Takako Matsumura-Tundisi

Biomass (dry weight and carbon content) of plankton crustacea from Broa reservoir (Sao Carlos, S.P.-Brazil) and its fluctuation across one year

The dominance patterns of the main zooplankton groups depend on whether they are analysed by numerical density or dry weight. This fact is discussed in relation to the trophic state of the system.Biomass of planktonic crustaceans from Broa reservoir was analysed by dry weight. For Argyrodiaptomus furcatus organic carbon was also determined. Values of 4.42 µg C ind.−1 and 6.83 µg C ind.−1 were obtained for males and females, respectively.Seasonal fluctuation of the species showed two peaks of abundance: the rainy season (summer), and the windy period (winter), these factors being thus the principal controlling forces for the growth of the populations.

A bacia hidrográfica do Tietê/Jacaré: estudo de caso em pesquisa e gerenciamento

A bacia do Tiete/Jacare e uma das 22 Unidades de Gestao de Recursos Hidricos (Ugrhis) do Estado de Sao Paulo. Um estudo desenvolvido de 2005 a 2007 detalhou as principais caracteristicas dessa bacia hidrografica, os usos do solo, a cobertura vegetal, as fontes pontuais e nao-pontuais de eutrofizacao e contaminacao e as vulnerabilidades da bacia, que conta com 34 municipios e uma populacao de 1.200.000 habitantes. A montagem de um banco de dados com as informacoes ecologicas, hidrologicas, climatologicas e economicas possibilitou estabelecer um programa de planejamento e gestao baseado em vulnerabilidades da bacia hidrografica, impactos das mudancas globais e futuras perspectivas para a gestao dos recursos hidricos. Um indice de qualidade da bacia hidrografica foi desenvolvido com a finalidade de apoiar o planejamento de longo prazo e a gestao de aguas superficiais e subterrâneas.

Predation on Ceriodaphnia cornuta and Brachionus calyciflorus by two Mesocyclops species coexisting in Barra Bonita reservoir (SP, Brazil)

Feeding experiments with two species of carnivorous copepod, Mesocyclops longisetus (Thiebaud) and Mesocyclops kieferi Van de Velde from Barra Bonita, a eutrophic reservoir in São Paulo, Brasil, were performed using two common types of prey: Ceriodaphnia cornuta, a cladoceran, with a mean body length of 464 µm (including spines) or 393 µm (without spines), and Brachionus calyciflorus, a rotifer with a mean body length of 350 µm (including spines) or 279 µm (without spines).Both species showed higher consumption rates on Brachionus than on Ceriodaphnia. For Mesocyclops longisetus, the average rates were: 2.19 prey ind−1 h−1 (Brachionus), and 1.30 prey ind−1 h−1 (Ceriodaphnia). For Mesocyclops kieferi, the rates were 1.85 prey ind−1 h−1 (Brachionus) and 0.60 prey ind−1 h−1 (Ceriodaphnia). These experimental data are discussed with reference to the dynamics of the predator and prey populations in the reservoir.

Biomass and production of Argyrodiaptomus furcatus, a tropical calanoid copepod in Broa Reservoir, southern Brazil

The biomass and the production of Argyrodiaptomus furcatus (Sars), the most abundant copepod in Broa Reservoir (Sao Carlos, Sao Paulo State), were estimated, determining in the laboratory the development time and the quantity of organic carbon and establishing the relationship between these two parameters. The daily production was calculated from P = B(1 − egt) and the annual production was obtained by integrating daily production against time. The maximum production of Argyrodiaptomus furcatus in the reservoir depends on the region considered and on the period of the year. The maximum production was 45.15 mg C m−3d−1 in March, 1976 at station II, region of macrophytes and 6.74 mg C m−3d−1 at station IV, near the dam. The mean production for the year is 6.26 mg C m−3d−1 at station II and 1.43 mg C m−3d−1 at station IV.

Consumption of zooplanktonic organisms by Astyanax fasciatus Cuvier, 1819 (Osteichthyes, Characidae) in Lobo (Broa) reservoir, São Carlos, SP, Brazil

The consumption of zooplanktonic organisms by young and adult fish of Astyanax fasciatus in Lobo Reservoir was studied from October 1978 to September 1979 by analysing the abundance of zooplankton in the gut of fishes and relating it to the variation of the zooplankton community in the lake. To analyse the diet the following methods were used: numeric frequency of occurrence, and frequency rate. Astyanax fasciatus showed a large spectrum of feeding. The young stage feeds mainly on zooplankton and macroinvertebrates (insect larvae) but the adults also consume algae and detritus. Even in relation to the zooplankton the young stage showed a food preference different from that of the adults, selecting copepods over cladocerans, while the adults consumed more cladocerans.

Predation on and by pelagic Turbellaria in some lakes in Brazil

Planktonic Turbellaria are of common occurrence in both natural and man-made lakes in Brazil. Experiments were performed in 1987 and 1989 to determine which zooplankton species are consumed by predatory Mesostoma sp. from three natural lakes in the Rio Doce Valley. Experiments were also performed in 1989 with a yet unidentified flatworm from Barra Bonita reservoir. Both predators consumed Daphnia and Ceriodaphnia at a high rate: 4 individuals per day in the case of Mesostoma sp., a large species and 1.5 ind day−1 in the case of the smaller species from Barra Bonita reservoir. Consumption of copepod nauplii, copepodids and adults was much lower, and Ostracoda were not consumed at all. Experiments on food selectivity showed a clear preference by the flatworms for cladocerans.In the lakes studied, flatworms are heavily preyed upon by larvae of Chaoborus and by Mesocyclops species.Turbellaria densities in the natural lakes were around 300 individuals per cubic meter, whereas in Barra Bonita reservoir, 1000 individuals per cubic meter was a mean value in a fifteen days study.

Checklist de Cladocera de água doce do Estado de São Paulo

In the present work an updated checklist of the species of Cladocera in the state of Sao Paulo is presented, based on previous check-list and a review of the recent studies which include in majority the studies developed within the BIOTA/FAPESP Program. Species inventory performed ten years ago revealed the occurrence of 112 species in Brazil and 84 species in the State of Sao Paulo. The present review shows the occurrence of 96 species of this group in the state of Sao Paulo, representing a 15% increase in the species richness. Among the 300 water bodies sampled in 23 units water resource management units (UGHRI) of Sao Paulo State within the scope of the BIOTA/FAPESP Program, the highest richness of Cladocera species was found in Mogi-Guacu and Aguapei units with 27 species recorded in each. Among the advances reached by the BIOTA/FAPESP Program it could be emphasized the wide geographic covering and the number of species recorded, with 12 new occurrences of native species and 2 exotic species as well. This study evidenced that still there are important gaps in the knowledge, particularly regarding the taxonomy, since many species regarded as cosmopolitan may be a complex of many species requiring taxonomical reviews and ecological studies of the species. It is believed that with the continuity of the studies, the richness of species of Cladocera can increase considerably.

Occurrence of species of the genusDaphnia in Brazil

Three species ofDaphnia are recorded from natural lakes and reservoirs in Brazil:Daphnia gessneri, Herbst, 1967,Daphnia ambigua, Scourfield, 1947 andDaphnia laevis, Birge, 1878. Some comments on their geographical distribution and ecology are made, showing the trend of the presence of these species in eutrophicated environments.

O estado atual do conhecimento da diversidade dos Cladocera (Crustacea, Branchiopoda) nas águas doces do estado de Minas Gerais

O objetivo do presente trabalho e apresentar uma check list atualizada dos registros existentes para especies de Cladocera nas aguas doces do Estado de Minas Gerais que possa servir de base para os estudos em andamento ou estudos futuros dentro do escopo do Programa Biota Minas. O trabalho baseia-se numa extensa revisao da literatura incluindo recentes revisoes taxonomicas, particularmente para alguns generos da familia Chydoridae. O levantamento realizado evidenciou a ocorrencia de 94 especies de Cladocera, distribuidos em 88 corpos de agua no estado de Minas Gerais. Estes cladoceros incluem representantes de 35 generos pertencentes a 7 das 8 familias com ocorrencia nas aguas doces da regiao Neotropical. Para os Cladocera em geral, a familia com maior riqueza foi a Chydoridae (Ordem Anomopoda) com um total de 47 especies registradas, correspondendo a 50% da riqueza total dos Cladocera. As demais familias, em ordem decrescente em relacao a riqueza de especies foram Daphnidae com 16, Macrothricidae com 9, Sididae e Bosminidae com 8 especies cada, Moinidae e Ilyocryptidae com 3 especies cada. Em relacao a ocorrencia nas bacias hidrograficas do estado de Minas Gerais, os dados obtidos evidenciaram registros de especies de cladoceros em 6 das 8 bacias principais. Contudo nao ha qualquer registro para as bacias dos rios Mucuri e Paraiba do Sul. Observa-se que a maior riqueza de especies de Cladocera em algumas bacias hidrograficas como as bacias do Rio Doce com 67 especies, e a bacia do Rio Grande com 65 especies resulta muito provavelmente do maior numero de estudos realizados nas mesmas, e que por outro lado, bacias com baixa riqueza de Cladocera como as bacias do rio Pardo (9 especies) e do Rio Jequitinhonha (3 especies) ou com nenhuma ocorrencia registrada (bacias do rio Mucuri e do rio Paraiba do Sul) resultam de poucos, ou nenhum estudo, respectivamente. Conclui-se que ha necessidade de ampliacao da cobertura geografica para amostragem de corpos de agua em outras bacias, particularmente aquelas localizadas na regiao norte e nordeste do estado de Minas Gerais.

Life cycle of Macrothrix flabelligera Smirnov, 1992 (Cladocera, Macrothricidae), recently reported in the Neotropical region

Information on the life cycle of individual species is vital to an understanding of their ecology, particularly their distribution. In this investigation, aspects of the Macrothrix flabelligera (Cladocera, Macrothricidae) life cycle were studied in laboratory cultures under controlled conditions. Neonates from parthenogenetic females previously acclimatized were isolated and grown at constant temperature, in a 12-h/12-h light/dark cycle. Organisms were fed with a suspension of Scenedesmus bijugus at a concentration of 105 cells ml−1. Daily measurements of body length and age were made, to obtain the growth rate, size and age of primipara. M. flabelligera had high fecundity rates, producing broods of 13.6 eggs female−1. At 23.0 °C, the duration of embryonic and post-embryonic development was 35.9 h and 4.9 days, respectively. The mean longevity was 12.7 days. A length–weight relationship was established and used to convert measured length into weight, in order to plot weight growth curves, as subsidiary information for future secondary production calculations.