Estrutura das comunidades de macroinvertebrados bentônicos de riachos de cabeceira sob a influência de diferentes estados de conservação da mata ripária
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Data
2018-03-01
Autores
Melo, Ana Liz Uchida
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Universidade Estadual Paulista (Unesp)
Resumo
Os ecossistemas aquáticos servem de habitat e local de alimentação para uma fauna bastante diversificada. Apesar da grande importância desses ambientes, o crescente aumento das populações humanas e o uso da terra para diferentes fins têm levado a uma intensa alteração desses locais e trazido diversos impactos para a fauna de invertebrados bentônicos. O objetivo deste trabalho foi analisar a possível influência de diferentes estados de conservação da mata ripária sobre a estrutura do habitat e da fauna de macroinvertebrados bentônicos. O trabalho foi realizado em 36 riachos localizados em quatro microbacias, na área suburbana e rural do município de Avaré, SP, sendo em cada microbacia estudados 3 riachos apresentando mata ripária nas duas margens (denominado perfil Mata), 3 com a mata totalmente excluída (perfil Pasto) e 3 com mata somente em uma das margens (perfil Intermediário). Entre outubro e dezembro de 2015 foi realizada a caracterização dos riachos utilizando um protocolo de análise física do habitat, que possibilita uma análise quantitativa ampla e, assim, uma caracterização detalhada do riacho, e a coleta dos invertebrados com amostrador surber (malha 250 µm). A análise dos dados ambientais mostrou uma separação nítida entre os riachos de mata e pasto, em função do substrato e mesohabitat, com os riachos de mata sendo caracterizados pelo substrato grosseiro e abrigo de folhas e os riachos de pasto pelo substrato fino e abrigo de macrófitas. Para a análise da composição da fauna (presença-ausência) houve uma separação dos riachos de perfis de vegetação ripária alterados (pasto e intermediário) do perfil florestado (mata) em todas as microbacias, diferença também confirmada quando analisados os índices ecológicos (abundância, riqueza e equitabilidade), com pelo menos um dos índices apresentando diferença significativa entre os riachos de mata e os de perfil alterado. Porém, a relação da abundância da fauna e dos parâmetros do ambiente com o estado de conservação da mata ripária mostrou padrões distintos de diferenciação dos perfis para cada microbacia analisada. Tais evidências salientam que outros fatores além do perfil da mata ripária estejam atuando sobre a estrutura da fauna. A escala de trecho (“reach scale”) utilizada no trabalho pareceu adequada para prever a distribuição das variáveis ambientais frente aos perfis de estado de conservação da mata ripária, enquanto que para fauna a escala que se mostrou mais adequada foi a de micro-habitat. Possivelmente, tanto características de escala local (substrato, mesohabitats), como regional (características da microbacia como área, rede hidrográfica, proximidade de áreas urbanas) devem ter agido em conjunto na determinação da composição da fauna.
Aquatic ecosystems serve as habitat and feeding place for a diversified fauna. Despite the great importance of these environments, the increase in human population and the use of land for different purposes had led to an intense alteration of these places and brought diverse impacts to the fauna of benthic invertebrates. This study aims to analyze the possible influence of different states of riparian vegetation conservation on the habitat and the structure of benthic invertebrates. The work was carried out in 36 streams located in four microbasins, in the suburban and rural area of the municipality of Avaré, SP. In each microbasin was studied 3 streams presenting riparian vegetation on both banks (Forest profile), 3 with forest completely excluded (Pasture profile) and 3 with this vegetation only in one margin (Intermediate profile). Between October and December 2015, the characterization of the streams was carried out using a protocol of physical analysis of the habitat, which allows a comprehensive quantitative analysis and, thus, a detailed stream characterization, and the invertebrates were sampled with a surber sampler (250 µm net). The analysis of the environmental data showed a clear separation between forest and pasture streams, as a function of the substrate and mesohabitat, with forest streams represented by coarse substrate and leaves shelter and pasture streams represented by fine substrate and macrophyte shelter. In the analysis of the fauna composition (presenceabsence), there was a separation of altered riparian vegetation profiles (pasture and intermediate) from the forest profile in all microbasins. The same difference was also confirmed for the analysis of ecological indexes (abundance, richness and equitability), with at least one of the indexes showing a significant difference between forest streams and those with altered profiles. However, the relation of fauna abundance and environmental parameters to the state of conservation of the riparian vegetation showed distinct patterns of profile differentiation for each microbasin analyzed. The results emphasizes that other factors besides the profile of the riparian vegetation are acting on the structure of the fauna. The reach scale used in the study seemed adequate to predict the distribution of the environmental variables in relation to the conservation status of riparian vegetation, whereas for fauna the micro-habitat scale was most appropriated. Possibly, both local (substrate, mesohabitats) and regional characteristics (microbasin characteristics such as area, hydrographic network, proximity to urban areas) should have acted together in determining the composition of the fauna
Aquatic ecosystems serve as habitat and feeding place for a diversified fauna. Despite the great importance of these environments, the increase in human population and the use of land for different purposes had led to an intense alteration of these places and brought diverse impacts to the fauna of benthic invertebrates. This study aims to analyze the possible influence of different states of riparian vegetation conservation on the habitat and the structure of benthic invertebrates. The work was carried out in 36 streams located in four microbasins, in the suburban and rural area of the municipality of Avaré, SP. In each microbasin was studied 3 streams presenting riparian vegetation on both banks (Forest profile), 3 with forest completely excluded (Pasture profile) and 3 with this vegetation only in one margin (Intermediate profile). Between October and December 2015, the characterization of the streams was carried out using a protocol of physical analysis of the habitat, which allows a comprehensive quantitative analysis and, thus, a detailed stream characterization, and the invertebrates were sampled with a surber sampler (250 µm net). The analysis of the environmental data showed a clear separation between forest and pasture streams, as a function of the substrate and mesohabitat, with forest streams represented by coarse substrate and leaves shelter and pasture streams represented by fine substrate and macrophyte shelter. In the analysis of the fauna composition (presenceabsence), there was a separation of altered riparian vegetation profiles (pasture and intermediate) from the forest profile in all microbasins. The same difference was also confirmed for the analysis of ecological indexes (abundance, richness and equitability), with at least one of the indexes showing a significant difference between forest streams and those with altered profiles. However, the relation of fauna abundance and environmental parameters to the state of conservation of the riparian vegetation showed distinct patterns of profile differentiation for each microbasin analyzed. The results emphasizes that other factors besides the profile of the riparian vegetation are acting on the structure of the fauna. The reach scale used in the study seemed adequate to predict the distribution of the environmental variables in relation to the conservation status of riparian vegetation, whereas for fauna the micro-habitat scale was most appropriated. Possibly, both local (substrate, mesohabitats) and regional characteristics (microbasin characteristics such as area, hydrographic network, proximity to urban areas) should have acted together in determining the composition of the fauna
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Palavras-chave
escala, insetos aquáticos, mesohabitat, microhabitat, microbacia, aquatic insects, mesohabitat, microbasin, microhabitat, scale