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UBC Theses and Dissertations

Impacts of climate change on the trophic functioning of the world ocean du Pontavice, Hubert

Abstract

Climate change impacts on marine life in the world ocean are expected to increase over the 21st century. In this thesis, I investigated the effects of climate change on biomass flows in marine food webs and their consequences on ecosystem structure and functioning. First, the transfer efficiency and biomass residence time are estimated in the world’ shelf seas from 1950 to 2010. Based on the projected ocean warming under two climate scenarios, I highlighted that biomass transfers may be faster and less efficient by 2100 without mitigation of greenhouse gases emissions. Then, using a modelling framework called EcoTroph that is based on a representation of biomass flow, I projected the future of consumer biomass in marine food webs. From the projected changes in temperature and primary production, marine animal biomass is estimated at each trophic level on a 1° x 1° grid of the global ocean from 1950 to 2100. The projections showed that the projected alteration of biomass flows may lead to a global decline in consumer biomass by 2100 under the “no mitigation policy” climate scenario, with more pronounced impacts at higher trophic levels. In the European waters, the EcoTroph model forced by a coupled hydrodynamic-ecosystem model is used to investigate the potential climate change effects on the ecosystem structure and functioning. The results revealed that biomass and catch may decrease by 2100 under the “no mitigation policy” scenario and if fishing mortality remains constant at its current value. Overall, this thesis showed that climate change would alter biomass flows in marine ecosystems, causing a decrease in the future ocean animal biomass and direct repercussions on fisheries.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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