Maria José dos Santos-Wisniewski

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.

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.

First record of the occurrence of Ceratium furcoides (Levander) Langhans 1925, an invasive species in the hydroelectricity power plant Furnas Reservoir, MG, Brazil

. This reservoir belongs to the Rio Grande Basin, located in the Southeast region of Brazil (46° 19’ W and 20° 40’ S). The reservoir has complex basin morphology, with a dendritic shape and heterogeneous characteristics, differing widely among the several compartments formed by its arms. Thus, there are marked differences in the water quality from place to place (Delgado, 1999).The specimens of

Invasion of the dinoflagellate Ceratium furcoides (Levander) Langhans 1925 at tropical reservoir and its relation to environmental variables

Dinoflagellates of the genus Ceratium are chiefly marine but there are rare occurrences in freshwater. In this study we analyze the invasion and progressive establishment of Ceratium furcoides, an exotic species, in the Furnas Reservoir. Samples were taken at 36 points in the reservoir, during the months of March, June, September and December, 2007. Measurements of some physical and chemical variables were simultaneously performed at each site. The occurrence of C. furcoides was registered at 20 sites, with densities varying between 0.57 and 28,564,913.0 ind.m-3. Blooms of this species were recorded in points which were classified as mesotrophic, coinciding with the places receiving high amounts of untreated domestic sewage. C. furcoides density was correlated with temperature, nutrients (nitrate and nitrite) and water electric conductivity. The highest density was recorded in June when temperature was low. The presence of Ceratium furcoides in the reservoir apparently has not yet affected the reservoir water quality or other plankton communities. However, if it becomes fully established it could perhaps become a problem in the reservoir or even to spread out to other reservoirs in Rio Grande basin.

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

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-1, 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.

New records of Parvalona parva (Crustacea: Anomopoda: Chydoridae) from Brazil, with first description of the male

The Neotropical species Parvalona parva (Daday, 1905) was previously reported only from two localities (Northern Argentina and Lencois Maranhenses, Brazil). In the present paper, seven new records of P. parva from Brazil are presented. The specimens were collected from small waterbodies located in the Federal District and the states of Sao Paulo, Para, and Pernambuco. These new records suggest that this species is not as rare as previously believed. The male, sexual female, and the lateral head pores of parthenogenetic females are described and illustrated for the first time.

Alona iheringula Sinev & Kotov, 2004 (Crustacea, Anomopoda, Chydoridae, Aloninae): life cycle and DNA barcode with implications for the taxonomy of the Aloninae subfamily.

Knowledge of reproductive rates and life cycle of the Cladocera species is essential for population dynamic studies, secondary production and food webs, as well as the management and preservation of aquatic ecosystems. The present study aimed to understand the life cycle and growth of Alona iheringula Kotov & Sinev, 2004 (Crustacea, Anomopoda, Chydoridae), a Neotropical species, as well as its DNA barcoding, providing new information on the Aloninae taxonomy. The specimens were collected in the dammed portion of the Cabo Verde River (21°26′05″ S and 46°10′57″ W), in the Furnas Reservoir, Minas Gerais State, Brazil. Forty neonates were observed individually two or three times a day under controlled temperature (25±1°C), photoperiod (12 h light/12 h dark) and feeding (Pseudokirchneriella subcapitata at a concentration of 105 cells.mL−1 and a mixed suspension of yeast and fish feed in equal proportion). Individual body growth was measured daily under optical microscope using a micrometric grid and 40× magnification. The species had a mean size of 413(±29) µm, a maximum size of 510 µm and reached maturity at 3.24(±0.69) days of age. Mean fecundity was 2 eggs per female per brood and the mean number of eggs produced per female during the entire life cycle was 47.6(±6.3) eggs per female. The embryonic development time was 1.79(±0.23) days and the maximum longevity was 54 days. The species had eight instars throughout its life cycle and four instars between neonate and primipara stage. The present study using molecular data (a 461 bp smaller COI fragment) demonstrated a deep divergence in the Aloninae subfamily.

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

Species of Chydoridae provide the main diversity of the Cladocera. These organisms have been the subject of many studies; some dealing with their role in energy flow in aquatic ecosystems, since they inhabit the littoral region of water bodies which undergo the first impacts from anthropic activities. The aim of this study is to increase knowledge about the life cycle of Coronatella rectangula (Sars, 1861), a species found in several water bodies in the state of Minas Gerais, Brazil. The life cycle was determined by the culture of parthenogenetic females under controlled conditions in the laboratory. Experimental cultures were maintained in growth chambers at a constant temperature of 23.6(±0.5)oC, through a 12 h light/12 h dark photoperiod. The organisms were fed on a suspension of Pseudokirchneriella subcapitata (Chlorophyceae) (105 cells.mL-1), and 0.02 mL of a mixed suspension of yeast and fish ration added per organism in equal proportions (1:1). Fifty parthenogenetic females with eggs were isolated and maintained until they produced neonates. Thirty of these neonates that had less than 24 hours were put in polypropylene bottles of 50 mL and kept in a germination chamber. These organisms were observed daily to obtain the parameters of the life cycle. Biomass and secondary production were also calculated. The embryonic development time of the specimens of C. rectangula was 1.68(±0.13) days and the time to reach primipara, was 2.48(±0.45) days. The mean fecundity of C. rectangula was two eggs/female/brood and the total number of eggs produced by the female during its life cycle was 27.8 eggs. During the whole life cycle, specimens of C. rectangula had a maximum of 14 seedlings, with two instars in the juvenile stage. Total biomass for C. rectangula was 36.66 µgDW.m-3(9.83 for the juvenile stage and 26.82 µgDW.m-3 for adults), and secondary production was 12.10 µgDW.m-3.day-1(8.34 µgDW.m-3.day-1 for egg production and 3.76 µgDW.m-3.day-1 for the juvenile stage).

The use of PCR-RFLP to genetically distinguish the morphologically close species: Ceriodaphnia dubia Richard, 1894 and Ceriodaphnia silvestrii Daday, 1902 (Crustacea Cladocera).

The cladocerans are important components of planktonic and benthic freshwater and good indicators of the trophic state of water bodies. The morphological taxonomy of many species of Cladocera is considered complex with minor differences separating some species. Nowadays, molecular techniques provide a powerful tool to identify and classify different taxonomical levels, using mainly ribosomal RNA genes (rRNA) as molecular markers. In the present work we performed PCR-RFLP to separate Ceriodaphnia dubia, an exotic species in Brazil and the native species Ceriodaphnia silvestrii, widely distributed in Brazilian freshwater. The RFLP analysis of the ITS1-5.8S-ITS2 region of rRNA genes showed to be different between C. dubia and C. silvestrii when using enzymes EcoRI, ApaI and SalI. Thus, the ITS1-5.8S-ITS2 region proved to be a useful molecular marker to differentiate the studied Ceriodaphnia species, which makes the task easier of telling apart species that are morphologically very similar. Also, this methodology might be interesting in determining the distribution of the exotic species C. dubia in Brazilian freshwaters, particularly in cases when C. dubia occurs in the absence of C. silvestrii, a particularly difficult task for ecologists who are not taxonomy specialists.

The influence of environmental factors on the seasonal dynamics and composition of Rotifera in the Sapucaí River arm of Furnas Reservoir, MG, Brazil

Seasonal fluctuations in the dynamics of the plankton rotifer populations in an oligo-mesotrophic branch of a tropical reservoir were analyzed with respect to the possible influence of environmental conditions (physical, chemical and biological), with emphasis on biological interactions. Samples were taken monthly from August 2006 to July 2007. The well-defined climatic seasons were reflected in variations of the physical and chemical properties of the water. The zooplankton community consisted mainly of Rotifera, Cladocera and Copepoda, with occasional representatives of Chaoborus brasiliensis (Diptera), Ostracoda, Protozoa and Turbellaria. Rotifera was the dominant group in zooplankton community in 5 of the 12 months of the study and were represented by 35 taxa. Redundancy analysis between the rotifer population abundances and the set of environmental variables showed significant (p < 0.05) positive correlations with the chlorophyll a in the rainy season. In the dry period, predation was probably the environmental factor that had the strongest effect on rotifer populations; in particular, the density of the cyclopoid Thermocyclops decipiens showed significant (p < 0.05) negative correlations with many of the rotifer population abundances. In addition, analysis of the co-occurrence of different rotifer species indicated strong competitive interactions between populations, during the rainy period (p < 0.001). Among the biotic environmental factors analyzed, algal biomass had an important role during the rainy period and inter-rotifer competition was also significant in these months. It was probably that predation by the cyclopoid copepod Thermocyclops decipiens determined the structure and dynamics of the rotifer populations in the Sapucai arm of the Furnas reservoir, during the dry period.