Effect of the riparian vegetation removal on the trophic network of Neotropical stream fish assemblage

Abstract

The study of the diet of fish is an important tool to assess different levels of environmental degradation, since the availability of food in the environment is a key factor for the fish occurrence. The removal of riparian vegetation usually degrades environmental quality, as this vegetation has an important role in providing energy to the ecosystem. This study investigates the effects of the removal of riparian vegetation on the fish assemblage trophic network. The study was carried out in two stretches of a southeastern Brazilian stream, one in a forest fragment and another in a pasture, during the wet and dry seasons of 2014. We analyzed the items consumed by each fish species using the frequency of occurrence and area of each item, which were combined to calculate the alimentary index, which was used to determine the food niche overlap of the fish and the specialization index of the trophic network. Aquatic Hexapoda, vegetal debris and organic matter dominated the trophic network of the two stretches. We detected higher values of food niche overlap in the forested stretch and more complex trophic networks in the pasture stretch. We found few seasonal variations in the items consumed and calculated indices in both stretches studied. The presence of grass on the banks in the pasture stretch and the importation of food resources from the upstream area may have provided a higher diversity of resources and consequently showed a more complex trophic network when compared to the forested stretch.Keywords: fish diet, food niche overlap, trophic organization.Efeito da remoção da vegetação ripária sobre a rede trófica de uma assembleia de peixes de um riacho neotropical RESUMO O estudo da alimentação de peixes é uma importante ferramenta para avaliar diferentes níveis de degradação ambiental, uma vez que a disponibilidade de alimentos no ambiente é um fator-chave para a ocorrência de peixes. A remoção da vegetação ripária geralmente causa uma grande perda de qualidade ambiental, uma vez que essa vegetação tem um importante papel em gerar energia para o ecossistema. Nós investigamos os efeitos da remoção da vegetação ripária sobre a rede trófica das assembleias de peixes. Nosso estudo foi conduzido em dois trechos de um riacho do sudeste brasileiro, um em um fragmento florestal e outro em uma pastagem, durante as estações chuvosa e seca de 2014. Analisamos os itens consumidos por cada espécie Rev. Ambient. Água vol. 13 n. 1, e2088 -Taubaté 2018 2 Pedro Sartori Manoel et al.de peixe utilizando a frequência de ocorrência e a área de cada item, que foram combinados para o cálculo do índice alimentar, o qual foi utilizado para determinar o valor médio da sobreposição de nicho alimentar da assembleia e o índice de especialização da rede trófica. As redes tróficas dos dois trechos foram dominadas por Hexapoda aquáticos, detritos vegetais e matéria orgânica. Observamos maiores valores de sobreposição de nicho alimentar no trecho florestado e redes tróficas mais complexas no trecho de pastagem. Verificamos poucas varia...

Impacts of an urban flood control infrastructure on the limnology and ichthyofauna of a basaltic Cuesta stream (southeast Brazil)

“…In terms of the fish fauna, eleven species (five orders) were found in the Cascata stream. This richness, obtained in only two samplings, is comparable to other studies carried out in the Botucatu Cuesta streams (first to fourth-order river stretches), including long-term researches (two decades), whose reported richness varied between 10 to a maximum of 26 species (Uieda and Barretto, 1999;Manoel and Uieda, 2018.…”

“…For the considered geological region, the Cuesta geological formation of Botucatu, the study is unique, as it focused on impacts generated by stream damming. Other regional studies searched to evaluated anthropic effects related to water quality deterioration (sewage contamination, traffic road contamination and siltation), suppression of riparian forests and intensification of land use by agriculture practices (Uieda and Barretto, 1999;Moretto and Nogueira, 2003;Gralhoz and Nogueira, 2006;Oliveira et al, 2014;Belluta et al, 2016Belluta et al, , 2020Manoel and Uieda, 2018.…”

Knowing biodiversity: Fishes from the Guareí River basin, a tributary of the Jurumirim reservoir, Paranapanema River, Brazil

“…However, several questions remain open, including total diversity, biogeographic patterns and ecological aspects, demanding further studies. The occurrence of Phenacorhamdia tenebrosa (Schubart, 1964) on the Upper Paraná River is a good example: although this fish was recorded by several studies (e.g., Schubart 1964;Manoel & Uieda 2018;Cavalli et al 2018;Vicentin et al 2019), more detailed information on its distribution is lacking. Perhaps more important is the fact that several waterbodies remain uninvestigated, especially small and mid-size water courses, which may harbor species unknown (i.e., undescribed) to science (Langeani et al 2007).…”