The impact of geomorphology of marsh creeks on fish assemblage in Changjiang River estuary

Tidal marshes are an important habitat and nursery area for fi sh.In the past few decades,rapid economic development in the coastal areas of China has led to the interruption and destruction of an increasing number of tidal marshes.The growing interest in tidal marsh restoration has increased the need to understand the relationship between geomorphological features and fi sh assemblages in the design of marsh restoration projects.We studied temporal variations in,and the effects of creek geomorphological features on,the estuarine tidal creek fi sh community.Using modifi ed channel nets,we sampled fi sh monthly from March 2007 to February 2008 from seven tidal creeks along an intertidal channel system in Chongming Dongtan National Nature Reserve.Fourteen creek geomorphological variables were measured or derived to characterize intertidal creek geomorphological features.The Gobiidae,with 10 species,was the most speciesrich family.The most abundant fi sh species were Liza affi nis,Chelon haematocheilus,and Lateolabrax maculatus.The fi sh community was dominated by juvenile marine transients,which comprised about 80% of the total catch.The highest abundance of fi sh occurred in June and July,and the highest biomass occurred in December.Canonical redundancy analyses demonstrated that depth,steepness,cross-sectional area,and volume signifi cantly affected the fi sh species assemblage.L.affi nis favored small creeks with high elevations.Synechogobius ommaturus,Acanthogobius luridus,and Carassius auratus preferred deep,steep creeks with a large cross-sectional area and volume.These fi ndings indicate that the geomorphological features of tidal creeks should be considered in the conservation and sustainable management of fi sh species and in the restoration of salt marshes.