Composition, structure and diversity of mesozooplankton in Las Guásimas Sonora, a Ramsar site in the Gulf of California, during 2010

Abstract

 The mesozooplankton community of Las Guásimas, a coastal lagoon at the coast of Sonora, Mexico, was investigated to determine, for the first time, their composition, structure and diversity monthly, given the high ecological and fisheries importance of this ecosystem and its designation as a RAMSAR site. Sampling was conducted at two representative sites from January to December 2010 with a conical net of 300 microns, recording environmental variables (temperature, salinity, dissolved oxygen). Settled volume, density and identity of mesozooplankton samples were determined. Seventy eight taxa were identified in samples, which were dominated by Acartia tonsa (66.9%) and Penilia avirostris (9.9%). Other important groups were chaetognaths, fish eggs, gastropods, and larvaceans. The density of organisms within the lagoon was higher than outside, where diversity was higher. The results suggest that the abundance, composition and diversity of the zooplankton community of Las Guásimas are influenced by environmental variables, mainly sea surface temperature, and biological aspects, such as predation and reproductive pulses. However, for a better understanding of the complex interactions observed it is necessary to continue with a regular monitoring of the ecosystem to generate long series of data to assess patterns of long-term change, given its uniqueness and ecological and economic importance in the Gulf of California