Are Aquatic Hemiptera Good İndicators of Environmental River Conditions?

Abstract

Aquatic Hemiptera are barely used as "indicators" because they are considered ubiquitous organisms of great dispersal capacity and a wide range of occupied habitats. Here, we address this topic analyzing the environmental factors determining the distribution of the species found in a northeastern Moroccan basin with a strong altitudinal gradient, as well as their capability of establishing assemblages and the niche breadth for each species. Between 2014 and 2017, we sampled 55 contrasted sites representing the heterogeneity of aquatic ecosystems in the study area, where we collected a total of 27 species. The relationships between the species and environmental variables were evaluated using the STATICO methods, showing a distribution mainly influenced by the changes in flow velocity and conductivity. The Bray–Curtis dissimilarity index identified four assemblages: (a) a running species group in upper freshwater streams; (b) a middle stream group preferring less flow velocity and moderate mineralization; (c) a third group, near to the mouth, occupying moderate running or lentic brackish waters; and (d) a fourth group linked with hypersaline standing environments. The use of Indicator Species Analysis (IndVal) found few but representative species for each assemblage. The OMI applied showed that the majority of species had a high niche breadth and, consequently, a low specialization. Our results highlighted the overall poor habitat requirement and very ubiquitous character of most species found. Only some of them, mainly the endemism Aphelocheirus pemae, can be considered key for biodiversity conservation purposes because of their low niche breadth and high indicator value. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.