Phytoplankton assemblage from Cajititlan Lagoon, Jalisco during the year 2015

Abstract

The phytoplankton community covers the unicellular-photosynthetic microorganisms, which are the basis of the complex trophic net of all aquatic ecosystems. The analysis of its assemblages is widely used to monitor the ecologic status of water bodies. However, none previous report of phytoplankton assemblages exists in the Laguna de Cajititlán-Jalisco, once a productive and ecologically healthy water body, that now presents recurrent fish mortality episodes. In this study, we present the results of a monthly phytoplankton monitoring performed in five sites among Laguna de Cajititlán-Jalisco over a year. The phytoplankton community harbored 50 phytoplankton species belonged to the phyla: Cyanobacteria, Chlorophyta, Bacillariophyta and Euglenozoa. Three different phytoplankton assemblages were detected in the monitoring period. However, all over the year, the most dominant and persistent species were cyanobacteria, which are frequently associated with high levels of eutrophication: Cylindrospermopsis sp. and Microcystis sp., Both cyanobacteria are potentially toxic. Therefore, exist a high possibility that this species contributed to the massive fish dead episodes. Our results, let us conclude that Ecological status of Laguna de Cajititlán-Jalisco is bad. We propose to implement environmental sanitation mechanisms in the Lagoon and continue the monitoring program until verify that the phytoplankton composition get modified and none toxic cyanobacteria could be the dominant phytoplankton component.