Spatio-Temporal Dynamics of Fish Early-Life Stages and Their Ecological Drivers in Xiangshan Bay, China

To investigate the dynamic characteristics of early fish life stages and their association with environmental factors in Xiangshan Bay, China, two surveys were conducted in the springs of 2023 and 2024 to collect fish eggs and larvae. A total of 21,221 eggs and 10,730 larvae of 23 species belonging to 5 orders and 13 families were collected. Dominant species identified from eggs included Scomberomorus niphonius, Konosirus punctatus, and Pennahia argentata, while dominant species of larvae included Engraulis japonicus, Planiliza haematocheilus, and Rhinogobius giurinus. Species diversity analysis showed that the diversity was higher in spring 2023 (H′ = 1.13) but decreased in spring 2024 due to the outbreak of dominant species (H′ = 0.86). Cluster analysis and non-metric multidimensional scaling ordination analysis revealed significant regional differentiation in the community structure of fish eggs and larvae between the springs of 2023 and 2024. Mantel test correlation and redundancy analyses indicated that temperature, salinity, dissolved oxygen, and chlorophyll-a concentration were the main environmental factors influencing the distribution of fish eggs and larvae. This study elucidates spatio-temporal patterns and environmental response mechanisms of early fish life stages in Xiangshan Bay, providing scientific support for the conservation and sustainable utilization of fishery resources in the National Fishery Germplasm Resource Reserve.