海南岛近岸海域鱼类群落及相似性特征研究OA

Fish stock serves as the foundation for fishery development and ecosystem stability.The Hainan Island,encompassing mangroves,coral reefs,estuaries,and upwelling systems,has rich diversity and distinct characteristics of fish communities in the nearshore waters of the island.To comprehensively clarify the spatiotemporal dynamics of fish community characteristics in nearshore waters of Hainan Island and systematically analyze the variations of species composition,dominant taxa,and resource abundance among different regions,we conducted two bottom trawl surveys in August and November 2024,corresponding to the southwest and northeast monsoon seasons respectively,and used a combination of statistical methods,including one-way analysis of variance,permutational multivariate analysis of variance,and principal coordinates analysis to analysis the variations of fish communities in different regions in nearshore waters of the island.The results showed that 451 species of fish were collected,dominated by resident and warm-water fish;the eastern Sanya-Lingshui waters had the highest number of species(228 species),whereas the Mulantou waters had the fewest number of species(116 species).The number of species in November was higher than that in August,and 223 species were the most common in both surveys.Sørensen's dissimilarity index divides the composition of fish in nearshore waters of Hainan Island into the southeastern(Wenchang,Qionghai-Wanning,and Lingshui-Qiongsanya waters),western(Ledong,Changjiang-Dongfang and Danzhou-Linggao waters),and northern(Qionghzhou Straits and Mulantou waters)zones.The highest abundance of fish stock was in the western Changjiang-Ledong Sea(22,036 ind./km2,536.8 kg/km2)and eastern Qionghai-Sanya Sea(18,656.9 ind./km2,383.4 kg/km2;P＜0.05),which overlapped with the coastal upwelling area.The abundance of fish in August(after the seasonal moratorium on fishing)(mean 23727.4 ind./km2,473.7 kg/km2)was significantly greater than that in November(mean 12,299.6 ind./km2,289.7 kg/km2;P＜0.001).The dominant species were small and low-value species,such as Saurida undosquamis,Terapon theraps,Thamnaconus hypargyreus,and Johnius grypotus.The composition of the dominant species varied among different waters in nearshore waters of Hainan Island;the dominant species included J.grypotus,Setipinna tenuifilis,and Cynoglossus macrolepidotus in northern waters,S.undosquamis,Saurida tumbil,Upeneus japonicus,and Champsodon snyderi in southern waters,and T.theraps,Pennahia macrocephalus,and J.grypotus in western waters.The similarity of the fish community in the southeastern waters of the nearshore waters of Hainan Island was distinguished from that in the western waters,and the fish communities in the northern waters were characterized by the transition between the southeastern and western waters.S.undosquamis,U.japonicus,T.hypargyreus,J.grypotus,T.theraps,and Brachypleura novaezeelandiae were the dominant species contributing to the differences of fish communities between the southeastern and western waters in nearshore waters of Hainan Island.Our study showed that fish communities in the nearshore waters of Hainan Island have clear spatial and temporal characteristics,which are consistent with the geographical environment characteristics around the island.Fish communities in the western waters of the island are mainly composed of non-rock reef bottom-dwelling species.These waters are located in the semi-enclosed bay of Beibu Gulf,which is driven by wind currents and has a sandy mud composition.In the southeastern waters,the dominant groups are shelf-rocky and reef fishes,and the waters are mainly influenced by the South China Sea Warm Current and upwelling.The trends of declining fish diversity,decreasing abundance,and increasing proportion of small fish were still evident in the nearshore waters of Hainan Island.Therefore,it is suggested that(1)Fundamental research on fish stock in the inshore waters of Hainan should be enhanced,and it necessary to clarify the mechanisms of fishery resource changes,diversity maintenance,and resource replenishment.(2)Catchable resources and fishing intensity in different areas in nearshore waters of Hainan Island should be reasonably planned,and fishing quota system and marine ecological compensation measures should be promoted.(3)Typical habitats such as mangroves,coral reefs,and seagrass beds should be primarily protected and restored to ensure the replenishment of fish stocks.(4)The system of permitted fishing gear and minimum mesh size should be strictly implemented to alleviate the pressure of non-selective fishing.(5)A standardized landing system for catches and socialized catches supervision system should be established to encourage broader people to participate in the protection of fishery resources.