Seasonal Variation In Trophic Niche Of Common Fish In The Min Estuary Based On Stable Isotope

Fish feeding ecology and trophic relationships are the important contents of marine ecotrophic dynamics.The Min Estuary of the East China Sea,as the largest estuary in Fujian Province,is the traditional coastal fishing ground.Studies on the fish ecology and foraging associations in this sea area are of significant scientific and practical value.Based on trawl survey of the Min Estuary in January?Winter?,May?Spring?,August?Summer?,and November?Autumn?in 2015,stable isotope analysis was used to study the trophic niche of the main fishes and trophic structure of the fish community.The main results were as follows:?1?There were extremely significant differences?p<0.01?in the?¹³C values and?¹⁵N values of Coilia mystus among all the seasons.There was a clear separation in the trophic niches between spring and other seasons.The average trophic level of Coilia mystus was 3.96.Combined with the stable isotopic mixture model analysis,it mainly feeded on zooplankton and crustacea and the mean contribution rate was 61.45%.The largest core trophic niche appeared in spring.?2?There were extremely significant differences?p<0.01?in the?¹³C values but no significant differences?p>0.05?in the?¹⁵N values of Collichthy lucidus among all the seasons.There was a clear separation in the trophic niches between spring and winter.The average trophic level of Collichthy lucidus was 3.62.Combined with the stable isotopic mixture model analysis,it mainly feeded on zooplankton and the mean contribution rate was 58.51%.The largest core trophic niche appeared in autumn.?3?There were extremely significant differences?p<0.01?in the?¹³C values and significant differences?p<0.05?in the?¹⁵N values of Harpadon nehereus among all the seasons.There was a clear separation in the trophic niches between spring and other seasons.The average trophic level of Harpadon nehereus was 3.59.Combined with the stable isotopic mixture model analysis,it mainly feeded on fish and the mean contribution rate was 50.1%.The largest core trophic niche appeared in winter.?4?According to IRI,a total of 22 species were identified as common fishes in the Min Estuary.Trophic structure of common fish remarkably varied in the four seasons,as TA,SEAc,CR,NR and CD increased in succession from summer,autumn,winter to spring.From the results in this study we deduced that seasonal differences in trophic structure of common fishes were related to the fish spawning migration and the diversity of food source.