Introduction:

The use of alluvial materials (sand, gravel, and boulders from riverbeds) has a direct impact on the associated wildlife. The most affected are those species of smaller size, poor vagility and small home range, such as some reptiles. This group was selected as an indicator of the impact of gravel pit installation due to its sensitivity to habitat disturbance.

Objective:

To determine the effects of alluvial material extraction on the diversity and structure of the reptile communities in river areas where gravel pits are installed.

Methods:

The study was carried out in the floodplains of the Tehuantepec River, Oaxaca, Mexico. Six transects of 300 m with a search width of 25 m were established, three at alluvial material extraction areas and three at non-extraction areas. In these two contrasting conditions, an inventory of reptiles was made. Also, relevant variables of the habitat of reptiles were evaluated. The alpha and beta diversity were compared between both conditions.

Results:

We registered 27 reptile species. In the alluvial material extraction areas, we observe a lower richness and abundance (14 species and 390 individuals) compared to the non-extraction areas (26 species and 1 205 individuals). The negative effect was greater in snakes, causing a 75 % difference in richness, while in lizards it was 32 %. The abundance of reptiles was correlated with bodies of water, sun exposure and herbaceous vegetation.

Conclusions:

The establishment of gravel pits and removal of alluvial materials has a strong impact on the diversity and structure of reptile communities. The negative effect is greater on snakes, which disappeared from the area from the gravel pits were established.