EMIBIOS: End-to-end Modelling and Indicators for BIOdiversity Scenarios
EMIBIOS is a international project funded by the French « Fondation pour la Recherche sur la Biodiversité ». It proposes to develop an end-to-end modelling approach to project future trajectories of marine biodiversity and associated ecosystem services under a combination of IPCC SRES and fisheries management scenarios in diverse marine ecosystems. The end-to-end model will ensure integration of the main components of the marine ecosystem from the physics, biogeochemistry, exploited fish species up to the fisheries and associated management and socio-economic contexts, while taking into account feedbacks within the environment-human system. Using this integrated modelling approach, the relevance of a set of biodiversity indicators for supporting decision-making will be evaluated under different scenarios of global change and fisheries management options.
Development of an integrated OSMOSE end-to-end modelling (OSMOSE E2E)
The two-ways coupling between the fish model OSMOSE and the bio-physical model ROMS-NPZD was a pioneer work developed specifically for the southern Benguela (Travers et al. 2009). Here, we aim at generalizing the approach to a family of climate models, so as to render the approach more generic.
This is a challenge requiring to handle differences in time and space scales, in units and key state variables, and to carefully select the number of species represented, as well as the number of coupling processes in order to keep the model tractable.
In addition, we will couple OSMOSE with the fisheries bio-economic model MEFISTO (Lleonart et al. 2003, Merino et al. 2007) with the aim of characterizing not only the ecological interaction but also the flow of information between ecosystems and the harvesting, economic and policy sectors involved, using the Gulf of Lions as a case study. This multidisciplinary approach is expected to reduce uncertainties about how fisheries regulations will interact with climate-induced effects on marine ecosystems and their biodiversity, allowing the optimal use of their services. Moreover, it will provide a tool to support fisheries management decision-making.
Modelling ecological impacts of climate change
In order to represent the main effects that climate change may induce on marine living organisms, the OSMOSE E2E model will take into account the following components. Firstly, the alteration by climate change of the production level and the species composition of the plankton, which form the base of the whole foodweb, will be accounted for in the hydrodynamic and biogeochemical sub-component models. Secondly, environmental variability, which is determinant for the survival of fish larvae and subsequent recruitment success of fish populations, will be implicitly taken into account in the calibration phase of OSMOSE to interannual time series (hindcast simulations). Finally, potential climate-induced changes in fish spatial distribution will be taken into account by integrating niche envelopes (Araujo and New 2007, Thuiller 2004) into OSMOSE-E2E modelling. This component is important to consider as such changes may induce spatial mismatch between predators and their prey (Durant et al. 2007) with expected cascade effects, and potential changes in the functioning of the whole ecosystem.
Simulating global change scenarios
Regional downscaling of IPCC scenarios will be done in other collaborating projects (MEECE, MERMEX, SESAME, PERSEUS, CLIMEUP). In terms of fishing scenarios, we will focus on those which would tend to destabilize the species composition of exploited communities by simulating on the one hand the overexploitation of low trophic level species (early signals of climate variability, high turnover rate, small mean size), and on the other hand the overexploitation of high trophic level species (low resilience, large mean size, high commercial value). The socio-economic scenarios will first account for demographic expansion, fish demand, and energy sources availability. Secondly, an evaluation of management actions advocated in the recent reform of the EC Common Fisheries Policy will be undertaken. By taking into account the potential effects of climate change on fish habitats and species composition, one of our ultimate objectives is to simulate the impacts of Marine Protected Areas (MPA) on biodiversity and fisheries yield, with the location and size of MPAs varying according to simulated changes in fish habitats. Simulations of the multispecies effects of MPAs using OSMOSE have already been conducted in the Benguela ecosystem (Yemane et al. 2009), but not in the context of climate change.
Cross-comparison between OSMOSE and EwE models
In all the ecosystems included in the project, there exists a complementary EwE modelling approach which represents the whole foodweb from the plankton up to top predators. To avoid conclusions being dominated by structural assumptions in the models and reduce model-based uncertainty, and to define possible trajectories of marine biodiversity under global change scenarios, we propose to systematically conduct a cross-comparison between OSMOSE and EwE models. This will be performed by means of a common set of trophic and biodiversity indicators (see Shin et al. 2004, Travers et al. 2010 for a similar approach already achieved by the team in the Benguela ecosystem).
Using models to evaluate biodiversity indicators
The biodiversity of the marine ecosystems under study will be characterized by a set of common indicators which will be selected against key criteria: measurability in all ecosystems, sensitivity to fishing pressure and management measures, understandable beyond the scientific audience. The term biodiversity is used sensu the CBD and will be focused to mean the abundance and distributions of and interactions between exploited species, communities and ecosystems. In addition, we will base our selection on the lists provided by the international IndiSeas WG (www.indiseas.org) and the EC MSFD. Both OSMOSE-E2E and EwE models will be used as test laboratories to document the behaviour of these biodiversity indicators under different scenarios of global change. In particular, the simulated scenarios will be used to evaluate which indicators used for tracking fishing effects (and consequently the effects of fisheries management measures) are less sensitive to climate change, i.e. are more exclusive to fishing pressure. The use of ecosystem models will also be extremely useful for estimating reference levels of indicators (e.g. target reference levels for optimizing fisheries yield, or tipping and threshold points beyond which the exploited communities are at risk) under current situation, and under different scenarios of global change.
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