O MERCÚRIO EM CETÁCEOS (MAMMALIA,CETACEA): UMA REVISÃO.

MERCURY IN CETACEANS (MAMMALIA, CETACEA): A REVIEW. Mercury (Hg) is one of the most studied elements concerning to its ecotoxicological aspects. Its main absorption route in marine vertebrates is through diet which, along the low rates of excretion, leads to the increase of the element's concentrations through the trophic chain. As top predators and presenting great longevity, cetaceans end up exhibiting high concentrations of the pollutant, with a long biological half-life in their tissues. Therefore, these animals are frequently used as sentinels of the environmental health related to mercury. The present review approaches the contaminant's body distribution, detoxification strategies and the possible influence of biological and ecological parameters on the pollutant accumulation, also presenting data on hepatic contamination of several species of cetaceans in different geographic regions. It has been observed similar concentrations in regions of South and North Hemispheres as well as higher concentrations than the hepatic tolerance limit for mammals (100-400µg/g wet weight) in the South Hemisphere and the Mediterranean. Keywords: Mercury; cetaceans; bioaccumulation; biomagnification; detoxification.MERCURIO EN CETÁCEOS (MAMMLIA, CETACEA): UNA REVISION. El mercurio es uno de los elementos mas estudiados desde el punto de vista toxicológico. Su principal vía de absorción en vertebrados marinos es a través de la dieta, que junto a la baja tasa de excreción, da lugar al incremento de la concentración de este elemento en la cadena trófica. Como los cetáceos son depredadores tope muy longevos, terminan presentando altas concentraciones de mercurio con una gran vida media biológica en sus tejidos. Por ello, estos animales son frecuentemente usados como centinelas de la salud ambiental relacionada al mercurio. La presente revisión trata sobre la distribución del contaminante en el cuerpo, las estrategias de detoxificación y la posible influencia de algunos parámetros biológicos y ecológicos en la acumulación de este contaminante. Además, se presentan datos de contaminación hepática  de diversas especies de cetáceos en diferentes regiones geográficas. Se han observado concentraciones similares en regiones del Hemisferio Sur y Norte, así como altas concentraciones sobre el límite de tolerancia hepático para mamíferos (100-400 µg/g peso húmedo) en el Hemisferio Sur y en el Mediterráneo.Palabra clave: Mercurio; cetáceos; bioacumulación; biomagnificación; detoxificación.O mercúrio (Hg) é um dos elementos mais estudados sob o ponto de vista toxicológico. Sua principal via de absorção em vertebrados marinhos se dá através da dieta, que junto à baixa taxa de excreção leva ao aumento das concentrações do elemento ao longo da cadeia trófica. Sendo predadores de topo de teias alimentares e apresentando grande longevidade, os cetáceos terminam por apresentar altas concentrações de Hg, com longa meia-vida biológica deste em seus tecidos. Desta forma, tais animais são freqüentemente utilizados como sentinelas da saúde ambiental em relação ao micropoluente em questão. A presente revisão aborda a distribuição corpórea do contaminante, estratégias de destoxificação e a possível influência de parâmetros biológicos e ecológicos na acumulação do poluente, apresentando ainda dados sobre contaminação hepática de diversas espécies de cetáceos em diferentes regiões geográficas

A transferência de cádmio de cefalópodes para cetáceos: uma revisão

Considering that environmental levels of cadmium have increased due to anthropogenic activity, surveillance on the concentrations of this toxic element in cetaceans and their prey is of special interest, since marine mammals appear as a choice material in the framework of ecotoxicology. Cephalopods role in the transfer of cadmium to cetaceans is well known in other regions of the planet and was also verified in Brazil. The high burden of cadmium ingested by cetaceans raise the question of a possible detrimental effect; however, as it seems that exposure has occurred during the evolution process, apparently these mammals are adapted.Considerando o fato de que os níveis ambientais de cádmio estão se elevando em decorrência de atividades antrópicas, a vigilância sobre as concentrações deste elemento tóxico em cetáceos e suas presas constitui matéria de especial interesse, principalmente levando-se em consideração que, no alicerce da ecotoxicologia, mamíferos marinhos apresentam-se como material de escolha. O papel dos cefalópodes na transferência de cádmio para cetáceos é conhecido em outras regiões do planeta, tendo sido verificado também no Brasil. A elevada carga de cádmio ingerida pelos cetáceos suscita a questão de um possível efeito deletério; entretanto, como a exposição parece ter ocorrido durante o processo evolutivo, aparentemente estes mamíferos estão adaptados

Cadmium concentrations in franciscana dolphin (Pontoporia blainvillei) from south brazilian coast

Franciscanas foram utilizadas como fonte de informação sobre a biodisponibilidade de cádmio em águas neríticas da Costa Sul do Brasil. Amostras de fígado, obtidas de 44 indivíduos capturados acidentalmente ao largo da costa do Rio Grande do Sul, foram analisadas através de EAA eletrotérmica. Concentrações de cádmio, idade, peso e comprimento totais dos golfinhos analisados variaram entre 39 e 4144 µg.kg-1 (peso úmido), um e cinco anos, 17,5 e 49,2 kg, e entre 105,3 e 156,8 cm, respectivamente. Em relação às concentrações hepáticas de cádmio em franciscanas, não houve diferença significativa entre os dados gerados pelo presente estudo e informação proveniente da literatura, referente ao Estado do Rio de Janeiro. As baixas concentrações de cádmio observadas podem ser atribuídas ao fato de as lulas da Família Loliginidae constituírem a principal presa para franciscanas, dentre os cefalópodes. Este estudo corrobora investigações sobre níveis de cádmio em lulas brasileiras e reforça a hipótese de que cefalópodes loliginídeos não constituem vetores importantes da transferência de cádmio para cetáceos.Franciscana dolphins were used as source of information on the bioavailability of cadmium in the neritic waters off South Brazilian Coast. Liver samples obtained from 44 individuals incidentally captured off Rio Grande do Sul State were analyzed by electrothermal AAS. Cadmium concentrations, age, total weight and length of the analyzed dolphins varied between 39 and 4144 µg.kg-1 (wet weight), one and five years, 17.5 and 49.2 kg, and between 105.3 and 156.8 cm, respectively. Concerning hepatic cadmium concentrations of franciscanas, there was no significant difference between data raised by the present study and information from literature, regarding Rio de Janeiro State. The low cadmium concentrations observed may be attributed to the fact that loliginid squids constitute the main cephalopod prey for franciscanas. This study corroborates investigations on cadmium levels in Brazilian squids and strengthened the hypothesis that cephalopods of Loliginidae Family do not constitute important vectors of the transfer of cadmium to cetaceans

MORPHOLOGY AND GROWTH OF THE VENTRICULAR MYOCARDIUM OF SOTALIA GUIANENSIS

A morfologia, o crescimento e o envelhecimento do coração, não só de Sotalia guianensis (boto-cinza), como também de todos os cetáceos é pouco conhecida. O objetivo do presente estudo foi avaliar a morfologia e o crescimento, utilizando macro e micromorfologia de amostras coletadas de corações de botos-cinza encontrados encalhados no litoral do Espírito Santo, Brasil. Os ventrículos foram avaliados na microscopia de luz e eletrônica, os corações foram mensurados e a densidade de volume de cardiomiócitos, tecido conjuntivo e vasos sanguíneos dos ventrículos foram determinadas. Diferenças estatísticas, regressões, correlações e curvas de crescimento foram aplicadas entre comprimento total, idade e variáveis morfológicas dos corações dos animais. A histologia e ultraestrutura dos ventrículos do boto-cinza são similares àquelas encontradas em outros mamíferos. Fibras colágenas dos tipos I e III foram predominantes no miocárdio, indicando tecido fibroso. O comprimento total e a idade correlacionaram-se com variáveis morfométricas externas, como a circunferência na região do sulco coronário e do terço distal do coração. Apenas a densidade de volume de cardiomiócitos (r=0,516) e do tecido conjuntivo (r=-0,503) do ventrículo direito apresentaram correlação com a idade. O crescimento em altura e circunferência do coração de S. guianensis ocorreu até aproximadamente dez anos de idade, excedendo a idade de maturidade física antes registrada para a espécie.  Morphology, growth and aging of the heart, not only of Sotalia guianensis, but also of all cetaceans, are relatively unknown. The aim of the present study was to evaluate the morphology and growth of the heart and myocardium, using macro and micro-morphology, of samples collected from hearts of stranded Guiana dolphins found in the coast of Espírito Santo, Brazil. The ventricles were examined with light and electron microscopy, the hearts were measured and the volume density of cardiomyocytes, connective tissue, and blood vessels of the ventricles were determined. Statistical differences, regressions, correlations, and growth curves were applied between total length and age of animals and morphological variables. No significant difference was found between males and females. The histology and ultrastructure of the Guiana dolphin´s ventricles are similar to those found in other mammals. Type-I and -III collagen fibers were predominant in the myocardium. Total length and age correlated with select external morphometric variables such as the circumference at the coronary sulcus and the circumference at the distal third. Only the volume density of cardiomyocytes (r = 0.516) and connective tissue (r = -0.503) of the right ventricle correlated with age. The growth of height and circumference of the heart of S. guianensis occurs until approximately ten years of age, exceeding the physical maturity age reported for the species

Trophic relationships and mercury biomagnification in Brazilian tropical coastal food webs

The present study investigated trophic relationships and mercury flow through food webs of three tropical coastal ecosystems: Guanabara, Sepetiba and Ilha Grande bays. The investigation was carried out through carbon and nitrogen stable isotopes (δ13C, δ15N) and total mercury (THg) determination in muscle from 35 species, including crustacean, cephalopod, fish and dolphin species. Detritivorous species showed the lowest average δ15N values in all bays. These species were 13C enriched in Sepetiba and Ilha Grande bays, suggesting the presence of 13C enriched macroalgae in their diet. The highest mean δ15N values were found in fish and benthic invertebrate feeders, as well as in species presenting demerso-pelagic feeding habit. The carbon and nitrogen isotopic findings showed different trophic relationship in food webs from Sepetiba, Guanabara and Ilha Grande bays. Guanabara Bay showed to be depleted in δ15N compared to both Sepetiba and Ilha Grande bays. The latter finding suggests substantial contribution of atmospheric nitrogen fixation by cyanobacteria. A positive linear relationship was found between log THg concentrations and δ15N values for Guanabara and Ilha Grande bays, but not for Sepetiba Bay. Our findings showed trophic magnification factors (TMF) above 1, demonstrating that THg is being biomagnified up the food chains in Rio de Janeiro bays. Highlights ► The δ13C and δ15N findings showed different trophic relationship in food webs from Rio de Janeiro bays. ► Guanabara Bay showed depleted δ15N values compared to Sepetiba and Ilha Grande bays. ► Ilha Grande Bay showed significant depleted δ13C values. ► Our findings indicate THg biomagnifications up food webs in Rio de Janeiro bays. ► Ilha Grande Bay food web showed the highest trophic magnification factor.“Ciencias do Mar” – Proc. 23038.051661/2009-1

Persistent toxic substances in the Brazilian Amazon: contamination of man and the environment

The organochlorine insecticide DDT was extensively used in Brazil since 1945, both for agricultural purposes and for vector control measures. In 1986 its uses were forbidden in agriculture and in 1997 it was also phased-out in vector controls programs. However, the presence of DDT in urban and forested soils, breast milk and aquatic biota is still common, especially at the Amazon region. The results gathered since the middle of the 90s indicate that environmental contamination with this pesticide is still relatively high. Due to the high fish consumption by traditional riverside populations, human breast milk may represent an important source of DDT exposure to newborns. New results on DDT and PCBs in red dolphin (Inia geoffrensis), an endemic aquatic mammal of the Amazon region, is also reported

Trophic Relationships and Habitat Preferences of Delphinids from the Southeastern Brazilian Coast Determined by Carbon and Nitrogen Stable Isotope Composition

To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ13C and δ15N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ13C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ13C value, while oceanic species showed significantly lower δ13C values. The highest δ15N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ15N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ13C values, but similar δ15N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ13C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area.Peer reviewe