Contribution of Estuarine and Coastal Habitats Within Nursery to the Diets of Juvenile Fish in Spring and Autumn
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Contribution of Estuarine and Coastal Habitats Within Nursery to the Diets of Juvenile Fish in Spring and Autumn Louise Day 1,2
&
Anik Brind’Amour 1 & Pierre Cresson 3 & Bastien Chouquet 4 & Hervé Le Bris 2
Received: 15 May 2020 / Revised: 31 July 2020 / Accepted: 25 August 2020 # Coastal and Estuarine Research Federation 2020
Abstract Coastal and estuarine nurseries are composed of habitats with different biotic and abiotic features. Quantifying the contribution of different habitats within nurseries to juvenile fish feeding would help identify those that are essential in the completion of their life cycle, by providing food resources that maximise growth and survival. Essential habitats for four bentho-demersal fish species (whiting, sea bass, plaice and common sole) in an estuarine nursery were identified using gut contents and stable isotopes. Habitats differed in isotopic ratios and benthic communities. The estuarine gradient defined the macrofauna communities and sources of organic matter used by primary consumers. Trophic niche overlaps and trophic contribution of habitats highlighted that the species used both intertidal and subtidal habitats as feeding grounds. Flatfish were local feeders and fed on prey available mainly in the habitat in which they were caught, suggesting feeding behaviour that required little energy for movement. Sea bass were concentrated in upstream habitats, with intertidal mudflats contributing for nearly half of its diet. Whiting had an ubiquitous feeding strategy, suggesting that it may target prey with the most energetic gain in the habitats. Hence, habitats were used simultaneously during the same season or asynchronously throughout the year by the juvenile fish studied, suggesting no preference for a specific habitat at the community scale. Finally, both trophic tracers demonstrated the trophic importance of intertidal mudflats, especially for the sea bass and common sole, with contributions up to the half and two-third of their diet respectively. Keywords Trophic tracers . Isotopic ratios . Gut contents . Seine estuary . Young-of-the-year
Introduction Coastal and estuarine areas act as nurseries for several marine species. The nursery concept has evolved throughout time, gaining accuracy in both spatial and temporal aspects of species utilisation (Heck et al. 1997; Beck et al. 2001, Able 2005;
Nagelkerken et al. 2015; Sheaves et al. 2015). Beck et al. (2001) formalised the concept and suggested quantitative ways of identifying nursery habitats for juvenile fish. According to these authors, a nursery is an area that has higher fish density, growth rates and survival rates than those in other coastal and estuarine areas. It is also physically connected to
Communicated by Steven Litvin Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12237-020-00823-z) contains supplementary material, which is available to authorized users. * Louise Day [email protected] Anik Brind’Amour [email protected] Pierre Cresson pierre.cress
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