Introduction
Forecasted long-term trends in environmental parameters, induced by climate changes, need to be considered in the ongoing and future management of blue food productions (sensu Blue food assessment, 2022), in order to attempt a sound adaptation to changes that are likely to affect these activities (Cochrane et al., 2009; FAO, 2015). Here we apply a dynamic food web model in a marine coastal area located in the Gulf of Venice (Northern Adriatic Sea), were longline mussel farms (Mediterranean mussel, Mytilius galloprovincialis) coexist with different types of fisheries, including, recreational, artisanal, clam dredging and trawling, and with important conservation assets, including a marine rocky bottom Natura 2000 site. Our final aim is to produce forecasts considering both scenarios of climate change and interaction of aquaculture with other uses of the sea, in order to support the analysis of future blue food production potential in the area in the framework of maritime spatial planning.
Methods
An existing food web model (based on Ecopath with Ecosim) of the northern Adriatic Sea was adapted to this coastal area (Donati et al., 2021), characterised by the presence of mussel farms, a sandy bottom hosting clam beds of high commercial importance, and biogenic rocky outcrops relevant for biodiversity conservation. 28 trophic groups were defined in the model, see Figure 1, considering different habitats and tolerance to environmental drivers. Mussel farming was characterised based on previous studies in the area (Brigolin et al., 2009). Fishing activities was described considering 6 different fleets (including different trawling gears, hydraulic dredge, artisanal and recreational fishery). Dynamic food web simulations were performed by introducing time series of water temperature and primary production (climate change) and fishing effort/aquaculture production (bluefood management). Simulations considered a time frame of 40 years, from 2014 to 2054, comparing 2 scenarios RCP, 4.5 and 8.5. Downscaling for forcing variables were taken both from the EURO-CORDEX CMIP5 and from biogeochemical model outputs (ERSEM), produced in the framework of the CERES H2020 project. The FWM provided as an output time series of group biomasses, catches, and ecosystem functioning indicators. The temporal variation of ecosystem functioning indicators and of trophic groups biomasses was assessed with respect to a baseline scenario.
Results and discussion
Tolerance curves identified (Figure 2left) and used in the dynamic FWM allowed to derive a comprehensive set of ecosystem functioning indicators under the two CC scenarios considered (as shown in Figure 2 right, considering only temperature induced changes). Higher percentage of variation was presented by those indicators associated to groups biomasses, as the commercial B and Kempton (K), showing decrease ranging between 10 and 15%. Indeed, different groups including species of high commercial interest presented a substantial biomass decrease. Results provided differing assessments when considering only variations in mussel aquaculture and fishery productivity, or the overall ecosystem functioning of the area. This is discussed with regard to the ecological carrying capacity concept.
Acknowledgements
This research was supported by the Interreg Italy-Croatia CASCADE “Costal and marine waters integrated monitoring systems for ecosystems protection AnD management”, and MSP-MED project “Towards the operational implementation of MSP in our common Mediterranean Sea”, EMFF Work Programme 2018 EASME tender EASME/EMFF/2018/1.2.1.5.
References
Bluefood assessment, 2022. https://bluefood.earth/. Last accessed 30/03/2022
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