Natural and anthropogenic organic brominated compounds in the southwestern Atlantic ocean: Bioaccumulation in coastal and oceanic dolphin species.

Marine pollution is considered a current driver of change in the oceans and despite the urgency to develop more studies, there is limited information in the southern hemisphere. This study aimed to analyze the levels and profiles of natural (MeO-PBDEs) and anthropogenic (BFRs: PBDEs, HBB, PBEB) organic brominated compounds in adipose tissue of two species of dolphins with different distribution and trophic requirements from the Southwestern Atlantic Ocean; the short-beaked common dolphin (Delphinus delphis) and the Fraser's dolphin (Lagenodelphis hosei). In addition, we aim to investigate maternal transfer and biological pattern relationship (sex, age, sexual maturity) in short-beaked common dolphin bioaccumulation. The levels of both groups of contaminants were in the same order of magnitude as those reported for other marine mammals on both a regional and global scale. BFRs profiles were dominated by BDE 28 and BDE 47 in short-beaked common dolphin and Fraser's dolphin, respectively, whereas 2-MeO-BDE 68 was the most abundant natural compound in both species. Evidence of maternal transfer, temporary increase in BDE 154 levels and no influence of sex, age, or sexual maturity on brominated compound concentration was observed in short-beaked common dolphin. This study fills a gap in the knowledge of the Southwestern Atlantic Ocean providing new information on emerging organic pollutants bioavailability for dolphins and, therefore, for the different trophic webs. In addition, it serves as a baseline for further contamination assessments.

Understanding trophic transference role in mercury biomagnification and bioaccumulation in the Atlantic spotted dolphin (Stenella frontalis).

Mercury is a metal of toxicological importance that occurs naturally. However, its concentration can be affected by anthropogenic activities and has the potential to bioaccumulate and biomagnify in food webs. Thus, knowing how its concentration varies along the trophic levels allows us to understand its potential risks to the biota. The present study aimed to investigate mercury transfer through the Stenella frontalis food web in Ilha Grande Bay (IGB), Rio de Janeiro state, Brazil. Samples of muscle and liver of S. frontalis were obtained from carcasses (n = 8) found stranded in the IGB, and its potential prey species were collected in fishing landings in the same Bay (n = 145). Total mercury (THg) concentrations were determined by atomic absorption spectrometry, and the δ15N was determined by an isotope ratio mass spectrometer. To investigate how trophic transfer affects mercury contamination in biota, six linear models were applied between THg logarithmic concentrations and δ15N or trophic position (TP). The trophic magnification factor (TMF) was calculated from each model to estimate the trophic transfer. Mean THg concentration in S. frontalis was higher in the liver than in muscle, but no correlation was found with age and δ15N values. Instead, the hepatic and muscular THg concentrations positively correlated with the trophic position. In the summer, THg concentration, TP, and δ15N values in prey species varied significantly, as well as in the winter, except for THg concentration. All trophic transfer models were significant in both seasons, and the TMF >1. The present study showed that trophic transfer is an essential factor in mercury biomagnification in both seasons but is not the unique driver. Both δ15N and TP could explain mercury trophic transfer, but TP better integrates metabolic diversity and seasonality.

Toxoplasma gondii in cetaceans of Brazil: a histopathological and immunohistochemical survey.

Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. In cetaceans, T. gondii infection is a significant cause of morbidity and mortality. Despite the worldwide range and broad cetacean host record of T. gondii infection, there is limited information on toxoplasmosis in cetaceans from the Southern hemisphere. We investigated the occurrence of T. gondii by histopathology and immunohistochemistry in tissue samples of 185 animals comprising 20 different cetacean species from Brazil. Three out of 185 (1.6%) animals presented T. gondii-associated lesions: a captive killer whale Orcinus orca, a free-ranging common bottlenose dolphin Tursiops truncatus and a free-ranging Guiana dolphin Sotalia guianensis. The main lesions observed in these animals were necrotizing hepatitis, adrenalitis and lymphadenitis associated with protozoal cysts or extracellular tachyzoites presenting immunolabeling with anti-T. gondii antibodies. This study widens the spectrum of species and the geographic range of this agent in Brazil, and provides the first reports of T. gondii infection in a captive killer whale and in a free-ranging common bottlenose dolphin in South America.

Toxoplasma gondii in cetaceans of Brazil: a histopathological and immunohistochemical survey / Toxoplasma gondii em cetáceos do Brasil: estudo histopatológico e imuno-histoquímico

Abstract Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. In cetaceans, T. gondii infection is a significant cause of morbidity and mortality. Despite the worldwide range and broad cetacean host record of T. gondii infection, there is limited information on toxoplasmosis in cetaceans from the Southern hemisphere. We investigated the occurrence of T. gondii by histopathology and immunohistochemistry in tissue samples of 185 animals comprising 20 different cetacean species from Brazil. Three out of 185 (1.6%) animals presented T. gondii-associated lesions: a captive killer whale Orcinus orca, a free-ranging common bottlenose dolphin Tursiops truncatus and a free-ranging Guiana dolphin Sotalia guianensis. The main lesions observed in these animals were necrotizing hepatitis, adrenalitis and lymphadenitis associated with protozoal cysts or extracellular tachyzoites presenting immunolabeling with anti-T. gondii antibodies. This study widens the spectrum of species and the geographic range of this agent in Brazil, and provides the first reports of T. gondii infection in a captive killer whale and in a free-ranging common bottlenose dolphin in South America.

Resumo Toxoplasmose é uma doença parasitária causada pelo protozoário Toxoplasma gondii. A infecção por T. gondii é uma causa significativa de morbidade e mortalidade, nos cetáceos. Apesar da abrangência mundial e amplo registro de espécies de cetáceos infectadas por T. gondii, informações sobre toxoplasmose em cetáceos do hemisfério sul são limitadas. Neste estudo pesquisou-se por meio de histopatologia e imuno-histoquímica a ocorrência de T. gondii em amostras de tecido de 185 animais, compreendendo 20 diferentes espécies de cetáceos que ocorrem no Brasil. Três dos 185 (1,6%) animais apresentaram lesões associadas a T. gondii: uma orca Orcinus orca mantida em cativeiro, um golfinho-nariz-de-garrafa Tursiops truncatus e um boto-cinza Sotalia guianensis de vida livre. As principais lesões observadas nesses animais foram hepatite, adrenalite e linfadenite necrotizantes associadas a cistos protozoários ou taquizoítos extracelulares, marcados com anticorpos anti-T. gondii. O presente estudo amplia o espectro de espécies susceptíveis a esse agente e o seu alcance geográfico no Brasil, fornecendo o primeiro relato da infecção por T. gondii em uma orca mantida em cativeiro e em um golfinho-nariz-de-garrafa de vida livre na América do Sul.

Comparative Immunopathology of Cetacean morbillivirus Infection in Free-Ranging Dolphins From Western Mediterranean, Northeast-Central, and Southwestern Atlantic.

Cetacean morbillivirus (CeMV; Paramyxoviridae) causes epizootic and interepizootic fatalities in odontocetes and mysticetes worldwide. Studies suggest there is different species-specific susceptibility to CeMV infection, with striped dolphins (Stenella coeruleoalba), bottlenose dolphins (Tursiops truncatus), and Guiana dolphins (Sotalia guianensis) ranking among the most susceptible cetacean hosts. The pathogenesis of CeMV infection is not fully resolved. Since no previous studies have evaluated the organ-specific immunopathogenetic features of CeMV infection in tissues from infected dolphins, this study was aimed at characterizing and comparing immunophenotypic profiles of local immune responses in lymphoid organs (lymph nodes, spleen), lung and CNS in CeMV-molecularly (RT-PCR)-positive cetaceans from Western Mediterranean, Northeast-Central, and Southwestern Atlantic. Immunohistochemical (IHC) analyses targeted molecules of immunologic interest: caspase 3, CD3, CD20, CD57, CD68, FoxP3, MHCII, Iba1, IFNγ, IgG, IL4, IL10, lysozyme, TGFß, and PAX5. We detected consistent CeMV-associated inflammatory response patterns. Within CNS, inflammation was dominated by CD3+ (T cells), and CD20+ and PAX5+ (B cells) lymphocytes, accompanied by fewer Iba1+, CD68+, and lysozyme+ histiocytes, mainly in striped dolphins and bottlenose dolphins. Multicentric lymphoid depletion was characterized by reduced numbers of T cells and B cells, more pronounced in Guiana dolphins. Striped dolphins and bottlenose dolphins often had hyperplastic (regenerative) phenomena involving the aforementioned cell populations, particularly chronically infected animals. In the lung, there was mild to moderate increase in T cells, B cells, and histiocytes. Additionally, there was a generalized increased expression of caspase 3 in lymphoid, lung, and CNS tissues. Apoptosis, therefore, is believed to play a major role in generalized lymphoid depletion and likely overt immunosuppression during CeMV infection. No differences were detected regarding cytokine immunoreactivity in lymph nodes, spleen, and lung from infected and non-infected dolphins by semiquantitative analysis; however, there was striking immunoreactivity for IFNγ in the CNS of infected dolphins. These novel results set the basis for tissue-specific immunophenotypic responses during CeMV infection in three highly susceptible delphinid species. They also suggest a complex interplay between viral and host's immune factors, thereby contributing to gain valuable insights into similarities, and differences of CeMV infection's immunopathogenesis in relation to body tissues, CeMV strains, and cetacean hosts.

Burst pulses of Guiana dolphin (Sotalia guianensis) in southeastern Brazil.

Acoustic studies of Guiana dolphin have been focused on whistles, with little known about pulse signals in this species. This study characterized the temporal and spectral properties of Guiana dolphin burst pulses. Groups of 2 to 23 Guiana dolphins were recorded while feeding and socializing in shallow waters in Guanabara Bay, southeastern Brazil, in 2013 and 2014. Burst pulse analysis involved two steps: signal detection and acoustic parameter analysis. Eight variables were analyzed for 197 total burst pulses: number of clicks, burst pulse duration, interclick interval, click duration, peak frequency, center frequency, -3 dB bandwidth, and -10 dB bandwidth. Mean burst pulse duration was 108.6 ms [standard deviation (SD) = 91.3] with a mean of 168 clicks (SD = 137.3). Burst pulses had short interclick interval (0.7 ms, SD = 0.3) and mean click duration of 300 µs (SD = 100). Mean peak frequency and center frequency were 28 kHz (SD = 11.6) and 29 kHz (SD = 11.0), respectively. Mean -3 dB bandwidth was 15 kHz (SD = 7.5) and mean -10 dB bandwidth was 40.5 kHz (SD = 14.3). The quantitative characterization of Guiana dolphin burst pulses is an important step in describing the full acoustic repertoire of this species.

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 (δ(13)C) and nitrogen (δ(15)N) 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 δ(13)C and δ(15)N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ(13)C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ(13)C value, while oceanic species showed significantly lower δ(13)C values. The highest δ(15)N 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 δ(15)N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ(13)C values, but similar δ(15)N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ(13)C 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.

Mercury-selenium relationships in liver of Guiana dolphin: the possible role of Kupffer cells in the detoxification process by tiemannite formation.

Top marine predators present high mercury concentrations in their tissues as consequence of biomagnification of the most toxic form of this metal, methylmercury (MeHg). The present study concerns mercury accumulation by Guiana dolphins (Sotalia guianensis), highlighting the selenium-mediated methylmercury detoxification process. Liver samples from 19 dolphins incidentally captured within Guanabara Bay (Rio de Janeiro State, Brazil) from 1994 to 2006 were analyzed for total mercury (THg), methylmercury (MeHg), total organic mercury (TOrgHg) and selenium (Se). X-ray microanalyses were also performed. The specimens, including from fetuses to 30-year-old dolphins, comprising 8 females and 11 males, presented high THg (0.53-132 µg/g wet wt.) and Se concentrations (0.17-74.8 µg/g wet wt.). Correlations between THg, MeHg, TOrgHg and Se were verified with age (p<0.05), as well as a high and positive correlation was observed between molar concentrations of Hg and Se (p<0.05). Negative correlations were observed between THg and the percentage of MeHg contribution to THg (p<0.05), which represents a consequence of the selenium-mediated methylmercury detoxification process. Accumulation of Se-Hg amorphous crystals in Kupffer Cells was demonstrated through ultra-structural analysis, which shows that Guiana dolphin is capable of carrying out the demethylation process via mercury selenide formation.

Organochlorine concentrations in franciscana dolphins, Pontoporia blainvillei, from Brazilian waters.

Blubber samples were collected from ten franciscana dolphins either incidentally captured in fishing operations or stranded on São Paulo (SP) and Paraná (PR) states littoral, Southeastern and Southern Brazilian coast, respectively. Determination of PCB, DDT and HCB concentrations were performed by capillary gas chromatograph coupled to electron capture detector (ECD). ΣDDT, ΣPCB and HCB concentrations ranged from 264 ng g(-1) to 5811 ng g(-1) lipid, from 909 ng g(-1) to 5849 ng g(-1) lipid and from 10 ng g(-1) to 61 ng g(-1) lipid, respectively. Regarding DDTs, the distribution of the mean percentages decreased in the following order: p,p'-DDE>p,p'-DDD>p,p'-DDT. The ΣDDT/ΣPCB ratio varied between 0.27 and 0.42 in Northern and Central SP coast, while in Southern SP and PR coast the values were 1.6 and 1.9, respectively. Dissimilarities in ΣDDT/ΣPCB ratios point to different sources of organochlorine compounds to franciscana dolphins in the study area. Considering the endocrine disruptive action of organochlorine compounds, the concentrations found in franciscana dolphins from Brazilian waters may represent an additional obstacle to the conservation of this endangered cetacean species.

Fisheries and conflicts in Guanabara Bay, Rio de Janeiro, Brazil

A despeito da magnitude da poluição de origem doméstica e industrial, a produção de pescado registrado em diferentes pontos de desembarque na Baía de Guanabara, entre abril de 2001 e março de 2002, foi ligeiramente superior a 19.000 t, correspondendo em valor a US$ 4.8 milhões. Quando se considera apenas o pescado direcionado para o mercado fresco, a captura total alcançou cerca de 6.300 t e um valor de US$ 3,7 milhões. Somente algumas poucas espécies alcançam densidades expressivas compatíveis com as pescarias comerciais. Entre os pequenos pelágicos, a sardinha boca-torta e a sardinha verdadeira são as espécies dominantes, enquanto para as demersais, a corvina, a tainha e os bagres perfazem a maior parte das capturas. As pescarias para o caranguejo, nos manguezais, e a coleta de mexilhões nos costões rochosos da entrada da baía e ilhas adjacentes são, também, importantes. A ausência de estatísticas pesqueiras prévias ao vazamento de 1,3 milhão de litros de óleo, em janeiro de 2000, levou à reivindicação de indenizações, por parte das organizações representativas dos pescadores, de valores correspondentes a cerca de 50 anos de produção de pescado na baía. Um sistema de coleta de dados pode ser estabelecido de forma participativa com as associações de pescadores locais. As pescarias relativamente estáveis na baía sugerem que inferências razoáveis podem ser obtidas sem que, necessariamente, se tenha uma cobertura completa de todos os pontos de desembarque.