AUTHOR=Wang Dong , Wan Rong , Li Zengguang , Zhang Junbo , Long Xiangyu , Song Pengbo , Zhai Lu , Zhang Shuo 

TITLE=The Non-stationary Environmental Effects on Spawning Habitat of Fish in Estuaries: A Case Study of Coilia mystus in the Yangtze Estuary

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.766616

DOI=10.3389/fmars.2021.766616

ISSN=2296-7745

ABSTRACT=The estuarine areas provide necessary spawning habitat, nursing habitat and migratory for a variety of fishes and the environmental conditions are of significant heterogeneity. Coilia mystus is the key commercial fish that spawns in the Yangtze Estuary and the yield has declined sharply in the past 30 years. In order to understand the spawning habitat selection mechanism of C. mystus, the geographically weighted regression (GWR) model was applied to explore the non-stationary effect of environmental variables (e.g., the sea surface temperature and the sea surface salinity) and geographical variables (e.g., the distance to the coast and the depth of water) on the egg density distribution of C. mystus. The data were derived from the spring and summer ichthyoplankton surveys carried out from 2019 to 2020 in the Yangtze Estuary, China. Model results showed that the key variables in different seasons had spatial non-stationary effects on the distribution of C. mystus’ spawning habitat, which were mainly caused by regional temperature rise and saltwater intrusion of the South Branch. In the spring, the sea surface salinity, the distance to the coast and the depth of water were the main impact factors, and the distance to the coast would determine the spawning habitat when the preferable environmental conditions were widely distributed. However, the sea surface temperature was most important in the summer and the relatively lower sea surface temperature was more crucial in the spawning habitat selection than the distance to the coast and the depth of water. The GWR model performed well in the study of C. mystus potential spawning habitat in the Yangtze Estuary. We recommend that more attention should be paid in regional variation of environmental factors to explore fish potential spawning habitat in estuarine areas.