Variação geográfica dos camarões Dendrobranchiata nas regiões sudeste e sul do Brasil: teste de hipóteses sobre o paradigma do efeito latitudinal
Data
2017-02-24
Autores
Grabowski, Raphael Cezar [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste estudo foi testar a hipótese de gradientes latitudinais na influência ambiental sobre parâmetros populacionais de Sicyonia dorsalis, Rimapenaeus constrictus e Pleoticus muelleri na costa sudeste do Brasil. As amostras foram realizadas em quatro regiões (Macaé (≈22ºS), Ubatuba (≈23ºS), Cananéia (≈25ºS) e São Francisco do Sul (≈26ºS)), utilizando barcos de pesca artesanal, em diferentes períodos entre julho de 2010 e junho de 2014. A influência dos fatores ambientais foi testada utilizando a análise de redundância (RDA) (p ≤ 0,05), e o período reprodutivo e de recrutamento foram considerados como os períodos com maior frequência de fêmeas reprodutivas e jovens, respectivamente, para cada região. Os parâmetros de crescimento foram analisados utilizando o modelo de crescimento de Von Bertalanffy, e a longevidade foi calculada a partir do mesmo modelo, invertido, comparando as curvas médias de cada região utilizando o teste F (p ≤ 0.05). Foram analisados 9.838 camarões, e em todas as regiões, as fêmeas atingiram maiores tamanhos, uma provável influência de seu sistema de cópula, o qual desconsidera o tamanho de machos, ou então uma adaptação para aumentar a fecundidade de fêmeas. As fêmeas também foram mais abundantes, uma consequência de diferentes atividades migratórias e taxas de mortalidade entre os sexos. Foi possível observar uma tendência à diminuição do tamanho corpóreo à medida que aumentou a latitude, o oposto à tendência esperada de aumento no tamanho corpóreo com o aumento da latitude, indicando uma conexão migratória entre grupos que podem pertencer a uma mesma população. A reprodução apresentou uma tendência à sazonalidade em maiores latitudes, possivelmente induzida pela sazonalidade na disponibilidade de alimento larval e na influência de massas de água na costa brasileira.
The aim of this study was to test the hypothesis of latitudinal gradients acting on the environmental influence over population parameters of Sicyonia dorsalis, Rimapenaeus constrictus and Pleoticus muelleri in the southeastern Brazilian coast. Samples were taken in four regions (Macaé (≈22ºS), Ubatuba (≈23ºS), Cananéia (≈25ºS) and São Francisco do Sul (≈26ºS)), using artisanal fishing boats, in different periods from July 2010 through June 2014. The influence of environmental factors was tested using the redundancy analysis (p ≤ 0.05), and the reproductive and recruitment periods were taken with the highest frequency of reproductive females and juvenile individuals, respectively, for each region. The growth parameters were analyzed using the Von Bertalanffy's growth model, while the individuals' longevity was calculated based on the same equation, but inverted, comparing growth curves from different regions using an F test (p ≤ 0.05). We analyzed 9,838 shrimps and, in all regions, females reached larger body sizes, a likely influence of their mating system, which does not consider males' body sizes; or an adaptation in order to increase females' fecundity. Females were also more abundant, a consequence of different migratory activities and mortality rates between sexes. It was possible to observe a decreasing tendency on body sizes as latitude increases, the opposite from what is expected according to the latitudinal effect paradigm, evidencing a migration connection between groups that may be part of the same population. The reproductive periodicity showed a seasonal tendency in higher latitudes, probably induced by the seasonality on the larval food availability and on the influence of water masses along the Brazilian coast.
The aim of this study was to test the hypothesis of latitudinal gradients acting on the environmental influence over population parameters of Sicyonia dorsalis, Rimapenaeus constrictus and Pleoticus muelleri in the southeastern Brazilian coast. Samples were taken in four regions (Macaé (≈22ºS), Ubatuba (≈23ºS), Cananéia (≈25ºS) and São Francisco do Sul (≈26ºS)), using artisanal fishing boats, in different periods from July 2010 through June 2014. The influence of environmental factors was tested using the redundancy analysis (p ≤ 0.05), and the reproductive and recruitment periods were taken with the highest frequency of reproductive females and juvenile individuals, respectively, for each region. The growth parameters were analyzed using the Von Bertalanffy's growth model, while the individuals' longevity was calculated based on the same equation, but inverted, comparing growth curves from different regions using an F test (p ≤ 0.05). We analyzed 9,838 shrimps and, in all regions, females reached larger body sizes, a likely influence of their mating system, which does not consider males' body sizes; or an adaptation in order to increase females' fecundity. Females were also more abundant, a consequence of different migratory activities and mortality rates between sexes. It was possible to observe a decreasing tendency on body sizes as latitude increases, the opposite from what is expected according to the latitudinal effect paradigm, evidencing a migration connection between groups that may be part of the same population. The reproductive periodicity showed a seasonal tendency in higher latitudes, probably induced by the seasonality on the larval food availability and on the influence of water masses along the Brazilian coast.
Descrição
Palavras-chave
Crescimento, Dendrobranchiata, Distribuição, Recursos pesqueiros, Reprodução