Navegando por Assunto "Ecologia reprodutiva"

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Aspectos da reprodução de espécies de ciclídeos de importância econômica em áreas de várzea do médio solimões
(Universidade Federal do Pará, 2013-02-13) SILVA, Tania Cristiane Gonçalves da; QUEIROZ, Helder Lima de; http://lattes.cnpq.br/3131281054700225
The Cichlidae family plays an important economic role in the Brazilian Amazon, since many of its species are valued as food and also as ornamental fish. The family presents one of the largest parental behaviors among the teleosts, and one of the more diverse among all vertebrates. Amazon fish show a great diversity of reproductive strategies and tactics and ensure the survival of the greatest possible number of offspring, and represent the result of long processes of natural selection and adaptation to seasonal fluctuations of environmental variables. However, many reproductive aspects of this family are still unknown or understudied in the Amazon. This work aimed to study the reproductive ecology of seven species of the family Cichlidae: Aequidens tetramerus, Astronotus ocelatus, Acarichthys heckelli, Acaronia nassa, Hypsellecara temporalis, Mesonauta insignis and Pterophyllum scalare. The study was conducted with specimens collected at Mamirauá Sustainable Development Reserve (MSDR), in the várzea ecosystem, made up of white water flooded environments, and influenced by annual flood pulses. The reserve is a protected area near Tefé, at Amazonas State, Brazil. For each species were evaluated the lengthweight relationship, condition factor, sex ratio, type and spawning period (seasonality), variations of the gonadosomatic relationship, fecundity and size at first sexual maturity (L50). For that, were used 209 specimens of A. tetramerus, 168 of A. ocellatus, 170 of A. heckelli, 178 of A. nassa, 109 of H. temporalis, 380 of M. insignis and 264 of P. scalare. All species showed an isometric growth, with exception of males of A. ocellatus which showed a negative allometric growth. The species bred throughout the year, with spawning activity peaks detected during the rising of the water level, and some additional activity during the flooding period. These were corroborated by RGS and condition factor indices. The overall sex ratio of the species was balanced, 1:1. Except for the species A. nassa, that showed a predominance of males of 0.5:1. All species showed a low fecundity, between 700 and 1500 mature oocytes. The species A. tetramerus, A. ocellatus and H. temporalis showed a partial spawning strategy, and A. nassa, P. scalare and M. insignis showed a total spawning strategy. The asymptotic length (L ∞) and the average length at first sexual maturity (L50) for females showed that all species have an early sexual maturation. The cichlids studied here presented two tactics groups of the main reproductive strategies, K and r. For the management of these species, it should be considered that these are low productivity fish species, and their reproductive seasonal peak and minimum size of capture, based on their L50, should be used to limit the catch.