Abstract:

Background and Aims: The Yellow River estuary and its adjacent waters serve as spawning, nursery, and feeding grounds for many important organisms, and are characterizd by abundant biological resources and high biodiversity. During recent decades, local environmental conditions and biological community structure have significantly changed under pressures of human activities and climate change. To advance ecological protection and high-quality development in the Yellow River basin, it is essential to clarify the current status of local biodiversity and its evolution. In this study, we reviewed and analyzed the survey data of 101 voyages from 1958 to 2020, to provide the zooplankton taxa list recorded in the Yellow River estuary and its adjacent waters, compare the inter-decadal variations of zooplankton taxa composition, analyze the inter-annual changes of dominant species and the diversity index. 

Progress: The results showed that 185 zooplankton taxa (primarily at the species level) were recorded in the Yellow River estuary and its adjacent waters, including 94 species of Arthropoda, 42 species of Cnidaria, 35 taxa of pelagic larvae, 6 species of Protozoa, 4 species of Urochordata, and 2 species each of Ctenophora and Chaetognatha. Among Arthropoda, there were 41 Copepoda species, 16 Mysida species, 12 Cumacea species, 7 Amphipoda species, 6 Cladocera species, 4 Isopoda species, 3 Decapoda species, 2 Ostracoda species, 2 Euphausiacea species, and 1 Anostraca species. In terms of taxa composition, the first record of Ctenophora species occurred after 2000. The gelatinous zooplankton, such as Cnidaria and Ctenophora, exhibited a trend of decreasing proportions of warm-temperate species and increasing proportions of warm-water species. While miniaturization occurred in Copepoda, with the proportion of small copepods increasing. The dominant species composition of macro- and meso-zooplankton showed a trend towards smaller individuals and an increase in gelatinous species. Additionally, the proportion of pelagic larvae increased. The high abundance of Noctiluca scintillans resulted in a sharp decrease in the Shannon-Wiener diversity index. 

Prospects: Future studies will need to consider the impacts of multiple factors on biodiversity, identify key drivers and critical impact processes, and focus on the effects of extreme climate events. Additionally, it is suggested to establish standardized biodiversity monitoring indicators and guidelines, to achieve biodiversity conservation and promote the healthy development of marine ecosystems.

Key words: Yellow River estuary, zooplankton, biodiversity, dominant species, marine survey