Structure and seasonal variability in fish food webs in a small macrotidal estuary (Canche estuary, Eastern English Channel) based on stable carbon and nitrogen isotope analysis

Loc’h, François Le; Rolet, Céline; Veillet, Guillaume; Munaron, Jean-Marie; Rabhi, Khalef; Djebar, Assia; Amara, Rachid; Lasram, Frida Ben Rais

doi:10.1016/j.rsma.2021.101694

Cited by 8 publications

(3 citation statements)

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“…The trophic position (TP; Cabana and Rasmussen, 1996) [ 53 ] of eels was calculated following Eq (4) : Where TP Base is the trophic position of isotopic baseline, δ 15 N is the nitrogen isotopic of eels, δ 15 N Base is the isotopic nitrogen of the baseline, and TDF is the trophic discrimination factor. Mean δ 15 N values of sediment organic matter (SOM) inside the Canche (between 4.67 to 7.19‰) [ 54 ] and the Somme (between 6.93 to 8.98‰) [ 55 ] estuaries at different salinity and seasons ( S1 Table ) were used as baseline resource to calculate the δ 15 N Base . The baseline resource used was considered as a TP set at 1 and the TDF has been set to 3.4‰ [ 56 ].…”

Section: Methodsmentioning

confidence: 99%

Role of estuarine habitats for the feeding ecology of the European eel (Anguilla anguilla L.)

et al. 2022

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This study aims to characterize and compare the feeding ecology of the European eels (Anguilla anguilla L.) during the continental phase (i.e. yellow and silver) along a salinity gradient (i.e. lower, middle and upper) in six northern France estuaries (i.e. brackish water). The diet and stable isotopic (i.e. δ15N and δ13C values) compositions of eels collected with a fyke net in six estuaries (Slack, Wimereux, Liane, Canche, Authie and Somme estuaries) located along the French coast of the eastern English Channel per season over a year were described by combining gut content and stable isotope analyses. Eel guts were dominated by typical BW prey, Malacostraca and Actinopterygii (54% and 40%, respectively), with the gammare Gammarus zaddachi and the green crab Carcinus maenas (38% and 14%, respectively), and smaller yellow eels of A. anguilla and juvenile European flounder, Platichthys flesus (19% and 14%, respectively) being the most frequently found in their guts. The δ13C values of a majority of eels confirmed the sea- and brackish water-specific carbon resources. Dietary and isotopic niche revealed no clear change between total length, silvering stages and seasons, but a significant difference between salinity gradients and estuaries. Eels δ13C values showed significant enrichment from upper to lower along the estuaries while the δ15N values showed an inverse effect, with the lowest values in the lower part and highest in the upper part. Higher variability in δ13C values in larger estuaries suggested that eels feed on a wide range of food sources than in smaller estuaries. While eels in the smaller estuaries fed mainly on Actinopterygii prey, eels in the larger ones had a lower trophic level (i.e. δ15N values) and fed mainly on Malacostraca prey. This spatial difference in dietary and isotopic niche is discussed in relation to biological structure of eel and environmental variables.

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Section: Methodsmentioning

confidence: 99%

Role of estuarine habitats for the feeding ecology of the European eel (Anguilla anguilla L.)

et al. 2022

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“…Although it is common for amounts of nitrogen to decrease as salinity increases from freshwater to marine water due to mixing (Baeta et al, 2009;Connolly et al, 2013), the δ 15 N observed confirmed the absence of a salinity gradient in EML. The δ 15 N is often used as a tracer to detect human sources of nitrogen, particularly in lagoon and estuarine environments (Vizzini & Mazzola, 2004;Vizzini et al, 2005;Bouaziz et al, 2021), As higher δ 15 N can be considered to originate from human activities (Fry, 2002;Vizzini & Mazzola, 2004;Vizzini et al, 2005). The δ 15 N in EML highlights relatively low anthropogenic nitrogen input, which could be due to the absence of human activities (Draredja et al, 2019).…”

Section: Potential Food Sources For Fish In El Mellah Lagoonmentioning

confidence: 99%

Fish food-web structure of a southern Mediterranean lagoon (El Mellah Lagoon, Algeria): what we can learn from stable isotope analysis

et al. 2023

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The structure of a fish food-web was described for the first time in a coastal lagoon in the southern Mediterranean Sea by analysing stable carbon and nitrogen isotopes of fish species and their potential food sources. The El Mellah Lagoon (EML) located in extreme north-eastern Algeria, is the only coastal lagoon in the southern Mediterranean with low human pressure due to few human activities and its protected status under the Ramsar Convention. We investigated the structure of the fish food-web in the spring at four stations in the lagoon that differed in their proximity to rivers and the channel, which connects to the sea. The results provided insight into ecological functions of EML as a feeding area for all fish species caught in the lagoon, in particular marine migrant juveniles and resident species. The δ13C results highlighted the importance of marine organic matter on the functioning of the EML fish food-web, to which organic matter in marine sediments and likely microphytobenthos contribute most. Our study also revealed the importance of seagrass (Ruppia sp.) for detritivorous fish (i.e., Mugilidae species) and for their potential to shelter a wide variety of benthic invertebrates that are potential food sources for benthivorous fish. Our study revealed the small influence of freshwater inputs on the functioning of the EML food-web and that juvenile marine fish may use the lagoon for reasons other than feeding, most likely to avoid predation and obtain physiological advantages.

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“…For example, Howe and Simenstad [ 17 ] referred to any marsh-derived organic material as autochthonous and riverine and marine phytoplankton as allochthonous because it originated from outside of their target study system. Conversely, Bouaziz et al [ 23 ] defined phytoplankton and aquatic macrophytes as autochthonous and any organic matter of terrestrial origin as allochthonous. For the sake of our study, we define allochthonous sources of organic matter as terrestrial in origin and autochthonous sources as aquatic in origin [ 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

Allochthonous marsh subsidies enhances food web productivity in an estuary and its surrounding ecosystem mosaic

Davis,

Woo,

De La Cruz

et al. 2024

PLoS ONE

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Terrestrial organic matter is believed to play an important role in promoting resilient estuarine food webs, but the inherent interconnectivity of estuarine systems often obscures the origins and importance of these terrestrial inputs. To determine the relative contributions of terrestrial (allochthonous) and aquatic (autochthonous) organic matter to the estuarine food web, we analyzed carbon, nitrogen, and sulfur stable isotopes from multiple trophic levels, environmental strata, and habitats throughout the estuarine habitat mosaic. We used a Bayesian stable isotope mixing model (SIMM) to parse out relationships among primary producers, invertebrates, and a pelagic and demersal fish species (juvenile Chinook salmon and sculpin, respectively). The study was carried out in the Nisqually River Delta (NRD), Washington, USA, a recently-restored, macrotidal estuary with a diverse habitat mosaic. Plant groupings of macroalgae, eelgrass, and tidal marsh plants served as the primary base components of the NRD food web. About 90% of demersal sculpin diets were comprised of benthic and pelagic crustaceans that were fed by autochthonous organic matter contributions from aquatic vegetation. Juvenile salmon, on the other hand, derived their energy from a mix of terrestrial, pelagic, and benthic prey, including insects, dipterans, and crustaceans. Consequently, allochthonous terrestrial contributions of organic matter were much greater for salmon, ranging between 26 and 43%. These findings demonstrate how connectivity among estuarine habitat types and environmental strata facilitates organic matter subsidies. This suggests that management actions that improve or restore lateral habitat connectivity as well as terrestrial-aquatic linkages may enhance allochthonous subsidies, promoting increased prey resources and ecosystem benefits in estuaries.

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Structure and seasonal variability in fish food webs in a small macrotidal estuary (Canche estuary, Eastern English Channel) based on stable carbon and nitrogen isotope analysis

Cited by 8 publications

References 83 publications

Role of estuarine habitats for the feeding ecology of the European eel (Anguilla anguilla L.)

Role of estuarine habitats for the feeding ecology of the European eel (Anguilla anguilla L.)

Fish food-web structure of a southern Mediterranean lagoon (El Mellah Lagoon, Algeria): what we can learn from stable isotope analysis

Allochthonous marsh subsidies enhances food web productivity in an estuary and its surrounding ecosystem mosaic

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