Marine Research Findings of the VECTORS Project

This website provides access to the research results of the VECTORS project, which can be used to support marine management decisions, policies and governance as well as future research and investment. VECTORS was a large scale project that brought together more than 200 expert researchers from 16 different countries. It examined the significant changes taking place in European seas, their causes, and the impacts they will have on society.

A metabolic scope based model of fish response to environmental changes

Eco-physiology studies, performed in laboratory under controlled conditions, provide an essential tool for quantifying the impact of environmental changes on the metabolism and behaviour of individual fish. One way of quantifying such impact is by measuring the Metabolic Scope (MS) of a fish and how it is affected by environmental factors. Laboratory experiments were performed to calculate the empirical mathematical equations describing the variation of the MS of flathead grey mullet, Mugil cephalus, under different environmental conditions (water temperature and water oxygen concentration). The equations obtained were introduced into a coupled hydrodynamic–ecological numerical model in order to reproduce the temporal and spatial variation in MS of a M. cephalus fish population in the Oristano Gulf and the Cabras Lagoon system (Italy), a typical Mediterranean shallow water environment. This approach, combined with observation on the temporal and spatial distribution of fishes, allowed predictions of fish habitat suitability.

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Setup of a habitat-suitability model based on ecophysiological equations to predict the effects of environmental changes on fish distributions.

The overall aim was to reproduce the ecosystem functioning and to evaluate the seasonal variation in MS of an M. cephalus population in a shallow water Mediterranean environment: the Oristano Gulf system and the Cabras Lagoon system (Western Mediterranean Sea). This was achieved by integrating the laboratory derived MS empirical equations1 into a coupled hydrodynamic (SHYFEM) - ecological (Biogeochemical Flux Model, BFM) numerical model. Numerical simulations were performed to reproduce the seasonal and spatial changes in the water temperature and dissolved oxygen and to investigate their effect on the relative suitability of the local environment, expressed as MS.

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The two environments (Oristano Gulf and Cabras Lagoon) were characterised by differences in temporal and spatial variability of the M. cephalus habitat suitability factor.

The results from the numerical simulations showed that during spring and the beginning of summer Cabras Lagoon provides a higher MS for M. cephalus than the Oristano Gulf. During the rest of the year, apart from transitional phases (Spring March, Autumn September), the gulf provides more suitable conditions and a higher MS for M. cephalus. Although the MS in the Cabras Lagoon is lower than in the gulf during most of the year, it is only towards the end of summer, when water temperature exceeds the fish optimal temperature, that the environmental conditions in the lagoon become physiologically less favourable to fish.

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Changes in MS, generated by seasonal variation in temperature and oxygen, are important factors responsible for triggering the onset of seasonal migration of fishes between the different environments.

Differences in MS between gulf and lagoon and migration patterns might in part explain the migratory patterns observed. Indeed, the simulated critical summer period (end-July to September, when MS became lower in the lagoon than in the Gulf) corresponds approximately to the timing of capture of M. cephalus, as they migrate out of the lagoon, obtained by fisheries data between 2007 and 2009. While the results obtained are specific for the investigated site and the selected fish species, the method described here can be applied to other marine environments and fish species. In addition, the present approach, if combined with observations on the spatial and temporal distribution of fish, can also represent a valuable management tool for predicting the relative productivity of fish populations, because of the relationship between MS and growth.

References

Lead Author:

Andrea Cucco
(andrea.cunospamcco@cnr.it)
Institute for Coastal Marine Environment of the National Research Council (IAMC-CNR)
Date of research: January 2015

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Could MPAs mitigate the effects of fishing? 

Ecology - Economy interactions in fisheries 

Fishing vessels interactions with other activities 

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This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 266445
© Vectors 2015. Coordinated by Plymouth Marine Laboratory.