Distribution and density of invasive mollusks of the Thiaridae family in freshwater environments of Tabasco, Mexico

Abstract

Background. Melanoides tuberculata and Tarebia granifera invasive species are characterized by easily colonize and settle in new areas; in addition to displace native species. Goals. To determine the distribution and density of invasive Thiarid species in freshwater environments (streams, rivers and lakes) of Tabasco. Methods. Samples were taken at 40 locations during 2011 and 2012 through several macroinvertebrate methods: corer, Petite Ponar dredge and a pushnet, physicochemical variables were also recorded in water and sediment. Results. Physicochemical water parameters registered maximum values of pH (8.8), OD (9.6 mg/l), temperature (33.9 °C), Conductivity (664 mS cm-1) and organic matter (9.6%) in lakes, and fecal coliform (790,000 UFC) and total coliforms (781,000 UFC) in rivers. A total of 4,689 individuals of M. tuberculata and T. granifera 20.408 individuals were captured, density distribution of M. tuberculata results in 84% in lagoons, 10% in rivers and 6% in streams, while T. granifera was registered with 50% in rivers, 43% in lagoons and 7% in streams. Conclusions. Presence of these invasive species is confirmed with a wide distribution in most of the freshwater environments of Tabasco State, with preference for lagoon and river environments, the impact of these invasive species in the environment is still unknown.