Comparison of inshore and offshore fish larval assemblages within the wider Yangtze River estuary (China)

Abstract

Summary It is hypothesized that fish larvae undertake vertical movements in estuarine waters. To test this hypothesis, a sampling period was selected during times when many spring‐spawning fish reach maximum abundance in coastal waters so that spring and summer variations in larval fish assemblages could be determined in the Yangtze River estuary. Six oceanographic surveys were conducted across the salinity gradient of an inshore (freshwater) and offshore area (brackish intersection) during spring (May) and summer (August) between 2010 and 2012. The fish larval community was dominated by species of Engraulidae, Gobiidae, Champsodontidae and Mugilidae. The pre‐flexion and flexion larval stages of euryhaline marine species, which are dependent on estuaries as nursery areas, were common. The brackish and marine larval assemblage was the most abundant with taxa such as Coilia mystus and Engraulis japonicus accounting for more than 57.3% of the total catch. Spatial differences in the taxonomic composition of larval fish assemblages were evident between the inshore and offshore areas. Additionally, the Yangtze River runoff regulatory functions as affected by the Three Gorges Reservoir operational mode (hydrological alternating operations) showed weak influences on fish and habitat environments. Low salinities from high freshwater inflow limited bay anchovy production in the inshore area.

Patterns of larval fish assemblages along the direction of freshwater input within the southern branch of the Yangtze Estuary, China: implications for conservation

“…However, declines of fish resources in the estuary have not subsided (Zhuang et al 2006;Jiang et al 2009). Patterns of larval fish assemblages reflect the spawning and nursery functions of an estuary for fish (Strydom 2015;Teodosio and Garel 2015;Jiang et al 2016). Various biotic or abiotic factors, such as zooplankton abundance, water temperature, salinity, and water runoff influence larval fish assemblages in estuaries (Cao et al 2007;Shuai et al 2016;Zhang et al 2016).…”

“…Previous studies on larval fish assemblages in the Yangtze Estuary have focused mainly on areas outside of the mouth (Liu et al 2008;Liu and Xian 2009;Jiang et al 2016). Detailed information covering the larval fish assemblage inside of the mouth is limited, with few exceptions describing the distribution of larvae and juveniles in the surf zones (Zhong et al 2005;Jiang et al 2009).…”

Effects of Estuarine Environmental Heterogeneity on the Habitat of Gobiidea Species Larvae

“…2006; Jiang et al. 2016). The entire survey region was divided into four subareas (A, B, C, and D; Figure 1B) based on geographic characteristics such as water depth and salinity.…”

“…Seven cruises were conducted in the YRE in 2018, 2019, and 2020 to collect the biological and environmental data analyzed here (Figure 1A). The surveys were carried out in the spring and summer during the breeding season for fish (Zhuang et al 2006;Jiang et al 2016). The entire survey region was divided into four subareas (A, B, C, and D; Figure 1B) based on geographic characteristics such as water depth and salinity.…”

Distribution and Abundance of Fish Larvae in South of Alas Strait, West Nusa Tenggara

“…It was reasonable because the location of the fish larvae at the station relatively close to the beach. The area is very fertile because of the nutrients that flowed from the river from the mainland (Jiang et al, 2015).…”