RESUMO
Mercury contamination has been aggravated by emerging environmental issues, such as climate change. Top predators present concerning Hg concentrations once this metal bioaccumulates and biomagnifies. This study evaluated total mercury (THg) concentrations in tissues of 43 franciscanas (Pontoporia blainvillei) from two populations: the Franciscana Management Area (FMA) IIb and FMA IIIa. Animals from FMA IIIa showed mean concentration 5-times and 2.5-times higher in the liver and kidney (4.73 ± 6.84 and 0.52 ± 0.51 µg.g-1, w.w., respectively) than individuals from FMA IIb (0.89 ± 1.04 and 0.22 ± 0.15 µg.g-1, w.w., respectively). This might be due to: (I) individuals sampled from FMA IIIa being larger and older, and/or (II) the area near FMA IIIa presents environmental features leading to higher THg availability. Coastal contamination can affect franciscanas' health and population maintenance at different levels depending on their life history and, therefore, it should be considered to guide specific conservation actions.
Assuntos
Golfinhos , Espécies em Perigo de Extinção , Monitoramento Ambiental , Mercúrio , Poluentes Químicos da Água , Animais , Mercúrio/análise , Mercúrio/metabolismo , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo , Oceano Atlântico , Golfinhos/metabolismo , Fígado/metabolismo , Rim/metabolismoRESUMO
Populations usually considered foraging generalists may include specialized individuals that feed on a restricted subset of the prey spectrum consumed by the population. By analyzing the time series of δ13C and δ15N values in sequential growth layer groups within tooth dentin, we measured population- and individual-level variation in resource use of three populations of Guiana dolphins (Sotalia guianensis)-Caravelas River, Babitonga Bay, and Norte Bay-along a latitudinal gradient in the southwestern Atlantic Ocean. We show that the Guiana dolphin at Caravelas River is a generalist population consisting of individual dietary specialists, likely due to the absence of other resident dolphin populations thus allowing individuals to target prey across a wide range of habitats. The Babitonga Bay population is also composed of individual specialists potentially due to the selective foraging behavior of some individuals on high-quality prey sources within and near the bay. In contrast, the Norte Bay population comprises individual generalists, which likely reflects its distinctive cohesive social organization, coexistence with two other dolphin species, and an opportunistic foraging strategy in response to resource fluctuations inherent to the southern limit of the species distribution. Although the Guiana dolphin is generally considered to be a dietary generalist at the population level, our findings reveal that the total niche width of populations and the degree of individual diet specialization are highly context dependent, suggesting dietary plasticity that may be related to a latitudinal gradient in resource availability and environmental conditions.
Assuntos
Golfinhos , Animais , Ecossistema , Dieta , Fatores de TempoRESUMO
Rough-toothed dolphins, Steno bredanensis, are closely associated with coastal waters in the Southwestern Atlantic Ocean, increasing the exposure to multiple stressors, such as chemical pollution. Persistent organic pollutants (POPs) are known to affect the health of cetacean species. To comprehend the potential impacts of POPs on populations' viability, it is necessary to distinguish populations and predict their risk of long-term exposure. Blubbers of rough-toothed dolphins (n = 28) collected along the southeastern (SE) and southern (S) Brazilian coast were screened for polychlorinated biphenyls (PCBs) and pesticides in a gas chromatograph coupled to a mass spectrometer. Based on the contamination profile, a discriminant function analysis separated the rough-toothed dolphins into three ecological populations: two coastal and one offshore. POP concentrations were the highest reported for the species worldwide and highest among the delphinids in Brazilian waters, reaching 647.9 µg g-1 lw for PCBs. The SE population presented 212.9 ± 163.0, S population presented 101.0 ± 96.7, and OCS/S population presented 183.3 ± 85.3 µg g-1 lw (mean ± SD) of PCBs. The potential risk of effects triggered by elevated PCB concentrations was assessed in an individual-based model. A risk of severe decline in population size is projected for the three populations in the next 100 years, especially in SE Brazil, varying between 67 and 99%.
Assuntos
Golfinhos , Poluentes Ambientais , Bifenilos Policlorados , Animais , Oceano Atlântico , Monitoramento Ambiental , Bifenilos Policlorados/análiseRESUMO
We investigated the trophic structure and habitat use of ten cetacean species occurring in the oceanic waters of the western South Atlantic using naturally-occurring stable isotopes. We analysed δ15N in individual amino acids (AA) to estimate cetacean trophic position (TP) and to evaluate the spatial differences in baseline δ15N (source AAs). We adjusted cetacean bulk-skin δ13C and δ15N for the effect of trophic level using their estimated TPs, obtaining δ13CAdjusted and δ15NAdjusted, respectively. These values were applied to estimate the overlap in the niche areas of cetacean baseline sources. Our analyses showed spatial segregation between Steno bredanensis and the remaining odontocetes, and the high δ15N in this species reflects its occurrence in neritic waters of the southern region. The highest TPs were observed in Physeter macrocephalus, Stenella attenuata and Globicephala melas, while the lowest TPs were reported for S. longirostris, S. clymene and Orcinus orca. Overall, source AA-δ15N showed similar patterns as those of baseline-δ15N (zooplankton) and were higher in species sampled in the southernmost region of the study area (e.g., Delphinus delphis). Isotopic niche areas estimated using δ13CAdjusted and δ15NAdjusted suggested high overlap in foraging area between S. frontalis and Tursiops truncatus, with the latter occupying a higher TP. Our analyses of δ15N in AAs provide a unique insight into the trophic ecology, forage areas and spatial segregation in resource use among these cetacean populations. Additionally, our work provides AA-δ15N baseline for future studies on the trophic ecology and habitat use of marine organisms in the western South Atlantic.
Assuntos
Aminoácidos , EcologiaRESUMO
RATIONALE: Stable carbon and nitrogen isotope ratios are widely used in ecological studies providing important information on the trophic ecology and habitat use of consumers. However, some factors may lead to isotopic variability, which makes difficult the interpretation of data, such as the presence of inorganic carbon in mineralized tissues. In order to remove the inorganic carbon, acidification is a commonly used treatment. METHODS: The effects of two methods of acidification were tested: (i) dentin acidification with 10% HCl using the 'drop-by-drop' technique, and (ii) dentin acidification in an 'HCl atmosphere', by exposing the dentin to vaporous 30% hydrochloric acid. Results were compared with untreated subsamples. The stable carbon and nitrogen ratios of untreated and acidified subsamples were measured using an elemental analyzer coupled to an isotope ratio mass spectrometer. RESULTS: The nitrogen isotopic ratios were statistically different between the two acidification treatments, but no significant changes in carbon isotopic ratios were found in acidified and untreated samples. CONCLUSIONS: The results indicated that acidification had no effect on carbon isotopic ratios of Neotropical otter tooth dentin, while introducing a source of error in nitrogen isotopic ratios. Therefore, we conclude that acidification is an unnecessary step for C and N stable isotope analysis.
Assuntos
Dentina/química , Lontras , Ácidos/química , Animais , Carbono/análise , Isótopos de Carbono/análise , Feminino , Ácido Clorídrico/química , Masculino , Espectrometria de Massas/métodos , Nitrogênio/análise , Isótopos de Nitrogênio/análise , Lontras/metabolismoRESUMO
RATIONALE: The analysis of stable isotopes in tissues such as teeth and bones has been used to study long-term trophic ecology and habitat use in marine mammals. However, carbon isotope ratios (δ(13) C values) can be altered by the presence of (12) C-rich lipids and carbonates. Lipid extraction and acidification are common treatments used to remove these compounds. The impact of lipids and carbonates on carbon and nitrogen isotope ratios (δ(15) N values), however, varies among tissues and/or species, requiring taxon-specific protocols to be developed. METHODS: The effects of lipid extraction and acidification and their interaction on carbon and nitrogen isotope values were studied for beaked whale (Ziphiidae) bone samples. δ(13) C and δ(15) N values were determined in quadruplicate samples: control, lipid-extracted, acidified and lipid-extracted followed by acidification. Samples were analyzed by means of elemental analysis isotope ratio mass spectrometry. Furthermore, the efficiency of five mathematical models developed for estimating lipid-normalized δ(13) C values from untreated δ(13) C values was tested. RESULTS: Significant increases in δ(13) C values were observed after lipid extraction. No significant changes in δ(13) C values were found in acidified samples. An interaction between both treatments was demonstrated for δ(13) C but not for δ(15) N values. No change was observed in δ(15) N values for lipid-extracted and/or acidified samples. Although all tested models presented good predictive power to estimate lipid-free δ(13) C values, linear models performed best. CONCLUSIONS: Given the observed changes in δ(13) C values after lipid extraction, we recommend a priori lipid extraction or a posteriori lipid normalization, through simple linear models, for beaked whale bones. Furthermore, acidification seems to be an unnecessary step before stable isotope analysis, at least for bone samples of ziphiids. Copyright © 2015 John Wiley & Sons, Ltd.
Assuntos
Métodos Analíticos de Preparação de Amostras/métodos , Osso e Ossos/química , Isótopos de Carbono/análise , Lipídeos/isolamento & purificação , Isótopos de Nitrogênio/análise , Baleias/metabolismo , Métodos Analíticos de Preparação de Amostras/normas , Animais , Osso e Ossos/metabolismo , Isótopos de Carbono/metabolismo , Concentração de Íons de Hidrogênio , Lipídeos/química , Espectrometria de Massas , Modelos Teóricos , Isótopos de Nitrogênio/metabolismoRESUMO
The ingestion of debris by marine fauna is a growing threat to biodiversity. This study aimed to evaluate and characterize litter ingestion by odontocetes from the Western South Atlantic. Between 2018 and 2022, 154 stomachs from six species were collected from stranded individuals and incidental captures. Stomach contents were analyzed with the naked eye and items of anthropic origin found were counted and physically/chemically characterized. Generalized Linear Models were used to evaluate the influence of biological factors on the presence/absence of litter in stomachs, and for Pontoporia blainvillei only, the influence of these factors on the number of ingested items was also tested; additionally, a temporal analysis of ingestion was done for this species (1994-2022). A total of 156 items, mainly macro-sized plastics made of polypropylene, were found in 52 stomachs of four species: Tursiops spp. (FO% = 3.3%), Steno bredanensis (10.0%), Delphinus delphis (28.6%) and P. blainvillei (47.5%). The presence/absence of litter was explained only by species (χ2 = 28.29 and p < 0.001). For P. blainvillei, a threatened species in the region, the number of items was positively influenced by individual size (χ2 = 6.01 and p = 0.01) and sex (χ2 = 7.93 and p = 0.005). There was an increase in plastic ingestion by this species over the years (χ2 = 121.6 and p < 0.001) and it was estimated that 75% of P. blainvillei stomachs will contain plastic by 2040. The ingestion of litter by odontocetes from the Western South Atlantic was confirmed and the potential risks posed by this type of pollution were evidenced, especially since these species also face other anthropic pressures. These results further demonstrate the increasing threat of litter in the ocean and highlight the importance of circularity of plastics and proper waste management.
RESUMO
Litter pollution is a growing concern, including for Antarctica and the species that inhabit this ecosystem. In this study, we investigated the microplastic contamination in three seal species that inhabit the Western Antarctic Peninsula: crabeater (Lobodon carcinophaga), leopard (Hydrurga leptonyx) and Weddell (Leptonychotes weddellii) seals. Given the worldwide ubiquity of this type of contaminant, including the Southern Ocean, we hypothesized that the three seal species would present anthropogenic debris in their feces. We examined 29 scat samples of crabeater (n = 5), leopard (n = 13) and Weddell (n = 11) seals. The chemical composition of the items found were identified using micro-Raman and micro-FTIR spectroscopies. All the samples of the three species presented anthropic particles (frequency of occurrence - %FO - 100 %). Fibers were the predominant debris, but fragments and filaments were also present. Particles smaller than 5 mm (micro debris) were predominant in all the samples. Leopard seals ingested significantly larger micro-debris in comparison with the other seal species. The dominant color was black followed by blue and white. Micro-Raman and micro-FTIR Spectroscopies revealed the presence of different anthropogenic pigments such as reactive blue 238, Indigo 3600 and copper phthalocyanine (blue and green). Carbon black was also detected in the samples, as well as plastic polymers such as polystyrene, polyester and polyethylene terephthalate (PET), polyamide, polypropylene and polyurethane These results confirm the presence of anthropogenic contamination in Antarctic seals and highlight the need for actions to mitigate the effects and reduce the contribution of debris in the Antarctic ecosystem.
Assuntos
Caniformia , Focas Verdadeiras , Animais , Regiões Antárticas , Plásticos , EcossistemaRESUMO
We analyzed δ13C and δ15N values in different tooth portions (Growth Layer Groups, GLGs) of franciscanas, Pontoporia blainvillei, to investigate their effect on whole tooth (WT) isotopic values and the implications for dietary estimates. Tooth portions included the dentin deposited during the prenatal development (PND), the first year of life (GLG1) deposited during the nursing period and the central part of the tooth with no distinction amongst subsequent GLGs (Center). Isotopic mixing models estimating the contribution of PND, GLG1 and Center to WT showed that GLG1 has a strong effect on WT isotope values in juveniles, while Center only starts to affect WT isotopic values from age four. Isotopic mixing models estimating prey contribution to the diet of juveniles using WT vs Center tooth portions significantly differed in dietary outputs, demonstrating that GLG1 influence on WT isotope values affects dietary estimates in young franciscanas. As the small tooth size and narrowness of the last GLGs hinder the analysis of individual layers, we recommend excluding GLG1 in studies based on teeth isotope composition in franciscanas and caution when interpreting isotopic values from the WT of other small cetaceans.
Assuntos
Golfinhos , Animais , Isótopos de Carbono , Isótopos de Nitrogênio , Dieta , Cetáceos , ViésRESUMO
Organic contaminants with toxic effects, like the conventional brominated flame retardants (BFRs) and BFRs of emergent concern, and their synergistic effects with other micropollutants, can be an additional threat to delphinids. Rough-toothed dolphins (Steno bredanensis) populations strongly associated with coastal environments already face a potential risk of decline due to high exposure to organochlorine pollutants. Moreover, natural organobromine compounds are important indicators of the environment's health. Polybrominated diphenyl ethers (PBDEs), pentabromoethylbenzene (PBEB), hexabromobenzene (HBB) and the methoxylated PBDEs (MeO-BDEs) were determined in the blubber of rough-toothed dolphins from three ecological populations from the Southwestern Atlantic Ocean (Southeastern, Southern and Outer Continental Shelf/Southern populations, SE, S, and OCS/S, respectively). The profile was dominated by the naturally produced MeO-BDEs (mainly 2'-MeO-BDE 68 and 6-MeO-BDE 47), followed by the anthropogenic BFRs PBDEs (mainly BDE 47). Median ΣMeO-BDE concentrations varied between 705.4 and 3346.0 ng g-1 lw among populations and ΣPBDE from 89.4 until 538.0 ng g-1 lw. Concentrations of anthropogenic organobromine compounds (ΣPBDE, BDE 99 and BDE 100) were higher in SE population than in OCS/S, indicating a coast - ocean gradient of contamination. Negative correlations were found between the concentration of the natural compounds and age, suggesting their metabolization and/or biodilution and maternal transference. Conversely, positive correlations were found between the concentrations of BDE 153 and BDE 154 and age, indicating low biotransformation capability of these heavy congeners. The levels of PBDEs found are concerning, particularly for SE population, because they are similar to concentrations known for the onset of endocrine disruption in other marine mammals and may be an additional threat to a population in a hotspot for chemical pollution.
Assuntos
Golfinhos , Retardadores de Chama , Poluentes Químicos da Água , Animais , Golfinhos/metabolismo , Éteres Difenil Halogenados/análise , Poluentes Químicos da Água/análise , Oceano Atlântico , Monitoramento Ambiental , Retardadores de Chama/análiseRESUMO
Kogia sima and Kogia breviceps are apex predators of mesopelagic trophic webs being far from most anthropogenic threats. However, chemical pollutants and naturally synthesized compounds may travel long distances. This study aimed to use kogiid whales as sentinels of mesopelagic trophic webs in the Southwestern Atlantic Ocean. Persistent organic pollutants (POPs), e.g., polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and metabolites, mirex, hexachlorobenzene (HCB), polybrominated diphenylethers (PBDEs), pentabromoethylbenzene (PBEB) and hexabromobenzene (HBB), and the naturally produced methoxylated BDE (MeO-BDEs) were determined in the blubber of 16 K. sima and 15 K. breviceps. Among the organochlorine compounds, DDTs were the main group found in K. sima and in K. breviceps (1636.6 and 3983.3 ng g-1 lw, respective medians), followed by PCBs (425.9 and 956.1 ng g-1 lw, respectively), mirex (184.1 and 375.6 ng g-1 lw, respectively), and HCB (132.4 and 340.3 ng g-1 lw, respectively). As for the organobromine, the natural MeO-BDEs were predominant (1676.7 and 501.6 ng g-1 lw, respectively), followed by PBDEs (13.6 and 10.3 ng g-1 lw, respectively) and PBEB (2.2 and 2.9 ng g-1 lw, respectively). In general, POPs concentration was higher in K. breviceps than in K. sima. Conversely, MeO-BDEs concentration was higher in K. sima than in K. breviceps. Differences in concentrations in these sympatric odontocetes were attributed to distinct species, sampling sites, and biological parameters and suggest some level of niche segregation. It is noteworthy the long-range reach and bioaccumulation of these synthetic compounds in an unexplored habitat, that present an increasing economic interest.
Assuntos
Poluentes Ambientais , Bifenilos Policlorados , Poluentes Químicos da Água , Animais , Bifenilos Policlorados/análise , Baleias/metabolismo , Hexaclorobenzeno/metabolismo , Mirex , Éteres Difenil Halogenados/análise , Bioacumulação , Poluentes Ambientais/metabolismo , Oceano Atlântico , Monitoramento Ambiental , Poluentes Químicos da Água/análiseRESUMO
On November 5th, 2015, the Fundão dam collapsed in Minas Gerais, southeastern Brazil, releasing millions of cubic meters of mud containing mining residue into the Doce River. Two weeks later, the mud arrived to the marine environment, triggering changes in franciscana dolphin habitat, Pontoporia blainvillei, from Franciscana Management Area Ia. This is an isolated population of the most endangered cetacean species in the South Atlantic Ocean. Organohalogen compounds (OHCs) may pose a threat to this endangered population because of their endocrine disrupting properties. Hence, this study sought to determine if there were differences in the bioaccumulation profile of OHC (PCBs, DDTs, Mirex, HCB, HCHs, PBDEs, PBEB, HBBZ and MeO-BDEs) in franciscana dolphins before and after dam collapse and to build a temporal trend. Blubber of 33 stranded individuals was collected in Espírito Santo state for organohalogen assessment between 2003 and 2019. Differences were found between franciscana dolphins collected prior to and after the disaster. Additionally, significant temporal trends for organochlorine pesticides and natural and anthropogenic organobromine were detected. The increase in pesticide concentrations after 2015 is suggestive of their reavailability in the environment. The decline in organobromine over time could be due to their debromination in the marine environment and alterations in the composition of their natural producers. PCBs remained stable during the period of the study. Our findings show an increase in endocrine disruptor concentrations, which is of great concern for this endangered population.
Assuntos
Desastres , Golfinhos , Praguicidas , Bifenilos Policlorados , Poluentes Químicos da Água , Animais , Brasil , Monitoramento Ambiental , Mineração , Bifenilos Policlorados/análise , Poluentes Químicos da Água/análiseRESUMO
Skipjack tuna (Katsuwonus pelamis) sustain a large-scale fishery in the southwest Atlantic Ocean (SWA), but information about its foraging ecology in this region is still limited. Here we use carbon (δ13C) and nitrogen (δ15N) stable isotope analysis of muscle from individuals collected in 2017-2018 (n = 383) to quantify diet composition and characterize movement patterns. We found a relatively small degree of variation in δ13C (range: -18.9 to -16.5) in comparison to δ15N values (6.7-14.7). At higher latitudes in the southern area (30-34°S), individuals had higher mean (±SD) δ15N values (12.2 ± 1.3) in comparison to those collected in the northern area (9.7 ± 1.5) between 20-26°S. At the northern area, isotope mixing models with informative priors showed that lanternfish (median: 50%) and krill (31%) were the primary foods. In the southern area, lanternfish (53%), krill (23%) and small pelagic fish (23%) were the primary food sources. Spatial shifts in diet composition were related to warming events that likely resulted in low abundance of sardines in the northern area. The latitudinal pattern in skipjack and krill δ15N values mirrored that of regional zooplankton isoscapes, suggesting residency at the timescale of isotopic turnover for muscle (~2-4 months), and that geographical variation in the baseline isotopic composition can be exploited to characterize seasonal movements of skipjack and other top marine consumers in this region.
Assuntos
Isótopos , Atum , Animais , Oceano Atlântico , Isótopos de Carbono/análise , Ecologia , Pesqueiros , Isótopos de Nitrogênio/análiseRESUMO
Aquatic mammals play an important role in community structure. The present study applied stable isotope analysis (SIA) to evidence trophic relationships and resource partitioning among aquatic mammals inhabiting different environments in the Amazon estuarine complex and adjacent coastal zone (AE) and Northeastern coast (NC) of Brazil. In addition, isotopic niche partitioning among Sotalia guianensis, Inia spp. and Trichechus inunguis within the AE was also evaluated, and ecological S. guianensis stocks were characterized. Among marine delphinids, the carbon isotopic composition in offshore species mirrored that of nearshore species, contradicting the pattern of decreasing δ13C values characteristic of many areas around the world including areas in Southeastern and Southern Brazil. Isotopic niches were highly distinct, with no overlap among the assessed species inhabiting the AE. Inia spp. and T. inunguis occupied significantly larger isotopic niche spaces, suggesting high habitat plasticity. S. guianensis inhabited two coastal regions indicating an ecological distinction. Nitrogen values were similar between S. guianensis from the NC and AE, indicating comparable trophic positions. However, NC specimens presented more variable δ13C values compared to those from AE. SIA results also allowed for insights concerning habitat use and the trophic ecology of dolphin species inhabiting different oceanographic regions off Northern/Northeast Brazil. These findings provide novel data on the stable isotope composition for cetaceans and sirenians from this region, and aid in furthering knowledge on the trophic ecology and habitat use of the investigated species.
Assuntos
Isótopos de Carbono/análise , Ecossistema , Estuários , Cadeia Alimentar , Mamíferos/fisiologia , Isótopos de Nitrogênio/análise , Animais , BrasilRESUMO
The estuarine dolphin, Sotalia guianensis, is one of the most abundant cetacean species in Brazil. Determination of age and of aspects associated with the development of this species is significant new studies. Counts of growth layer groups in dentin are used to estimate age of these animals, though other ways to evaluate development are also adopted, like the measurement of total length (TL). This study presents a procedure to evaluate the development of the estuarine dolphin based on the ossification pattern of forelimbs. Thirty-seven estuarine dolphins found in the state of Espírito Santo, Brazil, were examined. Age was estimated, TL was measured and ossification of epiphyses was examined by radiography. We analyzed results using the Spearman correlation. Inspection of radiographs allowed evaluation of the significance of the correlation between age and development of the proximal (r = 0.9109) and distal (r = 0.9092) radial epiphyses, and of the distal ulnar epiphyses (r = 0.9055). Radiographic analysis of forelimbs proved to be an appropriate method to evaluate physical maturity, and may be a helpful tool to estimate age of these animals in ecological and population studies.
Assuntos
Golfinhos/crescimento & desenvolvimento , Membro Anterior/crescimento & desenvolvimento , Osteogênese , Envelhecimento , Animais , Brasil , Golfinhos/fisiologia , Membro Anterior/fisiologiaRESUMO
Chlorinated pesticides, PCBs and PBDEs were analysed in nine blubber samples of Atlantic spotted dolphins, Stenella frontalis, incidentally captured during fishing operations in southern and southeastern Brazil between 2005 and 2007. The majority of compounds analysed were detected, suggesting widespread contamination over the region. Although the samples came from a location far from main coastal industrial areas, the results revealed an influence from such sources. Therefore, levels of PCBs (774-23659 ng g(-1) lipid wt.) and PBDEs (23-1326 ng g(-1) lipid wt.) detected seem to be related to the movement of individuals throughout near-shore and offshore waters. The sample from a lactating female exhibited a lower level of contamination and a distinct pattern, indicating selective transfer favouring less lipophilic compounds.