RESUMO
Persistent organic pollutants (POPs) were assessed for the first time in blue whales from the South Pacific Ocean. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB) and dichlorodiphenyltrichloroethane and its main metabolites (DDTs), were determined in 40 blubber samples from 36 free-ranging individuals and one stranded, dead animal along the coast of southern Chile between 2011 and 2013. PCBs were the most abundant pollutants (2.97-975â¯ng/g l.w.), followed by DDTs (3.50-537â¯ng/g l.w.), HCB (nd-77.5â¯ng/g l.w.) and PBDEs (nd-33.4â¯ng/g l.w). There was evidence of differences between sexes, with lower loads in females potentially due to pollutants passing to calves. POP concentrations were higher in specimens sampled in 2013; yet, between-year differences were only statistically significant for HCB and PBDEs. Lower chlorinated (pentaâ¯>â¯tetraâ¯>â¯tri) and brominated (tetraâ¯>â¯tri) congeners were the most prevalent among PCBs and PBDEs, respectively, mostly in agreement with findings previously reported in blue and other baleen whales. The present study provides evidence of lower levels of contamination by POPs in eastern South Pacific blue whales in comparison to those reported for the Northern Hemisphere.
Assuntos
Tecido Adiposo/metabolismo , Balaenoptera/metabolismo , Monitoramento Ambiental , Poluentes Químicos da Água/metabolismo , Animais , Chile , DDT/metabolismo , Feminino , Éteres Difenil Halogenados/metabolismo , Hexaclorobenzeno/metabolismo , Hidrocarbonetos Clorados/metabolismo , Masculino , Oceano Pacífico , Bifenilos Policlorados/metabolismoRESUMO
Steroid hormone assessment using non-invasive sample collection techniques can reveal the reproductive status of aquatic mammals and the physiological mechanisms by which they respond to changes in their environment. A portion of the eastern North Pacific blue whale (Balaenoptera musculus) population that seasonally visits the Gulf of California, Mexico has been monitored using photo-identified individuals for over 30â¯years. The whales use the area in winter-early spring for nursing their calves and feeding and it therefore is well suited for fecal sample collection. Using radioimmunoassays in 25 fecal samples collected between 2009 and 2012 to determine reproductive state and stress, we validated three steroid hormones (progesterone, corticosterone and cortisol) in adult female blue whales. Females that were categorized as pregnant had higher mean fecal progesterone metabolite concentrations (1292.6⯱â¯415.6â¯ng·g-1) than resting and lactating females (14.0⯱â¯3.7â¯ng·g-1; 23.0⯱â¯5.4â¯ng·g-1, respectively). Females classified as pregnant also had higher concentrations of corticosterone metabolites (37.5⯱â¯9.9â¯ng·g-1) than resting and lactating females (17.4⯱â¯2.0â¯ng·g-1; 16.8⯱â¯2.8â¯ng·g-1, respectively). In contrast, cortisol metabolite concentrations showed high variability between groups and no significant relationship to reproductive state. We successfully determined preliminary baseline parameters of key steroid hormones by reproductive state in adult female blue whales. The presence of pregnant or with luteal activity and known lactating females confirms that the Gulf of California is an important winter-spring area for the reproductive phase of these blue whales. The baseline corticosterone levels we are developing will be useful for assessing the impact of the increasing coastal development and whale-watching activities on the whales in the Gulf of California.
Assuntos
Balaenoptera/fisiologia , Fezes/química , Hormônios Esteroides Gonadais/análise , Reprodução/fisiologia , Animais , Balaenoptera/metabolismo , California , Corticosterona/análise , Corticosterona/metabolismo , Feminino , Hormônios Esteroides Gonadais/metabolismo , Gravidez , Progesterona/análise , Progesterona/metabolismo , Radioimunoensaio , Manejo de EspécimesRESUMO
In response to the explosion of the Deepwater Horizon and the massive release of oil that followed, we conducted three annual research voyages to investigate how the oil spill would impact the marine offshore environment. Most investigations into the ecological and toxicological impacts of the Deepwater Horizon Oil crisis have mainly focused on the fate of the oil and dispersants, but few have considered the release of metals into the environment. From studies of previous oil spills, other marine oil industries, and analyses of oil compositions, it is evident that metals are frequently encountered. Several metals have been reported in the MC252 oil from the Deepwater Horizon oil spill, including the nonessential metals aluminum, arsenic, chromium, nickel, and lead; genotoxic metals, such as these are able to damage DNA and can bioaccumulate in organisms resulting in persistent exposure. In the Gulf of Mexico, whales are the apex species; hence we collected skin biopsies from sperm whales (Physeter macrocephalus), short-finned pilot whales (Globicephala macrorhynchus), and Bryde's whales (Balaenoptera edeni). The results from our three-year study of monitoring metal levels in whale skin show (1) genotoxic metals at concentrations higher than global averages previously reported and (2) patterns for MC252-relevant metal concentrations decreasing with time from the oil spill.
Assuntos
Balaenoptera/metabolismo , Metais/metabolismo , Mutagênicos/metabolismo , Poluição por Petróleo , Pele/metabolismo , Cachalote/metabolismo , Baleias Piloto/metabolismo , Animais , Dorso , Balaenoptera/crescimento & desenvolvimento , Biópsia/veterinária , Cromo/metabolismo , Cromo/toxicidade , Monitoramento Ambiental , Feminino , Golfo do México , Masculino , Metais/toxicidade , Mutagênicos/toxicidade , Níquel/metabolismo , Níquel/toxicidade , Reprodutibilidade dos Testes , Caracteres Sexuais , Pele/efeitos dos fármacos , Espectrofotometria Atômica , Cachalote/crescimento & desenvolvimento , Distribuição Tecidual , Toxicocinética , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade , Baleias Piloto/crescimento & desenvolvimentoRESUMO
Stable isotope analysis in mysticete skin and baleen plates has been repeatedly used to assess diet and movement patterns. Accurate interpretation of isotope data depends on understanding isotopic incorporation rates for metabolically active tissues and growth rates for metabolically inert tissues. The aim of this research was to estimate isotopic incorporation rates in blue whale skin and baleen growth rates by using natural gradients in baseline isotope values between oceanic regions. Nitrogen (δ15N) and carbon (δ13C) isotope values of blue whale skin and potential prey were analyzed from three foraging zones (Gulf of California, California Current System, and Costa Rica Dome) in the northeast Pacific from 1996-2015. We also measured δ15N and δ13C values along the lengths of baleen plates collected from six blue whales stranded in the 1980s and 2000s. Skin was separated into three strata: basale, externum, and sloughed skin. A mean (±SD) skin isotopic incorporation rate of 163±91 days was estimated by fitting a generalized additive model of the seasonal trend in δ15N values of skin strata collected in the Gulf of California and the California Current System. A mean (±SD) baleen growth rate of 15.5±2.2 cm y-1 was estimated by using seasonal oscillations in δ15N values from three whales. These oscillations also showed that individual whales have a high fidelity to distinct foraging zones in the northeast Pacific across years. The absence of oscillations in δ15N values of baleen sub-samples from three male whales suggests these individuals remained within a specific zone for several years prior to death. δ13C values of both whale tissues (skin and baleen) and potential prey were not distinct among foraging zones. Our results highlight the importance of considering tissue isotopic incorporation and growth rates when studying migratory mysticetes and provide new insights into the individual movement strategies of blue whales.