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 regis tered 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.