Lagenorhynchus Albirostris Research Articles

Potential Relation Between Mercury Concentrations and Necropsy Findings in Cetaceans from sGerman Waters of the North and Baltic Seas

Concentrations of total mercury and methylmercury were analysed in muscle, kidney and liver samples from 57 harbour porpoises and three white-beaked dolphins, stranded or by-caught from the German waters of the North and Baltic Seas. Levels of total mercury ranged between 0.6 and 450 μg/g dry weight (dw) and of methylmercury between 0.2 and 26 μg/gdw. No differences in concentrations of either total mercury or methylmercury were observed between stranded and by-caught animals nor between males and females. However, a difference in mercury content of cetaceans from the North and Baltic Seas was found. A significant correlation between animal age and total mercury as well as methylmercury in all examined organs could be demonstrated. Pathological, microbiological and parasitological studies were performed on the animals. The majority of pathological lesions were caused by helminths. Lesions characteristic of acute or chronic intoxication with mercury could not be found. However, there were significant associations between mercury levels and severity of lesions with respective to nutritional state of the cetaceans examined, demonstrated by means of polychotomous logistic regression for ordinal variables and adjusted for the effects of age and location.

The use of a microsomal in vitro assay to study phase I biotransformation of chlorobornanes (toxaphene®) in marine mammals and birds : Possible consequences of biotransformation for bioaccumulation and genotoxicity

The factors determining the bioaccumulation of lipophilic compounds in wildlife are often poorly understood, partly because it is difficult to do in vivo experiments with animals such as marine mammals and birds. To evaluate the role of phase I biotransformation in the bioaccumulation process of chlorobornanes (toxaphene®), this was studied in in vitro assays with hepatic microsomes of animals that could be sampled shortly after death. The capacity of microsomes to metabolise a technical toxaphene mixture decreased in the order Phoca vitulina (harbour seal)⪢ Lagenorhynchus albirostris (whitebeaked dolphin)≅ Diomedea immutabilis (Laysan albatross)> Physeter macrocephalus (sperm whale). Harbour seal microsomes metabolised the chlorobornane (CHB) congeners CHB-32 and CHB-62; whitebeaked dolphin and Laysan albatross microsomes only metabolised CHB-32. Metabolism of CHB-26 and CHB-50 was never observed. The negative chemical ionisation (NCI−) mass spectra of some of the hydroxylated metabolites were obtained. The number of peaks in the toxaphene residues of wildlife extracts decreased in the order of increasing in-vitro biotransformation capacity. Thus, the results of the in vitro assays and residue analysis were in accordance, although assays with microsomes of more individuals of the same species are required for a more general conclusion at the species level. Finally, the effect of in vitro biotransformation was evaluated in terms of the genotoxic potential using the Mutatox® assay. Only technical toxaphene and CHB-32 were genotoxic in the direct assay, whereas the addition of rat S9 fraction or microsomes of harbour seal and albatross decreased the genotoxic response. Thus, organisms with a low ability to metabolise chlorobornanes, such as whales, may be most affected by the carcinogenic properties of toxaphene. A hypothetical reaction which fits the experimental results is discussed. Based on these results it is concluded that in vitro assays with microsomes of wildlife animals which died a natural cause can act as a valuable tool to assess the occurrence and effects of phase I metabolism. Some precautions are discussed, that should be taken to reduce the chance of false negative results.

Aerial surveys of cetaceans in the Gulf of St. Lawrence in 1995 and 1996

Aerial line-transect surveys of cetaceans were flown in the Gulf of St. Lawrence in late August and early September of 1995 and in late July and early August of 1996. Systematic north-south transects were spaced 15prime of longitude apart. In 1995, the study area comprised the entire Gulf, divided into three strata for analysis; 69% was flown. In 1996, a single stratum covered only the north shore shelf; 75% of the design was flown. The survey platform was a light high-winged aircraft with bubble windows flown at 213 m (700 ft). Ten species were seen. Minke whales (Balaenoptera acutorostrata), Atlantic white-sided dolphins (Lagenorhynchus acutus), and harbour porpoises (Phocoena phocoena) yielded enough sightings to support good estimates, while fin whales (Balaenoptera physalus), humpback whales (Megaptera novaeangliae), white-beaked dolphins (Lagenorhynchus albirostris), and long-finned pilot whales (Globicephala melas) yielded few sightings and unreliable estimates. Blue whales (Balaenoptera musculus) and belugas (Delphinapterus leucas) were seen too rarely to support any analysis. The tenth species was a small delphinid, not positively identified. Minke whales were ubiquitous, but more common in the northern strata. We estimated about 1000 in the whole Gulf in 1995 and about 600 in the northernmost stratum in 1996 (these numbers, and those following, are uncorrected for visibility bias). We estimated about 12 000 Atlantic white-sided dolphins in the Gulf in 1995, but in 1996 saw hardly any, perhaps because we flew the survey earlier. Harbour porpoises (12 000 in 1995 and 21 000 in 1996) were most numerous in the northern stratum, but were also widely distributed at lower densities in the central and southern Gulf. White-beaked dolphins (2500 in 1995 and 2500 in 1996) occurred only in the Strait of Belle Isle and the extreme northeastern Gulf. We estimated a few hundred fin whales in the northern and central strata and about 100 humpbacks, mostly in the northeast. Long-finned pilot whales were only seen in the southeastern Gulf, surveyed only in 1995 (about 1500).

Hydrographic Features, Cetaceans and the Foraging of Thick-billed Murres snd Other Marine Birds in the Northwestern Barents Sea

The at-sea distribution of thick-billed murres (Uria lomvia) in southeastern Svalbard waters was studied during the summers of 1992, 1993, and 1996. The Storfjordrenna region south of Svalbard was confirmed as an important foraging area for thick-billed murres; murre aggregations were located at distances of 85 to 126 km from the closest breeding colonies. Fish, mainly polar cod (Boreogadus saida), but also capelin (Mallotus villosus), were the main prey found in 16 murres and 3 black-legged kittiwakes (Rissa tridactyla) collected from these aggregations. Murres were seen flying with fish in their beaks at four locations 78 to 102 km away from the colonies. Murre aggregations were associated with frontal zones between cold Arctic waters and warmer Atlantic water, and in areas with strong stratification in salinity at 15-30 m. A positive association was found between the abundance of murres and the occurrence of cetaceans. Murres and other marine birds were often seen near surfacing cetaceans. The most common cetaceans were minke whales (Balaenoptera acutorostrata) and white-beaked dolphins (Lagenorhynchus albirostris).

Interactions Between Dutch Midwater Trawl and Atlantic White-sided Dolphins(Lagenorhynchus acutus) Southwest of Ireland

Incidental catches of cetaceans in the Dutch pelagic trawl fishery are largely restricted to late-winter early-spring in an area along the continental slope southwest of Ireland. Available evidence indicates that annual variations in such incidents are large. Using combined mid-water trawl by-catch and dolphin stomach content data, the hypothesis is put forward that Atlantic white-sided dolphin (Lagenorhynchus acutus), normally a more oceanic species, may actively search for mackerel (Scomber scombrus) closer to shore in early-spring, at least in some years. Supporting data were from an observer program during 1992–94, which covered seven trips representing 5% of the annual effort in the fishery. Also over the period 1989–94, a total of 71 records of by-catch incidents were collected (involving a minimum of 312 individuals), of which 41 occured in 1994 (172 individuals). Approximately 90% of the incidents occurred late-winter early-spring, when both the mackerel and horse mackerel (Trachurus trachurus) pelagic fisheries were operating in the same area, southwest of Ireland. Incidence frequency peaked by late February and March, when mackerel is known to move into the area during its southward migration. The Atlantic white-sided dolphin was the main cetacean species in the by-catch (83% of all identified individuals). Other species recorded included long-finned pilot whale (Globicephala melas), short-beaked common dolphin (Delphinus delphis), bottlenose dolphin (Tursiops truncatus) and the white-beaked dolphin (Lagenorhynchus albirostris). The stomachs of 47 Atlantic white-sided dolphins, 11 common dolphins, two bottlenose dolphins and one white-beaked dolphin were examined. Fresh mackerel remains were found in nearly all white-sided dolphin stomachs, whereas fresh horse mackerel remains occured only in stomachs of bottlenose and common dolphins. Deep-water fish otolith incidents suggested that white-sided, common and bottlenose dolphin had completely different diets before moving to the southwest of Ireland.

A preliminary study of the status of the White-beaked Dolphins, Lagenorhynchus albirostris, and other small cetaceans off the coast of Labrador

A preliminary study of the status of the White-beaked Dolphins, Lagenorhynchus albirostris, and other small cetaceans off the coast of Labrador

A contribution to the biology of the White-beaked Dolphin, Lagenorhynchus albirostris, in waters off Newfoundland

A contribution to the biology of the White-beaked Dolphin, Lagenorhynchus albirostris, in waters off Newfoundland

Erratum

Distribution and relative abundance of harbour porpoises (Phocoena phocoena L.), white-beaked dolphins (Lagenorhynchus albirostris Gray), and minke whales (Balaenoptera aucutorostra Lacepede) around the British Isles Please note the following corrections to Figures 1–7 of the paper.

Levels of alpha-HCH, lindane, and enantiomeric ratios of alpha-HCH in marine mammals from the northern hemisphere

The enantiomeric ratios of α-HCH were determined by chiral gas chromatography in blubber of marine mammals from regions of the northern hemisphere (North Sea, Baltic Sea, Arctic, and Iceland). Cetaceans (harbour porpoises and white-beaked dolphins) showed a preferential accumulation of (+)-α-HCH. In blubber of harbour seals, grey seals and harp seals (+)-α-HCH was also more abundant than (--α-HCH. Hooded seals formed an exception with a (+/-) enantiomeric ratio of α-HCH < 1.

Arctic marine mammals as integrators and indicators of mercury in the Arctic

Mercury concentrations were determined in liver, kidney and muscle of belugas, narwhal, whitebeaked dolphins, pilot whales, ringed seals, harp seals and walrus. Tissue collections and analyses were performed largely over the past 10 years. Sampling sites ranged across the Canadian Arctic from the Mackenzie Delta and Banks Island in the west, Grise Fjord in the north, the Atlantic coast in the east and south. High Hg levels in the liver of ringed seals from the western Arctic, collected in 1987 and 1988 were similar to previously-reported values for ringed seals collected in 1973 and 1972 from the same area. Comparison among different marine mammal species showed substantial inherent differences in Hg levels among different species. White-beaked dolphins and walrus had much less Hg than pilot whales. A comparison of Hg levels in ringed seals from locations across the Arctic and Hudson Bay showed that Hg was generally higher in ringed seals from the western than the eastern Arctic, indicating a possible influence of the different geological settings in the eastern and western Arctic. The effect of age was considered in these comparisons. A similar, but less pronounced effect was noted for belugas, with some possible anthropogenic influence on animals in Hudson Bay. The spatial trend in Hg levels in animals appeared to be largely present-day background concentration reflecting geological differences between the eastern and western Arctic. Higher Hg concentration were present in surficial sediments and coastal waters in the western Arctic than the eastern Arctic in accord with the Hg trend observed in seals and belugas.

Evaluation of the diet of Sowerby's beaked whale, Mesoplodon bidens, based on isotopic comparisons among northwestern Atlantic cetaceans

Sowerby's beaked whale, Mesoplodon bidens, is a poorly known and infrequently encountered species. Consequently, its behavior and habitat requirements are largely unknown. Evidence of the trophic level and diet of M. bidens was obtained through a comparison of δ13C and δ15N values for this species with those for eight other cetaceans and the basking shark, Cetorhinus maximus. The δ13C value for M. bidens (−18.5 ± 1.1‰) was similar to that for all other cetaceans (−18.7 to −17.2‰) except the sperm whale, Physeter macrocephalus, and the blue whale, Balaenoptera musculus (−22.8 and −20.1‰, respectively). At least a portion of the range of δ13C values for the cetaceans and the basking shark is thought to be related to variations in the lipid content of the samples. Nitrogen isotope values appear to reflect trophic position. Based on δ15N, organisms can be ordered along a trophic continuum bracketed by the planktivorous basking shark (9.9‰) and the piscivorous white-beaked dolphin, Lagenorhynchus albirostris (16.2‰). The trophic position of M. bidens (δ15N = 11.7‰) is intermediate between those of the pygmy sperm whale, Kogia breviceps (δ15N = 11.9‰), and the sperm whale, Physeter macrocephalus (δ15N = 11.1‰), and thus supports previous suggestions that these species feed at similar trophic positions. The estimated δ15N value of the diet of M. bidens, 8.7‰, is consistent with a diet that has a large contribution from small offshore squid, δ15N = 9.3‰.

Isolation of a virus with rhabdovirus morphology from a white-beaked dolphin (Lagenorhynchus albirostris).

A virus with rhabdovirus morphology which proved to be antigenically distinct from rabies virus and vesicular stomatitis virus was isolated from a dolphin that had beached on the Dutch coast. Neutralizing antibodies to this virus were found in several European marine mammal species.

Effect of temperature on egg hatching and survival of larvae of Anisakis simplex B (Nematoda: Ascaridoidea)

Eggs of the parasitic nematode Anisakis simplex B, obtained from a white-beaked dolphin (Lagenorhynchus albirostris Gray), were incubated in seawater at constant temperatures from −0.7 to 24.3 °C and hatching times determined. Eggs hatched at all temperatures except −0.7 °C. The number of days until hatching ranged from 3 at 24.3 °C to 74–81 at 1.9 °C. There was a declining curvilinear relationship between temperature and both hatching time and duration of the hatching period. The hatching period increased and became more variable with decreasing temperature and ranged from 5 days at 24.3 °C to 55–72 days at 3.8 °C. The percentage of eggs that hatched at each temperature was variable but generally fell in the range 30–60% and was not correlated with temperature. Survival times of hatched larvae peaked at 75–105 days at 8.6 °C, with a minimum of 3–8 days at 24.3 °C. Dimensions of eggs (length, width, volume) differed significantly among individual worms but were not correlated with worm size (wet weight). Egg hatching and larval survival characteristics indicate a species adapted to cold-temperate waters and are consistent with the known distribution of A. simplex B. Preliminary experiments indicated that harpacticoid copepods will ingest newly hatched larvae of A. simplex B and become infected, suggesting that these microcrustaceans may be involved in the life cycle of the nematode.

Measurements of the bodies and flukes of several cetacean species

Specimens of nine species of cetacean were obtained through an entrapment and stranding network. These were: harbour porpoise (Phocoena phocoena); white-sided dolphin (Lagenorhynchus acutus); white-beaked dolphin (Lagenorhynchus albirostris); common dolphin (Delphinus delphis); white whale (Delphinapterus leucas); Sowerby9s beaked whale (Mesoplodon bidens); minke whale (Balaenoptera acutorostrata); fin whale (Balaenoptera physalus); and sperm whale (Physeter macrocephalus). Measurements of length, body girths, fluke-planform offsets and fluke-section offsets are presented for these species. Values of body volume, mass, wetted-surface area, prismatic and volumetric coefficients, fluke area, aspect ratio and sweep angles were estimated from these measurements. Parameters derived from these measurements lay within narrow ranges of values for all species. Variation over these ranges may indicate a correlation between species and their relative swimming performance.

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.

Evidence of high‐frequency acoustic emissions from the white‐beaked dolphin (Lagenorhynchus albirostris)

Recordings of the signals from a school of white-beaked dolphins show that the frequency of their acoustic emissions extends to at least 305 kHz. These signals were detected by a sector scanning sonar used as a passive listening device of high bearing and time resolution. The records contain three types of signal, one of high intensity, one of a variable high repetition rate, and another showing a time-varying effect. Acoustic signals radiated by dolphins have been recorded and studied over a long period of time by many investigators. The purpose of this letter is to report evidence that acoustic emissions from white-beaked dolphins have significant energy at frequencies around 305 kHz, about one octave higher than previously observed. The observations discussed here were made aboard the fisheries research vessel CLIONE in the Wellbank flat area of the southern North Sea on 13 June 1970 between 1040 and 1110 h. When the dolphin signals were observed, the transmitter of the sector-scanning sonar in use was turned off, and the system was utilized as a passive listening device of high bearing and time resolution.

Microbiology of captive white‐beaked dolphins (Lagenorhynchus albirostris) with comments on epizootics

AbstractIn March 1983 six female white‐beaked dolphins (Lagenorhynchus albirostris) were rescued from an ice‐clogged bay in Newfoundland, Canada, and transported to Mystic Marinelife Aquarium in Mystic, Connecticut. Anal and blowhole samples (swabs) were collected at frequent intervals for bacteriological analysis. One dolphin died of neurogenic shock syndrome in transit. The others died at intervals of 1–101 days during the period of captivity. Staphylococci were implicated in the deaths of three of the five dolphins that remained alive after capture. Erysipelothrix rhusiopathiae probably caused the death of the fourth, and infection by unidentified Gram‐negative bacteria was responsible for death of the fifth dolphin. Bacteriophage typing of several Staphylococcus isolates showed three separate strains. Bacteria recovered from anal and blowhole samples before the white‐beaked dolphins were introduced into the aquarium water system included enterobacteria (Edwardsiella, Escherichia, Klebsiella), Plesiomonas, Aeromonas, Citrobacter, Pseudomonas, and Staphylococcus. The two dolphins that survived the longest (44 and 101 days) showed a predominance of species of Proteus, Morganella, and Pseudomonas. Several genera of potential significance to humans also were found (e.g., Vibrio alginolyticus, V. fluvialis, Erysipelothrix rhusiopathiae).

Comparative cochlear morphology in echolocating cetaceans

The anatomy of the cochlea of six species of odontocetes, or toothed whales (Physeter catadon, Grampus griseus, Lagenorhynchus albirostris, Phocoena phocoena, Tursiops truncatus, and Stenella longirostris) was compared using conventional micrography and radiographic techniques including edge enhancement x-ray, CT scan, magnification radiography, and digital subtraction. These species were selected for differences in frequency and patterning of normal and ultrasonic vocalizations in their natural environments. The cochlea were extracted post-mortem and preserved by injection. Whole cochlea were first examined radiographically for species-specific differences in gross morphology and topology, particularly for angular change of the scalae and torsion of membranal and neural components. Specimens were then decalcified and processed for SEM or thin section microscopy. Measurements obtained by both methods are presented and the advantages of the radiographic techniques discussed. The results are compared with the cetacean cochlear models of Wever [Wever et al., Proc. Natl. Acad. Sci. 68, 2381–2385 (1971)] and Fleischer [G. Fleischer, J, Paleon. 50 (1), 133–152 (1976)] and analyzed according to the dimension-frequency correlation techniques of Greenwood [D. D. Greenwood, J. Acoust. Soc. Am. 33, 1344–1356 (1961)] and Hinchcliffe and Pye [R. Hinchcliffe and A. Pye, Int. Audiol. 7, 259–288 (1968)]. [Work supported by NSF.]

Comparative observations on odontocete sonar signals from captive animals

In this paper a comparative analysis of typical sonar signals of several species of littoral and riverine dolphins in captivity is presented. The sonar wave shapes compared include those recently obtained from two species, whose acoustic behavior has not been described previously in literature, i.e., the off‐shore Lagenorhynchus albirostris and the fresh water population of Irrawadi; Orcaella brevirostris. The latter fit very well in the picture established thus far from a large collection of echolocation data. A study of these sonar signals reveals the noteworthy fact that—apart from the Commerson's signal—they all share a rather simple, basic wave shape. This can best be understood and classified in terms of the well‐known uncertainty relation in communication theory and enables us therefore to link bioacoustics with mathematical physics. The signals approach the theoretical lower bound for the product of the time duration and frequency bandwidth and could therefore be designated as “small time‐duration bandwidth” signals. They are thus well suited as a class of elementary optimal time‐frequency signals. The frequency range of interest in the first described class of cetacean sonar is situated at a dominant frequency below 100 kHz, while in the Phocaena and Commerson group this dominant value goes up to around 120 kHz. The latter thus enabling those small animals to resolve spatial differences in their habitat up to an order of magnitude of nearly a centimeter.

Heptachlor epoxide in marine mammals

The presence of heptachlor epoxide in harbour seals ( Phoca vitulina) and white-beaked dolphins ( Lagenorhynchus albirostris) has been confirmed by chemical derivatization and mass spectrometric analyses. An unknown compound at a retention time close to that of heptachlor epoxide interfered in the determination by electron capture detector—gas chromatography. On a WCOT CP-Sil 7 column programmed from 85 to 175°C two poorly separated peaks could be detected. Heptachlor epoxide contents up to 1.7 mg/kg (on a fat basis) were obtained, which were about 200 times lower than the PCB levels. The same ratio was also observed in fish from the same area.