top-down effect of fishing cascades down to zooplankton in unfavourable environmental conditions but dampens before it reaches phytoplankton. When considering both climate and fishing drivers together, it appears that top-down control dominates the link between top-predator fish and forage fish, whereas interactions between the lower trophic levels are dominated by bottom-up control. The forage fish functional group appears to be a central component of this ecosystem, being the meeting point of two opposite trophic controls. The set of combined scenarios shows that fishing pressure and upwelling-favourable wind stress have mostly dampened effects on fish populations, compared to predictions from the separate effects of the stressors. Dampened effects result in biomass accumulation at the top predator fish level but a depletion of biomass at the forage fish level. This should draw our attention to the evolution of this functional group, which appears as both structurally important in the trophic functioning of the ecosystem, and very sensitive to climate and fishing pressures. In particular, diagnoses considering fishing pressure only might be more optimistic than those that consider combined effects of fishing and environmental variability. DA - 2014 DB - OpenUCT DO - 10.1371/journal.pone.0094286 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2014 T1 - Combined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effects TI - Combined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effects UR - http://hdl.handle.net/11427/16170 ER - en_ZA
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pone.0094286en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/16170
dc.identifier.vancouvercitationTravers-Trolet M, Shin Y, Shannon LJ, Moloney CL, Field JG. Combined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effects. PLoS One. 2014; http://hdl.handle.net/11427/16170.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentMarine Research (MA-RE) Instituteen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_ZA
dc.rights.holder© 2014 Travers-Trolet et alen_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/4.0en_ZA
dc.sourcePLoS Oneen_ZA
dc.source.urihttp://journals.plos.org/plosoneen_ZA
dc.subject.otherBiomass (ecology)en_ZA
dc.subject.otherMarine fishen_ZA
dc.subject.otherPredationen_ZA
dc.subject.otherMarine ecosystemsen_ZA
dc.subject.otherPhytoplanktonen_ZA
dc.subject.otherZooplanktonen_ZA
dc.subject.otherEcosystemsen_ZA
dc.subject.otherFish physiologyen_ZA
dc.titleCombined fishing and climate forcing in the southern Benguela upwelling ecosystem: an end-to-end modelling approach reveals dampened effectsen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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