Effect of logged forests on diet of small characids from Neotropical streams

Abstract

Studies relating to fish trophic ecology provide important insights regarding their life history. However, there is a lack of information linking fish diet composition with riparian cover in small streams. To investigate whether diet composition varied between streams with pristine and logged forests, I compared the food items consumed by four characid species: Bryconops melanurus, Moenkhausia collettii, Moenkhausia dichroura, and Moenkhausia oligolepis. I sampled 18 first‐order streams in the eastern Amazon: six with pristine forest, six with conventional logging, and six with selective logging. All fish species were classified as omnivorous, with diverse food categories recorded in their diets: mainly terrestrial insects for Moenkhausia species and aquatic insect nymphs for B. melanurus. However, the relative importance of each category varied only in streams with conventional logged forests. In these streams, all fish species consumed mainly autochthonous items, especially aquatic insect nymphs. In addition, terrestrial insects and seeds were absent in these streams with reduced riparian cover. In summary, this study highlighted that fish diet in conventional logged forests strongly differed from areas with pristine and selective logged forests. This finding states that managed forests may support a diverse diet for fish community, similar to that found in pristine forests. Therefore, management and conservation strategies of riparian vegetation in Amazonian streams are important to maintain habitat and food quality, which may be associated with a diverse diet for fish species.

Human pressures degrade the ecological condition of the Upper Graipu River

“…These organism responses to multiple anthropogenic pressures enable assessing rapid causal link responses between environmental stressors and aquatic biota (Rosenberg & Resh, 1993;Barbour et al, 1999;. Furthermore, benthic macroinvertebrates play key roles in food chains, serving as food for other invertebrates and vertebrates, including fish, amphibians, reptiles, and birds (Agouridis et al, 2015;Rosa et al, 2023;Simeone, 2023). Benthic macroinvertebrates are commonly used in biomonitoring programs for diagnosing and assessing biotic condition in river basins in response to anthropogenic pressures (Karr, 1999;Callisto et al, 2019a;Feio et al, 2022).…”