Biomass and production of Cladocera in Furnas Reservoir, Minas Gerais, Brazil

Abstract

Secondary production of zooplankton, the main energy pathway in many aquatic ecosystems, is crucial to an Understanding of functioning of these systems function. In this study, we analyzed the magnitude and seasonal variations of the population density, biomass and secondary production of Cladocera in the Furnas Reservoir (Brazil). Samples were carried out monthly at 6 points in the reservoir, from August 2006 to July 2007. Main physical and chemical variables in the water column were measured in situ. Data on density, biomass and development times were obtained and used to calculate the secondary production of eight Cladocera species. The total production of Cladocera varied from 0.02 to 28.6 mgDWm -3 .day, among the sampling sites. The highest values were recorded in spring and summer months (September to January), and were correlated to the increase in the biomass of the phytoplankton. The mean production:biomass ratio was 0.32. The level of production in Furnas Reservoir fell within the range of those reported in the literature and was of the same order of magnitude of the production values recorded for oligotrophic reservoirs. Cladocera production differed spatially inside the Sapucaí compartment and also in the temporal scale, seasonally.Keywords: zooplankton, productivity, reservoir tropical, trophic state. Biomassa e produção de Cladocera no Reservatório de Furnas, Minas Gerais, Brasil ResumoA produção secundária do zooplâncton é uma variável importante no funcionamento dos ambientes aquáticos, sendo o principal caminho da energia em muitos ecossistemas. Neste trabalho, o principal objetivo foi determinar a magnitude e as mudanças sazonais na densidade, biomassa e produção secundária dos cladóceros, no Reservatório de Furnas. As amostragens de Cladocera foram realizadas mensalmente em seis pontos do reservatório no período de agosto de 2006 a julho de 2007. As principais variáveis físicas e químicas da coluna d´água foram medidas in situ. Dados de densidade, biomassa e tempo de desenvolvimento foram obtidos e utilizados para calcular a produção secundária de oito espécies de cladóceros. A produção total dos cladóceros variou, em média, de 0,02 a 28,6 mgPS.m .dia -1 entre os pontos amostrados. Os maiores valores foram registrados nos meses de primavera e verão, relacionados em parte com os aumentos na biomassa do fitoplâncton. A razão produção:biomassa foi 0,32. Os valores de produção do Reservatório de Furnas situam-se dentro da faixa de valores que são relatados na literatura e foi da mesma ordem de grandeza dos valores registrados para outros reservatórios oligotróficos. A produção de Cladocera apresentou diferenças em escala espacial dentro do compartimento Sapucaí e sazonalmente, em escala temporal.Palavras-chave: zooplâncton, produtividade, reservatório tropical, estado trófico.

Life history, biomass and production of Coronatella rectangula (Branchiopoda, Anomopoda, Chydoridae) from Minas Gerais

“…This value is higher than that recorded by Panarelli et al (2010) for this species (18 µgDW.m -3 ) in Coqueiral pond, which is colonized by macrophytes and is a pond adjacent to the Paranapanema River, influenced by it through a connection between them. Santos et al (2010) registered a much lower value for Alona verrucosa (2.5 µgDW.m -3 ), a species of the same family as C. rectangula. This difference in biomass may have occurred because in this study, and in that of Panarelli et al (2010), the samples were collected in ponds with macrophytes, while A. verrucosa was sampled in the limnetic region of a reservoir, where the occurrence of Chydoridae species is accidental.…”

“…Some factors affect the development and reproduction of cladocerans and, consequently, their secondary production, especially the use of organic matter by consumers, which is measured by increasing the biomass by time unit (Santos et al, 2010). The reproduction of Cladocera occurs most of the time asexually, by parthenogenesis.…”

Life cycle traits of Philodina roseola Ehrenberg, 1830 (Rotifera, Bdelloidea), a model organism for bioassays

“…The quality and quantity of food are controlling factors for secondary production in aquatic ecosystems (Santos et al 2010, Rajendiran and Subramanian 2007, Snell 2014 and an increase in the amount of food available leads to a rise in egg production , Strojsová et al 2009). According to Sarma et al (2005), the greater availability of food and higher temperatures in tropical, than in temperate regions favor the Rotifera, which are found in the majority of freshwater habitats and are often the group of zooplankton with the highest secondary production, by virtue of their short generation time and numerical dominance (Starkweather 1987, Walz 1997 Wallace 2002, Wallace and Snell 2010, Snell 2014, in spite of their small biomass at any given moment (Ruttner-Kolisko 1972).…”

Alona kaingang (Crustacea, Cladocera, Aloninae): a new species of the pulchella-group, with identification key to Neotropical species

“…The abiotic parameters of the pond water were as follows: pH 6.8-7.1, electrical conductivity 97. (Santos et al 2010).…”