Seascape Genetics of the Atlantic Spotted Dolphin (Stenella frontalis) Based on Mitochondrial DNA.

The Atlantic spotted dolphin (Stenella frontalis) is endemic to tropical, subtropical, and warm temperate waters of the Atlantic Ocean. Throughout its distribution, both geographic distance and environmental variation may contribute to population structure of the species. In this study, we follow a seascape genetics approach to investigate population differentiation of Atlantic spotted dolphins based on a large worldwide dataset and the relationship with marine environmental variables. The results revealed that the Atlantic spotted dolphin exhibits population genetic structure across its distribution based on mitochondrial DNA control region (mtDNA-CR) data. Analyses based on the contemporary landscape suggested, at both the individual and population level, that the population genetic structure is consistent with the isolation-by-distance model. However, because geography and environmental matrices were correlated, and because in some, but not all analyses, we found a significant effect for the environment, we cannot rule out the addition contribution of environmental factors in structuring genetic variation. Future analyses based on nuclear data are needed to evaluate whether local processes, such as social structure and some level of philopatry within populations, may be contributing to the associations among genetic structure, geographic, and environmental distance.

Brominated flame retardants and natural organobrominated compounds in a vulnerable delphinid species along the Brazilian coast.

Guiana dolphins, Sotalia guianensis, are vulnerable to extinction along their distribution on the Brazilian coast and assessing chemical pollution is of utmost importance for their conservation. For this study, 51 carcasses of Guiana dolphins were sampled across the Brazilian coast to investigate legacy and emerging brominated flame retardants (BFRs) as well as the naturally-produced MeO-BDEs. PBDEs and MeO-BDEs were detected in all samples analyzed, whereas emerging BFRs were detected in 16 % of the samples, all in Rio de Janeiro state. PBDE concentrations varied between 2.24 and 799 ng.g-1 lipid weight (lw), emerging BFRs between 0.12 and 1.51 ng.g-1 lw and MeO-BDEs between 3.82 and 10,247 ng.g-1 lw. Concentrations of legacy and emerging BFRs and natural compounds varied considerably according to the sampling site and reflected both the local anthropogenic impact of the region and the diversity/mass of biosynthesizers. The PBDE concentrations are lower than what was found for delphinids in the Northern Hemisphere around the same sampling period and most sampling sites presented mean concentrations lower than the limits for endocrine disruption known to date for marine mammals of 460 ng.g-1 lw, except for sampled from Santa Catarina state, in Southern Brazil. Conversely, MeO-BDE concentrations are higher than those of the Northern Hemisphere, particularly close to the Abrolhos Bans and Royal Charlotte formation, that are hotspots for biodiversity. Despite the elevated concentrations reported for this group, there is not much information regarding the effects of such elevated concentrations for these marine mammals. The distinct patterns observed along the Brazilian coast show that organobrominated compounds can be used to identify the ecological segregation of delphinids and that conservation actions should be planned considering the local threats.

Pyrethroid insecticides along the Southwestern Atlantic coast: Guiana dolphin (Sotalia guianensis) as a bioindicator.

The presence of pyrethroid compounds in hepatic tissue of Guiana dolphins (Sotalia guianensis) is reported for the first time. Twelve pyrethroids were determined in 50 animals from eight locations of the Brazilian coast. The highest average concentration of total pyrethroids (∑PYR) was 1166 ng.g-1 lw, with values ranging from 148 to 5918 ng.g-1 lw, in Ilha Grande Bay, Rio de Janeiro State, while the Espírito Santo State had the highest median, 568 ng.g-1 lw. Permethrin was the predominant compound in most areas, contributing for 42% to 81% of the ∑PYR, whereas cypermethrin was the most abundant compound in Guanabara and Sepetiba bays (79% and 81%, respectively), both located in Rio de Janeiro State. Biological factors were not correlated with pyrethroids concentration. Tetramethrin and es/fenvalerate compounds were negatively correlated to the age, suggesting degradation/metabolization capacity in these animals that increases throughout life. Despite being metabolized and excreted, the wide use of these pollutants is reflected in relevant concentrations found in Guiana dolphins. This is the first study evaluating pyrethroids in a representative number of hepatic samples and covering >2600 km of coast. The overall lack of information on pyrethroids in cetaceans highlights the importance of understanding the profile and distribution of these pollutants in dolphins which exclusively inhabit the Southwestern Atlantic coast.

Molecular confirmation of twinning in the West Indian Manatee (Trichechus manatus) / Confirmação molecular de gemelaridade em peixes-boi marinho (Trichechus manatus)

Abstract: Few twinning events have been recorded in the West Indian manatee (Trichechus manatus, Sirenia: Trichechidae) and no previous published study has provided confirmation of this phenomenon based in molecular tools. Here we investigate a possible case of twinning in an endangered Brazilian population of T. manatus using molecular tools. We analyzed two male neonates found stranded in Ceará State, on the northeastern coast of Brazil. The DNA of both individuals was isolated, and 10 microsatellite loci were amplified and genotyped. Following the identification of the alleles, the probabilities of identity by descent (∆7 and ∆8) and relatedness (rxy) were calculated using estimators that evaluate inbreeding. The two individuals shared most of the alleles, with differences in the genotypes being identified in only two loci. All the estimators identified a level of relatedness compatible with that found between siblings (selfed or outbred), indicating they were dizygotic twins. This is the first confirmed case of fraternal twins in free-ranging West Indian manatees in South America. The recognition of this type of twinning provides elements to improve actions for the rehabilitation of stranded animals and their subsequent release to the environment.

Resumo: Poucos eventos de gemelaridade foram registrados para o peixe-boi marinho (Trichechus manatus, Sirenia: Trichechidae) e nenhum estudo previamente publicado confirmou esse fenômeno com base em ferramentas moleculares. Aqui investigamos um possível caso de gemelaridade em uma ameaçada população brasileira de T. manatus utilizando ferramentas moleculares. Foram analisados dois neonatos machos encontrados encalhados no Ceará, costa nordeste do Brasil. O DNA dos indivíduos foi isolado e 10 loci microsatélites foram amplificados e genotipados. Após a identificação dos alelos, as probabilidades de identidade por descendência (∆7 e ∆8) e relação (rxy) foram calculadas usando estimadores que avaliam endogamia. Os dois indivíduos partilharam a maioria dos alelos, com diferenças nos genótipos sendo identificadas em apenas dois loci. Todos os estimadores identificaram um nível de parentesco compatível com o encontrado entre irmãos (com e sem endogamia), o que aponta para o fato de serem gêmeos dizigóticos. Este é o primeiro caso confirmado de gêmeos fraternais em peixes-boi marinho de vida livre na América do Sul. O reconhecimento deste tipo de gemelaridade fornece elementos para aprimorar ações que visem a reabilitação de animais encalhados e sua posterior soltura ao ambiente.

Toxic heritage: Maternal transfer of pyrethroid insecticides and sunscreen agents in dolphins from Brazil.

Pyrethroids (PYR) and UV filters (UVF) were investigated in tissues of paired mother-fetus dolphins from Brazilian coast in order to investigate the possibility of maternal transfer of these emerging contaminants. Comparison of PYR and UVF concentrations in maternal and fetal blubber revealed Franciscana transferred efficiently both contaminants to fetuses (F/M > 1) and Guiana dolphin transferred efficiently PYR to fetuses (F/M > 1) different than UVF (F/M < 1). PYR and UVF concentrations in fetuses were the highest-ever reported in biota (up to 6640 and 11,530 ng/g lw, respectively). Muscle was the organ with the highest PYR and UVF concentrations (p < 0.001), suggesting that these two classes of emerging contaminants may have more affinity for proteins than for lipids. The high PYR and UVF concentrations found in fetuses demonstrate these compounds are efficiently transferred through placenta. This study is the first to report maternal transfer of pyrethroids and UV filters in marine mammals.

Organochlorine concentrations (PCBs, DDTs, HCHs, HCB and MIREX) in delphinids stranded at the northeastern Brazil.

Organochlorine compounds are highly persistent in the environment, causing bioaccumulation and biomagnification through the marine food chain. To verify the bioaccumulation pattern of DDT and its metabolites, as well as PCBs, Mirex, HCHs and HCB, samples of subcutaneous adipose tissue from 25 Guiana dolphins (Sotalia guianensis), two Fraser's dolphins (Lagenodelphis hosei), two spinner dolphins (Stenella longirostris), one spotted dolphin (Stenella frontalis), and one striped dolphin (Stenella coeruleoalba) were analyzed. The collected specimens were found stranded in northeastern Brazil between 2005 and 2011. The concentrations were reported in µg·g(-1) lip, varying from 0.02 to 17.3 for ΣPCB, from 0.003 to 5.19 for ΣDDT, from 0.005 to 0.16 for ΣHCH, from 0.002 to 0.16 for HCB, and from 0.02 to 2.38 for Mirex. The PCBs dominated the bioaccumulation pattern for both the Guiana and spinner dolphins; for the other species, DDT was the major compound. A discriminant function analysis revealed the differences in the organochlorine accumulation patterns between the Guiana dolphin (S. guianensis) and the continental shelf/oceanic dolphins (S. frontalis and S. longirostris). The results also show that the concentrations of organochlorine compounds found in the delphinids in northeastern Brazil were lower than the delphinids found in other regions of Brazil, as well as other locations worldwide with intense agroindustrial development and/or a larger population.