Background.

Papaloapan river´s lower basin is very important for its extensive wetlands and biota presented. However this area is very impacted by several economic activities (sugar mill and oil extraction) mainly.

Goals.

The aim of the study was to determine the diversity of crustaceans in the lower basin of Papaloapan river.

Methods.

The collection of organisms is carried out in the dry and rainy seasons in 2013, diurnal sampling with diverse collectors was apply and registering physiochemical variables of the water in different tributaries of the basin.

Results.

Río Blanco had the highest salinity and total dissolved solids (2.9 ups and 2704 mg / l) respectively. The lower oxygen concentration was recorded in San Agustín and Blanco rivers (1.009 y 2.09 mg / l) respectively. A total of 4,587 organisms were collected corresponding to ten families, twelve genera and sixteen species. Potimirim mexicana and Hyalella azteca dominated in terms of density with 34% and 26% in dry season, in the rainy season Macrobrachium sp., and P.mexicana dominated in density with 59% y 30% respectively. The greatest spatial diversity in dry season was in Blanco river with (H’=0.29) and minimum in Playa Vicente (H’=0.37), in rainy season highest diversity was in Sontecomapan (H’=1.08), while Blanco river showed the minimum diversity (H’=0.29).

Conclusions.

The macroinvertebrates including crustaceans, are primordial organisms into aquatic systems to play an important role in recycling organic matter and energy transfer to different trophic levels, the knowledge of the dynamic and population structure of this communities and it´s ecology will allow us distinguish between changes by human affectations in aquatic systems and its surrounding and changes produced naturally.