Zhang, Y.; Yan, S.; Wang, W., and Wang, M., 2021. Habitat use by fish across tidal cycles in a tropical estuarine mangrove ecosystem (Dongzhaigang Bay, Hainan, China). Journal of Coastal Research, 37(1), 156–167. Coconut Creek (Florida), ISSN 0749-0208.

Mangroves wetlands are recognized as nursery areas for large numbers of marine organisms. Yet, many properties of this nursery function remain poorly understood. In this study, the seasonal use of a tropical mangrove bay by fish assemblages over tidal cycles was investigated in 2009. Fish were sampled using centipede nets from three sites (located in the mouth, middle, and top of the bay) at Dongzhaigang Bay, Hainan, China. At each site, three replicates were sampled from each of the three different habitat types (i.e. vegetated area, creek, and mudflat). A generalized linear mixture model was used to explore the spatial and temporal variations in fish assemblages. The results showed that fish species richness, abundance, and biomass per sampling unit were significantly lower in the vegetated areas and mudflats than in the creeks. In the vegetated areas, fish species richness, abundance, and biomass per sampling day were significantly higher during spring tides than during neap tides. However, a similar pattern was not found both along the creeks and on the mudflats. In addition, tidal height showed a positive effect on biomass per sampling unit, especially in the vegetated areas; meanwhile, effects on species richness and abundance were not significant. The results indicate that larger tidal amplitude could support more fish (both richness and abundance) in the vegetated areas, which might occur because larger tidal amplitude provides fish with access to more habitats. These results provide basic knowledge related to mangrove management at an important fish nursery ground.