MAJOR PREDATORS AND PREDATION PRESSURE OF FIVE KEYSTONE PREY SPECIES IN HAIZHOU BAY

This study aims to understand the fluctuation of predation pressure and natural mortality of keystone prey species in the food web of Haizhou Bay. Keystone prey species play a crucial role in the energy flow and material transference in the marine food webs. Researches on the importance of keystone prey species in the food web can provide a scientific basis for the restoration of ecosystem and conservation of fishery resources. Based on the bottom trawl survey data in Haizhou Bay and stomach contents analysis, the predation pressure index (PPI) of five keystone prey species (including Leptochela gracilis, Alpheus japonicus, Loligo sp., Larimichthys polyactis and Oratosquilla oratoria) were used to analyze the major predators of these prey species and their predation pressure. Results showed that the PPI of Chelidonichthys kumu to L. gracilis and Loligo sp. was the highest, being 168.89 and 75.77, respectively. The PPI of Miichthys miiuy to A. japonicus and O. oratoria was the highest, being 39.41 and 9.85, respectively. The PPI of Muraenesox cinereus to L. polyactis was the highest (5.50). Anova showed that there was no significant difference in PPI in different years (P>0.05), and there were significant differences among predators (P<0.05). The natural mortality coefficient varied with the fluctuation of predation pressure index. There were differences in the feeding habits of these predators, which will help to reduce the food competition among them and benefit the ecosystem stability. Trophic interactions between species are instrumental in maintaining the stability of ecosystems. These keystone prey species play a vital part in the food web and can directly affect the structure and function of ecosystems, providing energy for the high trophic level predators and contributing to the energy flow and material circulation in the food web. Based on the findings of the present study, it is suggested to strengthen the research in the field of keystone prey species, explore the relationship between species, and analyze in-depth the ecological function and regulation mechanism of keystone prey species. This is pivotal in maintaining ecosystem stability and species diversity and developing ecosystem-based fishery management strategies.