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- ItemThe effect of salinity on larval development of spider crab Libinia spinosa (Brachyura, Majidae) reared in the laboratory(1999) Hereu, Clara María; Calazans, Danilo Koetz deOvigerous females of Libinia spinosa were collected in the oceanic region adjacent to the Patos Lagoon and were maintained in the laboratory at 20° and 30 PSU until spawning. After hatching larvae were transferred to compartmented plastic boxes of approximately 25 ml with filtered sea water of different salinities (25, 30 and 35 PSU) and kept under photoperiod of 12 h light: 12 h dark. Water was changed every other day, and larvae were checked daily to assess molt and death rates. Larvae were fed Artemia sp. nauplii newly hatched. Survival to megalopa was higher at salinitiesof 30 and 35 than at salinity 25. Although larvae reached megalopal phases in all three salinities mortality was 100% during this phase. Salinity had no effect on duration of zoea stage I whereas development of zoea II was significantly delayed in the lowest salinity tested. The results obtained were compared to other species of the same genus which were maintained under similar conditions. Nevertheless, there is a difference between the larval development length reported in another study for this species, where the mean length of larval stages was longer.
- ItemSurf zone diatoms: a review of the drivers, patterns and role in sandy beaches food chains(ELSEVIER, 2014) Odebrecht, Clarisse; Preez, Derek Richard du; Abreu, Paulo Cesar Oliveira Vergne de; Campbell, Eileen ElaineThe accumulation of high biomass of diatoms in the surf zone is a characteristic feature of some sandy beaches where the wave energy is sufficiently high. A few species of diatoms, called surf diatoms, thrive in this harsh environment. The main processes driving the spatial and temporal distribution of surf diatoms as well as their standing biomass and growth were described twenty to thirty years ago based on studies conducted on the western coast of the United States of America and South African beaches. Since then, over fifty locations around the world have been reported to have surf diatom accumulations with most (three-quarters) of these being in the southern hemisphere. Their occurrence is controlled by physical and chemical factors, including wave energy, beach slope and length, water circulation patterns in the surf zone and the availability of nutrients to sustain the high biomass. The main forces driving the patterns of temporal variability of surf diatom accumulations are meteorological. In the short term (hours), the action of wind stress and wave energy controls the diatom accumulation. In the intermediate time scale (weeks to months), seasonal onshore winds of sufficient strength, as well as storm events are important. Furthermore, anthropogenic disturbances that influence the beach ecosystem as well as large-scale events, such as the El Niño Southern Oscillation, may lead to significant changes in surf diatom populations in the long term (inter-annual). Surf diatoms form the base of a short and very productive food chain in the inshore of the sandy beaches where they occur. However, the role of surf diatoms in the microbial food web is not clear and deserves further studies.
- ItemA análise da cadeia produtiva dos catados como subsídio à gestão costeira: as ameaças ao trabalho das mulheres nos manguezais e estuários no Brasil(2012) Walter, Tatiana; Wilkinson, John; Silva, Angelus Giuseppe Pereira daO presente artigo apresenta a aplicação do aporte analítico dos sistemas agroalimentares associado à Sociologia Econômica na análise de questões afeitas à pesca artesanal, tendo como perspectiva uma abordagem sistêmica e territorializada, centrais à gestão costeira. Para tal, analisou a cadeia produtiva dos catados oriundos da mariscagem em oito municípios litorâneos da Bahia por meio de um aporte teórico-analítico diversificado que permitiu a compreensão dos diversos fenômenos que afetam a atividade das mulheres na produção de catados, incluindo aqueles oriundos da dinâmica territorial. A coleta de dados concatenou a análise de informações pretéritas com pesquisa-observante e realização de entrevistas semiestruturadas, no período de julho de 2009 a junho de 2010, envolvendo informações sobre 94 comunidades pesqueiras. Os resultados denotam a complexidade em torno das estratégias de comercialização, ainda que os fluxos de produção estejam predominantemente circunscritos à região. Verificou-se que, considerando as demais atribuições das mulheres, tanto na elaboração de outros produtos pesqueiros como frente aos afazeres domésticos, tem-se na degradação dos manguezais um processo que concatena sobrecarga de trabalho com perda de produção e renda. Degradação esta oriunda da expansão urbana, do turismo e da poluição relacionada à maricultura e à atividade petrolífera. Dois outros fatores são importantes entraves nesta cadeia produtiva: as exigências sanitárias que discriminam as práticas domésticas em torno do beneficiamento dos catados e a falta de saúde laboral associada à ausência de mecanismos de seguridade social. Em relação aos resultados obtidos, este conjunto de fatores representa uma ameaça às marisqueiras, no que tange à manutenção de sua reprodução social. Conclui-se, ainda, que o aporte teórico-analítico adotado é adequado à análise das questões afetas à atividade pesqueira, especialmente por contemplar uma abordagem capaz de inseri-la como parte da gestão costeira.
- ItemThe small-scale urban reservoir fisheries of Lago Paranoá, Brasília, DF, Brazil(2007) Walter, Tatiana; Petrere Junior, MiguelIn many cases in large urban centers, which have appropriate waterbodies, small-scale fisheries are the only source of cheap protein for the poor. In Lago Paranoá, located in Brasília, the capital city of Brazil, fishing was studied by conducting interviews with 53 fishers filling in logbooks from March, 1999 to March, 2000 in three fishing communities. The fishers come from the poorest towns around Brasília, known as satellite-towns. They have been living there on average for 21.7 years (s = 9.6 years), their families have 4.9 members (s = 3.6) on average and 44.2% do not have a basic education. However, such characteristics are similar to the socioeconomic indices of the metropolis where they live. In spite of being illegal between 1966 and 2000, fishing generated an average monthly income of U$ 239.00 (s = U$ 171.77). The Nile Tilapia Oreocrhromis niloticus is the main captured species (85% of a total number of landings in weight of 62.5 t.). Fishing is carried out in rowing boats, individually or in pairs. The fishing equipment used are gillnets and castnets. Gillnets were used actively, whereby the surface of the water is beaten with a stick to drive Tilapias towards nets as they have the ability to swim backwards. This fishing strategy was used in 64.7% of the fisheries, followed by castnets (31.1%) and by gillnets which were used less (4.2%). The fish is sold directly in the streets and fairs of the satellite-towns to middlemen or to bar owners. Three communities have different strategies in terms of fishing equipments, fishing spots and commercialization. Consequently, there are statistically significant differences in relation to the monthly income for each one of these communities.
- ItemLoricate Choanoflagellates from the South Atlantic coastal zone (~32 °S) including the description of Diplotheca tricyclica sp. nov.(2008) Bergesch, Marli; Odebrecht, Clarisse; Moestrup, ØjvindThe biodiversity of marine heterotrophic protists is poorly known in the South Atlantic coastal zone (~32 °S) especially regarding the nanoflagellates. The presence of loricate choanoflagellates was reported for the first time in the Patos Lagoon estuary and the adjacent coastal zone. Seventeen species of eleven genera of loricate choanoflagellates were observed between October 1998 and May 2000 in fixed water samples (lugol’s solution + glutaraldehyde) in a JEM 100-SX transmission electron microscope. Most species were recorded in euhaline and mixopolyhaline waters during the spring and summer, none in autumn and a few (four) in winter. The absence of choanoflagellates at the more sheltered inshore stations is due freshwater influence, and at the beach station, probably due the strong wave action. The probably cosmopolitan species Pleurasiga minima , Cosmoeca norvegica , C. ventricosa and Parvicorbicula circularis were present in spring or summer in the estuary channel and coastal area while Stephanoeca diplocostata which apparently prefers lower temperature, was recorded in winter. Calotheca alata and Campyloacantha spinifera are mainly temperate species and were present in spring. The new species Diplotheca tricyclica was recorded at the estuary channel in the summer 1999, in high salinity water.
- ItemThe last 25,000 years in the Eastern Plateau of Southern Brazil according to Alpes de São Francisco record(Elsevier, 2010) Leonhardt, Adriana; Lorscheitter, Maria LuisaThe palaeoenvironmental history has been studied based on palynology of a sedimentary profile from the Alpes de São Francisco bog (29290 3500S, 50370 1800W), São Francisco de Paula municipality, Rio Grande do Sul eastern Plateau, extreme Southern Brazil. The results indicate a regional cold and dry climate between 25,000 and 12,500 yr BP, interpreted from the grassland vegetation, forest taxa were present in refuges and the shallow local lake began to fill in. Climatic conditions became more aride after 16,000 yr BP, when grassland became rare. From 12,500 yr BP onwards, the climate began to change and at 11,000–9700 yr BP a warm and moist climate permitted the slight migration of pioneer arboreal taxa from refuges and locally a marsh formation. Between 9700 and 6500 yr BP a warm and dry climate resulted in reduction of grassland, confined the forest in refuges, dried out the marsh. The gradual increase of humidity between 6500 and 4000 yr BP allowed migration of forests from refuges and a bog developed. Between 4000 and 2000 yr BP Araucaria forest spread, indicating moister climate. The local bog expanded. From 2000 yr BP onwards, humid but warmer climate seems to result in a lower reproductive capacity of Araucaria forest taxa limiting its expansion. The bog reached the present-day in a decline condition. The results are compared to previous records from Southern Brazil highlands and some places from Argentina in order to better elucidate the climatic and vegetational history of these important South America areas during the late Quaternary.
- ItemPalinomorfos do perfil sedimentar de uma turfeira em São Francisco de Paula, Planalto Leste do Rio Grande do Sul, Sul do Brasil(2007) Leonhardt, Adriana; Lorscheitter, Maria Luisa(Palynomorphs of the sedimentary profile of a bog, São Francisco de Paula, Eastern Plateau of Rio Grande do Sul, southern Brazil). This paper aims at giving basic reference material to the study of plant succession in the Quaternary Brazilian southern plateau. Therefore, it presents the palynological analysis of 22 samples, taken along one sedimentary profile of 286 cm, in a bog of Rio Grande do Sul Eastern Plateau, corresponding approximately to the last 25000 years. The chemical processing of the samples followed the conventional method and the analysis was made by light microscopy. Palynomorphs corresponding to 10 fungi, 6 algae, 3 bryophytes and 16 pteridophytes were examined. The material, especially spores, is described and illustrated. The descriptions are accompanied, whenever possible, by ecological data of the original organism.
- ItemRetention time generates short-term phytoplankton blooms in a shallow microtidal subtropical estuary(Elsevier, 2015) Odebrecht, Clarisse; Abreu, Paulo Cesar Oliveira Vergne de; Carstensen, JacobIn this study it was hypothesised that increasing water retention time promotes phytoplankton blooms in the shallow microtidal Patos Lagoon estuary (PLE). This hypothesis was tested using salinity variation as a proxy of water retention time and chlorophyll a for phytoplankton biomass. Submersible sensors fixed at 5 m depth near the mouth of PLE continuously measured water temperature, salinity and pigments fluorescence (calibrated to chlorophyll a) between March 2010 and 12th of December 2011, with some gaps. Salinity variations were used to separate alternating patterns of outflow of lagoon water (salinity <8; 46% of the time) and inflow of marine water (salinity >24; 35% of the time). The two transition phases represented a rapid change from lagoon water outflow to marine water inflow and a more gradually declining salinity between the dominating inflow and outflow conditions. During the latter of these, a significant chlorophyll a increase relative to that expected from a linear mixing relationship was observed at intermediate salinities (10e20). The increase in chlorophyll a was positively related to the duration of the prior coastal water inflow in the PLE. Moreover, chlorophyll a increase was significantly higher during austral spring-summer than autumn-winter, probably due to higher light and nutrient availability in the former. Moreover, the retention time process operating on time scales of days influences the long-term phytoplankton variability in this ecosystem. Comparing these results with monthly data from a nearby long-term water quality monitoring station (1993e2011) support the hypothesis that chlorophyll a accumulations occur after marine inflow events, whereas phytoplankton does not accumulate during high water outflow, when the water residence time is short. These results suggest that changing hydrological pattern is the most important mechanism underlying phytoplankton blooms in the PLE.
- ItemPólen de gimnospermas e angiospermas do perfil sedimentar de uma turfeira em São Francisco de Paula, Planalto Leste do Rio Grande do Sul, Sul do Brasil(2008) Leonhardt, Adriana; Lorscheitter, Maria Luisa(Pollen of gymnosperms and angiosperms of the sedimentary profile of a bog, São Francisco de Paula, Eastern Plateau of Rio Grande do Sul, southern Brazil). This pollen catalogue aims at helping the study of paleoenvironmental reconstructions by palynology of sediments in southern Brazil Plateau. It presents gymnosperms and angiosperms pollen found in a sedimentary profile from a bog of Rio Grande do Sul Eastern Plateau. The profile has 286 cm long, corresponding approximately to the last 25,000 years. The 22 samples were collected in regular intervals in the profile, chemically treated following the standard method and analyzed by light microscopy. Pollen grains from two gymnosperms and 43 angiosperms (one Magnoliidae, five Hamamelidae, six Caryophyllidae, six Dillenidae and 25 Rosidae) are presented. The pollen material is described and illustrated. The descriptions are accompanied, whenever possible, by ecological data of the original sporophyte.
- ItemThe productivity history in the Southwestern Atlantic as inferred from coccolitophore record fot the last 130 kyr(2013) Leonhardt, Adriana; Toledo, Felipe Antonio de Lima; Coimbra, João CarlosIn this work, fossil assemblages of coccolithophorids, oxygen stable isotopes (Globigerinoides ruber), and radiocarbon dating were used as proxies. The sediment core, obtained on the slope of Campos Basin, was analyzed, comprising the last 130 kyr. The results show that placolith-bearing taxa, such as Gephyrocapsa spp. and Emiliania huxleyi, as well as Florisphaera profunda, which inhabits the lower photic zone, dominated the assemblage during the whole study interval. Over the past 130 kyr, there was a relationship between productivity (based on N ratio) and climate cyclicity. In a general way, it can be said that sensu stricto interglacial stages (MIS 5e and the Holocene) showed low productivity, while the others (MIS 5d-a, 4, 3 and 2) had large fl uctuations. During interglacial-like conditions, a northward shift in the Intertropical Convergence Zone position would take place, along with a weakening of the NE winds associated with the Southern Atlantic Subtropical High and a weakening of the Brazil Current, leading to the maintenance of the water stratifi cation. On the other hand, during glacial-like conditions, the inverse conditions would be favorable to a shallower nutricline, increasing productivity in surface waters. Maximum productivity is achieved between 14-6.5 ky (during deglaciation), which could be a refl ection of the events of the Last Glacial Maximum.