Geographic variation of persistent organic pollutant levels in humpback whale (Megaptera novaeangliae) feeding areas of the North Pacific and North Atlantic

Zooplankton as an indicator of the status of contamination of the Mediterranean Sea and temporal trends

Zooplankton has been intensively used as bioindicators of water pollution at global level, however, only few comprehensive studies have been conducted from the Mediterranean Sea and manly dated back to the 1970s. To redress the urgent need for updated data, this study provides information on the presence and levels of contaminants in zooplankton from the Tyrrhenian Sea. Although banned, both PCBs (46.9 ± 37.2 ng g-1) and DDT (8.9 ± 10.7 ng g-1) are still present and widespread, but their contamination appears to be a local problem and to be declining over the past 50 years. Zooplankton accumulates high levels of certain TEs, including Zn (400 ± 388 ppm) and Pb (35.3 ± 45.5 ppm), but shows intermediate concentrations of other TEs, including Cd (1.6 ± 0.9 ppm) and Hg (0.1 ± 0.1 ppm), comparing with both strongly polluted and more pristine marine habitats, which may reflect a general improvement.

Multiscale relationships between humpback whales and forage species hotspots within a large marine ecosystem

Fluctuations in prey abundance, composition, and distribution can impact predators, and when predators and fisheries target the same species, predators become essential to ecosystem-based management. Because of the difficulty in collecting concomitant predator-prey data at appropriate scales in patchy environments, few studies have identified strong linkages between cetaceans and prey, especially across large geographic areas. During summer 2018, a line-transect survey for cetaceans and coastal pelagic species was conducted over the continental shelf and slope of British Columbia, Canada, and the US West Coast, allowing for a large-scale investigation of predator-prey spatial relationships. We report on a case study of humpback whales (Megaptera novaeangliae) and their primary prey-Pacific herring (Clupea pallasii), northern anchovy (Engraulis mordax), and krill-using generalized additive models to explore the relationships between whale abundance on 10-km transect segments and prey metrics. Prey metrics included direct measures of biomass densities on segments and an original hotspot metric. For each prey species, segments in the upper fifth percentile for biomass density (across all segments) were designated hotspots, and whale counts on a segment were evaluated for their relationship to number of hotspot segments (species-specific and multispecies) within 25, 50, or 100 km. Whale abundance was not strongly related to direct measures of biomass densities, whereas models using hotspot metrics were more effective at describing variation in whale abundance, underscoring that evaluating prey at relevant and measurable scales is critical in patchy, dynamic marine environments. Our analysis highlighted differences in the distribution and prey availability for three humpback whale distinct population segments (DPSs) as defined under the US Endangered Species Act, including threatened and endangered DPSs that forage within the California Current Large Marine Ecosystem. These linkages provide insights into which prey species whales may be targeting in different regions and across multiple scales and, consequently, how climatic variability and anthropogenic risks may differentially impact these distinct predator-prey assemblages. By identifying scale-appropriate prey hotspots that co-occur with humpback whale aggregations, and with targeted, consistent prey sampling and estimations of potential consumption rates by whales, these findings can help inform the conservation and management of humpback whales within an ecosystem-based management framework.

Persistent organic pollutants in female humpback whales Megaptera novaeangliae from the Gulf of Maine

Contaminant studies in cetaceans can provide information about pollutant levels and patterns in a given region. Due to the confounding effects of reproductive status and maternal offloading in females, these studies typically focus on males. However, an improved understanding of contaminant burdens in female cetaceans is needed to better assess potential impacts to populations. The objectives of this study were to characterize concentrations of persistent organic pollutants (POPs) in blubber of female humpback whales across age classes and to also better characterize maternal offloading of these pollutants to their offspring. A total of 36 blubber biopsy samples of female humpback whales (Megaptera novaeangliae) from the Gulf of Maine were analyzed to examine contaminant loads across females of different ages. Sampled individuals were individually-identified from longitudinal studies and assigned to age class (i.e., adult, subadult, juvenile, calf). Analysis was performed using gas chromatography/mass spectrometry (GC/MS) of POPs including polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), chlordanes (CHLDs), polybrominated diphenyl ethers (PBDEs), hexachlorocyclohexanes (HCHs). The most abundant POPs were PCB congeners, with summed values ranging from 280 to 12,000 ng/g, lipid weight, which is above recent estimates of the threshold for adverse health effects. We found significant differences in mean values between adults and juveniles and between adults and subadults, with the exception of the less persistent HCHs for the latter. We also found significant differences in mean levels of ∑HCHs between the juveniles and subadults. Changes over age are consistent with maternal offloading and potentially important for evaluating population health and viability.

J, Jacobsen JK, Scordino JJ, Lang AR, Baugh KA, Bolton JL, Brüniche-Olsen A, Calambokidis J, Martínez-Aguilar S, Subbiah S, Gribble MO, Godard-Codding CAJ. Influence of Life-History Parameters on Persistent Organic Pollutant Concentrations in Blubber of Eastern North Pacific Gray Whales (Eschrichtius robustus)

Exposure to persistent organic pollutants (POPs) can significantly impact marine mammal health, reproduction, and fitness. This study addresses a significant 20-year gap in gray whale contaminant monitoring through analysis of POPs in 120 blubber biopsies. The scope of this substantial sample set is noteworthy in its range and diversity with collection between 2003 and 2017 along North America's west coast and across diverse sex, age, and reproductive parameters, including paired mothers and calves. Mean blubber concentrations of polychlorinated biphenyls (∑PCBs), dichlorodiphenyltrichloroethanes (∑DDTs), and chlordanes (∑CHLs) generally decreased since previous reports (1968-1999). This is the first report of polybrominated diphenyl ethers (PBDEs) and select hexachlorocyclohexanes (HCHs) in this species. Statistical modeling of the 19 most frequently detected compounds in this dataset revealed sex-, age-, and reproductive status-related patterns, predominantly attributed to maternal offloading. Mean POP concentrations differed significantly by sex in adults (17 compounds, up to 3-fold higher in males) but not in immatures (all 19 compounds). Mean POP concentrations were significantly greater in adults versus immatures in both males (17 compounds, up to 12-fold) and females (13 compounds, up to 3-fold). POP concentrations were detected with compound-specific patterns in nursing calves, confirming maternal offloading for the first time in this species.

Global PBDE contamination in cetaceans. A critical review

This review summarizes the most relevant information on PBDEs' occurrence and their impacts in cetaceans at global scale, with special attention on the species with the highest reported levels and therefore the most potentially impacted by the current and continuous release of these substances. This review also emphasizes the anthropogenic and environmental factors that could increase concentrations and associated risks for these species in the next future. High PBDE concentrations above the toxicity threshold and stationary trends have been related to continuous import of PBDE-containing products in cetaceans of Brazil and Australia, where PBDEs have never been produced. Non-decreasing levels documented in cetaceans from the Northwest Pacific Ocean might be linked to the increased e-waste import and ongoing production and use of deca-BDE that is still allowed in China. Moreover, high levels of PBDEs in some endangered species such as beluga whales (Delphinapterus leucas) in St. Lawrence Estuary and Southern Resident killer whales (Orcinus Orca) are influenced by the discharge of contaminated waters deriving from wastewater treatment plants. Climate change related processes such as enhanced long-range transport, re-emissions from secondary sources and shifts in migration habits could lead to greater exposure and accumulation of PBDEs in cetaceans, above all in those species living in the Arctic. In addition, increased rainfall could carry greater amount of contaminants to the marine environment, thereby, enhancing the exposure and accumulation especially for coastal species. Synergic effects of all these factors and ongoing emissions of PBDEs, expected to continue at least until 2050, could increase the degree of exposure and menace for cetacean populations. In this regard, it is necessary to improve current regulations on PBDEs and broader the knowledge about their toxicological effects, in order to assess health risks and support regulatory protection for cetacean species.

Humpback whales (Megaptera novaeangliae) breeding off Mozambique and Ecuador show geographic variation of persistent organic pollutants and isotopic niches

Humpback whales (Megaptera novaeangliae) from the Southern Hemisphere carry information on persistent organic pollutants (POPs) from their feeding zones in Antarctica to their breeding grounds, making this species a sentinel of contaminants accumulation in the Southern Ocean. This study aimed to evaluate driving factors, namely feeding areas, trophic level, and sex, affecting POP concentrations in the blubber of humpback whales breeding off Mozambique and off Ecuador. Biopsies of free-ranging humpback whales including blubber and skin were collected in 2014 and 2015 from Ecuador (n = 59) and in 2017 from Mozambique (n = 89). In both populations, HCB was the major contaminant followed by DDTs > CHLs > PCBs > HCHs > PBDEs. POP concentrations were significantly higher in males compared to females. HCB, DDTs, HCHs and PBDEs were significantly different between whales from the Mozambique population and the Ecuador population. Sex and feeding habits were important driving factors accounting for POP concentrations in Ecuador whales. The whales from our study had some of the lowest POP concentrations measured for humpback whales in the world. These whales fed predominantly on krill as reflected from the low δ¹³C and δ¹⁵N values measured in the skin. However, the isotopic niches of whales from Mozambique and Ecuador did not overlap indicating that the two populations are feeding in different areas of the Southern Ocean.

Eighty years of chemical exposure profiles of persistent organic pollutants reconstructed through baleen whale earplugs

Despite decades of effort, significant knowledge gaps still exist regarding the global transport and distribution of persistent organic pollutants (POPs) in marine ecosystems, especially for periods prior to the 1970s. Furthermore, for long-lived marine mammals such as baleen whales, POPs impacts on early developmental (first years of life), as well as lifetime exposure profiles for periods of use and phase-out, are not well characterized. Recently, analytical techniques capable of reconstructing lifetime (i.e., birth to death; ~6 mos. resolution) chemical exposure profiles in baleen whale earplugs have been developed. Earplugs represent a unique opportunity to examine the spatiotemporal trends of POPs in the marine ecosystem. Baleen whale earplugs were collected from six whales (one blue whale (Balaenoptera musculus) and five fin whales (Balaenoptera physalus)), including four from archived collections and two from recent strandings. Lifespans for some of these individuals date back to the 1930s and provide insight into early periods of POP use. POP concentrations (reported in ng g^-1 dry wt.) were determined in laminae (n = 35) and were combined with age estimates and calendar year to reconstruct lifetime POP exposure profiles and lifetime bioaccumulation rates. Dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs) were found to be the most dominant POPs (spanning the past 80 y), were detected as early as the 1930s and were ubiquitous in the North Pacific and Atlantic Oceans. Lifetime bioaccumulation rates determined using baleen whale earplugs were 56 times higher in the North Pacific as compared to the North Atlantic. This suggest baleen whales from the North Pacific may be to be exposed to increased levels of POPs.

Concentrations and profiles of organochlorine contaminants in North Pacific resident and transient killer whale (Orcinus orca) populations

Organochlorine (OC) profiles have been used as chemical "fingerprints" to infer an animal's foraging area. North Pacific killer whale (Orcinus orca) populations are exposed to different levels and patterns of OCs based on their prey, distribution, and amount of time spent in a particular area. To characterize concentrations and profiles of OCs found in various populations of North Pacific killer whales, polychlorinated biphenyls (PCBs), including dioxin-like congeners, DDTs, and hexachlorobenzene (HCB), were measured in biopsy blubber samples of photo-identified resident (fish-eating) and transient (mammal-eating) killer whales collected from 1994 through 2002 from Russian Far East waters to the waters of the west coast of the United States, representing 10 populations. We compared blubber OC concentrations based on ecotype (resident vs. transient), sex and reproductive maturity, and geographic area. We also examined OC mixtures to determine if we could detect segregated geographical areas (foraging areas) among the six populations with sufficient sample sizes. Transients had significantly higher OC concentrations than residents and adult male whales had consistently higher OC levels compared to adult females, regardless of ecotype. Our OC profile findings indicate segregated foraging areas for the North Pacific killer whales, consistent with observations of their geographic distributions. Several potential health risks have also been associated with exposure to high levels of contaminants in top-level predators including reproductive impairment, immune suppression, skeletal deformities, and carcinoma. The results of this baseline study provide information on the geographic distribution of OCs found in North Pacific killer whales, results which are crucial for assessing the potential health risks associated with OC exposure in this species.

First assessment of pollutant exposure in two balaenopterid whale populations sampled in the Svalbard Archipelago, Norway

Pollutant concentrations are poorly known for the largest animals on Earth, blue whales Balaenoptera musculus and fin whales Balaenoptera physalus. In this study, concentrations of persistent organic pollutants (POPs) were determined in blubber biopsies and stable isotope values for nitrogen (δ¹⁵N) and carbon (δ¹³C) were measured using skin biopsies for 18 blue whales and 12 fin whales sampled in waters surrounding the Svalbard Archipelago, Norway. The samples were collected in summer during the period 2014-2018. POPs were dominated by DDTs, PCBs and toxaphenes, with median concentrations in blue/fin whales being 208/341, 127/275 and 133/233 ng/g lipid weight, respectively. Linear models indicated that pollutant concentrations were 1.6-3 times higher in fin whales than in blue whales, which is likely related to the higher trophic positions of fin whales, as indicated by their higher δ¹⁵N. Lower δ¹³C in fin whales suggests that they feed at higher latitudes than blue whales; these values were not correlated with pollutant concentrations. Pollutant levels were approximately twice as high in males compared to females (intraspecifically), which indicates that females of these species offload pollutants to their offspring during gestation and lactation, similar to many other mammalian species. Pollutant concentrations in balaenopterid whales from Svalbard waters were generally much lower than in conspecific whales from the Mediterranean Sea or the Gulf of California, but higher than those in conspecifics from the Antarctic Peninsula.

Organic contaminants as an ecological tool to explore niche partitioning: a case study using three pelagic shark species

Chemical contaminant profiles are linked to an animal's niche, providing a potential tool by which to assess resource partitioning in pelagic species. As proof of concept, we examined contaminant signatures in three species of sharks (Isurus oxyrinchus, Prionace glauca, and Alopias vulpinus) known to overlap in both space and time. Since these sharks comprise a predatory guild within the Southern California Bight (SCB), we predicted that species may partition spatial and dietary resources to limit the extent of competitive exclusion. Indeed, species were distinguishable by both total contaminant loads and their contaminant fingerprint, as random forest analysis found that species could be correctly classified 96% of the time. Our results demonstrate the utility of chemical analyses for ecological studies, and how contaminant tracers can be used in combination with traditional methods to elucidate how species may undergo niche partitioning to reduce competition for overlapping resources within predatory guilds.

Species-Specific Characteristics Influence Contaminant Accumulation Trajectories and Signatures Across Ontogeny in Three Pelagic Shark Species

Factors influencing organic contaminant accumulation in sharks, especially across ontogeny, are not well-known. Contaminant concentrations were measured in three species of sharks (Blue, Shortfin Mako, and Common Thresher) across a range of size classes (neonatal to adult) that vary in their ecological and physiological characteristics. Empirical data was compared to a theoretical framework that predicted the shape of lifetime accumulation curves. We found that a one-size-fits-all accumulation model was not appropriate as species-specific characteristics had a significant effect on contaminant accumulation trajectories. Maternal offloading likely has an important effect on determining neonatal shark contaminant starting points, and trophic ecology and physiology may interact to affect the shape of species' contaminant accumulation curves. Makos were found to have the highest accumulation potential and Blues the lowest, with Threshers being intermediate in accumulation potential. Changes in species' ecology and/or physiology were also reflected in contaminant signature changes over ontogeny. If contaminant concentrations are to be used as a proxy for risk, species-specific characteristics need to be taken into account when estimating contaminant exposure and its potential negative effects on shark health and human consumption safety.

Bridging disciplines to advance elasmobranch conservation: applications of physiological ecology

A strength of physiological ecology is its incorporation of aspects of both species' ecology and physiology; this holistic approach is needed to address current and future anthropogenic stressors affecting elasmobranch fishes that range from overexploitation to the effects of climate change. For example, physiology is one of several key determinants of an organism's ecological niche (along with evolutionary constraints and ecological interactions). The fundamental role of physiology in niche determination led to the development of the field of physiological ecology. This approach considers physiological mechanisms in the context of the environment to understand mechanistic variations that beget ecological trends. Physiological ecology, as an integrative discipline, has recently experienced a resurgence with respect to conservation applications, largely in conjunction with technological advances that extended physiological work from the lab into the natural world. This is of critical importance for species such as elasmobranchs (sharks, skates and rays), which are an especially understudied and threatened group of vertebrates. In 2017, at the American Elasmobranch Society meeting in Austin, Texas, the symposium entitled `Applications of Physiological Ecology in Elasmobranch Research' provided a platform for researchers to showcase work in which ecological questions were examined through a physiological lens. Here, we highlight the research presented at this symposium, which emphasized the strength of linking physiological tools with ecological questions. We also demonstrate the applicability of using physiological ecology research as a method to approach conservation issues, and advocate for a more available framework whereby results are more easily accessible for their implementation into management practices.

Metal Levels in Whales from the Gulf of Maine: A One Environmental Health approach

One Environmental Health has emerged as an important area of research that considers the interconnectedness of human, animal and ecosystem health with a focus on toxicology. The great whales in the Gulf of Maine are important species for ecosystem health, for the economies of the Eastern seaboard of the United States, and as sentinels for human health. The Gulf of Maine is an area with heavy coastal development, industry, and marine traffic, all of which contribute chronic exposures to environmental chemicals that can bioaccumulate in tissues and may gradually diminish an individual whale's or a population's fitness. We biopsied whales for three seasons (2010-2012) and measured the levels of 25 metals and selenium in skin biopsies collected from three species: humpback whales (Megaptera novaeangliae), fin whales (Balaenoptera physalus), and a minke whale (Balaenoptera acutorostrata). We established baseline levels for humpback and fin whales. Comparisons with similar species from other regions indicate humpback whales have elevated levels of aluminum, chromium, iron, magnesium, nickel and zinc. Contextualizing the data with a One Environmental Health approach finds these levels to be of potential concern for whale health. While much remains to understand what threats these metal levels may pose to the fitness and survival of these whale populations, these data serve as a useful and pertinent start to understanding the threat of pollution.

First results on zooplankton community composition and contamination by some persistent organic pollutants in the Gulf of Tadjoura (Djibouti)

The Gulf of Tadjoura is located in the Horn of Africa and is widely recognized as an important site where the zooplanktivorous whale sharks seasonally aggregate from October to February. The surface zooplankton community (0-3m) was weekly sampled from November 2016 to February 2017 in two sites during the whale shark aggregation period. A total of 12 phyla were identified. Copepoda represented the most abundant and diverse group with 29 different genera, and contributed with an average of 82% of the mean zooplankton density of approximately 6600indm^-3. During the sampling period, copepods were dominated numerically by Calanoida (3600indm^-3), followed by Poicilostomatatoida (1300indm^-3). Within the copepods, Paracalanidae, Calanidae, Oncaeidae and Miraciidae were the most common families. The temporal trend in zooplankton biomass at both stations revealed the highest peak in December (41.3±36.4mgm^-3), and the lowest in February (6.6±3.3mgm^-3). As no information is available on the occurrence of legacy contaminants use and release in this area, analysis revealed the consistent presence of both DDT and PCB residues in zooplankton samples in the Gulf of Tadjoura. Total PCB ranged from approximately 110 to 637ngg^-1 d.w., while total DDT from 21 to 80ngg^-1 d.w. The proportion of primary DDT in the total residue was higher than DDE and DDD, which strongly suggests that the area might actually be subjected to DDT inputs of the parent compound.

Predicting the effects of polychlorinated biphenyls on cetacean populations through impacts on immunity and calf survival

The potential impact of exposure to polychlorinated biphenyls (PCBs) on the health and survival of cetaceans continues to be an issue for conservation and management, yet few quantitative approaches for estimating population level effects have been developed. An individual based model (IBM) for assessing effects on both calf survival and immunity was developed and tested. Three case study species (bottlenose dolphin, humpback whale and killer whale) in four populations were taken as examples and the impact of varying levels of PCB uptake on achievable population growth was assessed. The unique aspect of the model is its ability to evaluate likely effects of immunosuppression in addition to calf survival, enabling consequences of PCB exposure on immune function on all age-classes to be explored. By incorporating quantitative tissue concentration-response functions from laboratory animal model species into an IBM framework, population trajectories were generated. Model outputs included estimated concentrations of PCBs in the blubber of females by age, which were then compared to published empirical data. Achievable population growth rates were more affected by the inclusion of effects of PCBs on immunity than on calf survival, but the magnitude depended on the virulence of any subsequent encounter with a pathogen and the proportion of the population exposed. Since the starting population parameters were from historic studies, which may already be impacted by PCBs, the results should be interpreted on a relative rather than an absolute basis. The framework will assist in providing quantitative risk assessments for populations of concern.

Extensive Core Microbiome in Drone-Captured Whale Blow Supports a Framework for Health Monitoring

The pulmonary system is a common site for bacterial infections in cetaceans, but very little is known about their respiratory microbiome. We used a small, unmanned hexacopter to collect exhaled breath condensate (blow) from two geographically distinct populations of apparently healthy humpback whales (Megaptera novaeangliae), sampled in the Massachusetts coastal waters off Cape Cod (n = 17) and coastal waters around Vancouver Island (n = 9). Bacterial and archaeal small-subunit rRNA genes were amplified and sequenced from blow samples, including many of sparse volume, as well as seawater and other controls, to characterize the associated microbial community. The blow microbiomes were distinct from the seawater microbiomes and included 25 phylogenetically diverse bacteria common to all sampled whales. This core assemblage comprised on average 36% of the microbiome, making it one of the more consistent animal microbiomes studied to date. The closest phylogenetic relatives of 20 of these core microbes were previously detected in marine mammals, suggesting that this core microbiome assemblage is specialized for marine mammals and may indicate a healthy, noninfected pulmonary system. Pathogen screening was conducted on the microbiomes at the genus level, which showed that all blow and few seawater microbiomes contained relatives of bacterial pathogens; no known cetacean respiratory pathogens were detected in the blow. Overall, the discovery of a shared large core microbiome in humpback whales is an important advancement for health and disease monitoring of this species and of other large whales. IMPORTANCE The conservation and management of large whales rely in part upon health monitoring of individuals and populations, and methods generally necessitate invasive sampling. Here, we used a small, unmanned hexacopter drone to noninvasively fly above humpback whales from two populations, capture their exhaled breath (blow), and examine the associated microbiome. In the first extensive examination of the large-whale blow microbiome, we present surprising results about the discovery of a large core microbiome that was shared across individual whales from geographically separated populations in two ocean basins. We suggest that this core microbiome, in addition to other microbiome characteristics, could be a useful feature for health monitoring of large whales worldwide.

Temporal trends of PBDEs and emerging flame retardants in belugas from the St. Lawrence Estuary (Canada) and comparisons with minke whales and Canadian Arctic belugas

An exponential level increase of the ubiquitous halogenated flame retardant (HFR) class polybrominated diphenyl ether (PBDE) has been documented during the 1990s in endangered belugas (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Eastern Canada. The recent worldwide bans and regulations of PBDE mixtures led to their replacement by alternative HFRs (so-called emerging HFRs) that are increasingly being reported in various environmental compartments. There are, however, limited knowledge on the spatial and temporal trends of PBDEs and emerging HFRs in cetaceans, especially after restrictions on PBDE usage. The first objective of this study was to investigate the occurrence of HFRs (35 PBDE congeners and 13 emerging compounds) in the blubber of belugas and minke whales (Balænoptera acutorostrata) found dead in the Estuary or Gulf of St. Lawrence as well as belugas from Nunavik (Canadian Arctic) collected as part of the Inuit subsistence hunt. A second objective was to investigate the trends of HFR concentrations in SLE beluga males between 1997 and 2013. PBDEs were the most abundant HFRs in all three whale populations, while hexabromobenzene (HBB), Chlordene Plus (CPlus), Dechlorane Plus (DP), and Dechlorane 604 Component B (Dec-604 CB) were quantified in the majority of blubber samples. Overall, concentrations of emerging HFRs were notably greater in SLE belugas compared to the two other whale populations, with the exception of DP and Dec-604 CB that were found in greater concentrations in Canadian Arctic belugas. No significant trend in blubber PBDE concentrations was found in SLE belugas during this 17-year period. This suggests that global PBDE regulations are too recent to observe changes in PBDE concentrations in belugas from this highly HFR-exposed environment. In contrast, concentrations of HBB and CPlus in SLE belugas decreased slightly from 1997 to 2013, while DP increased up until 2000 and decreased slightly thereafter. The occurrence and temporal variations of PBDEs and their replacement products in these cetaceans warrant continuous monitoring.

Linking pollutant exposure of humpback whales breeding in the Indian Ocean to their feeding habits and feeding areas off Antarctica

Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo large-scale seasonal migrations between summer feeding grounds near Antarctica and their reproductive winter grounds in the Indian Ocean. The main scope of the current study was to investigate chemical exposure of humpback whales breeding in the Indian Ocean by providing the first published data on this breeding stock concerning persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), DDT and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs), and methoxylated PBDEs (MeO-PBDEs). Analyses of stable isotopes δ¹³C and δ¹⁵N in skin resulted in further insight in their feeding ecology, which was in agreement with a diet focused mainly on low trophic level prey species, such as krill from Antarctica. POPs were measured in all humpback whales in the order of HCB > DDTs > CHLs > HCHs > PCBs > PBDEs > MeO-BDEs. HCB (median: 24 ng g^-1 lw) and DDTs (median: 7.7 ng g^-1 lw) were the predominant compounds in all whale biopsies. Among DDT compounds, p,p'-DDE was the major organohalogenated pollutant, reflecting its long-term accumulation in humpback whales. Significantly lower concentrations of HCB and DDTs were found in females than in males (p < 0.001). Other compounds were similar between the two genders (p > 0.05). Differences in the HCB and DDTs suggested gender-specific transfer of some compounds to the offspring. POP concentrations were lower than previously reported results for humpback whales sampled near the Antarctic Peninsula, suggesting potential influence of their nutritional status and may indicate different exposures of the whales according to their feeding zones. Further investigations are required to assess exposure of southern humpback whales throughout their feeding zones.

Serum POP concentrations are highly predictive of inner blubber concentrations at two extremes of body condition in northern elephant seals

Long-lived, upper trophic level marine mammals are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Internal tissues may accumulate and mobilize POP compounds at different rates related to the body condition of the animal and the chemical characteristics of individual POP compounds; however, collection of samples from multiple tissues is a major challenge to ecotoxicology studies of free-ranging marine mammals and the ability to predict POP concentrations in one tissue from another tissue remains rare. Northern elephant seals (Mirounga angustirostris) forage on mesopelagic fish and squid for months at a time in the northeastern Pacific Ocean, interspersed with two periods of fasting on land, which results in dramatic seasonal fluctuations in body condition. Using northern elephant seals, we examined commonly studied tissues in mammalian toxicology to describe relationships and determine predictive equations among tissues for a suite of POP compounds, including ΣDDTs, ΣPCBs, Σchlordanes, and ΣPBDEs. We collected paired blubber (inner and outer) and blood serum samples from adult female and male seals in 2012 and 2013 at Año Nuevo State Reserve (California, USA). For females (N = 24), we sampled the same seals before (late in molting fast) and after (early in breeding fast) their approximately seven month foraging trip. For males, we sampled different seals before (N = 14) and after (N = 15) their approximately four month foraging trip. We observed strong relationships among tissues for many, but not all compounds. Serum POP concentrations were strong predictors of inner blubber POP concentrations for both females and males, while serum was a more consistent predictor of outer blubber for males than females. The ability to estimate POP blubber concentrations from serum, or vice versa, has the potential to enhance toxicological assessment and physiological modeling. Furthermore, predictive equations may illuminate commonalities or distinctions in bioaccumulation across marine mammal species.

Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants

As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N=24), we satellite tracked and sampled the same seals before and after their approximately seven month long foraging trip. For males, we sampled different adults and sub-adults before (N=14) and after (N=15) the same foraging trip. For females, we calculated blubber burdens for all compounds. The highest POP concentrations in males and females were found for ∑DDTs and ∑PCBs. In blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females, ∑DDT and ∑PBDEs were highly correlated in blubber and serum. While ∑PCBs were highly correlated with ∑DDTs and ∑PBDEs in blubber and serum for males, ∑PCBs showed weaker correlations with both compounds in females. As females gained mass while foraging, concentrations of nearly all POPs in inner and outer blubber significantly decreased; however, the absolute burden in blubber significantly increased, indicating ingestion of contaminants while foraging. Additionally, we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences in ∑DDTs, ∑PBDEs, MeO-BDE 47, as well as the ratio of ∑DDTs to ∑PCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations of ∑DDTs and ∑PBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in (13)C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in deep ocean food webs.

Organochlorine pesticides and PCBs in Southern Right Whales (Eubalaena australis) breeding at Península Valdés, Argentina

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were assessed in blubber from 35 dead Southern Right Whales (SRW - Eubalaena australis) stranded at Península Valdés, Argentina. The life cycle includes a feeding period in high productivity areas of the South West Atlantic and a reproductive period in coastal template waters of Argentina. Organochlorine pesticides showed higher concentrations (22.6±13.8 ng·g(-1)ww) than PCBs (7.5±10 ng·g(-1)ww). Among pesticides, HCHs, DDTs, endosulfans, dieldrin, chlordans, heptachlor epoxide, and trans-nonachlor were detected. p,p'-DDE and p,p'-DDT were present in 69% and 26% of samples, respectively. p,p'-DDT/p,p'-DDE ratio showed low values (<0.33) as a result of aged DDT inputs. However, the occurrence of only p,p'-DDT in some samples suggests a recent pesticide input. α-HCH/γ-HCH ratio (<DL-0.37) indicated no recent contribution of technical HCH mixture and/or current use of lindane. Dieldrin was present in 77% of the samples and endosulfan was detected in all samples with predominance of α- (75%) over β-endosulfan (19%) and scarce contribution of endosulfan sulphate (7%), suggesting a recent input of this insecticide to the environment in the SRW foraging area. A predominance of pentachlorobiphenyls was observed. In 21 samples at least one PCB indicator was found and PCB #118, highly toxic, contributed in 5% to total PCBs. Although all these organochlorine compounds are forbidden they were bioaccumulated in the blubber of SRW with a predominance of endosulfans, the more recently used pesticide. The absence of data on chemical pollutants in stranded dead whales is highlighted as a priority for research. This is the first study on levels, compositional patterns, and organochlorine sources in SRW. Moreover, more research including milk, and other tissues/organs is recommended considered that in the studied specimens, mostly calves, pollutants are likely transferred from the mother during pregnancy and nursing.

Persistent organochlorines in 13 shark species from offshore and coastal waters of Korea: Species-specific accumulation and contributing factors

Data on persistent organochlorines (OCs) in sharks are scarce. Concentrations of OCs such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were determined in the muscle tissue of 13 shark species (n=105) collected from offshore (Indian and Pacific Oceans) and coastal waters of Korea, to investigate species-specific accumulation of OCs and to assess the potential health risks associated with consumption of shark meat. Overall OC concentrations were highly variable not only among species but also within the same species of shark. The concentrations of PCBs, DDTs, chlordanes, hexachlorobenzene, and heptachlor in all shark species ranged from <LOQ (limit of quantification) to 184 (mean: 35.0), <LOQ to 1135 (58.2), <LOQ to 56.2 (4.31), <LOQ to 18.8 (1.64) and <LOQ to 77.5 (1.37)ng/g lipid weight, respectively. The determined concentrations of PCBs and DDTs in shark in our study were relatively lower than those reported in other studies. Aggressive shark species and species inhabiting the Indian Ocean had the highest levels of OCs. Inter-species differences in the concentrations and accumulation profiles of OCs among shark species could be explained by differences in feeding habit and sampling locations. Several confounding factors such as growth velocity, trophic position, and regional contamination status may affect the bioaccumulation of OCs in sharks. Hazard ratios of non-cancer risk for all the OCs were below one, whereas the hazard ratios of lifetime cancer risks of PCBs and DDTs exceeded one, implying potential carcinogenic effects in the general population in Korea. This is the first report to document the occurrence of OCs in sharks from Korea.

Persistent organic pollutant concentrations in blubber of 16 species of cetaceans stranded in the Pacific Islands from 1997 through 2011

Persistent organic pollutants (POPs) are toxic man-made chemicals that bioaccumulate and biomagnify in food webs, making them a ubiquitous threat to the marine environment. Although many studies have determined concentrations of POPs in top predators, no studies have quantified POPs in stranded cetaceans within the last 30 years around the Hawaiian Islands. A suite of POPs was measured in the blubber of 16 cetacean species that stranded in the tropical Pacific, including Hawai'i from 1997 to 2011. The sample set includes odontocetes (n=39) and mysticetes (n=3). Median (range) contaminant concentrations in ng/g lipid for the most representative species category (delphinids excluding killer whales [n=27]) are: 9650 (44.4-99,100) for ∑DDTs, 6240 (40.8-50,200) for ∑PCBs, 1380 (6.73-9520) for ∑chlordanes, 1230 (13.4-5510) for ∑toxaphenes, 269 (1.99-10,100) for ∑PBDEs, 280 (2.14-4190) for mirex, 176 (5.43-857) for HCB, 48.1 (<5.42-566) for ∑HCHs, 33.9 (<2.42-990) for ∑HBCDs, 1.65 (<0.435-11.7) for octachlorostyrene and 1.49 (<2.07-13.1) for pentachlorobenzene. ∑PCB concentrations in these Pacific Island cetaceans approach and sometimes exceed proposed toxic threshold values. Backward stepwise multiple regressions indicated the influence of life history parameters on contaminant concentrations when performed with three independent variables (species category, year of stranding, and sex/age class). No temporal trends were noted (p>0.063), but sex/age class influences were evident with adult males exhibiting greater contaminant loads than adult females and juveniles for ∑DDT, ∑PCBs, ∑CHLs, and mirex (p≤0.036). POP concentrations were lower in mysticetes than odontocetes for many compound classes (p≤0.003). p,p'-DDE/∑DDTs ratios were greater than 0.6 for all species except humpback whales, suggesting exposure to an old DDT source. These POP levels are high enough to warrant concern and continued monitoring.

Anthropogenic (PBDE) and naturally-produced (MeO-PBDE) brominated compounds in cetaceans--a review

This paper reviews the available data on brominated flame retardants, the polybrominated diphenyl ethers (PBDEs), as well as on the naturally-produced methoxylated polybrominated diphenyl ethers (MeO-PBDEs) in cetacean tissues around the world. Levels and possible sources of both compound classes are discussed. Odontocete cetaceans accumulate higher PBDE concentrations than mysticete species. PBDE contamination was higher in cetaceans from the Northern hemisphere, whereas MeO-PBDE levels were higher in animals from the Southern hemisphere. Southern resident killer whales from NE Pacific presented the highest levels reported in biota, followed by bottlenose dolphins from North Atlantic (U.K. and U.S. coast). Many species presented PBDE concentrations above threshold levels for health effects in odontocetes. Time trend studies indicate that PBDE concentrations in odontocetes from Japan, China, U.S. and Canada coastal zones have increased significantly over the past 30 years. Studies from U.K. waters and NE Atlantic showed a decrease and/or stability of PBDE levels in cetacean tissues in recent decades. The highest MeO-PBDE concentrations were found in dolphins from Tanzania (Indian Ocean), bottlenose dolphins from Queensland, Australia (SW Pacific), and odontocetes from coastal and continental shelf waters off southeastern Brazil (SW Atlantic). The upwelling phenomenon and the presence of coral reef complexes in these tropical oceans may explain the large amounts of the naturally-produced organobromines. Considering that these bioaccumulative chemicals have properties that could cause many deleterious effects in those animals, future studies are required to evaluate the potential ecotoxicological risks.

Effects of age, adipose percent, and reproduction on PCB concentrations and profiles in an extreme fasting North Pacific marine mammal

Persistent organic pollutants, including polychlorinated biphenyls (PCBs), are widely distributed and detectable far from anthropogenic sources. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometers to forage in coastal and open-ocean regions of the northeast Pacific Ocean and then return to land where they fast while breeding and molting. Our study examined potential effects of age, adipose percent, and the difference between the breeding and molting fasts on PCB concentrations and congener profiles in blubber and serum of northern elephant seal females. Between 2005 and 2007, we sampled blubber and blood from 58 seals before and after a foraging trip, which were then analyzed for PCBs. Age did not significantly affect total PCB concentrations; however, the proportion of PCB congeners with different numbers of chlorine atoms was significantly affected by age, especially in the outer blubber. Younger adult females had a significantly greater proportion of low-chlorinated PCBs (tri-, tetra-, and penta-CBs) than older females, with the opposite trend observed for hepta-CBs, indicating that an age-associated process such as parity (birth) may significantly affect congener profiles. The percent of adipose tissue had a significant relationship with inner blubber PCB concentrations, with the highest mean concentrations observed at the end of the molting fast. These results highlight the importance of sampling across the entire blubber layer when assessing contaminant levels in phocid seals and taking into account the adipose stores and reproductive status of an animal when conducting contaminant research.

Levels and trends of PBDEs and HBCDs in the global environment: status at the end of 2012

In this paper, we have compiled and reviewed the most recent literature, published in print or online from January 2010 to December 2012, relating to the human exposure, environmental distribution, behaviour, fate and concentration time trends of polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) flame retardants, in order to establish their current trends and priorities for future study. More data are now becoming available for remote areas not previously studied, Indian Ocean islands, for example. Decreasing time trends for penta-mix PBDE congeners were seen for soils in northern Europe, sewage sludge in Sweden and the USA, carp from a US river, trout from three of the Great Lakes and in Arctic and UK marine mammals and many birds, but increasing time trends continue in polar bears and some birds at high trophic levels in northern Europe. This may be partially a result of the time delay inherent in long-range atmospheric transport processes. In general, concentrations of BDE209 (the major component of the deca-mix PBDE product) are continuing to increase. Of major concern is the possible/likely debromination of the large reservoir of BDE209 in soils and sediments worldwide, to yield lower brominated congeners which are both more mobile and more toxic, and we have compiled the most recent evidence for the occurrence of this degradation process. Numerous studies reported here reinforce the importance of this future concern. Time trends for HBCDs are mixed, with both increases and decreases evident in different matrices and locations and, notably, with increasing occurrence in birds of prey. Temporal trends for both PBDEs and HBCD in Asia are unclear currently. A knowledge gap has been noted in relation to metabolism and/or debromination of BDE209 and HBCD in birds. Further monitoring of human exposure and environmental contamination in areas of e-waste recycling, particularly in Asia and Africa, is warranted. More data on temporal trends of BDE and HBCD concentrations in a variety of matrices and locations are needed before the current status of these compounds can be fully assessed, and the impact of regulation and changing usage patterns among different flame retardants determined.

Blue whale earplug reveals lifetime contaminant exposure and hormone profiles

Lifetime contaminant and hormonal profiles have been reconstructed for an individual male blue whale (Balaenoptera musculus, Linnaeus 1758) using the earplug as a natural aging matrix that is also capable of archiving and preserving lipophilic compounds. These unprecedented lifetime profiles (i.e., birth to death) were reconstructed with a 6-mo resolution for a wide range of analytes including cortisol (stress hormone), testosterone (developmental hormone), organic contaminants (e.g., pesticides and flame retardants), and mercury. Cortisol lifetime profiles revealed a doubling of cortisol levels over baseline. Testosterone profiles suggest this male blue whale reached sexual maturity at approximately 10 y of age, which corresponds well with and improves on previous estimates. Early periods of the reconstructed contaminant profiles for pesticides (such as dichlorodiphenyltrichloroethanes and chlordanes), polychlorinated biphenyls, and polybrominated diphenyl ethers demonstrate significant maternal transfer occurred at 0-12 mo. The total lifetime organic contaminant burden measured between the earplug (sum of contaminants in laminae layers) and blubber samples from the same organism were similar. Total mercury profiles revealed reduced maternal transfer and two distinct pulse events compared with organic contaminants. The use of a whale earplug to reconstruct lifetime chemical profiles will allow for a more comprehensive examination of stress, development, and contaminant exposure, as well as improve the assessment of contaminant use/emission, environmental noise, ship traffic, and climate change on these important marine sentinels.

Metabolic concentration of lipid soluble organochlorine burdens in the blubber of southern hemisphere humpback whales through migration and fasting

Southern hemisphere humpback whales undertake the longest migrations and associated periods of fasting of any mammal. Fluctuations in lipid energy stores are known to profoundly affect the toxicokinetics of lipophilic organochlorine compound (OC) burdens. Results from blubber biopsy sampling of adult, male humpback whales at two time points of the annual migration journey revealed dramatic concentration effects for the majority of OC compounds. The observed concentration effect was, however, not linear with measured average blubber lipid loss indicating significant redistribution of OCs and hence the importance of alternate lipid depots for meeting the energetic demands of the migration journey. Applying lipophilic OC burdens as novel tracers of whole-body lipid dynamics, the observed average concentration index suggests an average individual weight loss of 13% over 4 months of the migration journey. This value is based upon lipid derived energy and is in good agreement with previous weight prediction formulas. Notably, however, these estimates may greatly underestimate individual weight loss if significant protein catabolism occurs. Biomagnification factors between migrating southern hemisphere humpback whales and their principal prey item, Antarctic krill, closely resembled those of baleen whales feeding on herbivorous zooplankton in the Arctic. This study emphasizes the importance of considering prolonged periods of food deprivation when assessing chemical risks posed to wildlife. This is of particular importance for Polar biota adapted to extremes in ecosystem productivity.