Composição, abundância e diversidade de Brachyura (Crustacea: Decapoda) acompanhante da pesca de arrasto do camarão sete-barbas no Litoral sul de São Paulo
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Data
2016-02-24
Autores
Bochini, Gabriel Lucas [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os objetivos deste estudo foram: 1) investigar a composição taxonômica de Brachyura; 2) avaliar a assembleia destes por meio dos índices ecológicos; 3) verificar a relação das espécies em função dos fatores abióticos; e 4) analisar se há sincronismo entre os períodos reprodutivos das espécies mais abundantes em comparação ao camarão alvo da pesca X. kroyeri. Foram realizadas coletas mensais (julho/12 a junho/14) na região marinha (4 estações amostrais: E1, E2, E3 e E4) e na região de Mar Pequeno (MP) (3 estações amostrais: E5, E6, e E7), com um barco camaroeiro equipado com redes “double rig”. Foram calculados o índice de Shannon (H), a equidade (J’) a Riqueza (S) e o Índice de Valor Ecológico (IVE), e avaliou-se as relações entre espécies X estações amostradas e entre regiões X períodos (análise de cluster). A temperatura variou entre as estações do ano (maior no verão e menor no inverno), mas não variou entre as regiões amostradas. Já a salinidade variou entre as regiões, sendo menor no MP. O sedimento foi composto pela mistura de areia fina e muito fina. O teor de matéria orgânica foi similar entre as estações de coleta, com exceção de E4 e E5. A concentração média de clorofila variou entre as estações do ano, sendo maior no verão e menor no inverno. Um total de 19.501 indivíduos de Brachyura foi coletado, representados por 25 espécies, 18 gêneros e 13 famílias, sendo elas: Portunidae, Aethridae, Leucosiidae, Epialtidae, Menippidae, Pinnotheridae, Inachoididae, Dromiidae, Inachidae, Sesarmidae, Pilumnidae, Xanthidae e Hymenosomatidae. A riqueza variou durante os períodos (16 espécies no primeiro e 22 no segundo) e foi menor em MP em todas as estações do ano, com exceção do inverno/13. A família Portunidae foi a mais representativa (87,64%, n= 17.090). A temperatura correlacionou positivamente com as abundâncias de C. danae, C. ornatus e H. pudibundos (RDA). As fêmeas ovígeras (FO) de C. danae foram predominantes (87,61%) e coletadas em todos os meses; as demais espécies juntas somaram 12,39% e apresentaram período reprodutivo sazonal. Com exceção de L. ferreirae, as fêmeas ovígeras (FO) foram mais abundantes no verão/14, porém houve segregação espacial entre as espécies, principalmente entre as congêneres. Para cada Brachyura coletado, capturou-se aproximadamente 6 exemplares de X. kroyeri. O pico reprodutivo (primavera e verão) de X. kroyeri foi similar à maioria dos Brachyura, provavelmente devido às maiores temperaturas. A temperatura foi o principal fator correlacionado com a abundância temporal dos indivíduos, pois além de influenciar no crescimento e no processo reprodutivo em crustáceos, pode controlar a maturação dos ovócitos nas fêmeas. As FO de C. ornatus, P. mediterranea, P. punctata, H. pudibundus e L. ferreirae habitam preferencialmente as áreas de maior abundância de X. kroyeri, o que pode prejudicar os estoques dessas espécies. Houve o primeiro registro de Teramnonotus monodi em Cananéia, ampliando a área de ocorrência da espécie do Rio de Janeiro para o sul de São Paulo. Os resultados do presente estudo mostraram relações preocupantes entre a captura de X. kroyeri e de Brachyura, principalmente devido às variações encontradas nas abundâncias ao longo do ano e na composição da riqueza, pois a maioria das espécies são raras e pouco abundantes. A região de Cananéia é de extrema importância como área de reprodução, migração e estabelecimento da riqueza de braquiúros. Visando à manutenção do ambiente marinho, torna-se extremamente necessária uma gestão pesqueira que aborde múltiplas espécies e que considere a comunidade como um todo. Para proteger a reprodução dos Brachyura e de X. kroyeri, o presente estudo propõe uma adequação ao período de defeso, ou seja, ampliar o período incluindo o verão.
The aims of the present study were: 1) to investigate the taxonomic composition of Brachyura; 2) to evaluate the brachyuran assemblage through ecological indexes; 3) to verify the relationship between species and abiotic factors; and 4) to analyze if there is synchronization between the reproductive periods of the most abundant species in relation to the fishery target shrimp X. kroyeri. Sampling was performed monthly (July/12 to June/14) in the marine region (4 sampling stations: E1, E2, E3 and E4) and at the Mar Pequeno region (MP) (3 sampling stations: E5, E6, and E7) with a shrimping boat equipped with double rig nets. Shannon index (H), equity (J'), Richness (S) and the Ecological Value Index (IVE) were calculated, as well as the relationships between species X sampled stations and between regions X periods (cluster analysis). Temperature varied among seasons (higher in summer and lower in winter) but did not differ among sampled regions. Salinity varied among regions and it was lower at MP. The sediment was composed by a mix of fine and very fine sand. The organic matter content was similar among sampling stations, excepting E4 and E5. The mean chlorophyll concentrations varied among seasons (higher in summer and lower in winter). A total of 19,501 Brachyuran individuals were collected, represented by 25 species, 18 genera and 13 families, as follows: Portunidae, Aethridae, Leucosiidae, Epialtidae, menippidae, Pinnotheridae, Inchoididae, Dromiidae, Inachidae, Sesarmidae, Pilumnidae, Xanthidae and Hymenosomatidae. Richness varied during periods (16 species in the first one and 22 in the second) and was lower in MP in all seasons, excepting winter/13. The Portunidae family was the most representative (87.64%, n=17,090). Temperature was positively correlated with abundances of C. danae, C. ornatus and H. pudibundos (RDA). Ovigerous females (OF) of C. danae were predominant (87.61%) and collected in every month; the other species together represented 12.39%, showing a seasonal reproductive period. With the exception of L. ferreirae, ovigerous females (OF) were more abundant in the summer/14, but with spatial segregation among species, especially among congeners. For each Brachyuran collected, about 6 specimens of X. kroyeri were captured. The reproductive peak (spring and summer) of X. kroyeri was similar to most brachyuran probably due to the higher temperatures. The temperature was the main factor correlated with temporal abundance of individuals, since it influences on growth and reproductive processes in crustaceans, besides controlling oocyte maturation in females. The FO of C. ornatus, P. mediterranea, P. punctata, H. pudibundus and L. ferreirae preferably inhabit the areas of greatest abundance of X. kroyeri, which could affect the stocks of these species. There was the first record of Teramnonotus monodi in Cananéia, expanding the area of occurrence of the species from Rio de Janeiro to the south of São Paulo. The results of the present study showed worrying relations between the capture of X. kroyeri and Brachyuran species, mainly due to variations found in abundance throughout the year and richness composition, since most species are rare and not very abundant. The Cananéia region is of great importance as an area of reproduction, migration and establishment of brachyuran species. Aiming the maintenance of the marine environment, it is extremely required a fisheries management that address multiple species and consider the community as a whole. To protect the reproduction of Brachyura and X. kroyeri, this study proposes an adjustment to the closed season, i.e., to extend the period to include the summer.
The aims of the present study were: 1) to investigate the taxonomic composition of Brachyura; 2) to evaluate the brachyuran assemblage through ecological indexes; 3) to verify the relationship between species and abiotic factors; and 4) to analyze if there is synchronization between the reproductive periods of the most abundant species in relation to the fishery target shrimp X. kroyeri. Sampling was performed monthly (July/12 to June/14) in the marine region (4 sampling stations: E1, E2, E3 and E4) and at the Mar Pequeno region (MP) (3 sampling stations: E5, E6, and E7) with a shrimping boat equipped with double rig nets. Shannon index (H), equity (J'), Richness (S) and the Ecological Value Index (IVE) were calculated, as well as the relationships between species X sampled stations and between regions X periods (cluster analysis). Temperature varied among seasons (higher in summer and lower in winter) but did not differ among sampled regions. Salinity varied among regions and it was lower at MP. The sediment was composed by a mix of fine and very fine sand. The organic matter content was similar among sampling stations, excepting E4 and E5. The mean chlorophyll concentrations varied among seasons (higher in summer and lower in winter). A total of 19,501 Brachyuran individuals were collected, represented by 25 species, 18 genera and 13 families, as follows: Portunidae, Aethridae, Leucosiidae, Epialtidae, menippidae, Pinnotheridae, Inchoididae, Dromiidae, Inachidae, Sesarmidae, Pilumnidae, Xanthidae and Hymenosomatidae. Richness varied during periods (16 species in the first one and 22 in the second) and was lower in MP in all seasons, excepting winter/13. The Portunidae family was the most representative (87.64%, n=17,090). Temperature was positively correlated with abundances of C. danae, C. ornatus and H. pudibundos (RDA). Ovigerous females (OF) of C. danae were predominant (87.61%) and collected in every month; the other species together represented 12.39%, showing a seasonal reproductive period. With the exception of L. ferreirae, ovigerous females (OF) were more abundant in the summer/14, but with spatial segregation among species, especially among congeners. For each Brachyuran collected, about 6 specimens of X. kroyeri were captured. The reproductive peak (spring and summer) of X. kroyeri was similar to most brachyuran probably due to the higher temperatures. The temperature was the main factor correlated with temporal abundance of individuals, since it influences on growth and reproductive processes in crustaceans, besides controlling oocyte maturation in females. The FO of C. ornatus, P. mediterranea, P. punctata, H. pudibundus and L. ferreirae preferably inhabit the areas of greatest abundance of X. kroyeri, which could affect the stocks of these species. There was the first record of Teramnonotus monodi in Cananéia, expanding the area of occurrence of the species from Rio de Janeiro to the south of São Paulo. The results of the present study showed worrying relations between the capture of X. kroyeri and Brachyuran species, mainly due to variations found in abundance throughout the year and richness composition, since most species are rare and not very abundant. The Cananéia region is of great importance as an area of reproduction, migration and establishment of brachyuran species. Aiming the maintenance of the marine environment, it is extremely required a fisheries management that address multiple species and consider the community as a whole. To protect the reproduction of Brachyura and X. kroyeri, this study proposes an adjustment to the closed season, i.e., to extend the period to include the summer.
Descrição
Palavras-chave
Bycatch, Cananéia-SP, Caranguejos, Crabs