Efeito da retirada da mata ripária sobre a estrutura dos grupos funcionais de alimentação em assembleias de macroinvertebrados bentônicos
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Data
2018-02-28
Autores
Ono, Erika Ramos
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Universidade Estadual Paulista (Unesp)
Resumo
Macroinvertebrados bentônicos são comumente utilizados como bioindicadores da qualidade do habitat em riachos. Estes estudos podem ser realizados através de uma abordagem taxonômica ou funcional da comunidade. Na abordagem funcional, a classificação em grupos funcionais de alimentação (FFG - Functional Feeding Groups) baseia-se nos mecanismos de apreensão do alimento e nos recursos consumidos. O estudo teve o objetivo de verificar o efeito de alterações na mata ripária sobre a estrutura dos FFG em comunidades de macroinvertebrados bentônicos. Estudamos 36 riachos, separados em três tipos de entorno: com mata ripária nas duas margens (florestado), com mata em uma das margens e pastagem na outra (intermediário) e sem mata nas duas margens (pastagem). A análise das variáveis ambientais indicou uma diferenciação dos riachos florestados e da maioria dos intermediários devido a maiores valores de material alóctone e oxigênio dissolvido e menores de vegetação nas margens e substrato fino, quando comparados aos de pastagem. A análise da abundância da fauna em cada FFG indicou uma diferença entre entornos somente para coletores, com valores significativamente menores nos florestados quando comparados aos de pastagem e intermediários. Já a análise aplicada aos dados de presença-ausência mostrou diferença entre entornos somente para os predadores, indicando diferença significativa na composição entre riachos florestados e de pastagem. A análise da diferenciação dos entornos considerando em conjunto os FFG e as variáveis ambientais reforçou um agrupamento maior dos riachos florestados, influenciados por menores valores de substrato fino e vegetação nas margens. Os maiores valores destas duas variáveis determinaram o agrupamento da maioria dos riachos de pastagem e estiveram associados com a maior presença de filtradores, predadores e coletores. Os raspadores estiveram relacionados com a combinação de maiores valores de oxigênio e menores de sólidos totais dissolvidos e os fragmentadores, com os menores valores de sólidos totais dissolvidos. Assim, a abordagem funcional utilizada no presente trabalho permitiu comprovar a propriedade do uso de macroinvertebrados como indicadores ecológicos da qualidade do habitat em função do nível de preservação da mata ripária, quando analisados em conjunto com variáveis do ambiente direta ou indiretamente relacionadas com os mecanismos de coleta do alimento. Uma forte relação entre riachos com retirada da mata ripária e algumas características do habitat relacionadas com perda de qualidade ambiental, como menor entrada de material alóctone e maior de substrato fino, pode ser estatisticamente comprovada.
Benthic macroinvertebrates are commonly used as bioindicators of the habitat quality in streams. These studies may be carried out through analyzes with taxonomic or functional approach of the assemblage. In the functional approach, the classification of macroinvertebrates into Functional Feeding Groups (FFG) is based on the mechanisms of food´s apprehension and the resources consumed. This study aimed to verify the effect of the changes in riparian forest upon the structure of FFG in assemblages of benthic macroinvertebrates. We studied 36 streams, separated in three types of land use: with riparian forest on both banks (forest), with forest on one of the banks and pasture on another (intermediate) and without forest on both banks (pasture). The analysis of environmental variables showed a differentiation of the forest and most of the intermediate streams due to high values of allochthonous material and dissolved oxygen and low amounts of vegetation on the banks and unconsolidated substrate, when compared to pasture streams. The analysis of the abundance of the fauna in each FFG indicated a difference between types of land use only for gathering collectors, with significantly low abundance in forested streams when compared to pasture and intermediate ones. On the other hand, analysis applied to the presence-absence data showed distinction between land uses only for predators, indicating significant difference in the composition of forest and pasture streams. The analysis of the differentiation of land uses considering the FFG and the environmental variables together reinforced a larger grouping of the forest streams, influenced by low values of unconsolidated substrate and vegetation on the banks. The highest values of these two variables determined the grouping of most of the pasture streams and were associated with the greater presence of filtering collectors, predators and gathering collectors. The scrapers were related to the combination of high oxygen values and low total dissolved solids and the shredders, with the lowest values of total dissolved solids. Thus, the functional approach used in this study allowed proving the property of using macroinvertebrates as ecological indicators of habitat quality according to the preservation of riparian forest, when analyzed together with environmental variables direct or indirectly related to the mechanisms of food acquisition. A strong relationship between streams with riparian forest absence and some habitat characteristics related to loss of environmental quality, such as low input of allochthonous material and high of unconsolidated substrate, could be statistically proven.
Benthic macroinvertebrates are commonly used as bioindicators of the habitat quality in streams. These studies may be carried out through analyzes with taxonomic or functional approach of the assemblage. In the functional approach, the classification of macroinvertebrates into Functional Feeding Groups (FFG) is based on the mechanisms of food´s apprehension and the resources consumed. This study aimed to verify the effect of the changes in riparian forest upon the structure of FFG in assemblages of benthic macroinvertebrates. We studied 36 streams, separated in three types of land use: with riparian forest on both banks (forest), with forest on one of the banks and pasture on another (intermediate) and without forest on both banks (pasture). The analysis of environmental variables showed a differentiation of the forest and most of the intermediate streams due to high values of allochthonous material and dissolved oxygen and low amounts of vegetation on the banks and unconsolidated substrate, when compared to pasture streams. The analysis of the abundance of the fauna in each FFG indicated a difference between types of land use only for gathering collectors, with significantly low abundance in forested streams when compared to pasture and intermediate ones. On the other hand, analysis applied to the presence-absence data showed distinction between land uses only for predators, indicating significant difference in the composition of forest and pasture streams. The analysis of the differentiation of land uses considering the FFG and the environmental variables together reinforced a larger grouping of the forest streams, influenced by low values of unconsolidated substrate and vegetation on the banks. The highest values of these two variables determined the grouping of most of the pasture streams and were associated with the greater presence of filtering collectors, predators and gathering collectors. The scrapers were related to the combination of high oxygen values and low total dissolved solids and the shredders, with the lowest values of total dissolved solids. Thus, the functional approach used in this study allowed proving the property of using macroinvertebrates as ecological indicators of habitat quality according to the preservation of riparian forest, when analyzed together with environmental variables direct or indirectly related to the mechanisms of food acquisition. A strong relationship between streams with riparian forest absence and some habitat characteristics related to loss of environmental quality, such as low input of allochthonous material and high of unconsolidated substrate, could be statistically proven.
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Palavras-chave
abordagem funcional, indicador biológico, insetos aquáticos, invertebrados aquáticos, aquatic insects, aquatic invertebrates, biological indicator, functional approach