Interdecadal changes in keystone species of fish community during autumn in the Yellow Sea

Abstract:

Keystone species play an important role in structural stability of a community and changes in diversity. Using Yellow Sea autumn survey data for 1985, 2001, 2009, and 2018, we constructed the topological structure of the food-web network of the Yellow Sea fish community and analyzed the interdecadal changes of keystone species in the Yellow Sea fish community. The food webs included 67~103 different fish species and 300~449 prey-predator relationships. The structural density of these food webs ranged from 0.198 to 0.227, and interspecies connectivity ranged between 0.044 and 0.074, consistent with fish communities under natural conditions. The keystone species of the autumn fish community in the Yellow Sea from 1985 to 2018 were Engraulis japonicus, Lophius litulon, and Larimichthys polyactis, remaining unchanged for nearly 30 years. E. japonicus is the keystone prey in the fish community, while L. polyactis as a species that controls the fragmentation of community, both resources decline. As the keystone predator, L. litulon resources have gradually increased. From 1985 to 2018, the dominant species in the Yellow Sea changed significantly in autumn, gradually shifting from L. polyactis and Pampus argenteus to Harpadon nehereus, Liparis tanakae, and E. japonicus. The Margalef richness index (Rw, Rn) and Shannon diversity index (H'w, H'n) calculated by weight and quantity have gradually decreased and have rebounded significantly in 2018, while Pielou evenness index (J'w, J'n) fluctuated slightly. The keystone species in the Yellow Sea did not change in autumn; however, the dominant species changed significantly, while the community structure fluctuated slightly but still remained in a relatively stable state.