Floristic composition and diversity of benthic diatoms of Lake Chalco, Mexico

Abstract

In the benthic diatoms of Lake Chalco species that respond to changes in nutrients, temperature and light predominate, and show significant ecological features to assess the disturbance caused by urban pressure, agricultural influence and overexploitation of the aquifer. In order to analyze the possible functionality of the aquatic environment, the composition and dominance of species was documented in detail. Sufficiency of sampling effort (rarefaction) was determined. The diversity of Shannon (H’) and the equity of Pielou (J’) based the characterization of the community and Simpson’s dominance value (D) was calculated to detect impoverishing processes of diversity. The diversity was low, with a marked dominance of species in which small central diatoms stood out. Its presence is analyzed as benthic populations, in an environmental situation of frequent disturbance. The continuous presence of the dominant ones, far from representing a stable state, reveals a highly competitive ecosystem and suggests a tendency towards the decrease of biodiversity. Three taxa constituted new records for Mexico; one of them is new record for the Americas. The importance of floristic studies is highlighted in this ecosystem which, although fragile, is important because it acts as a thermal regulator in the Chalco Valley.