Freshwater shrimps (Macrobrachium depressimanum and Macrobrachium jelskii) as biomonitors of Hg availability in the Madeira River Basin, Western Amazon.

Total mercury (THg) concentrations measured in two freshwater shrimp species (Macrobrachium depressimanum and Macrobrachium jelskii) showed a relationship with the location of artisanal and small-scale gold mining (ASGM) from the Madeira River Basin, Western Amazon. Between August 2009 and May 2010, 212 shrimp samples were collected in the confluence of the Madeira River with three of its tributaries (Western Amazon). THg concentration was quantified in the exoskeleton, hepatopancreas and muscle tissue of the shrimps by cold vapor atomic absorption spectrophotometry. There were no significant differences between the two shrimp species when samples came from the Madeira River, but Hg concentrations were significantly lower in a tributary outside the influence of the gold mining area. Average THg concentrations were higher in the hepatopancreas (up to 160.0 ng g-1) and lower in the exoskeleton and muscle tissue (10.0-35.0 ng g-1 and < 0.9-42.0 ng g-1, respectively). Freshwater shrimps from the Madeira River respond to local environmental levels of Hg and can be considered as biomonitors for environmental Hg at this spatial scale. These organisms are important for moving Hg up food webs including those that harbor economic significant fish species and thus enhancing human exposure.

Mercury Concentrations in Tuna (Thunnus albacares and Thunnus obesus) from the Brazilian Equatorial Atlantic Ocean.

Average total Hg concentrations measured in muscle of two species of tuna (Thunnus obesus and T. albacares) captured in the Brazilian Equatorial Atlantic Ocean varied from 95 to 1748 ng.g-1 wet weight in T. obesus and 48 to 500 ng.g-1 wet weight in T. albacares. Higher concentrations in T. obesus are probably related to foraging on deep water carnivorous fish. Smaller individuals of both species showed the lowest concentrations, but a significant positive relationship between fish weight and length and Hg concentrations was found for T. obesus, but not for T. albacares. Largest individuals (>30 kg) of T. obesus showed Hg concentrations ≥1000 ng.g-1, surpassing the legal limits for human consumption, although the average concentration for this species was much lower (545 ng.g-1). Concentrations in T. albacares from the Brazilian Equatorial were lower than those found in the African and in the North Atlantic. No comparison could be made for T. obesus due to few studies for this species in the Atlantic Ocean.

Long-Term (2002-2015) Changes in Mercury Contamination in NE Brazil Depicted by the Mangrove Oyster Crassostraea rhizophorae (Guilding, 1828).

Mercury concentrations in oysters from four estuaries in northeastern Brazil varied following source changes during the past 13 years. Concentrations were higher in urban estuaries relative to rural areas, but decreased in the 13-years interval following improvements in solid wastes disposal and sewage treatment. In rural estuaries, the one located in an environmental protection area showed no changes in Hg concentrations in the period. However, in the Jaguaribe estuary, remobilization from soils and sediments due to regional environmental changes, increased Hg concentrations in oysters to values similar to the most contaminated metropolitan sites.

Food preferences and Hg distribution in Chelonia mydas assessed by stable isotopes.

Mercury (Hg) is a highly toxic pollutant that poses in risk several marine animals, including green turtles (Chelonia mydas). Green turtles are globally endangered sea turtle species that occurs in Brazilian coastal waters as a number of life stage classes (i.e., foraging juveniles and nesting adults). We assessed total Hg concentrations and isotopic signatures ((13)C and (15)N) in muscle, kidney, liver and scute of juvenile green turtles and their food items from two foraging grounds with different urban and industrial development. We found similar food preferences in specimens from both areas but variable Hg levels in tissues reflecting the influence of local Hg backgrounds in food items. Some juvenile green turtles from the highly industrialized foraging ground presented liver Hg levels among the highest ever reported for this species. Our results suggest that juvenile foraging green turtles are exposed to Hg burdens from locally anthropogenic activities in coastal areas.

Mercury (Hg) in fish consumed by the local population of the Jaguaribe River lower basin, Northeast Brazil.

The knowledge of Hg concentrations in fish is of considerable interest since these organisms are a major source of protein to coastal human populations and fishing communities. The main source of human exposure to Hg contamination occurs through the consumption of fish. In this paper, we compare Hg concentration in 13 fish species from Jaguaribe River lower basin and an adjacent coastal region in the northeastern coast of Brazil. We sampled fish from three stretches of the river: fluvial, estuarine, and marine regions. We tested the hypothesis that Hg concentration in muscle tissue vary according to species, location, and trophic level. Significant differences were observed among species and trophic level, but these could not be observed among the regions studied. As expected, the highest concentrations were observed in carnivorous fish (5.6-107.5; 26.9 ± 18.8 ng g(-1)). Hg concentrations observed in this study are similar to those observed in regions of low environmental contamination. We estimated Hg intake to vary between 0.02 and 0.22 ng Hg kg body weight(-1) week(-1), for the average body weight of 56.7 kg, which was considered as low exposure and therefore, a low risk to consumers of fish from the regions studied.

Mercury in indigenous, introduced and farmed fish from the semiarid region of the Jaguaribe river Basin, NE Brazil.

Indigenous, introduced and farmed fish species were collected from the Jaguaribe Basin, NE Brazil to assess total and methyl mercury concentrations in muscle tissue and to determine its relationship with fish origin. The results obtained from introduced species were compared to the Hg content of their original area of occurrence, which is located in the Amazon region. Farmed and wild individuals of Oreochromis niloticus (tilapia) were also compared. Introduced species presented lower Hg contents compared to their Amazonian counterparts. Wild individuals of O. niloticus also presented higher Hg contents than farmed individuals with similar sizes. However, methyl Hg concentrations were not significantly different between the two groups. Total Hg and methyl Hg concentrations were higher in carnivorous species, especially those from the Amazon region, and surpassed the Brazilian guidelines for fish consumption. Based on their Hg content, Jaguaribe basin fish do not pose a significant threat to human consumption.

Monitoring mercury in green sea turtles using keratinized carapace fragments (scutes).

The green sea turtles are facing a very high risk of extinction in the wild and the impacts of heavy metals contamination contributes with the decline of their populations. It is very important to assess noninvasive and nonlethal methods for monitoring Hg contamination in sea turtles. Thus, Hg concentrations were measured in keratinized fragments (scutes) and internal tissues of green sea turtles from the Ceará coast to test the usefulness of scutes as a monitoring subject for sea turtles. A significantly positive correlation was found between Hg concentrations in muscle and scutes, which demonstrate that scutes can be used as a predictive matrix of Hg concentration in muscle tissue of green sea turtles.

The influence of Castanhão reservoir on nutrient and suspended matter transport during rainy season in the ephemeral Jaguaribe river (CE, Brazil).

Measurements of nutrient and suspended matter concentrations and loads entering and leaving the Castanhão reservoir during the rainy season were carried out to assess the influence of this large reservoir on land-sea fluvial transport in the ephemeral Jaguaribe river basin. Spatial variation indicated statistically significant attenuation of concentrations only for total phosphorous and suspended matter across the reservoir. Strong retention of nutrients and suspended matter loads by the reservoir was observed with average trapping efficiency of 89% for dissolved silicon, 98% of soluble reactive phosphorus, 71% for ammonium, 87% for total nitrogen, 98% for total phosphorus and 97% for suspended matter compared to the reservoir inflow. The dam operational procedure defined by the ephemeral conditions of the river reduced water releases compared to reservoir inflow and induced strong retention of nutrient and suspended matter loads within the reservoir when fluvial transfer occurs in this semiarid watershed.

Mercury distribution in a mangrove tidal creek affected by intensive shrimp farming.

In this study, the Hg distributions in water and sediments from a mangrove creek that receives intensive shrimp farming effluents were determined. The average dissolved and particulate Hg concentrations in the water varied from 3.1 to 9.2 ng L(-1) and from 4.4 to 9.4 ng L(-1), respectively. However, the Hg concentrations in the suspended particulate matter and the bottom sediments varied from 95.4 to 115.7 ng g(-1) and from 1.6 to 10.3 ng g(-1), respectively. A Ward quadratic distance cluster analysis based on the Hg concentrations and hydro- and geochemical parameters (oxygen, salinity, temperature, pH, and organic matter and aluminum content) showed the effects of shrimp farming effluents on the Hg distribution pattern. Furthermore, these results were supported by the Hg distribution in the sediment cores. This study emphasizes the necessity of including Hg as a potential pollutant when monitoring the environmental impacts of intensive shrimp farming.

Metals in water, sediments, and biota of an offshore oil exploration area in the Potiguar Basin, Northeastern Brazil.

Metal concentrations were evaluated in water, bottom sediments, and biota in four field campaigns from 2002 to 2004 in the Potiguar Basin, northeastern Brazil, where offshore oil exploration occurs. Analyses were performed by inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry. Total metal concentrations in water (dissolved + particulate) and sediments were in the range expected for coastal and oceanic areas. Abnormally high concentrations in waters were only found for Ba (80 µg l(-1)) and Mn (12 µg l(-1)) at the releasing point of one of the outfalls, and for the other metals, concentrations in water were found in stations closer to shore, suggesting continental inputs. In bottom sediments, only Fe and Mn showed abnormal concentrations closer to the effluent releasing point. Metal spatial distribution in shelf sediments showed the influence of the silt-clay fraction distribution, with deeper stations at the edge of the continental shelf, which are much richer in silt-clay fraction showing higher concentrations than shallower sediments typically dominated by carbonates. Metal concentrations in estuarine (mollusks and crustaceans) and marine (fish) organisms showed highest concentrations in oysters (Crassostrea rhizophorae). Fish tissues metal concentrations were similar between the continental shelf influenced by the oil exploration area and a control site. The results were within the range of concentrations reported for pristine environments without metals contamination. The global results suggest small, if any, alteration in metal concentrations due to the oil exploration activity in the Potiguar Basin. For monitoring purposes, the continental inputs and the distribution of the clay-silt fraction need to be taken into consideration for interpreting environmental monitoring results.

Mercury emission factors from intensive shrimp aquaculture and their relative importance to the Jaguaribe River Estuary, NE Brazil.

This study estimated Hg emission factors (EFs) and total Hg loading to the Jaguaribe Estuary, NE Brazil, from intensive shrimp farming, and compares this with other local anthropogenic activities. The EF reached 83.5 mg ha(-1) cycle(-1) (about 175 mg ha(-1) year(-1)), resulting in an annual Hg load to the estuary of 0.35 kg. The calculated EF is comparable to Hg EFs from urban wastewaters (200 mg ha(-1)) and solid waste disposal (400 mg ha(-1) year(-1)) from cities located in the estuary's basin. However, due to the smaller area of aquaculture (2,010 ha), total annual loads are much lower than from these other sources (75 and 150 kg year(-1), respectively). Since shrimp farming effluents are released directly into the estuary, the estimated high EF raises environmental concerns with this expanding industry, suggesting the inclusion of this element in ongoing environmental monitoring programs.

Anthropogenic sources and distribution of phosphorus in sediments from the Jaguaribe River estuary, NE, Brazil.

This paper estimates annual P emission to the Jaguaribe River estuary, NE Brazil, responsible for approximately 30% of the country's farmed shrimp production. Emissions increased three times between 2001 and 2006 and reached 43.9 t.year-1. These emissions make aquaculture the third main source of P for this estuary and are much smaller than emissions from agricultural sources and slightly lower than emissions from wastewater. Their relative contribution also increased from 10.5% to 20.5%. Temporal variability of P concentrations in estuarine bottom sediments also suggest an increase, but not as evident as the emissions. The spatial distribution and speciation of P (total P and inorganic P) in sampling stations located upstream and downstream from the main aquaculture area confirmed the importance of this source. Inorganic P was the dominant form present in sediments downstream and showed an increase from 67% to 75% of the total P present in the sediment.

Mercury accumulation and metallothionein expression from aquafeeds by Litopenaeus vannamei Boone, 1931 under intensive aquaculture conditions.

This study describes the accumulation of Hg and metallothionein gene expression in Litopenaeus vannamei Boone, 1931 with aquafeeds as the major source of Hg. Trials were conducted under controlled conditions in experimental tank facilities with high (indoor tanks) and low (outdoor tanks) Hg aquafeeds concentrations. Aquafeeds were the sole source of Hg for the shrimps and concentrations varied from 5.4 to 124 ng.g-1 d.w.. In the three animal fractions analysed; muscle (6,3 - 15,9 ng.g-1); hepatopancreas (5,1 - 22,0 ng.g-1) and exoskeleton (3,0 - 16,2 ng.g-1), Hg concentrations were significantly lower in the outdoor trials submitted to Hg-poor aquafeeds. Maximum shrimp muscle Hg concentrations were low (36.4 ng.g-1 w.w.) relative to maximum permissible concentrations for human consumption and Hg content in muscle and hepatopancreas were significantly correlated with Hg content in aquafeeds. Highest Hg concentrations in the exoskeleton of animals exposed to Hg-richer aquafeed, suggested that a detoxification mechanism is taking place. On the other hand the metallothionein suffered no variation in its relative expression in any of the experiments, meaning that the contact with feed containing the observed Hg concentrations were not sufficient to activate gene transcription. It was not possible, under the experimental design used, to infer Hg effects on the biological performance of the animals.

Fate of copper in intensive shrimp farms: bioaccumulation and deposition in pond sediments.

We present the distribution of Cu in water, sediments and biomass from intensive shrimp (Litopenaeus vannamei Boone, 1931)) farming in northeastern Brazil. The results show no difference in dissolved Cu concentrations between waters entering and leaving the ponds. However, there was a large export of particulate Cu to adjacent environments, showed by extremely high particulate (112 microg.L-1) Cu concentrations in draining waters. Copper concentrations in the bottom sediments of the pond varied with depth from 10 to 20 microg.g-1, being 5 to 7 times higher than the local background. Pond management procedures result in a peculiar vertical distribution of Cu with peak values occurring at sub-surface depths in pond bottom sediments. Bioavailable Cu reaches about 20% of the total Cu content in sediments. Notwithstanding the relatively high Cu bioavailability, concentrations in shrimp muscle (23.2 to 63.4 microg.g-1 d.w.) were similar to reported values for reared and natural L. vannamei populations, and much lower than acceptable maximum limits for human consumption. Concentrations in the exoskeleton were always higher than in muscle. Increasing Cu mass, and to a lesser extent Cu concentrations in muscle tissues, occurred simultaneously to a decrease in Cu mass and concentrations in the exoskeleton and vice versa, suggesting a dynamical exchange of Cu between the two compartments. Although Cu fate in intensive shrimp culture does not result in increasing Cu exposure to consumers, the activity is an important source of this metal to adjacent ecosystems, in particular in the pristine environments where most aquaculture activities in NE Brazil takes place.

Fate of copper in intensive shrimp farms: bioaccumulation and deposition in pond sediments / Dinâmica do cobre na carcinicultura intensiva: bioacumulação e deposição em sedimentos de tanques de criação

We present the distribution of Cu in water, sediments and biomass from intensive shrimp (Litopenaeus vannamei Boone, 1931)) farming in northeastern Brazil. The results show no difference in dissolved Cu concentrations between waters entering and leaving the ponds. However, there was a large export of particulate Cu to adjacent environments, showed by extremely high particulate (112 µg.L-1) Cu concentrations in draining waters. Copper concentrations in the bottom sediments of the pond varied with depth from 10 to 20 µg.g-1, being 5 to 7 times higher than the local background. Pond management procedures result in a peculiar vertical distribution of Cu with peak values occurring at sub-surface depths in pond bottom sediments. Bioavailable Cu reaches about 20 percent of the total Cu content in sediments. Notwithstanding the relatively high Cu bioavailability, concentrations in shrimp muscle (23.2 to 63.4 µg.g-1 d.w.) were similar to reported values for reared and natural L. vannamei populations, and much lower than acceptable maximum limits for human consumption. Concentrations in the exoskeleton were always higher than in muscle. Increasing Cu mass, and to a lesser extent Cu concentrations in muscle tissues, occurred simultaneously to a decrease in Cu mass and concentrations in the exoskeleton and vice versa, suggesting a dynamical exchange of Cu between the two compartments. Although Cu fate in intensive shrimp culture does not result in increasing Cu exposure to consumers, the activity is an important source of this metal to adjacent ecosystems, in particular in the pristine environments where most aquaculture activities in NE Brazil takes place.

Este trabalho apresenta a distribuição de Cu em água, sedimentos e biomassa em uma fazenda de cultivo intensivo do camarão Litopenaeus vannamei Boone, 1931, no Nordeste do Brasil. Os resultados mostraram não haver diferenças entre as concentrações de Cu nas águas afluentes e efluentes da fazenda. Entretanto, foi verificada uma grande exportação de Cu para áreas adjacentes associada ao material em suspensão. Nas águas efluentes, a concentração de Cu particulado atingiu até 112 µg.L-1. Em sedimentos, as concentrações de Cu variaram com a profundidade da coluna sedimentar de 10 a 20 µg.g-1, sendo estes valores de 5 a 7 vezes mais altos que as concentrações naturais dos solos e sedimentos locais. O manejo dos tanques de criação resulta em perfis de distribuição de Cu em sedimentos com maiores concentrações em subsuperfície. A biodisponibilidade do Cu nestes sedimentos é elevada e atinge cerca de 20 por cento da concentração total. Apesar da biodisponibilidade elevada, as concentrações de Cu em músculo do L. vannamei (23.2 a 63.4 µg.g-1 peso seco) são similares aos valores reportados para populações naturais da espécie e em diversos de cultivo em outros países, e estão bem abaixo dos limites máximos permitidos para consumo humano. As concentrações de Cu no exoesqueleto foram maiores que no músculo. Um aumento da massa de Cu em músculo ocorreu simultaneamente à diminuição do Cu no exoesqueleto e vice-versa sugerindo uma troca dinâmica do Cu entre os dois compartimentos. Embora a presença do Cu no cultivo intensivo do L. vannamei não represente exposição significativa para os consumidores, a atividade é fonte importante de Cu para os sistemas aquáticos adjacentes.

Tracing of dissolved organic matter from the Sepetiba Bay (Brazil) by PARAFAC analysis of total luminescence matrices.

Fluorescent excitation-emission matrices (FEEM) of the fluorescent dissolved organic matter (FDOM) are widely used for DOM characterization and tracing. In this work, a set of FEEM from sampling campaigns in the Sepetiba Bay (Brazil) was decomposed into independent components using the parallel factor analysis (PARAFAC) algorithm. Four independent components were extracted describing the total fluorescence of the FDOM. The well described peaks A, C, M, B and T were found, and a new peak, A', linked to the C peak, was detected. Relative contribution of each of four components to the total fluorescence confirms that the coastal water has DOM of terrestrial origin, except for the 275Ex/400-500Em range (nm), which primarily occurs in marine waters.

Total-Hg and organic-Hg in Cephalopholis fulva (Linnaeus, 1758) from inshore and offshore waters of NE Brazil.

To investigate whether source proximity or bioavailability is the major factor controlling both Hg concentration and Hg speciation in marine fishes, total- and organic-Hg content in muscle and liver tissues from different populations of Cephalopholis fulva (piraúna) from inshore and offshore waters of the Brazilian northeastern coast were analyzed. Average total-Hg in muscle (104 ng x g(-1) w.w.) and liver (2,865 ng x g(-1) w.w.) tissues, as well as organic-Hg concentrations in muscle (169 ng x g(-1) w.w.) and liver (1,038 ng x g(-1) w.w.), were much higher in the offshore population of C. fulva than in the inshore ones. In the inshore population total-Hg and organic-Hg average concentrations in muscle tissue were similar and reached only 49 ng x g(-1) w.w., while in liver they reached 412 ng x g(-1) w.w. for total-Hg and 180 ng x g(-1) w.w., for organic-Hg. Concentrations of both Hg species in the two populations were higher in liver than in muscle. The average percentage contribution of organic-Hg to the total Hg content was higher in muscle (98-100%) than in liver (42-53%), but similar between the two populations. Total-Hg and organic-Hg concentrations in muscle and liver from the offshore population showed significant (P < 0.05) positive correlation with fish length. However, in the inshore population only the total-Hg and organic-Hg in muscle tissues correlate significantly with fish size. Although the coastal environments are enriched in total Hg relative to open waters, the significant higher Hg concentrations in the offshore population of C. fulva and the significant correlation found between organic-Hg in liver with fish size suggest higher bioavailability of Hg in offshore waters relative to inshore ones.

Dial organic carbon fluctuations in a mangrove tidal creek in Sepetiba bay, Southeast Brazil

The carbon (C) concentration and flux, as dissolved organic carbon (DOC), particulate organic carbon (POC) and macrodetritus (MD), were quantified through 4 tidal cycles in a mangrove tidal creek in Southeastern Brazil. DOC was the major fraction of the total C concentration, accounting for 68 and 61 percent of the total C concentration during ebb and flood periods respectively. Concentrations of DOC (Ebb = 3,41 ± 0,57 mgC.L-1 and Flood = 3,55 ± 0,76 mgC.L-1) and POC (Ebb = 1,73 ± 0,99 mgC.L-1 and Flood = 1,28 ± 0,45 mgC.L-1) were relatively similar during the four tidal cycles. Macrodetritus presented a wide variation with concentration peaks probably related to external forces, such as winds, which enrich the ebb flow with leaf litter. DOC and POC fluxes depended primarily on tidal and net water fluxes, whereas MD fluxes were not. The magnitude of the DOC and POC fluxes varied with the area flooded at high tide, but not the MD fluxes. DOC was the major form of carbon export to Sepetiba Bay. During the four tidal cycles, the forest exported a total of 1,2 kg of organic carbon per ha, mostly as DOC (60 percent), followed by POC (22 percent) and MD (18 percent).

As concentrações e fluxos de carbono orgânico sob forma de carbono orgânico dissolvido (COD), carbono orgânico particulado (COP) e macrodetritos (MD) foram quantificadas durante 4 ciclos de maré em canal de maré na Floresta Experimental de Itacuruçá, Baía de Sepetiba, RJ, litoral sudeste do Brasil. COD foi a fração mais importante para a concentração total de carbono orgânico, contribuindo com 68 e 61 por cento da concentração total de C nos períodos de maré vazante e enchente, respectivamente. As concentrações de COD (vazante = 3.41 ± 0.57 mgC.L-1 e enchente = 3.55 ± 0.76 mgC.L-1) e COP (vazante = 1.73 ± 0.99 mgC.L-1 e enchente = 1.28 ± 0.45 mgC.L-1) foram similares durante os 4 ciclos de maré. A fração macrodetritos apresentou uma ampla variabilidade com máximos de concentração relacionados a fatores externos como ventos, que enriqueceram as águas de vazante com macrodetritos. A magnitude dos fluxos de COD e COP, mas não os de macrodetritos, relacionaram-se com os fluxos de água e a conseqüente área inundada pela maré. A fração COD foi a mais importante forma de exportação de carbono orgânico pelo manguezal. Durante os 4 ciclos monitorados, a floresta exportou um total de 1.2 kg de carbono orgânico, 60 por cento sob forma de COD, seguido pelo COP (22 por cento) e pela fração macrodetritos (18 por cento).

Total-Hg and organic-Hg in Cephalopholis fulva (Linnaeus, 1758) from inshore and offshore waters of NE Brazil

To investigate whether source proximity or bioavailability is the major factor controlling both Hg concentration and Hg speciation in marine fishes, total- and organic-Hg content in muscle and liver tissues from different populations of Cephalopholis fulva (piraúna) from inshore and offshore waters of the Brazilian northeastern coast were analyzed. Average total-Hg in muscle (104 ng.g-1 w.w.) and liver (2,865 ng.g-1 w.w.) tissues, as well as organic-Hg concentrations in muscle (169 ng.g-1 w.w.) and liver (1,038 ng.g-1 w.w.), were much higher in the offshore population of C. fulva than in the inshore ones. In the inshore population total-Hg and organic-Hg average concentrations in muscle tissue were similar and reached only 49 ng.g-1 w.w., while in liver they reached 412 ng.g-1 w.w. for total-Hg and 180 ng.g-1 w.w., for organic-Hg. Concentrations of both Hg species in the two populations were higher in liver than in muscle. The average percentage contribution of organic-Hg to the total Hg content was higher in muscle (98-100 percent) than in liver (42-53 percent), but similar between the two populations. Total-Hg and organic-Hg concentrations in muscle and liver from the offshore population showed significant (P < 0.05) positive correlation with fish length. However, in the inshore population only the total-Hg and organic-Hg in muscle tissues correlate significantly with fish size. Although the coastal environments are enriched in total Hg relative to open waters, the significant higher Hg concentrations in the offshore population of C. fulva and the significant correlation found between organic-Hg in liver with fish size suggest higher bioavailability of Hg in offshore waters relative to inshore ones.

As concentrações de Hg-total e Hg-orgânico foram determinadas em diferentes populações de Cephalopholis fulva (piraúna) capturadas em águas costeiras e em bancos oceânicos do litoral nordeste do Brasil. A comparação entre as duas populações permitiu investigar o efeito da proximidade de fontes sobre as concentrações, e a especiação de Hg em músculo e fígado desta espécie. As concentrações médias de Hg-total em músculo (104 ng.g-1 w.w.) e fígado (2,865 ng.g-1 w.w.), assim como as concentrações de Hg-orgânico em músculo (169 ng.g-1 w.w.) e fígado (1,038 ng.g¹ w.w.) foram muito maiores na população capturada nos bancos oceânicos do que na população costeira. Nesta, as concentrações médias de Hg-total e Hg-orgânico na musculatura de C. fulva foram similares e baixas (49 ng.g-1 w.w.), enquanto que atingiram 412 ng.g-1 w.w. de Hg-total e 180 ng.g-1 w.w. de Hg-orgânico no fígado destes animais. As concentrações das duas espécies de Hg foram significativamente maiores no fígado do que na musculatura. A contribuição percentual média de Hg-orgânico para a concentração total de Hg nos peixes foi maior para músculo (98-100 por cento) que para fígado (42-53 por cento), mas semelhante entre as duas populações. As concentrações de Hg-total e Hg-orgânico na musculatura e no fígado de C. fulva mostraram-se positivamente correlacionadas com o tamanho do animal (P < 0,05). Entretanto, na população costeira somente as concentrações destas espécies de Hg na musculatura apresentaram correlações significativas com o tamanho do animal. Embora o ambiente costeiro seja relativamente enriquecido em Hg, em relação aos bancos oceânicos, as maiores concentrações de Hg foram verificadas na população oceânica de C. fulva. A correlação significativa entre Hg-orgânico no fígado e tamanho do animal no fígado sugerem uma maior biodisponibilidade do Hg em águas oceânicas quando comparada às águas costeiras.

Dial organic carbon fluctuations in a mangrove tidal creek in Sepetiba bay, Southeast Brazil.

The carbon (C) concentration and flux, as dissolved organic carbon (DOC), particulate organic carbon (POC) and macrodetritus (MD), were quantified through 4 tidal cycles in a mangrove tidal creek in Southeastern Brazil. DOC was the major fraction of the total C concentration, accounting for 68 and 61% of the total C concentration during ebb and flood periods respectively. Concentrations of DOC (Ebb = 3.41 +/- 0.57 mgC.L-1 and Flood = 3.55 +/- 0.76 mgC.L-1) and POC (Ebb = 1.73 +/- 0.99 mgC.L-1 and Flood = 1.28 +/- 0.45 mgC.L-1) were relatively similar during the four tidal cycles. Macrodetritus presented a wide variation with concentration peaks probably related to external forces, such as winds, which enrich the ebb flow with leaf litter. DOC and POC fluxes depended primarily on tidal and net water fluxes, whereas MD fluxes were not. The magnitude of the DOC and POC fluxes varied with the area flooded at high tide, but not the MD fluxes. DOC was the major form of carbon export to Sepetiba Bay. During the four tidal cycles, the forest exported a total of 1.2 kg of organic carbon per ha, mostly as DOC (60%), followed by POC (22%) and MD (18%).