Dominant species drive seasonal dynamics of the fish community in the Min estuary, China

Fishery resources are currently facing multiple stresses such as overfishing, pollution and climate change. Looking into processes and mechanisms of the dynamic fish community through detailed quantitative analyses contributes to effective conservation and management of fishery resources. The Min estuary plays an important role in maintaining fisheries in southeastern coastal China, therefore the fish community in the brackish area was investigated and analyzed in this study. A total of 127 species belonging to 91 genera, 49 families and 14 orders were sampled in 2015. Eight indices reflecting four aspects of fish communities were determined, i.e. species richness, species evenness, heterogeneity and taxonomy. Differences between the indices were nonsignificant, suggesting that the use of a single diversity descriptor could not provide a full explanation. Nine dominant species in the Min estuary showed seasonal turnover by rational use of resources and co-occurring species showed correspondingly adequate habitat preferences and feeding habits to avoid competition. The species Harpadon nehereus occurred as the dominant species in three seasons except spring. High values of niche overlap among common or rare species and lower values of niche overlap among all dominant species effectively brought the diversity of the fish community into a state of equilibrium.