Structure of the diatom communities of the sediments of Lake Cocibolca and its relationship with the natural and anthropogenic events

Abstract

In order to identify diatoms and thier behavior in a sediment profile and thier relation topl natural and anthropogenic events, sediment sampling was carried out in Cocibolca Lake. A total of 46 taxa were identified with the highest diversity at the PLN I site (41 taxa) and the least at the PLN II site (24 taxa). The most representative genus in the PLN I were: Aulacoseira (12.20%), Fragilaria (7%), Navicula (12.20%), Nitzschia (7.32%), Pseudostaurosira (12.20%), and Surirella (9.76%). At the PLN II site they were: Aulacoseira (20.83%), Nitzschia (12.50%), Pseudostaurosira (12.50%), Surirella (8.33%), Cyclotella (8.33%) and Synedra (8 , 33%). Within the genus Aulacoseira the species A. muzzanensis showed to be the most dominant (44%; PLN I) and (64.58% PLN II).

Of the species found, four of them (Aulacoseira ambigua, A. subartica, Discotella stelligera and Stephanodiscus) show significant oscillations such as the replacement of one species by another that depends on environmental changes in the aquatic environment. The PLN I site shows more evidence of the changes that the body of water had at some time, which is reflected in the dominance of one species when another disappears. Presumably, for a time the conditions of the lake varied, being better observed at this site.

The application of the Shannon and Simpson indices show that the PLN I site is where the highest calculated values ​​are observed (1,081 and 2,412 bit) respectively