Determining the Structure of the Community of Dominant Fish Species Associated to Soft Bottoms in the Lagoon of La Paz, B.C.S. México

The study of fish communities from coastal lagoons allows a better understanding of role of these organisms in these systems, and the effect of anthropogenic impact. The aim of the present study was to determine the community structure, in particular dominance of fish species associated to soft bottoms in the lagoon of La Paz, while the specific objectives considered Determine the physicochemical parameters of the localities and their relationship with the dominant species, determine the structure of soft bottom species by using the ecological indexes of specific richness of Margalef (IRE), Shannon-Weaver (H '), Pielou’s evenness (J'), Simpson (Dsi),determine the ecological role of the dominant species according to the BVI and determine the resident and transitory species according to their zoogeographic affinity. Six bimonthly samplings were carried out in seven localities from November 2016 to September 2017 and physicochemical parameters were recorded. Analysis of temperature showed differences between two marked seasons, warm and cold. Species richness showed differences between months and localities. Shannon-Weaver index and Pielou’s evenness showed significant differences only between months. Simpson’s index suggests a high diversity. According to the BVI, 15 species from the families Haemulidae, Sciaenidae and Gerreidae, were the most biologically important. Zoogeographic affinity analysis showed that 58% of the species prefer the Province of Cortez. Dominant species recorded in this study play a key role in soft-bottom systems like the lagoon of La Paz.