Keystone species of fish community in the Laizhou Bay

Keystone species play a decisive role in community structure and stability, and the key species study has both important theoretical and practical significance for the entire ecosystem. In this paper, we tried to screen out the fishery key species from the fish community in the Laizhou Bay based on the bottom trawl survey data in May, 2011. Firstly, we established a relationship network of the 24 fish species according to the predation relationships among fish populations. Then 13 network important indices were calculated using the Ucinet 6 and CoSBiLab Graph1.0 software. A hierarchical clustering was conducted to show the relationships between 13 network indices, and 3 Key Player Problem parameters were calculated using keyplayer1.44 programme. The result showed these 13 indices can be divided into 4 different information groups: a (D, CC, IC, TI¹ and TI⁷), basic information group; b (D_in, H_in and K_t), input information group; c (D_out, H_out and K_b), output information group; d (BC and K), control information group. The species were identified as the key species based on the information of 13 indices and 3 Key Player Problem parameters. Liparis tanakae (D, D_in, BC, CC, IC, H_in, TI¹, TI⁷, K, K_t, F, ^DF and ^DF) and Amblychaeturichthys hexanema (D_out, H_out and K_b) had the highest rank among the 24 study species, and closely tied to others in the fish community, controlled the structure and energy flow of the community, indicating that they were the key species in fish community in the Layzhou Bay. And L. tanakae was the key predator which could control the density of the predators and other competitors in fish community while A. hexanema was the key prey which could restrict the density of other prey species by maintaining the density of the predator.