Trophic structure of macroinvertebrates in tropical pasture streams

Abstract

Aim The aim of this study was to describe the diet of stream macroinvertebrates and to determine their trophic groups. Methods Invertebrates were sampled with D nets in three pasture streams. They were identified to genus level and submitted to gut content analysis, except for fluid feeders such as hemipterans, to which diet data was obtained from the literature. Trophic groups were determined based on a similarity analysis using the Bray-Curtis similarity coefficient. Results Five trophic groups were defined: fine-detritivores (feed mostly on fine particulate organic matter - FPOM), coarse-detritivores/herbivores (feed mostly on coarse particulate organic matter - CPOM - and plant material), omnivores, specialist-predators (prey upon aquatic insects only), and generalist-predators. Ephemeroptera, Diptera (except Tanypodinae), Coleoptera, and Trichoptera (except Smicridea) were detritivores. The caddis Macronema (Trichoptera) fed exclusively on plant detritus and Tanypodinae and Smicridea were classified as omnivores. The odonate families Calopterygidae and Gomphidae were classified as specialist-predators, while Macrobrachium (Decapoda), Belostoma, and Limnocoris (Hemiptera) were generalist-predators. Conclusions The great quantity and frequency of occurrence of FPOM consumed by most taxa highlight the importance of this food resource for macroinvertebrate communities from tropical streams. Furthermore, observed variations on trophic group assignment for some taxa indicate the generalist and opportunistic nature of these aquatic invertebrates. Such findings reinforce the importance of conducting gut content analysis on macroinvertebrates to understand their role in the structure and functioning of tropical streams.

Structure of aquatic macroinvertebrate communities in streams of a sub-basin in the Pampa Biome, Southern Brazil

“…This is mainly due to the fact that the most abundant families (Hydropsychidae, Philopotamidae and Simuliidae) are mostly collector-filters. However, it is important to highlight that some families or groups may have a generalist habit, adapting to food resources availability (Silveira-Manzotti et al 2016). De Castro et al (2016) found that changes in land use, such as the cultivation of sugar cane and livestock, can lead aquatic macroinvertebrate assemblages to exhibit more generalist feeding habits.…”

“…Studying them is important because the macrobenthic organisms are known as indicators of anthropogenic stress due to their sedentary habitat. Furthermore, they maintain various levels of interaction between the community and environment (Bieger et al 2010;Silveira-Manzotti et al 2016;Brraich and Kaur 2017). The structure of the aquatic macroinvertebrate community provides precise and local information on recent events.…”

Diet of Phylloicus (Trichoptera: Calamoceratidae) caddisfly larvae in forest streams of western Pará, central Brazilian Amazonia

“…In this case, the presence of FPOM (detritus) in the stomach contents of the Phylloicus larvae may be related primarily to the availability of this material in the habitat (Henriques-Oliveira et al, 2003;Chará-Serna et al, 2012). This reinforces the importance of this food resource in tropical freshwater ecosystems (Palmer et al, 1993;Motta & Uieda., 2004;Ceneviva-Bastos & Casatti, 2014;Silveira-Manzotti et al, 2016), related to microbial activity, which accelerates decomposition, increasing the nutritional quality of this detritus for these invertebrates (Robinson et al, 1998;Graça, 2001).…”