Capturing the big picture of Mediterranean marine biodiversity with an end-to-end model of climate and fishing impacts

Abstract

The Mediterranean Sea is one of the main hotspots of marine biodiversity in the world. The combined pressures of fishing activity and climate change have also made it a hotspot of global change amidst increasing concern about the worsening status of exploited marine species. To anticipate the impacts of global changes in the Mediterranean Sea, more integrated modelling approaches are needed, which can then help policymakers prioritize management actions and formulate strategies to mitigate impacts and adapt to changes. The aim of this study was to develop a holistic model of marine biodiversity in the Mediterranean Sea with an explicit representation of the spatial, multispecies dynamics of exploited resources subject to the combined influence of climate variability and fishing pressure. To this end, we used the individual-based OSMOSE model (Object-oriented Simulator of Marine ecOSystEms), including 100 marine species (fish, cephalopods and crustaceans) representing about 95% of the total declared catch, at a high spatial resolution (400 km2) and a large spatial scale (the entire Mediterranean basin)the first time such a resolution and scale have been modelled. We then combined OSMOSE with the NEMOMED 12 physical model and the Eco3M-S biogeochemical low trophic level model to build the endto-end model, OSMOSE-MED. We fitted OSMOSE-MED model with observed or estimated biomass and commercial catch data using a likelihood approach and an evolutionary optimization algorithm. The outputs of OSMOSE-MED were then verified against observed biomass and catch data, and compared with independent datasets (MEDITS data, diet composition and trophic levels). The model resultsat different hierarchical levels, from individuals to the scale of the ecosystemwere consistent with current knowledge of the structure, functioning and dynamics of the ecosystems in the Mediterranean Sea. While the model could be further improved in future iterations, all the modelling stepsthe comprehensive representation of key ecological processes and feedback, the selective parameterization of the model, and the comparison with observed data in the validation processstrengthened the predictive performance of OSMOSE-MED and thus its relevance as an impact model to explore the future of marine biodiversity under scenarios of global change. It is a promising tool to support ecosystem-based fishery management in the Mediterranean Sea. Highlights ► An End-to-End model (OSMOSE-MED) was built at the whole Mediterranean scale. ► One hundred marine species, representing 95 % of total declared catches, were embedded. ► OSMOSE-MED was fitted to observed and estimated data of biomass and catch. ► Results were consistent with current knowledge and observations on the system. ► The model can be used in support to fisheries management and biodiversity conservation.

Contrasted patterns in climate change risk for Mediterranean fisheries

“…The objective of this CRA was to determine the species and nations most at risk in the Mediterranean Sea, that is, those that would experience the strongest impacts from climate change. The studied species were taken from recent modelling studies on marine biodiversity in the Mediterranean Sea (Moullec, Barrier, et al, 2019; Moullec, Velez, et al, 2019). This selection was composed of 86 fish species among the 635 species included in the FishMed database (Albouy et al, 2015), chosen based on data availability (i.e.…”

“…Availability of traits, abundance and spatial distribution data were key to this selection since these were necessary to determine species’ sensitivity and their geographical shifts due to climate change. Together, these species represent 95% of the declared fisheries catches in the Mediterranean Sea between 2006 and 2013 and play major roles in food web dynamics and ecosystem functioning (FAO, 2006–2017; Moullec, Velez, et al, 2019). The Mediterranean coast is composed of 22 countries.…”

Copernicus Marine Service Ocean State Report, Issue 5

“…Spedicato, Zupa, et al 2019), and the development of ecosystem models (e.g. Grüss et al 2018;Moullec et al 2019). Sampling protocols of multiannual surveys are usually standardised for sampling design, gear geometry, sampling season, sampling locations to allow comparability of the trawl survey data across space and time.…”

The Celtic Sea Through Time and Space: Ecosystem Modeling to Unravel Fishing and Climate Change Impacts on Food-Web Structure and Dynamics

“…Despite their interest in predicting past, current, and future species distributions, habitat modeling approaches have still been rarely coupled to ecosystem models (Grüss et al, 2016;Coll et al, 2019;Moullec et al, 2019b). In this study, we successfully integrated the outputs of a statistical habitat model into a spatial trophic model.…”