Navegando por Assunto "Cichla"

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Acesso aberto (Open Access)
Analysis of propagule pressure and genetic diversity in the invasibility of a freshwater apex predator: the peacock bass (genus Cichla)
(2014-03) CARVALHO, Daniel Cardoso de; OLIVEIRA, Denise Aparecida Andrade de; SAMPAIO, Maria Iracilda da Cunha; BEHEREGARAY, Luciano Bellagamba
An important step in invasive biology is to assess biological variables that could be used to predict invasion success. The study of genetics, evolution, and interactions of invasive and native species in invaded ranges provides a unique opportunity to study processes in population genetics and the capability of a species' range expansion. Here, we used information from microsatellite DNA markers to test if genetic variation relates to propagule pressure in the successful invasion of an apex predator (the Amazonian cichlid Cichla) into Southeastern Brazilian River systems. Invasive populations of Cichla have negatively impacted many freshwater communities in Southeastern Brazil since the 1960s. Reduction of genetic variation was observed in all invasive populations for both Cichla kelberi (CK) and Cichla piquiti (CP). For instance, heterozygosity was lower in the invasive range when compared to native populations from the Amazon basin (CP HE = 0.179/0.44; CK HE = 0.258/0.536 respectively). Therefore, despite the successful invasion of Cichla in southeast Brazil, low genetic diversity was observed in the introduced populations. We suggest that a combination of factors, such as Cichla's reproductive and feeding strategies, the "evolutionary trap" effect and the biotic resistance hypothesis, overcome their depauperete genetic diversity, being key aspects in this apex predator invasion.
Acesso aberto (Open Access)
A pesca comercial dos tucunarés Cichla Spp. (Peciformes, Cichlidae) no Reservatório da UHE-Tucuruí, Rio Tocantins, PA
(Universidade Federal do Pará, 2007) BOTELHO, Marília Cunha; BARTHEM, Ronaldo Borges; http://lattes.cnpq.br/4192105831997326
This study describes the freshwater fishery based on peacock bass ("tucunaré") Cichla spp. in the lower Tocantins River, Pará state, northern Brazil, in the area influenced by the Tucuruí hydroelectric dam, with emphasis on the reservoir. The study was divided in two parts: Chapter I describes the commercial peacock bass fishery with relation to fishing gear, fishing strategies, utilized environments, seasonality, and local fishing management according to the fishermen’s perception. The fishermen’s local knowledge was studies, including their ethnobiological classification of peacock bass types, and the social, ecological, and economical aspects involved. Interviews with fishermen and participation observation were conducted in situ. The Tucurui reservoir peacock bass fishery is of great importance in the social and economic life of these fishermen and is their main income source. This fishery occurs in specific places in the lake and uses rudimentary methods and equipment. According to the fisherman, production is influenced by environmental variables and by the use of guild nets, that the fishermen say drives away peacock bass from the fishing environments. The use of environments for fishing is the main source of conflict among fisherman. Social relations among fishermen in a system of partnership and the presence of middlemen diminish the the fisherman’s income. Fishermen possess consistent knowledge on the ecology and behavior of peacock bass. Their system of fish classification recognizes three ethnospecies, two of which constitute a single scientific species. Chapter II treats peacock bass yields at landing points in the lake, from 1997 to 2003, according to data furnished by ELETRONORTE, and a measure of fishing effort was considered that was most adequate for these data. The data were analyzed according to port, fishing gear, type of boat, fishing grounds, and river flood cycle. The data demonstrated that different cities possess fishing fleets with their own characteristics and that these utilize nearby fishing grounds. The greatest yields were during periods of flooding and subsidence of water levels, with hook and line fishery being responsible for most of the catch. Canoes were the most used boats. The yield data at landing points indicate that this fishery is more important in cities and areas located on the lake. Fish yield for unit of effort only shows adequate statistical behavior when analyzed for fishing grounds and the adjusted units of effort are number of fisherman per days of fishing, after logarithmic transformation.