Mobile generalist species dominate the food web succession in a closed ecological system, Chenghai Lake, China

Abstract

As amplified by climate changes and anthropogenic activities, mobile generalist species have been dominating the food web succession in a closed ecosystem. However, compared to marine ecosystem, the internal mechanism of generalist species affecting freshwater community were paid less attentions. In this study, the association of mobile generalist species and native apex predator was identified in Chenghai Lake, where was taken as the study case of a closed ecosystem to create the succession dynamic of food web from 1983 to 2019. Weighted food web analysis (WFWA) approach was applied to determine keystoneness and interaction strength of each species node, which is achieved through the quantification of the direct impacts on food web nodes from its biomass. As shown in the results, in the food web of 1983, there were nearly 25 nodes and 80 links, while in 2009, there were 22 nodes and 58 links, however, in 2019, there were 16 nodes and 25 links. In 2019, the three original specialized apex predator nodes were disappear. The keystoneness of each species was − 0.048, − 0.109 and − 0.742 respectively. During the nearly 40-year succession, including 13 native species had gone within 10 years, which were difficult to find its trace. The omnivorous alien species have occupied an absolute dominant niche, exhibiting the characteristics of mobile generalist species in 2019. The keystoneness of these species was − 0.194, − 0.235 and − 0.236 respectively. In general, from 1983 to 2019, the nodes have decreased by 36% and links have dropped by 68.75% on average in Chenghai Lake food web. In this study, (a)revealing the associations between mobile generalist species and native apex predators; (b) distinguishing the keystone species affecting food web structural; (c) developing food web analysis approach and determining the succession dynamic of Chenghai Lake. These findings improve the understanding of potential impacts from mobile generalist species in closed ecosystem. • Establishing mechanism of mobile generalist species dominating aquatic food web. • Screening the key species affecting structural variation of food web. • Determining succession dynamic for the food web of Chenghai Lake. • Constructing a food web analysis method to apply with real aquatic food web.