Migration dynamics of clupeoids in the Schelde estuary: a stable isotope approach
Guelinckx, J.; Maes, J.; De Brabandere, L.; Dehairs, F.A.; Ollevier, F.P. (2006). Migration dynamics of clupeoids in the Schelde estuary: a stable isotope approach. Est., Coast. and Shelf Sci. 66(3-4): 612-623. dx.doi.org/10.1016/j.ecss.2005.11.007
In: Estuarine, Coastal and Shelf Science. Academic Press: London; New York. ISSN 0272-7714; e-ISSN 1096-0015, more
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| Keywords |
Amphidromic systems
Behaviour > Migrations
Geography > Biogeography
Isotopes > Carbon isotopes
Isotopes > Nitrogen isotopes
Nursery grounds
Clupea harengus Linnaeus, 1758 [WoRMS]; Clupeidae Cuvier, 1816 [WoRMS]; Sprattus sprattus (Linnaeus, 1758) [WoRMS]
ANE, Netherlands, Westerschelde [Marine Regions]; ANE, North Sea [Marine Regions]; Belgium, Zeeschelde [Marine Regions]
Marine/Coastal; Brackish water |
| Author keywords |
biogeography; carbon and nitrogen stable isotopes; nursery grounds; amphidromy; Clupeidae; North Sea |
| Abstract |
Large numbers of young of the year herring (Clupea harengus L.) and sprat (Sprattus sprattus (L.)) typically enter and remain within North Sea estuaries during the winter months. The main purpose of this study was to examine their migration dynamics between the North Sea and the Schelde estuary using C and N stable isotopes. Prior to this, stomach contents were used to verify the isotopic differences between the food sources at the sampling stations. From May 2000 to April 2001 fish were collected monthly in the upper and lower estuary. Muscle tissue and stomach contents were analyzed for d13C and d15N using an EA-IRMS. Based on the stomach contents, it was demonstrated that d15N could not be used as a tracer for fish migration because the longitudinal estuarine d15N gradient had reversed completely during autumn. The d13C gradient, however, was found to be reliable for studying fish movement in the Schelde estuary. Seasonal movements of clupeoids in the Schelde estuary were analyzed by separating the temporal abundance patterns into migration groups based on their muscle isotopic composition. Immigration and emigration seem to occur continuously throughout the year. Most exchange occurred in November. During winter, immigration remained high but gradually decreased. Although the herring and sprat abundance further declined in the estuary during February and March, large seaward emigration was not fully demonstrated. As temporal overlap between immigration and emigration is concluded the results support the hypothesis that migration to estuarine nurseries is individually based. |
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