Climatic impacts of fresh water hosing under Last Glacial Maximum conditions: a multi-model study

Fresh water hosing simulations, in which a fresh water flux is imposed in the North Atlantic to force fluctuations of the Atlantic Meridional Overturning Circulation, have been routinely performed, first to study the climatic signature of different states of this circulation, then, under present or future conditions, to investigate the potential impact of a partial melting of the Greenland ice sheet. The most compelling examples of climatic changes potentially related to AMOC abrupt variations, however, are found in high resolution palaeo-records from around the globe for the last glacial period. To study those more specifically, more and more fresh water hosing experiments have been performed under glacial conditions in the recent years. Here we compare an ensemble constituted by 11 such simulations run with 6 different climate models. All simulations follow a slightly different design, but are sufficiently close in their design to be compared. They all study the impact of a fresh water hosing imposed in the extra-tropical North Atlantic. Common features in the model responses to hosing are the cooling over the North Atlantic, extending along the sub-tropical gyre in the tropical North Atlantic, the southward shift of the Atlantic ITCZ and the weakening of the African and Indian monsoons. On the other hand, the expression of the bipolar see-saw, i.e., warming in the Southern Hemisphere, differs from model to model, with some restricting it to the South Atlantic and specific regions of the southern ocean while others simulate a widespread southern ocean warming. The relationships between the features common to most models, i.e., climate changes over the north and tropical Atlantic, African and Asian monsoon regions, are further quantified. These suggest a tight correlation between the temperature and precipitation changes over the extra-tropical North Atlantic, but different pathways for the teleconnections between the AMOC/North Atlantic region and the African and Indian monsoon regions.

New perspectives on the synoptic and mesoscale structure of Hurricane Catarina

This work explores in detail synoptic and mesoscale features of Hurricane Catarina during its life cycle from a decaying baroclinic wave to a tropical depression that underwent tropical transition (TT) and finally to a Category 2 hurricane at landfall over Santa Catarina State coast, southern Brazil. This unique system caused 11 deaths mostly off the Brazilian coast and an estimated half billion dollars in damage in a matter of a few hours on 28 March 2004. Although the closest meteorological station available was tens of kilometres away from the eye, in situ meteorological measurements provided by a work-team sent to the area where the eye made landfall unequivocally reproduces the tropical signature with category 2 strength, adding to previous analysis where this data was not available. Further analyses are based mostly on remote sensing data available at the time of the event. A classic dipole blocking set synoptic conditions for Hurricane Catarina to develop, dynamically contributing to the low wind shear observed. On the other hand, on its westward transit, large scale subsidence limited its strength and vertical development. Catarina had relatively cool SST conditions, but this was mitigated by favourable air-sea fluxes leading to latent heat release-driven processes during the mature phase. The ocean`s dynamic topography also suggested the presence of nearby warm core rings which may have facilitated the transition and post-transition intensification. Since there were no records of such a system at least in the past 30 years and given that SSTs were generally below 26 degrees C and vertical shear was usually strong, despite all satellite data available, the system was initially classified as an extratropical cyclone. Here we hypothesise that this categorization was based oil inadequate regional scale model outputs which did not account for the importance of the latent heat fluxes over the ocean. Hurricane Catarina represents a dramatic event on weather systems in South America. It has attracted attention worldwide and poses questions as whether or not it is a symptom of global warming. (C) 2009 Elsevier B.V. All rights reserved.

A Lagrangian identification of major sources of moisture over Central Brazil and La Plata Basin

[1] This work examines the main sources of moisture over Central Brazil and La Plata Basin during the year through a new Lagrangian diagnosis method which identifies the humidity contributions to the moisture budget over a region. This methodology computes budgets of evaporation minus precipitation by calculating changes in the specific humidity along back-trajectories for the previous 10 d. The origin of all air masses residing over each region was tracked during a period of 5 years (2000-2004). These regions were selected because they coincide with two centers of action of a known dipole precipitation variability mode observed in different temporal scales (from intra seasonal up to inter decadal timescales) and are related to the climatic variability of the South American Monsoon System. The results suggested the importance of the tropical south Atlantic as a moisture source for Central Brazil, and of recycling for La Plata basin. It seems that the Tropical South Atlantic plays an important role as a moisture source for Central Brazil and La Plata basin along the year, particularly during the austral summer. The north Atlantic is also an additional source for both regions during the austral summer.

Tide-topography interaction along the eastern Brazilian shelf

In the Tropics, continental shelves governed by western boundary currents are considered to be among the least productive ocean margins in the world, unless eddy-induced shelf-edge upwelling becomes significant. The eastern Brazilian shelf in the Southwest Atlantic is one of these, and since the slight nutrient input from continental sources is extremely oligotrophic. It is characterized by complex bathymetry with the presence of shallow banks and seamounts. In this work, a full three-dimensional nonlinear primitive equation ocean model is used to demonstrate that the interaction of tidal currents and the bottom topography of the east Brazil continental shelf is capable of producing local upwelling of South Atlantic Central Water, bringing nutrients up from deep waters to the surface layer. Such upper layer enrichment is found to be of significance in increasing local primary productivity. (c) 2005 Elsevier Ltd. All rights reserved.

Dinâmica reprodutiva e parasitária de quatro espécies de peixes das águas costeiras do Sudoeste do Oceano Atlântico, Brasil

The present study investigated the reproductive dynamics and parasitism of four species of marine fishes: serra Spanish mackerel, Scomberomorus brasiliensis, Atlantic leatherjacks, Oligoplites saurus and O. palometa,, and Atlantic bumper, C. chrysurus, during the period of August, 2005 to July, 2007, in the coastal waters of Southwest Atlantic Ocean, Brazil. The collected fish samples were measured, weighed, dissected, the gonads were weighed and examined to separate the sex. The gonadosomatic index (GSI), fecundity, type of spawning, the breeding season, the macro and microscopic characterization of the gonads were determined. The ectoparasites from the branchial chambers and bucal cavity of the fish were collected, measured, weighed and identified. The sex ratio of the study fish species were approximately 1M:1F, however, there was a predominance of males of O. palometa (3M:2F). The GSI of fishes varied according to their reproductive cycle and the stage of gonadal maturation. The highest values of GSI and the spawning period coincided with the rainy period of the region. The females presented total spawning and the fecundity was positively correlated with the weight of the ovary and the body. Four stages of development of the gonads immature, maturing, mature and spent were identified macroscopically and histological analyses of ovaries revealed the different phases of oocyte development. Three species of isopod parasites were identified in the study fishes: Livoneca redmmanni, Rocinela signata and Cimothoa spinipalpa. The first two species occurred in the branchial cavities of C. chrysurus and S. brasiliensis. The isopod C.spinipalpa (a new species) was registered for the first time in the bucal cavity of O. saurus and O. palometa. The parasitic isopods preferred the branchial chambers and the bucal cavity of the host fishes as these were protected microhabitats. The isopods parasitized the immature, maturing and mature fishes. The prevalence of infection of isopods in the hosts varied from 16 to 21%, though in O. palometa it was 60%. In the rainy period the highest isopod parasitic occurrence was registered, however, this did not prejudice the normal reproductive cycle of the host fish.

FIRST ZOEAL STAGE and MEGALOPA of UCA (UCA) MARACOANI (DECAPODA: BRACHYURA), WITH COMMENTS on THE LARVAL MORPHOLOGY of SOUTH-AMERICAN SPECIES of OCYPODIDAE

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Levantamento florístico de Floresta Atlântica no sul do Estado de São Paulo, Parque Estadual Intervales, Base Saibadela

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The cetacean offal connection: Feces and vomits of spinner dolphins as a food source for reef fishes

At Fernando de Noronha Archipelago, southwest Atlantic, reef fishes associated with spinner dolphins (Stenella longirostris) were recorded when the cetaceans congregated in a shallow inlet. In the reef waters the dolphins engaged in several behaviors such as resting, aerial displays and other social interactions, as well as eliminative behaviors such as defecating and vomiting. Twelve fish species in seven families were recorded feeding on dolphin offal. The black durgon (Melichthys niger) was the most ubiquitous waste-eater, and its group size was positively and significantly correlated with dolphin group size. The durgons recognized the postures a dolphin adopts prior to defecating or vomiting, and began to converge to an individual shortly before it actually voided. Offal was quickly fed upon, and the fishes concentrated in the area occupied by the dolphins until the latter left the shallows. Since all the recorded offal-feeding species feed on plankton or drifting algae, feeding on cetacean droppings may be regarded as a switch from foraging on drifting organisms to foraging on drifting offal, a predictable food source in the inlet. Further instances of this cetacean-fish association are predicted to occur at sites where these mammals congregate over reefs with clear water and plankton-eating fishes.

Improving methods in gap ecology: Revisiting size and shape distributions using a model selection approach

Questions: We assess gap size and shape distributions, two important descriptors of the forest disturbance regime, by asking: which statistical model best describes gap size distribution; can simple geometric forms adequately describe gap shape; does gap size or shape vary with forest type, gap age or the method used for gap delimitation; and how similar are the studied forests and other tropical and temperate forests? Location: Southeastern Atlantic Forest, Brazil. Methods: Analysing over 150 gaps in two distinct forest types (seasonal and rain forests), a model selection framework was used to select appropriate probability distributions and functions to describe gap size and gap shape. The first was described using univariate probability distributions, whereas the latter was assessed based on the gap area-perimeter relationship. Comparisons of gap size and shape between sites, as well as size and age classes were then made based on the likelihood of models having different assumptions for the values of their parameters. Results: The log-normal distribution was the best descriptor of gap size distribution, independently of the forest type or gap delimitation method. Because gaps became more irregular as they increased in size, all geometric forms (triangle, rectangle and ellipse) were poor descriptors of gap shape. Only when small and large gaps (> 100 or 400m2 depending on the delimitation method) were treated separately did the rectangle and isosceles triangle become accurate predictors of gap shape. Ellipsoidal shapes were poor descriptors. At both sites, gaps were at least 50% longer than they were wide, a finding with important implications for gap microclimate (e.g. light entrance regime) and, consequently, for gap regeneration. Conclusions: In addition to more appropriate descriptions of gap size and shape, the model selection framework used here efficiently provided a means by which to compare the patterns of two different types of forest. With this framework we were able to recommend the log-normal parameters μ and σ for future comparisons of gap size distribution, and to propose possible mechanisms related to random rates of gap expansion and closure. We also showed that gap shape varied highly and that no single geometric form was able to predict the shape of all gaps, the ellipse in particular should no longer be used as a standard gap shape. © 2012 International Association for Vegetation Science.

Estudo observacional sobre os eventos de seca meteorológica e hidrológica na região de Marabá-PA no sudeste da Amazônia Oriental

O objetivo do presente trabalho foi investigar os aspectos observacionais dos eventos de seca meteorológica e hidrológica na região de Marabá localizada no sudeste do Pará na Amazônia oriental. Utilizou-se uma base de dados mensais de precipitação e cota no período de 1971 a 2010. Os eventos de seca meteorológica foram selecionados através de índices de precipitação negativa (segundo a metodologia do índice de anomalia de chuva- IAC) e os eventos de seca hidrológica do rio Tocantins foram baseados em índices extremos de cota fluviométrica abaixo do normal (através da metodologia da anomalia padronizada). Para as condições de seca meteorológica, os eventos concentram-se em sua grande maioria nas categorias de seca Fraca (FRA) e Moderada (MOD), com maior frequência de seca FRA nos meses de Fevereiro (38%), Junho (37%) e Dezembro (34%), enquanto que a seca MOD é mais frequente em Agosto (39%), Setembro (42%) e Outubro (32%). Quanto aos eventos de seca hidrológica (cota fluviométrica abaixo do normal) do rio Tocantins, os resultados mostram que a ocorrência mensal dos eventos é aleatória e pode ser observado ao longo de todo ano, independente do mês ser de enchente ou vazante. A duração dos eventos não apresenta regularidade ao longo do período estudado. Quanto à estrutura dinâmica dos padrões oceânicos e atmosféricos de grande escala associados aos eventos de seca meteorológica e hidrológica observaram-se que os eventos estão relacionados com um padrão de aquecimento (El Niño) no Pacífico equatorial e condições de aquecimento no Atlântico tropical norte, cujas condições oceano-atmosféricas de grande escala propiciam a intensificação tanto do ramo descendente zonal da célula de Walker como do ramo descendente meridional da célula de Hadley, que induzem a inibição significativa da atividade convectiva, explicando consequentemente a ocorrência dos eventos de seca na região. Analisou-se também a relação entre os eventos de seca e o registro de focos de calor (queimadas) na região de Marabá, durante os anos de 2000 a 2009, sendo que a correlação em torno de 43% confirma a sinergia entre seca e queimada, ou seja, a floresta torna-se mais inflamável sob condições de déficit hídrico.

Interações tróficas entre espécies pelágicas do Atlântico Sudoeste: utilizando isótopos estáveis e inferência bayesiana

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Clinical manifestations and experimental studies on the spine extract of the toadfish Porichthys porosissimus

Toadfish are fish from the family Batrachoididae that are found in marine and brackish environment around the world. Among the toadfish, Porichthys genus is very common, where Porichthys porosissimus, also called Atlantic Midshipman is found in Southwest Atlantic, from Rio de Janeiro, Brazil to eastern Argentina. There was no consensus about the classification of the genus Porichthys as venomous fish because so far there are no published Studies regarding human envenomations and/or toxic activities induced in animal models. Herein, we report two conclusive envenoming in human beings caused by P porosissimus spines, with clear signs and symptoms that were very important for the development of our experimental studies. We demonstrated that the P. porosissimus spine extract, now venom, can induce nociceptive and edematogenic responses in mice as well an induction of an inflammatory response elicited by intravital microscopy and leukocyte migration. Finally, we identified in the P. porosissimus spine extract, through analysis by mass spectrometry, the presence of proteins previously detected in the venoms of other fish species and other venomous animals. We believe that based on our studies we will dismiss the non-venomous nature of this fish and clarify this issue. (C) 2014 Elsevier Ltd. All rights reserved.

Vibrio cholerae O1 detection in estuarine and coastal zooplankton

Vibrio cholerae is an autochthonous marine bacterium, and its association with diverse planktonic crustaceans has been extensively investigated; however, the presence of V. cholerae on individuals of most phyla of planktonic animals is still incompletely understood. The objective of this study was to analyze the distribution of V. cholerae serogroup O1 associated with specific zooplankton taxa in an estuary and the adjacent continental shelf of the southeastern Brazilian coast. The occurrence of the bacterium was assessed in zooplankton samples, specifically on the most abundant taxa, using direct fluorescence assay (DFA) and direct viable count-direct fluorescence assay (DVC-DFA) methods. Vibrio cholerae O1 was detected in 88% of samples collected from the Santos-Bertioga estuary and in 67% of samples from the shelf. The salinity of the estuarine water ranged from 21.8 to 34.6, significantly lower than the shelf water which was 32.1-36.1. Salinity was the only environmental variable measured that displayed a significant correlation with the presence of V. cholerae (P < 0.05). Vibrio cholerae O1 was detected in chaetognaths, pluteus larvae of echinoderms and planktonic fish eggs (Engraulidae), all new sites for this bacterium.

A note on a mineralogical analysis of the sediments associated with the Plata River and Patos Lagoon outflows

Riverine waters bring to seas a variety of suspended materials, which are ultimately deposited on the shelf or exported to the deep ocean. Investigation of the mineralogical contents of these continental-borne constituents on seafloors may reveal valuable information about the environmental conditions in the drainage basin. In this note we report results of X-ray diffraction and other analysis of sediments in bottom samples collected on the continental shelf under influence of the Plata River and the Patos Lagoon, in South America. The analysis reveals that non-clay materials are mostly concentrated south of 33 degrees S, while clay sediments are relatively more abundant further north. We propose that such distributions are controlled by the circulation pattern and water mass distribution of the lower and upper layers, respectively. (C) 2008 Elsevier Ltd. All rights reserved.