Nymphal feeding habits of two Anacroneuria species (Plecoptera, Perlidae) from Sierra Nevada de Santa Marta, Colombia

Abstract

The knowledge of the diet of aquatic insects is important to assess the use of resources and overlap of trophic niche between species, as well as to understand their role in the food web of the freshwater ecosystems they inhabit. This is particularly necessary in tropical areas where information on this topic is scarce. The aim of the present work is to describe the feeding habits of the species Anacroneuria marta Zúñiga & Stark, 2002 and A. caraca Stark, 1995 in the middle section of the Río Gaira (Sierra Nevada de Santa Marta, Colombia). We sampled nymphs on three dates during the rainy and dry seasons in two major different microhabitats of the reach (leaf accumulations and gravel) in 2014. The nymphal diet of a total of 87 and 90 individuals of A. caraca and A. marta, respectively, was studied. With this information, niche breadth for each species and niche overlap between them in terms of trophic resources were calculated. The major trophic resource for both species in the dry and rainy season was the invertebrate animal matter. In the dry season, fine particulate organic matter was also important in the diet of A. caraca, and A. marta ingested a large quantity of coarse particulate organic matter in the rainy season. Larvae of Trichoptera were the most ingested prey in both species, followed by larvae of Chironomidae, Coleoptera Hydrophilidae, and nymphs of Ephemeroptera. No differences in diet between both species were detected, so this could favor niche overlap in terms of trophic resources and could lead to competition between them. The possible ecological scenarios are discussed.