Though many studies have demonstrated top-down control by macroconsumers on benthic communities and ecosystem processes in tropical streams, few have simultaneously addressed such effects across a gradient of riparian vegetation loss. Here, we investigated if potential top-down effects induced by macroconsumers interact with native vegetation changes of tropical karst streams in Brazil. We experimentally excluded macroconsumers (e.g., fish and shrimp) from benthic habitats of seven streams with a range of forest cover from 20% to 100% and examined the effects on benthic invertebrate and periphyton communities. Across sites, the absence of macroconsumers had no effects on mean chlorophyll-a concentrations, total dry mass or abundance of benthic invertebrates. However, the periphyton community significantly differed between control and treatment replicates. Overall, experimental exclusion of macroconsumers resulted in weak or negligible effect on benthic communities, which contrasts a significant proportion of related literature conducted elsewhere. Such top-down effects have been poorly studied in tropical karstic streams to date.
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We thank Waldeir Dias, Bruno Martínez, Guilherme Dalponti, Jonas Corrêa, Debora Moreira, and Emanuele Moura for their generous help in the field and laboratory. We are indebted to the Universidade Federal do Mato Grosso do Sul (Campus de Bonito), Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio) for the logistic support. Dr. Timothy Moulton and Dr. Walter Dodds provided insightful comments on earlier drafts of the manuscript. The research was supported by Planalto da Bodoquena: redes de interações em longo Prazo (PELD) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) by a doctoral scholarship and CAPES, FUNDECT/PAPOS (processo 23/200.638/2014). Finally, Chatham University and Kansas State University generously provided logistic supports for visiting scholarship.
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Corrêa, E.C., de Oliveira Roque, F., Utz, R.M. et al. Effects of macroconsumers on benthic communities across a gradient of vegetation loss in tropical karst streams. Hydrobiologia 836, 21–34 (2019). https://doi.org/10.1007/s10750-019-3917-8
- Electric exclusion experiment
- Consumer exclusion
- Riparian vegetation
- Top-down control