Abstract
Estuaries, where fresh and salty water converge, provide abundant nutrients for ichthyoplankton. Ichthyoplankton, including fish eggs, larvae, and juveniles, are important fishery recruitment resources. The Yangtze Estuary and its adjacent waters comprise a typical large-scale estuary and supply many important fish spawning, feeding, and breeding areas. In this study, 1,291 ichthyoplankton individuals were collected in the Yangtze Estuary in spring, from 2013 to 2020. The aims of the study were to provide detailed information on characteristics of the ichthyoplankton assemblage, explore interannual variation, and evaluate the effects of environmental variables on the temporal variation in assemblage structure. Twenty-six species in seventeen families were identified. The dominant species were Coilia mystus, Chelidonichthys spinosus, Engraulis japonicus, Hypoatherina valenciennei, Larimichthys polyactis, Salanx ariakensis, Stolephorus commersonnii, and Trachidermus fasciatus. The ichthyoplankton assemblage changed significantly over time, and Chelidonichthys spinosus became one of the dominant species. Canonical correspondence analysis showed that temperature and chlorophyll a were the key factors affecting the assemblage structure in the Yangtze Estuary in spring.
Highlights
Estuaries are semi-closed coastal water bodies that are freely connected to the open sea, in which the seawater is diluted by fresh water produced by land drainage (Day, 1981; Potter et al, 1990)
Other environmental indicators, including dissolved oxygen (DO), pH, total phosphorus (TP), total nitrogen (TN), suspended particulate matter (SPM), chemical oxygen demand (COD), and chlorophyll a (Chla), were determined in the study according to GB/T 12763-2007 specifications for oceanographic surveys (Standardization Administration of China (SAC), 2007)
The assemblage structure changed significantly in the Yangtze Estuary according to the index of relative importance (IRI) values for spring 2013–2020 (Table 2)
Summary
Estuaries are semi-closed coastal water bodies that are freely connected to the open sea, in which the seawater is diluted by fresh water produced by land drainage (Day, 1981; Potter et al, 1990). Estuaries are considered to be among the most productive and nutrient-rich ecosystems on earth, and provide important habitat for a variety of species (Hodgson et al, 2020). Many species complete some or all of their life histories in estuaries, and these areas are important foraging and breeding habitats for many fish species (Sheaves et al, 2015; Xian et al, 2016; Lefcheck et al, 2019). More than 90% of economical species, including fish, have been depleted, and biomass is lower than 50% of its historical abundance in some estuaries. The main drivers of this change are resource overexploitation and habitat loss (Lotze et al, 2006)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
