Dinâmica populacional e biodiversidade dos ermitões (Decapoda, Anomura) ao longo do litoral sudeste do Brasil
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Data
2019-02-22
Autores
Stanski, Gilson
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Compreender os processos que determinam a riqueza de espécies é essencial para entender a estruturação espacial e o funcionamento das comunidades. Assim, o objetivo desse estudo foi analisar a riqueza e a diversidade de ermitões nas regiões de Macaé (RJ), Ubatuba (SP) e Cananéia (SP) e verificar quais os fatores ambientais influenciam na vida das espécies. Os animais foram coletados mensalmente em profundidades de 5 a 20m, com um barco camaroeiro. Macaé apresentou 332 indivíduos (3 spp), Ubatuba 674 indivíduos (8 spp) enquanto que em Cananéia ocorreram 498 indivíduos distribuídos em 7 espécies. Ubatuba e Cananéia apresentaram 6% de diferenciação (Jaccard), Ubatuba e Macaé 45% e Cananéia e Macaé 40%. A alta riqueza em Ubatuba atribui-se por ser uma região de transição faunística. Já Cananéia demonstra baixa diversidade, embora segunda maior riqueza, devido ao expressivo aporte de água doce junto ao transporte de material orgânico em suspensão nesta região, o que favorece a presença de espécies dominantes filtradoras e tolerantes a baixa salinidade, como Isocheles sawayai. Além da maior riqueza, Ubatuba apresentou índices de diversidade (H'=1.64) e equitabilidade (E=0.78) elevados, o que evidencia baixa dominância, como constatado no índice de Berger-Parker (D=0.34). Em contrapartida, Macaé apresentou os índices menores de diversidade (H'=0.89) e equitabilidade (E=0.61), consequentemente com maior dominância (D=0.58), constatando-se a presença expressiva de Loxopagurus loxochelis com padrão de ocorrência em águas mais frias, por ser uma região sob a influência da ressurgência de Cabo Frio-RJ. A temperatura foi o principal fator ambiental que apresentou influência na presença das espécies. Outro fator que pode explicar a diferença de riqueza e diversidade entre as regiões é a abundância de conchas de gastrópodes disponíveis aos animais, as quais são vitais para a vida do ermitão. Das conchas de gastrópodes, Macáe apresentou a menor riqueza com a apenas 13 espécies, inferior a Cananéia (21 espécies) e Ubatuba com 33 espécies. Portanto, os processos ambientais e biológicos regionais influenciam o padrão de diversidade dos ermitões estudados.
Comprehend the processes that determine these differences are essential for understanding the spatial structuring and functioning of communities. So, the aim of this study was to analyze the richness and diversity of hermit crabs along a latitudinal gradient and to verify the influence of environmental factors. The animals were collected monthly with a shrimp boat in depths of 5 to 20m, in Macaé (RJ), Ubatuba (SP) and Cananéia (SP) regions. Macaé, region of lower latitude, presented 332 individuals (3 spp), Ubatuba 674 individuals (8 spp) while in Cananéia there were 498 individuals distributed in 7 species. Ubatuba and Cananéia presented 6% of differentiation (Jaccard), Ubatuba and Macaé 45% and Cananéia and Macaé 40%. The high richness in Ubatuba is attributed to being a region of faunistic transition. Cananéia, however, shows low diversity, although second richest, due to the expressive contribution of fresh water to the transport of organic material in suspension in this region, which favors the presence of dominant filter benthic species and tolerant to low salinity, such as Isocheles sawayai. Beyond of greater species richness, Ubatuba presented high diversity (H '= 1.64) and equitability (E = 0.78), and low dominance, as observed in the Berger-Parker index (D = 0.34). On the other hand, Macaé presented the lowest diversity indexes (H '= 0.89) and equitability (E = 0.61), with higher dominance (D = 0.58), by the expressive presence of Loxopagurus loxochelis favoured by influence of the resurgence of Cabo Frio-RJ because the species has pattern of occurrence in colder waters. The temperature was the main environmental factor that showed influence in the presence of the species. Another factor that may explain the difference in richness and diversity between regions is the abundance of gastropod shells available to animals, which are vital to the life of the hermit crabs. Macáe presented the lowest richness of shells of gastropods with 13 species, less that Cananéia (21 species) and Ubatuba with 33 species. Therefore, regional environmental and biological processes influence the diversity pattern of the hermit crabs studied.
Comprehend the processes that determine these differences are essential for understanding the spatial structuring and functioning of communities. So, the aim of this study was to analyze the richness and diversity of hermit crabs along a latitudinal gradient and to verify the influence of environmental factors. The animals were collected monthly with a shrimp boat in depths of 5 to 20m, in Macaé (RJ), Ubatuba (SP) and Cananéia (SP) regions. Macaé, region of lower latitude, presented 332 individuals (3 spp), Ubatuba 674 individuals (8 spp) while in Cananéia there were 498 individuals distributed in 7 species. Ubatuba and Cananéia presented 6% of differentiation (Jaccard), Ubatuba and Macaé 45% and Cananéia and Macaé 40%. The high richness in Ubatuba is attributed to being a region of faunistic transition. Cananéia, however, shows low diversity, although second richest, due to the expressive contribution of fresh water to the transport of organic material in suspension in this region, which favors the presence of dominant filter benthic species and tolerant to low salinity, such as Isocheles sawayai. Beyond of greater species richness, Ubatuba presented high diversity (H '= 1.64) and equitability (E = 0.78), and low dominance, as observed in the Berger-Parker index (D = 0.34). On the other hand, Macaé presented the lowest diversity indexes (H '= 0.89) and equitability (E = 0.61), with higher dominance (D = 0.58), by the expressive presence of Loxopagurus loxochelis favoured by influence of the resurgence of Cabo Frio-RJ because the species has pattern of occurrence in colder waters. The temperature was the main environmental factor that showed influence in the presence of the species. Another factor that may explain the difference in richness and diversity between regions is the abundance of gastropod shells available to animals, which are vital to the life of the hermit crabs. Macáe presented the lowest richness of shells of gastropods with 13 species, less that Cananéia (21 species) and Ubatuba with 33 species. Therefore, regional environmental and biological processes influence the diversity pattern of the hermit crabs studied.
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Palavras-chave
Anomura, dominância, fauna acompanhante