Looking for a place: How are tadpoles distributed within tropical ponds and streams?

Abstract

Microhabitat use by tadpoles has been little documented, especially for neotropical anuran species. Here we describe microhabitat use by tadpoles in two different aquatic systems, lentic and lotic, in the Atlantic Rainforest. We sampled tadpoles in 98 sites within lentic habitats, and 187 sites within lotic habitats. We categorized each of the sites sampled according to its environmental features, such as aquatic vegetation cover, substrate type, and depth. To describe the tadpoles’ preferences in microhabitat use according to the environmental features, we performed a Canonical Correspondence Analysis for lentic and lotic water bodies separately. We noticed that in ponds, groups of tadpoles belonging to different species occurred in similar microhabitat types, determined especially by vegetation cover, depth, and organic matter. In contrast, stream-dwelling species showed particular preferences for specific microhabitat types, determined mostly by the kind of substrate (e.g., leaf litter, rock cover). Thus, in streams, the use of particular environmental features leads to differences in microhabitat use among species, driving the segregation of species within streams according to each microhabitat type. Therefore, pond-dwelling tadpoles tend to occur in similar environmental microhabitat, resulting in a greater number of species using the same type of microhabitat, than stream-dwelling tadpoles.