Influência da estrutura dos corpos d’água sobre a riqueza e diversidade de anfíbios anuros em uma área antropizada no município de Cruz das Almas, Bahia

Abstract

Habitat heterogeneity is an important predictor of the richness and diversity of organisms. According to this theory, more complex habitats tend to support greater species richness and diversity. For anurans, studies that seek to understand the effects of heterogeneity on richness and diversity are very important for make possible the understanding of the effects of anthropization in the dynamics of the assemblages. The present study analyzed the influence of the heterogeneity of six water bodies on the richness and diversity of anurans. The study was carried out in the community of Tuá, Cruz das Almas Municipality, Bahia State, from December 2017 to February 2018 and August to October 2018. Seven descriptors of the heterogeneity were collected: size, depth, temperature, interior vegetation, marginal vegetation, marginal vegetation on water mirror and margin profile. The Shannon Diversity Index was used to establish the diversity of anurans in water bodies, The Spearman correlation was used to verify the existence of association between the descriptors and the richness and diversity and a Similarity (Bray-Curtis) was used to verify similarities between ponds structure and between richness the abundance. Finally, a Canonical Correspondence Analysis (ACC) was used to check an association of each species with the sampled ponds. We found 18 species, distributed in genus Boana (3), Dendropsophus (4), Leptodactylus (4), Scinax (2), Phyllomedusa (1), Physalaemus (1), Pithecopus (1), Pseudopalodicula (1), Rinhella (1). Leptodactylidae and hylidae were the families with more occurrence in the ponds. The Shannon index revealed that the most of the ponds had diversities above 1,9 with emphasis for PT1 (2,0), PP2 (2,2) and PP3 (2,1). The analysis of similarity based in structure of the water bodies showed that the most of the pond had similarity above 80%, revealing a high degree of homogeneity, the same result found for richness and abundance. Spearman correlation showed a significant relationship only between the abundance and the size of the ponds (p = 0.03), evidencing that larger water bodies tend to support more species. The ACC revealed that the species responded differently to the gradients of heterogeneity. Nevertheless, some species presented generalist behavior in the use of ponds. Considering that the most of the ponds presented structural similarity, which may be due of the anthropic action, we believe that difference in species composition among the ponds may be due of the interaction, with reduction of the levels of overlap through partition. The high degree of disturbance in ponds, due of the anthropic action, affects the availability of spatial resources for the anurans, however, favors the establishment of species that present greater plasticity. Thus, the level of structural complexity found in the six ponds seems to exert different effects on the different species.