Tissues Of Dolphins Research Articles

Morphological and molecular observations on the status of Crassicauda magna, a parasite of the subcutaneous tissues of the pygmy sperm whale, with a re-evaluation of the systematic relationships of the genus Crassicauda.

Members of the genus Crassicauda (Nematoda: Spirurida) are parasites of the body tissues of whales and dolphins. Owing to the large size of worms and difficulties in the recovery of entire nematodes from the tissues of hosts, limited information is available on morphological descriptions of both male and female worms. Furthermore, there are currently no available sequence data for this genus to assist with such identifications. This paper describes for the first time features of the anterior extremity and the male tail of Crassicauda magna, suggesting that Crassicauda duguyi may be a synonym of this species. In addition, molecular data are presented for the genus for the first time suggesting that the genus belongs within the superfamily Acuarioidea rather than within the Habronematoidea, in which it is currently placed.

Mercury and selenium in stranded Indo-Pacific humpback dolphins and implications for their trophic transfer in food chains.

As top predators in the Pearl River Estuary (PRE) of China, Indo-Pacific humpback dolphins (Sousa chinensis) are bioindicators for examining regional trends of environmental contaminants in the PRE. We examined samples from stranded S. chinensis in the PRE, collected since 2004, to study the distribution and fate of total mercury (THg), methylmercury (MeHg) and selenium (Se) in the major tissues, in individuals at different ages and their prey fishes from the PRE. This study also investigated the potential protective effects of Se against the toxicities of accumulated THg. Dolphin livers contained the highest concentrations of THg (32.34±58.98 µg g−1 dw) and Se (15.16±3.66 µg g−1 dw), which were significantly different from those found in kidneys and muscles, whereas the highest residue of MeHg (1.02±1.11 µg g−1 dw) was found in dolphin muscles. Concentrations of both THg and MeHg in the liver, kidney and muscle of dolphins showed a significantly positive correlation with age. The biomagnification factors (BMFs) of inorganic mercury (Hginorg) in dolphin livers (350×) and MeHg in muscles (18.7×) through the prey fishes were the highest among all three dolphin tissues, whereas the BMFs of Se were much lower in all dolphin tissues. The lower proportion of MeHg in THg and higher Se/THg ratios in tissues were demonstrated. Our studies suggested that S. chinensis might have the potential to detoxify Hg via the demethylation of MeHg and the formation of tiemannite (HgSe) in the liver and kidney. The lower threshold of hepatic THg concentrations for the equimolar accumulation of Se and Hg in S. chinensis suggests that this species has a greater sensitivity to THg concentrations than is found in striped dolphins and Dall’s porpoises.

Essential and non-essential heavy metals in skin and muscle tissues of franciscana dolphins (Pontoporia blainvillei) from the southern Argentina coast

Franciscana dolphin, Pontoporia blainvillei, is a small and ‘vulnerable’ cetacean, which exhibits coastal marine habits according to the IUCN (2008). The aim of this work was to determine the presence of essential (Zn and Cu) and non-essential (Cd, Pb, Cr and Ni) heavy metals in skin (n=33) and muscle (n=36) tissues of franciscana dolphins from southern Buenos Aires, establishing the influence of biological parameters on the accumulation of these pollutants. Histological standardised methods were used to determine both age and sexual maturity of the dolphins. Heavy metal concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Zn was 8-fold higher than Ni in the skin. Zn was significantly affected by the age of the specimens and might be influenced by the state of body condition. Ni showed a behaviour pattern similar to that of non-essential heavy metals. The relationship between Ni and Zn concentration determined in skin and muscle might provide a tool for studying the general condition of endangered marine mammal species such as franciscana dolphins.

Unique seasonal forage bases within a local population of bottlenose dolphin (Tursiops truncatus)

AbstractUsing photo‐identification data, bottlenose dolphin (Tursiops truncatus) populations can be differentiated based on their use of particular estuaries or coastal habitats. Questions remain, however, about the validity of such fine‐scale population partitioning and whether the resulting assemblages utilize unique forage bases. To address the issue of forage base use, stable isotopes of carbon (δ13C), nitrogen (δ15N) and sulfur (δ34S) were analyzed from skin tissues (n= 74) of bottlenose dolphins sampled seasonally along the coast and in three estuaries near Charleston, South Carolina. Autumn values of δ34S, δ15N, and δ13C and summer values of δ34S indicated that dolphins sampled from these four assemblages utilized unique forage bases, despite limited sample sizes. Likewise, autumn and spring differences in δ15N and δ13C values were evident in the North Edisto River, and in δ34S from dolphins sampled from all three estuarine assemblages; no seasonal differences were identified in the coastal assemblage. Results demonstrate the importance of considering spatial and temporal variation in forage base when developing local management plans for bottlenose dolphin and highlight the discriminatory power of δ34S for estuarine and coastal marine mammals. These results also suggest that stable isotopes could be developed as a complementary tool for photo‐identification based partitioning of bottlenose dolphin populations.

Mercury concentrations in the tissues of bottlenose dolphins (Tursiops truncatus) and striped dolphins (Stenella coeruloalba) stranded on the Croatian Adriatic coast

The concentrations of total mercury in muscle (17 samples), liver (16 samples) and kidney tissues (16 samples) of both bottlenose (<I>Tursiops truncatus</I>) and striped dolphins <I> (Stenella coeruloalba</I>) were analyzed by cold vapour atomic absorption (AA) spectroscopy. The dolphins were found dead at different locations along the east Adriatic over a 10-year period starting in 1990. In this study, the magnitude of mercury contamination of dolphins which are indicators of contamination of the Adriatic as well as the Mediterranean Sea was determined. Our results represent the first investigation of heavy metal concentrations in dolphins sampled along the Croatian coast of the Adriatic Sea. Total mercury levels were high, ranging from 1.51 to 136.7 mg/kg in muscle, from 2.04 to 143.1 in kidney and from 10.35 to 1 833 mg/kg in liver tissues (expressed as wet weight). These results were examined for differences based upon age and tissue type. A high correlation was observed between total mercury concentration and age, and adult dolphins (10 samples) contained statistically significant higher concentrations of mercury compared to juvenile (seven samples) dolphins. Mercury concentrations were generally the highest in liver tissue. The presence of high mercury levels in dolphins is attributed to natural as well as anthropogenic sources.

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDs) in tissues of humans, dolphins, and sharks from the United States

Concentrations of tetrabromobisphenol A (TBBPA) and α-, β-, and γ-isomers of hexabromocyclododecanes (HBCDs) were determined by liquid chromatography–tandem mass spectrometry (LC–ESI-MS/MS) in human adipose tissue obtained in New York City, and in three marine top-level predators – bottlenose dolphin, bull shark, and Atlantic sharpnose shark – collected from coastal waters of Florida, USA. The overall mean concentrations (mean ± SD) of TBBPA and HBCDs were 0.048 ± 0.102 and 0.333 ± 0.571 ng/g lipid wt in human adipose tissue samples, 1.2 ± 3 and 7.38 ± 18 ng/g lipid wt in bottlenose dolphin blubber, 9.5 ± 12 and 77.7 ± 128 ng/g lipid wt in bull shark muscle, and 0.872 ± 0.5 and 54.5 ± 88 ng/g lipid wt in Atlantic sharpnose shark muscle. Overall mean concentrations of HBCDs were 5–10-fold higher than mean TBBPA concentrations, in all of the samples analyzed. The highest concentrations of TBBPA and HBCDs were detected in the bull shark muscle at concentrations of 35.6 and 413 ng/g, lipid wt, respectively. Concentrations of TBBPA and HBCDs, after log-transformation, were significantly correlated with each other in human adipose tissue and bottlenose dolphin blubber, but not in bull shark muscle samples. In the human adipose tissue samples, the concentrations of HBCDs were 3–4 orders of magnitude lower than the concentrations of polybrominated diphenyl ethers (PBDEs) previously reported for the same set of tissue samples. Concentrations of HBCDs in human samples from the United States were 1–5-fold lower than the concentrations reported from several European countries. HBCD concentrations in bottlenose dolphins from the United States were 1–2 orders of magnitude lower than the concentrations reported for other cetacean species from Europe. The present report is the first to determine levels of TBBPA and HBCDs in humans, bottlenose dolphins, and sharks from the United States.

Determination of the immunotoxic potential of heavy metals on the functional activity of bottlenose dolphin leukocytes in vitro

Heavy metals may affect the immune system of cetaceans. But no information exists on their effects on the bottlenose dolphin ( Tursiops truncatus) immune system, although this species is a coastal top predator which can bioaccumulate high concentrations of them. This work studies the effects of Hg (1, 5 and 10 mg/L), Al (2,5, 25 and 50 mg/L), Cd (1, 10, 20 and 40 mg/L), Pb (1, 10, 20 and 50 mg/L) and Cr (1 and 10 mg/L), on the function of phagocytes and lymphocytes isolated from the peripheral blood of bottlenose dolphins under in vitro conditions. Cell viability, apoptosis, lymphocyte proliferation and phagocytosis were evaluated. Viability and lymphoproliferation were measured with Alamar Blue assay, and apoptosis and phagocytosis were evaluated with flow cytometry. Apoptosis was detected as mechanism of cell death after cadmium and mercury exposure. A significant reduction in the lymphoproliferative response was registered by exposure to 1 mg/L of mercury, 10 mg/L of cadmium and 50 mg/L of lead. Decreased phagocytosis was also observed at 5 mg/L of mercury, 50 mg/L of aluminium and 10 mg/L of cadmium. Chromium did not present any effects on any immune assay at the concentrations tested. The concentrations of heavy metals that were found to affect the functional activity of bottlenose dolphin leukocytes are within the environmental ranges reported in the tissues of bottlenose dolphins. These results support the hypothesis that exposure to these contaminants, particularly mercury and cadmium could lead to a reduction in host resistance to disease in these animals.

Modeling of acoustically enhanced bubble growth in supersaturated biological media

Recent measurements and predictions of dissolved nitrogen concentration in tissues of dolphins and whales following repeated dives have indicated that the gas concentration may reach 300% of saturation [Houser et al., ‘‘Can diving-induced tissue nitrogen supersaturation increase the chance of acoustically driven bubble growth in marine mammals?,’’ J. Theor. Biol. 213, 183–195 (2001)]. This has generated renewed interest in whether underwater sound may increase the likelihood of decompression sickness in these cetaceans. One potential mechanism is bubble growth due to rectified diffusion. Eller and Flynn [‘‘Rectified diffusion during nonlinear pulsations of cavitation bubbles,’’ J. Acoust. Soc. Am. 37, 493–503 (1965)] modeled rectified diffusion by solving a Rayleigh-Plesset equation for the acoustically driven bubble dynamics, coupled to a quasianalytical diffusion model that accounts for increase of the equilibrium bubble radius. Crum and Mao [‘‘Acoustically enhanced bubble growth at low frequencies and its implications for human diver and marine mammal,’’ J. Acoust. Soc. Am. 99, 2898–2907 (1996)] used similar models to consider dissolved gas saturations up to 223% and demonstrated significantly enhanced bubble growth at sound-pressure levels above 210 dB (re: 1 μPa). We are revisiting this problem by extending these models and considering wider ranges of parameters. A principal difference is that the gas diffusion is modeled by solving the full partial differential equation numerically. Not only does this approach circumvent analytical approximations, it permits taking into account variations in gas concentration associated with dive-profile-dependent hydrostatic pressure variations. [Work supported by ONR.]

Organochlorine Pesticides, Polychlorinated Biphenyls, and Polybrominated Diphenyl Ethers in Irrawaddy Dolphins from India

The Irrawaddy dolphin (Orcaella brevirostris) is at risk of extinction throughout its range as a result of incidental catches, habitat degradation, and pollution. Populations of Irrawaddy dolphins are constrained by the species' narrow habitat requirement-lagoons, estuaries, rivers, and lakes-and are therefore particularly vulnerable to the effects of human activities. In this study, for the first time, concentrations of organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were determined in tissues of Irrawaddy dolphins collected from Chilika Lake, India, to understand the status of contamination. Dichlorodiphenyltrichloroethane and its metabolites (DDTs) were the predominant contaminants found in Irrawaddy dolphins; the highest concentration found was 10,000 ng/g lipid weight in blubber. Hexachlorocyclohexanes (HCHs) were the second most prevalent contaminants in dolphin tissues. Concentrations of PCBs, chlordanes, hexachlorobenzene, tris(4-chlorophenyl)methane, and tris(4-chlorophenyl)methanol were in the ranges of few ng/g to few hundreds of ng/g on a lipid-weight basis. In general, concentrations of OC pesticides and PCBs in Irrawaddy dolphins were lower than the concentrations reported for coastal and riverine dolphins collected in Asia. PBDEs were detected in the blubber of Irrawaddy dolphins at concentrations ranging from 0.98 to 18 ng/g lipid weight. BDE congener 47 accounted for 60% to 75% of the total PBDE concentrations. Although these results establish the baseline levels of persistent organic pollutants in Irrawaddy dolphins, efforts should be made to decrease the sources of contamination by DDTs and HCHs in Chilika Lake.

Elemental composition of liver and kidney tissues of rough-toothed dolphins (Steno bredanensis).

On December 14, 1997, 62 rough-toothed dolphins (Steno bredanensis) stranded on Cape San Blas, on the Florida coast of the Gulf of Mexico. Approximately 30 animals died either on the beach or in rehabilitation facilities. Two were successfully rehabilitated and released. Liver, kidney, blubber, and muscle tissues were collected from 15 animals that died on the beach. Portions of the liver and kidney from each dolphin were analyzed using instrumental neutron activation analysis and inductively coupled plasma mass spectrometry to determine mass fractions of 37 elements. Levels of several electrolytes (Na, Cl, K, Br, Rb, I, Cs) and of the essential trace elements Fe, Cu, and Zn in both tissues were similar to those found in other Odontoceti. Mass fractions of Ca ranged from 60 mg/kg to 1,200 mg/kg (wet mass basis), indicating significant inhomogeneity in the kidney tissues of several animals. Necropsy reports noted that the kidneys of many of these animals contained fibrous nodules. The measured Ca inhomogeneity may be due to mineralization of the fibrous kidney tissue. Hepatic levels of Hg and Se were at the high end of the ranges generally found in livers of other Odontoceti and were slightly higher in animals with fibrous kidneys than in the others. Mass fractions of Se, Ag, and Hg in liver tissues increased with the size and age of the animals indicating accumulation of these elements in the liver with age. Results also indicate that Se and Hg accumulate in rough-toothed dolphin kidney. Accumulation of these elements with age has been reported commonly for marine mammals and other species.

Methylmercury and total mercury distribution in tissues of gray whales (Eschrichtius robustus) and spinner dolphins (Stenella longirostris) stranded along the lower Gulf of California, Mexico

Four gray whales Eschrichtius robustus and eleven spinner dolphins Stenella longirostris were found stranded along the coasts of the lower Gulf of California, Mexico. Muscle, kidney and liver samples from all the specimens were used for mercury (Hg) analysis. Mean concentrations of total Hg (THg) were significantly different (P < 0.05) in all the tissues of spinner dolphins, resulting in a decreasing order liver>kidney>muscle. Mean values of THg in the three tissues of gray whales were not statistically different. Similarly, methylmercury (MeHg) levels in the analyzed tissues of dolphins and whales were not statistically different. Considering species-related differences, it seems that THg and MeHg levels in the studied marine mammals did not play a key role in the stranding of the specimens, though more studies about the implications of Hg compounds in stranding events are necessary.

Mercury, organic-mercury and selenium in small cetaceans in Taiwanese waters

Total Hg (∑Hg), organic-Hg (O-Hg) and Se bioaccumulations in small cetaceans distributed in Taiwanese waters of the Taiwan Strait and the southwestern Pacific have been investigated for the first time. The results could represent the baseline metal concentrations of marine mammals in the southwestern Pacific, where volcanic activities are possibly the major source of mercury to the environments. Muscle samples of four species of small cetaceans were collected from animals accidentally caught by tuna-longline fisheries from 1994 through 1995. In total, 53 pantropical spotted dolphins, Stenella attenuata, nine spinner dolphins, S. longirostris, five bottlenose dolphins, Turiops truncatus and four Risso's dolphins, Grampus giseus were analyzed. In addition, two stranded pantropical spotted dolphins were investigated. Cold vapour AAS and ICP-MS were used in the analysis of Hg and Se, respectively. Significant species difference was found in the four species of small cetaceans. Among them, the pantropical spotted dolphin showed the highest mean concentration (mg/kg wet wt.) of both ∑Hg (3.64±2.19) and O-Hg (2.79±1.23), whereas the Risso's dolphin had the highest mean concentrations of Se (1.77±1.29). There was no significant sex difference with respect to metal bioaccumulation in the samples of S. attenuata. Significant correlations between body length (BL) and ∑Hg, as well as O-Hg concentrations were observed in pantropical spotted (Sa) and spinner dolphins (Sl). The linear relationships were Sa: ∑Hg=−8.290+0.066BL, r=0.421; Sl: ∑Hg=−2.735+0.025BL, r=0.875; Sa: O-Hg=−3.723+0.036BL, r=0.408; and Sl: O-Hg=−3.017+0.025BL, r=0.870. However, a demethylation phenomenon that decreasing the percentage of O-Hg coupled with increasing levels of Se was observed when the ∑Hg concentrations in the muscle tissues of dolphins reached 4 mg/kg wet wt.

Heavy metals in the tissues of common dolphins ( Delphinus delphis) stranded on the Portuguese coast

The concentrations of Hg, Sn, Cr, Zn, Ni, Co, Cd, Mn, Fe and Cu were determined in the liver, kidney and muscle of 24 common dolphins stranded on the Portuguese coast between 1995 and 1998. Nitric acid was used to extract the metals from the tissues for analysis by inductively-coupled plasma/atomic emission spectroscopy (ICP/AES). Those metals with relatively higher concentrations included Fe, Zn and Hg, particularly in liver. Other metals including Cr, Ni and Cd tended to show much lower levels, or were even undetected (e.g. Co). Different metals seemed to show different temporal trends, although due to substantial variations of the mean concentrations for each year obtained, such temporal pattern has to be studied further. Total Hg concentration in the kidney, muscle and particularly liver, were higher in females than in males. Total Hg concentrations in all the organs increased with body length of dolphins, whilst those of Zn and Cu in muscle decreased with dolphin length. A strong correlation was found between essential metals Zn and Cu in muscle, possibly resulting from sequestration of these metals by metallothionein. In addition, significant co-associations existed between the same metal (e.g. Hg, Sn and Zn) in different organs.

Bioaccumulation profiles of polychlorinated biphenyl congeners and organochlorine pesticides in Ganges river dolphins

AbstractIsomer‐specific concentrations of polychlorinated biphenyls (PCBs) including non‐, mono‐, and di‐ortho‐substituted congeners, DDT and its metabolites, hexachlorocyclohexane (HCH) isomers, chlordane compounds, and hexachlorobenzene (HCB) were determined in river dolphin blubber and prey fishes collected during 1993 through 1996 from the River Ganges in India. Concentrations of organochlorines were also measured in the milk and liver of dolphins, benthic invertebrates, and sediments. The DDTs and PCBs were the predominant compounds found in dolphin tissues and fish that comprise the diet of dolphins. Concentrations of DDTs and PCBs in the blubber of dolphins were in the range of 30 to 120 and 1.5 to 25 μg/g, lipid weight, respectively. Pentaand hexachlorobiphenyls collectively accounted for 68 to 80% of the total PCB concentrations in river dolphins. Hexachlorobiphenyl congener 138 (2,2′,3,4,4′,5′‐) was the most abundant in dolphin blubber and prey fishes. The isomer/congener pattern of PCBs and organochlorine pesticides suggested that there is less metabolism due to cytochrome P450 enzymes in Ganges river dolphins than in marine or terrestrial mammals. The mean 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin equivalents (TEQs) estimated in river dolphin blubber was greater than those that can cause adverse effects in mink. Comparison of organochlorine concentrations in river dolphins with those of the values reported for samples analyzed during 1988 through 1992 suggested that the contamination by these compounds has increased in the River Ganges.

Trace metal pollution in Hong Kong: Implications for the health of Hong Kong's Indo-Pacific hump-backed dolphins ( Sousa chinensis)

The territorial waters of Hong Kong are highly contaminated with anthropogenic pollutants, including trace metals. Hong Kong's population of Indo-Pacific hump-backed dolphins ( Sousa chinensis) inhabits an area where a high volume of sewage waste discharge and the close proximity of contaminated mud pits mean a considerable potential for trace metal contamination. Trace metal concentrations in the muscle tissue of fish caught from areas of high dolphin abundance are notable. However, in order to gauge the amount of trace metal consumed by dolphins, whole fish must be analysed. Whole fish from areas of high dolphin abundance have considerably higher trace metal loads than muscle tissue alone. Considering the consumption of prey items by dolphins, a daily intake of trace metals was estimated as As, 410–518; Cd, 34–44; Co, 4–5; Cr, 40–50; Cu, 44–56; Hg, 51–66; Mo, 22–27; Ni, 19–24; Pb, 320–403; Se, 99–125 and Zn, 388–490 (μg kg −1 body wt. per day). Concentrations of arsenic, chromium, lead, molybdenum and nickel in dolphin tissues were an order of magnitude lower than in prey items, suggesting these elements may be excreted by this species. Mercury concentrations in dolphin tissues were, however, an order of magnitude higher than in prey items and could be considered potentially health threatening (max: 906 μg kg −1 dry wt.). Hong Kong's Indo-Pacific hump-backed dolphin population has a high dietary intake of trace metals which may, especially in the case of mercury, be a cause for concern.

Sources and Accumulation of Butyltin Compounds in Ganges River Dolphin,Platanista gangetica

Concentrations of butyltin compounds (mono-, di-, and tri-butyltin) were determined in dolphin (Platanista gangetica), fish, invertebrates and sediment collected from the River Ganges, India, in order to understand the contamination levels, sources, and potential for biomagnification in freshwater food chains. Total butyltin concentration in dolphin tissues was up to 2000 ng g 2 1 wet wt, which was about 5‐10 times higher than in their diet. The concentrations in fish and benthic invertebrates, including polychaetes, were 3‐10 times greater than in sediment. The biomagnification factor for butyltins in river dolphin from its food was in the range 0.2‐7.5. Butyltin concentrations in Ganges river organisms were higher than those reported for several persistent organochlorine compounds. Discharge of untreated domestic sewage was one of the major sources of butyltin residues in Ganges river biota. High concentrations of butyltin compounds in freshwater food chains suggest the need to assess their toxic effects in aquatic organisms and to regulate their use. © 1997 by John Wiley & Sons, Ltd.

Copper, cadmium and zinc in liver, kidney and muscle tissues of bottlenose dolphins ( Tursiops truncatus) stranded in Florida

Copper, cadmium and zinc in liver, kidney and muscle tissues of bottlenose dolphins ( Tursiops truncatus) stranded in Florida

Nucleic acid hybridization analyses confirm the presence of a hitherto unknown morbillivirus in mediterranean dolphins

In 1990 an epidemic caused by a morbillivirus was noticed among Mediterranean dolphins. RNA was extracted from the tissues of dolphins and from cell cultures infected with a corresponding dolphin morbillivirus isolate. By nucleic acid hybridization this RNA was compared to RNA extracted from animal tissue or cell cultures infected with canine distemper virus (CDV), phocine distemper virus (PDV) or measles virus (MV). The presence of morbillivirus RNA in the dolphin tissue was demonstrated. Morbillivirus N, P, M and F gene mRNAs were detected in the RNA from dolphin morbillivirus infected cells. These mRNA species seemed to be of approximately the same size as the corresponding mRNA species of CDV, PDV and MV. The results of the comparison demonstrated that the dolphin morbillivirus is genetically different from CDV, PDV and MV. No indication of a close relationship between the dolphin isolate and either CDV, PDV or MV was found.

Metals and organochlorines in dolphins and porpoises of Cardigan Bay, West Wales

Concentrations of seven metals (Cr, Ni, Cu, Zn, Cd, Hg, and Pb) and a range of organochlorine pesticides, individual chlorobiphenyl congeners, and total polychlorinated biphenyls (PCB) have been determined in tissues of dolphins, porpoises, seals, and a variety of food chain species and sediments from Cardigan Bay, West Wales. Elevated concentrations of metals were not seen in any of the animal tissues examined. Higher than expected levels of organochlorine compounds were found in tissues of dolphins and porpoises; these concentrations are not derived from local pollution, but come from the animals' normal diet which did not show markedly elevated levels of organochlorines. The level of organochlorine bioaccumulation seen in some of the cetaceans analysed is much higher than found previously; this may have serious health implications for populations of those species around the coasts of NW Europe.

Organochlorine chemical and heavy metal contaminants in white-beaked dolphins (Lagenorhynchus albirostris) and pilot whales (Globicephala melaena) from the coast of Newfoundland, Canada.

Polychlorinated biphenyls (∑PCB), DDT isomers (∑DDT), chlordanes (∑CHLOR), toxaphene, chlorobenzenes and hexachlorocyclohexane isomers and seven elements (As, Cd, Cu, Hg, Pb, Se, Zn) were determined in tissues of 41 stranded pilot whales (Globicephala melaena) and 27 ice-entrapped white-beaked dolphins (Lagenorhynchus albirostris) from Newfoundland, Canada. Cadmium, Hg, As and Se were significantly higher in pilot whale kidney and liver than in dolphin tissues. Mercury in liver and blubber, and Cd in kidney, of pilot whales were positively correlated with age. Cadmium levels in both species were much higher than reported for other cetaceans from Canadian east coast waters. Lead concentrations in dolphin kidney and mucles were 5 times higher than in pilot whales. Levels of ∑PCB (sum of 49 congeners) in blubber samples ranged from 31 to 61 mg/kg (lipid wt) in female and male dolphins, respectively, and from 5.6 to 12 mg/kg in female and male pilot whales. ∑DDT and toxaphene were present at similar levels to ∑PCB while mean ∑CHLOR (sum of seven components) ranged from 1.6 to 17 mg/kg in blubber of pilot whales and dolphins, respectively. The presence of high levels of toxaphene in the blubber of both species was unexpected and may be due to increased use of this pesticide during the 1970's. Higher levels of all organochlorine chemicals in blubber, as well as Pb in kidney and muscle, of dolphins than in pilot whales may reflect greater exposure to contaminants because of overwintering and feeding in Gulf of St. Lawrence waters.