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The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Mangroves are relevant ecosystems due to their ecological role, economic use, and social importance. One of the most abundant and important species in Brazilian mangroves is the exploited crab Ucides cordatus. This study focuses on this species and the aim was to evaluate the concentration of trace elements in the hepatopancreas of ovigerous females, eggs (pre-hatching and hatching stages), and for the first time, in newly hatched larvae. Ovigerous females were captured in two Southeastern Brazil mangroves (Guanabara Bay and Paraíba do Sul River’s secondary estuary) and spawning was held in spawning tanks, in the laboratory. Some females were not taken to the tanks, but they were frozen right after collection. There was no significant difference in trace element concentration between these females and those kept in the spawning tanks. Both essential and non-essential trace elements were detected in newly hatched larvae. Comparing with the adult female, the elements Zn, Cu, and Mn showed the highest concentrations in larvae and eggs. Vanadium, Cr, and Mn concentrations were significantly higher in hatching eggs than observed in newly hatched larvae, indicating the retention of elements in the eggshell. Considering the V (0.17 - 1.17 μg.g−1 dry weight), Cu (14.1 - 41.1 μg.g−1 dry weight), and Zn (235.4 - 263.9 μg.g−1 dry weight) concentrations in newly hatched larvae, with the same order of magnitude observed in suspended particulate matter (SPM) and sediments in suspension, the planktonic larval dispersion could result in the transport of elements beyond the mangrove, and their introduction in coastal waters.

Sepetiba Bay has a wealth of fish species (total 148) as well as a vast area of mangroves and numerous rocky islands, which are important sites of reproduction for marine life. This peculiar environment of the Brazilian coast hosts one of the most important industrial centres of south-eastern Brazil. This site has been impacted for decades by the release of industrial emissions and effluents with high metal loads by the steel industry. The ranges of metal concentrations in fish muscle from the species Micropogonias furnieri, Genidens genidens, Cathorops spixii, Notarius grandicassis, Diapterus rhombeus, Selene vomer, Prionotus punctatus, Citharichthys spilopterus, Achirus lineatus, Trinectes paulistanus, Symphurus tessellatus and Hypanus guttatus were measured (Al: 0.02-555.9 µg g-1 d.w., As: 0.0002-20.1 µg g-1 d.w., Cd

The Bragantina Platform is an onshore basin of the Brazilian equatorial margin, including the Pirabas Formation, the youngest bioclastic-dominated formation in the area (early–middle Miocene), testifying to the final demise of carbonate factories along this margin area and the transition to a siliciclastic-dominated sedimentation. Although the greatest part of the Pirabas Formation is overlain by the Barreiras Formation and the post-Barreiras deposits, the outcrops provide the opportunity to investigate these Neogene successions that are the onshore equivalent of the large offshore basins (e.g. Amapá Formation: Foz do Amazonas and Ilha de Santana Formation: Pará-Maranhão) of the margin. The latter are deemed to represent an important target for reservoir models. Aiming to thoroughly describe the Pirabas Formation deposits and provide a quantitative and simple approach to analysing the outcropping successions, this study examines seven different successions and a quarry using palaeontological and petrographical methods. Similar to the modern Brazilian equatorial margin, the siliciclastic fraction in the Pirabas Formation rocks decreases as the distance from the coast increases, whereas the bioclastic material is found in greater amounts offshore. However, while the carbonate production close to the Amazon River mouth currently occurs hundreds of kilometres offshore, the carbonate factories in coastal along the Pirabas platform are also located in coastal waters. This indicates that the terrigenous input over the carbonate rocks was still lower than that found at present. The combining analysis of the skeletal and foraminiferal assemblages enabled a separation of protected embayments (characterised by seagrass-related assemblages), exposed areas (characterised by bioclastic shoals) and mangrove forests (characterised by dark fine-grained sediments). This accurate approach serves as an unprecedented reference for the northeastern part of the South American equatorial margin and lays the foundation for future research.

Mercury (Hg) is a toxic globally spread pollutant that has been found at increasing concentrations in the South Atlantic Ocean. The present work provides the first insight into the total mercury (HgT, unfiltered waters) content in the water of the Brazilian Exclusive Economic Zone (BEEZ), within a 24°S to 20°S. Water samples were collected from surface to 3400 m depth along transects, and analyzed with atomic fluorescence. The mean HgT concentration for the Tropical Water mass (TW) was 6.3 ± 1.4 pM (n = 16), for the South Atlantic Central Water (SACW), 5.9 ± 0.7 pM (n = 8), for the Antarctic Intermediate Water (AAIW), 5.0 ± 0.6 pM (n = 2), for the Upper Circumpolar Deep Water (UCDW), 6.5 pM (n = 1), and for the North Atlantic Deep Water (NADW), 5.7 ± 0.9 pM (n = 12). HgT concentrations were highest throughout the BEEZ in comparison with other parts of the Atlantic Ocean, farther from the coast.

The contamination of coastal environments by metallurgical wastes involves multiple biogeochemical processes; accordingly, understanding metal behavior and risk evaluation of contaminated areas, such as Sepetiba Bay (Rio de Janeiro. Brazil), remains challenging. This study coupled Zn isotopic analyses with sequential extractions (BCR) to investigate the mechanisms of Zn transfer between legacy electroplating waste and the main environments in Sepetiba Bay. This metallurgical waste showed a light bulk isotopic signature (delta(66/64) Znbulk(JMC )= +0.30 +/- 0.01 parts per thousand 2 s, n = 3) that was not distinct from the lithogenic geochemical baseline, but was different from signature of mangrove sediment considered as anthropogenic end member (delta(66/64) Zn-JMC = +0.86 +/- 0.15 parts per thousand) in a previous isotopic study in this area. Zn isotopic compositions of sediment samples (ranging from +0.20 to +0.98 parts per thousand) throughout the bay fit a mixing model involving multiple sources, consistent with previous studies. In the metallurgic zone, the exchangeable/carbonate fraction (ZnF1) exhibited high Zn concentrations (ZnF1 9840 mu g g(-1)) and a heavy isotopic composition (delta(66/64) ZnF1(JMC) = +1.10 +/- 0.01 parts per thousand). This finding showed that, in some cases, the bulk isotopic signature of waste is not the most relevant criterion for evaluating trace metal dispersion in the environment. Indeed, based on the BCR. it was observed that part of the anthropogenic metallurgical Zn was redistributed from the exchangeable/carbonate fraction in the waste to the surrounding mangrove sediment. Then, this contaminated sediment with heavy delta(66/64) Zn values was exported to other coastal environments. In Sepetiba Bay, contaminated sediments revealed a large concentration of ZnF1 fraction (up to 400 mu g g(-1)) with a heavy Zn isotopic signature. This signature also matched the Zn isotopic signature of oysters in Sepetiba Bay reported by other studies; hence, measurement of the isotopic exchangeable/carbonate fraction has important implications for tracing the transfer of anthropogenic Zn to biota.

Arsenic (As) is a dangerous and carcinogenic element and drinking water is its main pathway of human exposure. Gold mines are widely recognized as important sources of As pollution. This work proposes the assessment of As distribution along watersheds surrounding "Morro do Ouro" gold mine (Paracatu, southeastern Brazil). A balance approach between filtered As fluxes (As 0.45 μm) and suspended particulate material (AsSPM) in different river segments was applied. Ultrafiltration procedure was used to categorize As into the following classes: particulate 0.1 μm, colloidal 0.1 μm to 10 kDa, dissolved 10 kDa to 1 kDa, and truly dissolved 1 kDa. By applying this approach, arsenic contributions from mining facilities were quantified in order to identify critical fluvial segments and support decision makers in actions of remediation. The mass balance indicated the occurrence of a decreasing gradient from upstream to downstream: (i) of the As concentrations higher than the limit established by Brazilian law (10 μg L

O consumo de flúor presente em águas superficiais e subterrâneas é uma prática comum em diversos países. Além de abordar a temática controversa quanto ao consumo do flúor, este artigo apresenta um estudo de caso de avaliação de risco à saúde humana pelo consumo de águas fluoretadas, provenientes do Parque de Águas Minerais, localizado na região Centro-Sul do Estado do Rio de Janeiro. As concentrações de flúor foram medidas entre outubro de 2014 e agosto de 2015 em três poços de água mineral e em seus respectivos fontanários, sendo as fontes denominadas popularmente de Fonte Alcalina Terrosa Cálcica, Alcalina Terrosa Ferruginosa e Alcalina Terrosa Magnesiana. Foi avaliada a possibilidade de haver riscos para o desenvolvimento de fluoroses e aumento de fraturas ósseas nas populações consumidoras. Esta pesquisa modelou a ingestão diária dessas águas com flúor por receptores residenciais dos tipos: bebês, infantes, crianças, adolescentes e adultos. Foi constatado que os grupos de bebês e infantes podem estar mais sujeitos a riscos crônicos para o desenvolvimento de fluorose dentária na fonte de água mineral Alcalina Terrosa Magnesiana. Recomenda-se que a água mineral dessa fonte não seja consumida pelos grupos de crianças.

Study Region: Porous aquifer system of Northeastern Guanabara Bay, Rio de Janeiro, Brazil. Study Focus: The present work aimed to comprehend the geochemical processes responsible for the considerable range of salinity (48 to 5651 μS. cm−1) through chemical composition of groundwater (hydrogeochemical modeling through PHREEQC) allied to chemical ratios (Cl/Br ratio) and stable isotopes data (δ18O and δ2H). New hydrological insights for the region: The PHREEQC modeling showed that high pH and low pe values conditioning the main processes controlling the hydrogeochemical evolution of groundwater in that region. The salinity origins should be explained by 4 hypotheses: 1) a group related to recharge zones, close to the basin headboard or connected to the fractured aquifers from the basement rocks (low Cl/Br ratio and predominance of light δ18O and δ2H isotopes; 2) a group formed by groundwater with high Cl/Br ratio and predominance of heavy δ18O and δ2H isotopes, associated to dissolution processes of Tertiary brackish water environment sediments; 3) a group formed by groundwater with low Cl/Br ratio, high Cl− concentrations and low δ18O and δ2H, related to groundwater under influence of Caceribu River (high content of domestic effluents); and 4) a group composed by groundwater with high salinity, high Cl− concentrations and enrichment of δ18O and δ2H, located at a mangrove area, where the influence of seawater intrusion in the aquifer is recognized. Keywords: Chloride/bromide ratio, PHREEQC hydrochemical modeling, Guanabara Bay porous aquifer, Regional hydrogeochemistry, Tertiary/quaternary sediments

Outcrops of Neogene carbonates of the North Brazilian platform occur exclusively along the equatorial coast and represent some of the few existing examples of Neogene carbonate systems of the Atlantic coast of South America. The Pirabas Formation (early-middle Miocene) is the northernmost part of this platform. Although onshore mainly consists of small and scattered outcrops, it considerably extends in the subsurface keeping record of relevant geological and paleontological episodes of tropical South American history. Intending to improve the knowledge of South American carbonate and providing a solid basis for future comparisons between the Pirabas Basin and other, largely subsurface, Cenozoic basins, this research investigates the Aricuru outcrops by combining a standard petrographical and paleontological approach with advanced microCT analyses. The Aricuru area is characterized by mixed siliciclastic-carbonate sand-sized deposits, which probably deposited after the early Miocene according to the palynological assemblage. The bioclastic fraction of the rock is dominated by benthic foraminifera (mostly soritids, amphisteginids, small rotaliids, and small miliolids, typical of marginal marine environments), bryozoans, calcareous algae (Halimeda), echinoderms and mollusks. The abundant siliciclastic fraction together with the taxonomic composition of the foraminiferal, echinodermal, crustacean, ichnofossil and fish assemblages indicates deposition in a tropical coastal environment featuring both protected and more exposed sectors. The carbonate system probably developed under abundant nutrient supply, which fostered heterotroph suspension feeders over hermatypic corals. The demise of this system was most likely caused by a growth in siliciclastic input due to increased rainfall in the coastal area. The sedimentary evolution of the Pirabas Formation is similar to the one of the Foz do Amazonas Basin, and fits well with the general evolutionary trend of Cenozoic carbonate factories of the region, indicating the potential of the Pirabas subsurface record for understanding other Cenozoic basins, their paleoenvironmental significance, and their potential as oil, gas and water reservoirs.

The Pirabas Formation (early to middle Miocene) from the equatorial margin of North Brazil is characterized by a shallow-marine carbonate platform with high fossil diversity and abundant micro- and macrofossil remains. The Pirabas Formation represents a unique carbonate system along the Atlantic margin of South America that developed before the onset of the Amazon delta. We studied the palaeontology and lithofacies of outcrops of the uppermost Pirabas Formation and found that was deposited in a coastal marine environment with marginal lagoons under the influence of a tidal regime and tropical storms. The remains of calcareous algae, molluscs, crustaceans, echinoiderms, bryozoans, solitary corals, fish and marine mammals, together with foraminifera, ostracods and other marine microfossils, shaped a biogenic framework, that together with the post-depositional processes of dissolution of skeletal grains, is responsible for the mean packstone-floatstone porosity of 14.9%. The palaeontological framework and the petrophysical characterization of the carbonate rocks from the uppermost Pirabas Formation outcrop represent a baseline to interpret the entire Pirabas Formation in the subsurface stratigraphic sections (cores) of this important Neogene unit. Considering that carbonate rocks account for ~50% of oil and gas reservoirs around the world, this research provides a model for Neogene tropical carbonate deposits useful for carbonate petroliferous reservoirs in the Brazilian equatorial basins.

A total of 64 sediment samples were collected along a stretch of about 988 km of the Trans-Amazonian Federal Highway, between Maraba and Itaituba, Para State, in order to characterize the distribution of metals and trace elements. Due to the lithological and geological diversity along this stretch of the Amazon, the study region was divided in three distinct tracks. Statistical data analysis (Spearman correlation and Principal Factor Analysis) shows strong signature and predominance of regional rocks chemistry, such as mafic-ultramafic-bearing elements (Ni and Cr) and hydrothermalism-bearing elements such as Cu and Pb. Enrichment factors were calculated for three different normalizer agents: 1) Fe and Mn, representing the Fe and Mn (hydr)oxides, 2) Al representing clay minerals, and 3) organic matter (OM). The Fe and Mn (hydr)oxides showed to be the most proficient metal carrier among the geological matrices, likely due to the larger lithological diversity. On the other hand, OM positively correlated to trace element distribution.

cited By 1; International audience; Mercury (Hg) is considered a global pollutant, and the scientific community has shown great concern about its toxicity as it may affect the biota of entire systems, through bioaccumulation and bioamplification processes of its organic form, methylmercury (MeHg), along food web. However, few research studies deal with bioaccumulation of Hg from marine primary producers and the first-order consumers. So, this study aims to determine Hg distribution and concentration levels in phytoplankton and zooplankton in the Cabo Frio Bay, Brazil, a site influenced by coastal upwelling. The results from Hg speciation analyses show that inorganic mercury Hg(II) was the predominant specie in plankton from this bay. The annual Hg species distribution in plankton shown mean concentration of 2.00 ± 1.28 ng Hg(II) g−1 and 0.15 ± 0.08 ng MeHg g−1 wet weight (phytoplankton) and 2.5 ± 2.03 ng Hg(II) g−1 and 0.25 ± 0.09 ng MeHg g−1 wet weight (zooplankton). Therefore, upwelling zones should be considered in the Hg biogeochemical cycle models as a process that enhances Hg(II) bioaccumulation in plankton, raising its bioavailability and shelf deposition. © 2014, Springer International Publishing Switzerland.

The mangrove crab Ucides cordatus is widespread in the Brazilian coast, which has an important role in nutrient cycling. This species reproduces in summer and females carry eggs about a month, when they maintain contact with water and sediments. It remains unclear if trace metals can be absorbed or adsorbed by the eggs during development. The present study aims to investigate, for the first time, trace metal concentrations in ovigerous female tissues and eggs of U. cordatus in two areas with different metal pollution levels in the Southeastern Brazil. Samples were collected in two different mangroves, Guanabara Bay (GB) highly polluted environment and Paraíba do Sul River (PSR). In both populations, we observed significant increase of V, Cr, and Mn concentrations along eggs maturation. The higher metals averages were found in PSR population. This trend was reported since the 1990s and lower concentrations in GB marine organisms were attributed to reducing conditions, high organic load, and the presence of sulfide ions. These conditions restrict the bioavailability of metals in the bay, with exception of Mn. No significant differences were observed in gills and muscles. In both populations of the present study, V, Zn, As, and Pb were higher in eggs of initial stage, whereas Mn, Ni, Cu, and Cd were higher in hepatopancreas. Beside this, V, Cr, Mn, As, and Pb showed an increase concerning egg development. Thus, V, As, and Pb in eggs come from two sources previous discussed: females and environment. Zinc came mainly from females due to essential function. Those new information should be considered as one of the mechanisms of trace metal transfer to the trophic chain, between benthonic and pelagic environment.

This study demonstrates the accumulation of Zn, Cd and Cu in the digestive gland of the oyster Crassostrea rhizophorae in response to the contamination of sediments and discusses the potential use of this specific organ in monitoring metal contamination in tropical areas. Sediment and oyster samples were collected from coastal Rio de Janeiro sites with different levels of human impact: Sepetiba Bay, Guanabara Bay and the Paraty coast. Metal concentrations were measured using inductively coupled plasma optical emission spectrometry (ICP OES). Significant statistical differences (p 0.05) in Cu among the sampling sites. The highes...

In this study, we measured the mercury concentration in 27 different fish species with high commercial value. Samples were taken from a region characterized by the diversity of aquatic environments. Mercury concentration in marine fish species varied from 30.4 to 216 ng g(-1), while in estuarine species, it varied from 12.4 to 60.3 ng g(-1). Compared to mercury concentration in marine species, none of the specimens from estuarine environment has reached a mercury concentration of 100 ng g(-1). However, mercury concentrations in species from the freshwater Patos lagoon are remarkably higher (15.3 to 462 ng g(-1)) than those from the estuarine or marine region. Even though mercury concentrations in these fish species did not exceed the maximum level (500 ng g(-1)) allowed by WHO for human consumption, they represent the main food source for sea birds and mammals coming from South Pole during their migration period.

The aim of present study was to evaluate the Hg concentration in two species of fish (Astyanax sp and Corydoras paleatus) and its potential use as a biomonitor, in order to know if the use of pesticides and fertilizers in paddy can enhance the Hg contamination to adjacent aquatic environment. Methods: Soil, suspended particulate matter and fish samples were sampled in a paddy field in South Brazil. A cold vapor system, coupled with a GBC 932 atomic absorption spectrophotometer was used for total Hg determinations in samples. Results: The paddy soil shows Hg concentration 2-fold higher (mean 31 ng g-1) in comparison to background areas (not cultivated). Suspended particle matter Hg concentration in paddy channels (mean 232.5 ± 44.2 ng g–1) are 1.5 times higher than the regional background. The analyzed fish specimens Astyanax sp in paddy showed Hg concentration 4-fold higher and significant different to background area. The mean Hg concentration in fish was: 51.7 ± 19.5 ng g–1 in Astyanax sp and 156.8 ± 44.0 ng g–1 in Corydoras paleatus. Conclusions: Considering the linear regression and Man whitney test hypothesis to Hg concentration in fish tissue from paddy suggests that Astyanax sp. can be a good biomonitor of Hg contamination, whereas Corydoras paleatus is a potential biomonitor. However, more studies with Corydoras are necessary in order to aggregate consistency to this hypothesis O objetivo do presente estudo foi avaliar a concentração de Hg em duas espécies de peixes (Astyanax sp e Corydoras paleatus) e seu uso potencial como biomonitor, a fim de saber se o uso de pesticidas e fertilizantes na lavoura pode levar a contaminação por Hg ao ambiente aquático adjacente. Métodos: Solo, material particulado em suspensão e amostras de peixes foram coletadas em um campo de arroz no sul do Brasil. Um sistema de vapor frio acoplado a um espectrofotômetro de absorção atômica (GBC 932) foi usado para as determinações de Hg total nas amostras. Resultados: O solo da lavoura de arroz apresentou concentração de Hg 2 vezes mais elevada (média de 31 ng g–1), em comparação com a área controle (não cultivado). A concentração de Hg no material particulado em suspensão dos canais de irrigação do arroz (média de 232,5 ± 44,2 ng g–1) é 1,5 vezes mais elevada do que na área controle. Os espécimes de peixes Astyanax sp analisados na área de cultivo mostraram concentração de Hg 4 vezes maior e, significativamente diferentes da área controle. A concentração média de Hg em peixes foi: 51,7 ± 19,5 ng g–1 em Astyanax sp e 156,8 ± 44,0 ng g–1 em Corydoras paleatus. Conclusões: Considerando a regressão linear e o teste de hipótese de 192 Kütter, V.T. et al. Acta Limnologica Brasiliensia Since 1908, the rice production is cultivated in paddies in the Southern Brazil (Beskow, 1986). Nowadays, Brazil is the ninth largest rice producer in the world (Wong, 2004). The Rio Grande do Sul State produces 68% of the national production (CONAB, 2013). This region is part of the Pampa Biome that covers about 63% of Rio Grande do Sul State (IBAMA, 2004). The Pampa has a great biodiversity including endemic species, some of them endangered or at risk of extinction (Marques et al., 2002). Notwithstanding the considerable number of endangered species, this region has received little attention in terms of environmental research (Bencke, 2010). The paddy has a considerable impact on aquatic animals, since many species that inhabit nearest areas, swamps and lagoons, move to them after the flood. Furthermore, this environment has great ecological significance because it represents an important feeding, resting and breeding area for birds, including migratory species that comes from North and South America’s (Dias & Burger, 2005). Studies with fish demonstrated that this animal group is a good indicator of environmental health (Van der Oost et al, 2003; Raimundo et al., 2011). In this group, the main Hg incorporation in tissue occurs through feeding (Kidd et al., 1995; Snodgrass et al., 2000). The MeHg is absorbed by the gut and accumulated in tissues, where it can be biomagnified because of the long half-life of this compound (Lacerda & Malm, 2008). Therefore, as predator fish are in the top of the food web, they have the highest concentrations of this metal in relation to species which are at the bottom. Mirlean et al. (2005), who investigated Hg levels in lakes near the paddy region in the Southern Brazil, found that the main source of Hg in this area is the atmospheric deposition. In this same study, the authors have proposed the use of Astyanax sp as a bioindicator of Hg contamination in studied area, once these species have shown a good correlation with Hg levels in the environment. The genus Astyanax has been appointed by several authors as an excellent biomonitor of aquatic ecosystems, responses of countless biomarkers, such as histopathological assays (Prado et al., 2011; 1. Introduction Mercury (Hg) is considered a highly toxic metal and has been used in the composition of pesticides utilized in rice fields (Smart & Hill, 1968). In Brazil, the use of pesticides containing Hg was banned in the 70’s. Although the input of anthropogenic Hg had been stopped at these sites after the banishment, its effects persist in the environment and biota. Studies on paddies in Japan have reported an insignificant reduction of Hg soil contamination over eight years of study (Nakagawa & Yumita, 1998). Furthermore, more recent studies in paddies reported high concentration of methylmercury (MeHg) in rice grains (Zhang et al., 2010a,b; Zhao et al., 2010; Zhu et al., 2011; Peng et al., 2012; Rothenberg et al., 2012; Li et al., 2013). In Brazil, the study developed by Silva et al. (2010) found Hg concentrations ranging from 2.2 to 4.4 ng g-1 in rice grains. Actually the large use of fertilizers in the rice production can intensify the methylation process in paddy fields due to bacteria growth stimulation. Amongst the three Hg forms, the organic form MeHg is the most toxic to humans even in low concentrations (Zahir et al., 2005). Although Hg presents low concentration in water, it can be potentially biomagnified, reaching very higher concentrations in predatory fish, which can result in an increased risk of developing health problems when consumed by humans (NRC, 2000). According to the report of the Committee on the Toxicological Effects of Methylmercury in the United States, the major source of human exposure to MeHg is the consumption of contaminated fish (NRC, 2000). Innumerous studies have been demonstrated that more than 80% of the total Hg present in fish tissue is in the form of MeHg (Silva et al., 2011; Kannan et al., 1998). The characteristics of paddy are favorable to the process of Hg conversion into MeHg by anaerobic microorganisms (Rothenberg & Feng, 2012). Moreover, some studies have demonstrated that this process can also occur in the intestine of some fish species when they are fed with inorganic mercury (Rudd et al., 1980; Leaner & Mason, 2002). de Man Whitney para a concentração de Hg em tecidos de peixes da lavoura de arroz, sugere que Astyanax sp. pode ser uma bom biomonitor de contaminação Hg, enquanto Corydoras paleatus é um biomonitor potencial. No entanto, mais estudos com Corydoras são necessárias, a fim de agregar consistência a este estudo

We investigated the role of plankton in the vanadium (V) cycle at Cabo Frio, Rio de Janeiro state, Brazil, a region with high V concentration in the atmospheric particles due to marine aerosol. The concentrations of V in plankton vary from 0.08 to 20.9 µg g-1 (zooplankton), 0.1 to 28.4 µg g-1 (phytoplankton > 64 µm) and < 0.0005 to 49.0 µg g-1 (small phytoplankton > 20 µm). The V speciation in biomolecules was performed by the use of two strategies: (i) coupling of size exclusion chromatography (SEC) for the fractionation of species with inductively coupled plasma mass spectrometry (ICP-MS) and (ii) with size exclusion anionic exchange chromatography with UV-Vis detector coupled to inductively coupled plasma mass spectrometry (SEC-AE-UV-Vis-ICP-MS). The results showed a single fraction containing V associated with a biomolecule in the range of 8 to 16 kDa, with isoeletric points above 8. The preliminary analyses using matrix-assisted laser desorption-ionization-time of flight (MALDI-TOF) do not permit to identify such biomolecule, considering the broader size range of the proteins obtained. Nós investigamos o papel do plâncton no ciclo do vanádio (V) em Cabo Frio, Rio de Janeiro, Brasil, uma região com alta concentração de V nas partículas atmosféricas, devido ao aerossol marinho. As concentrações de V no plâncton variaram de 0,08-20,9 µg g-1 (zooplâncton), 0,1-28,4 µg g-1 (fitoplâncton > 64 µm) e < 0,0005-49,0 µg g¹ (pequeno fitoplâncton > 20 µm). A especiação de V associado a biomoléculas foi realizada por duas estratégias: (i) o acoplamento de cromatografia de exclusão de tamanho (SEC) para o fracionamento de espécies com espectrometria de massas com plasma indutivamente acoplado (ICP-MS) e (ii) cromatografia de exclusão de tamanho por troca aniônica com detector UV-Vis acoplado a espectrometria de massas com plasma indutivamente acoplado (SEC-AE-UV-Vis-ICP-MS). Os resultados mostraram uma única fração contendo V associada a uma biomolécula na faixa de 8 a 16 kDa, com ponto isoelétrico acima de 8. Resultados preliminares usando MALDI-TOF não permitem identificar a biomolécula, considerando a larga faixa de massa molecular obtida.

This long-term study, performed during the years 2003–2005 and 2008–2009, investigated the carbon (C), nitrogen (N), and phosphorus (P) contents of the phyto- and zooplankton communities and the nutrient regime of Cabo Frio Bay, SE Brazil. The information intends to serve as baseline of the plankton C, N, and P stoichiometry for the calibration of biogeochemical and ecological models in support to future findings related to the local and regional phenomena of climatic change. Cabo Frio Bay is a small semienclosed system set adjacent to a region subject to sporadic coastal upwelling. Zooplankton exhibited average annual C, N, and P contents of 11.6 ± 6.9 %, 2.8 ± 1.8 %, and 0.18 ± 0.08 %, and phytoplankton (>20 μm) 6.8 ± 6.0 %, 1.6 ± 1.5 %, and 0.09 ± 0.08 %, respectively. The C/N/P ratios correspond to the lowest already found to date for a marine environment. The low C contents must have been brought about by a predominance of gelatinous zooplankton, like Doliolids/ Salps and also Pteropods. Average annual nutrient concentrations in the water were 0.21 ± 0.1 μM for phosphate, 0.08 ± 0.1 μM for nitrite, 0.74 ± 1.6 μM for nitrate, and 1.27 ± 1.1 μM for ammonium. N/P ratios were around 8:1 during the first study period and 12:1 during the second. The plankton C/N/P and N/P nutrient ratios and elemental concentrations suggest that the system was oligotrophic and nitrogen limited. The sporadic intrusions of upwelling waters during the first study period had no marked effect upon the systems metabolism, likely due to dilution effects and the short residence times of water of the bay.

Mercury distribution in the oceans is controlled by complex biogeochemical cycles, resulting in retention of trace amounts of this metal in marine biota. The impact of upwelling processes in this metal behavior has been overlooked. Data from literature are insufficient to evaluate the risks associated with the presence of mercury in the fish collected in upwelling areas and its consumers. Therefore, the aim of the present work was to perform a study of mercury speciation in four fish species belonging to different trophic levels from Cabo Frio-Brazil upwelling region. The total mercury content vary of 53 ng g-1 (Sardinella brasiliensis -sardine) to 1215 ng g-1 (Cynoscion striatus -striped weakfish) and, with exception of the planktivorous fish, methylmercury levels reaches circa 90% of total mercury concentration.A distribuição de Mercúrio nos oceanos é controlada por um complexo ciclo biogeoquímico, resultando na retenção de pequenas quantidades na biota marinha. O impacto dos processos de ressurgência costeira no comportamento desse metal tem sido negligenciado. Dados da literatura são insuficientes para elucidar o risco associado com a presença de mercúrio em peixes capturados em áreas de ressurgência e seus consumidores. Portanto o objetivo do presente trabalho foi realizar um estudo de especiação de mercúrio em quatro espécies de peixes pertencentes a diferentes níveis tróficos da região de ressurgência de Cabo Frio-Brasil. O conteúdo total de mercúrio variou de 53 ng g-1 (Sardinella brasiliensis -sardinha) to 1215 ng g-1 (Cynoscion striatus -pescada) e, com exceção da espécie planctivora, os níveis de metilmercúrio atingem cerca de 90% da concentração total de mercúrio.