Lagenorhynchus Albirostris Research Articles

Identification and Characterization of a Tandem Repeat in Exon III of the Dopamine Receptor D4 (DRD4) Gene in Cetaceans

A large number of mammalian species harbor a tandem repeat in exon III of the gene encoding dopamine receptor D4 (DRD4), a receptor associated with cognitive functions. In this study, a DRD4 gene exon III tandem repeat from the order Cetacea was identified and characterized. Included in our study were samples from 10 white-beaked dolphins (Lagenorhynchus albirostris), 10 harbor porpoises (Phocoena phocoena), eight sperm whales (Physeter macrocephalus), and five minke whales (Balaenoptera acutorostrata). Using enzymatic amplification followed by sequencing of amplified fragments, a tandem repeat composed of 18-bp basic units was detected in all of these species. The tandem repeats in white-beaked dolphin and harbor porpoise were both monomorphic and consisted of 11 and 12 basic units, respectively. In contrast, the sperm whale harbored a polymorphic tandem repeat with size variants composed of three, four, and five basic units. Also the tandem repeat in minke whale was polymorphic; size variants composed of 6 or 11 basic units were found in this species. The consensus sequences of the basic units were identical in the closely related white-beaked dolphin and harbor porpoise, and these sequences differed by a maximum of two changes when compared to the remaining species. There was a high degree of similarity between the cetacean basic unit consensus sequences and those from members of the horse family and domestic cow, which also harbor a tandem repeat composed of 18-bp basic units in exon III of their DRD4 gene. Consequently, the 18-bp tandem repeat appears to have originated prior to the differentiation of hoofed mammals into odd-toed and even-toed ungulates. The composition of the tandem repeat in cetaceans differed markedly from that in primates, which is composed of 48-bp repeat basic units.

Temporal Variability of Cetaceans near Halifax, Nova Scotia

Annual and seasonal trends in sightings of coastal cetaceans near Halifax, Nova Scotia, were studied using observations from whale watching and dedicated research vessels from late spring to early fall of 1996 to 2005. Four species of cetaceans routinely used the area during the summer: White-beaked and Atlantic White-sided dolphins (Lagenorhynchus albirostris and L. acutus), Harbour Porpoises (Phocoena phocoena), and Minke Whales (Balaenoptera acutorostrata). The dolphin species were temporally separated, with White-beaked Dolphins being common earlier in the summer than White-sided Dolphins. White-sided Dolphins were unusually abundant in 1997, and were found in larger groups (mean = 46.5 ± 46.19 sd) than Whitebeaked Dolphins (mean = 9.1 ± 5.19 SD). The area also appears to be an important habitat for dolphin calves and juveniles of both species. Fin Whales (B. physalus) were commonly observed in relatively large groups in 1997, but were uncommon or absent in other years. Humpback Whales (Megaptera novaeangliae), Blue Whales (B. musculus) and North Atlantic Right Whales (Eubalaena glacialis) were uncommon in the area, although Humpback Whales were sighted frequently in 1997. Increased numbers of White-sided Dolphins, Fin and Humpback whales in 1997 may be explained by increased prey abundance and decreased sea-surface temperatures.

Stomach contents of English Channel cetaceans stranded on the coast of Normandy

During 1998–2003 stomach contents of 47 marine mammals stranded on the coast of Normandy were analysed. The animals were first examined by a veterinary network and stomach contents were analysed at the University of Caen. The sample comprised: 26 common dolphins (Delphinus delphis), four bottlenose dolphins (Tursiops truncatus), seven harbour porpoises (Phocoena phoecoena), five grey seals (Halichoerus grypus), two long-finned pilot whales (Globicephala melas), one white beaked dolphin (Lagenorhynchus albirostris), one minke whale (Balaenoptera acurostrata) and one striped dolphin (Stenella coeruleoalba). The identification of food items was done using hard parts (i.e. fish otoliths and cephalopod beaks). Diet indices were computed including prey frequency and percentage by number. Common dolphins ate mainly gadoid fish (Trisopterus sp.), gobies and mackerel (Scomber scombrus). Cephalopods occurred in small numbers in the diet and commercially important species (cuttlefish and common squid) were scarce.

Climate change and the cetacean community of north-west Scotland

1. Climate change is thought to affect the composition and structure of local ecological communities. We investigate whether ocean warming around north-west Scotland since 1981 has been associated with changes in the local cetacean community. 2. Analysis of strandings from 1948 to 2003 found that no new species per decade were recorded in north-west Scotland between 1965 and 1981. This rose to 2.0 new species per decade from 1988 onwards. The new species recorded since 1988 are generally restricted to warmer waters, while those recorded prior to 1981 regularly occur in colder waters. 3. In the period 1992 to 2003, the relative frequency of stranding of white-beaked dolphin, a colder water species, has declined while strandings of common dolphin, a warmer water species, have increased. Similarly, sightings surveys conducted in May–September 2002 and 2003 show that the relative occurrence and abundance of white-beaked dolphins have declined and common dolphins increased in comparison to previous studies. 4. These observations are consistent with changes in the local cetacean community being driven by increases in local water temperature. If such temperature changes continue, some formerly abundant cold-water species, such as white-beaked dolphins, may be lost from this cetacean community. In a wider context, such changes may lead to populations of cetaceans moving out of areas specifically designated for their protection as they respond to changes in local oceanic conditions.

Estimated transmission beam pattern of clicks recorded from free-ranging white-beaked dolphins (Lagenorhynchus albirostris).

Recordings were made from white-beaked dolphins in Icelandic waters using a four-hydrophone array in a star configuration. The acoustic signals were amplified and sampled to a hard disk at a rate of 800 kHz per channel. The 3 and 10 dB beamwidths were calculated to be 8 degrees and 10 degrees, respectively, indicating a narrower transmission beam for white-beaked dolphins than that reported for bottlenose dolphins (Tursiops truncatus). The beamwidth was more similar to that found for belugas (Delphinapterus lucas). The measured beam pattern included large side lobes, perhaps due to the inclusion of off-axis clicks, even after applying several criteria to select only on-axis clicks. The directivity index was calculated to be 18 dB when using all data for angles from 0 degrees-50 degrees. The calculated sound radiation from a circular piston with a radius of 6 cm driven by a white-beaked dolphin click had a beam pattern very similar to the measured beam pattern for the main transmission lobe of the white-beaked dolphin. The directivity index was 29 dB. This is the first attempt to estimate the directionality index of dolphins in the field.

Echolocation signals of wild dolphins

Most of our understanding of dolphin echolocation has come from studies of captive dolphins performing various echolocation tasks. Recently, measurements of echolocation signals in the wild have expanded our understanding of the characteristics of these signals in a natural setting. Measuring undistorted dolphin echolocation signals with free swimming dolphins in the field can be a challenging task. A four hydrophone array arranged in a symmetrical star pattern was used to measure the echolocation signals of four species of dolphins in the wild. Echolocation signals of the following dolphins have been measured with the symmetrical star array: white-beaked dolphins in Iceland, Atlantic spotted dolphins in the Bahamas, killer whales in British Columbia, and dusky dolphins in New Zealand. There are many common features in the echolocation signals of the different species. Most of the signals had spectra that were bimodal: two peaks, one at low frequencies and another about an octave higher in frequency. The source level of the sonar transmission varies as a function of 20logR, suggesting a form of time-varying gain but on the transmitting end of the sonar process rather than the receiving end. The results of the field work call into question the issue of whether the signals used by captive dolphins may be shaped by the task they are required to perform rather than what they would do more naturally.

Echolocation signals of dusky dolphins (Lagenorhynchus obscurus) in Kaikoura, New Zealand.

An array of four hydrophones arranged in a symmetrical star configuration was used to measure the echolocation signals of the dusky dolphin (Lagenorhynchus obscurus) near the Kaikoura Peninsula, New Zealand. Most of the echolocation signals had bi-modal frequency spectra with a low-frequency peak between 40 and 50 kHz and a high-frequency peak between 80 and 110 kHz. The low-frequency peak was dominant when the source level was low and the high frequency peak dominated when the source level was high. The center frequencies in the dusky broadband echolocation signals are among the highest of dolphins measured in the field. Peak-to-peak source levels as high as 210 dB re 1 microPa were measured, although the average was much lower in value. The levels of the echolocation signals are about 9-12 dB lower than for the larger white-beaked dolphin (Lagenorhynchus albirostris) which belongs to the same genus but is over twice as heavy as the dusky dolphins. The source level varied in amplitude approximately as a function of the one-way transmission loss for signals traveling from the animals to the array. The wave form and spectrum of the echolocation signals were similar to those of other dolphins measured in the field.

Perfluorinated chemicals infiltrate ocean waters: link between exposure levels and stable isotope ratios in marine mammals.

This is the first study to report on concentrations of perfluorinated organochemicals (FOCs) in marine mammals stranded along the southern North Sea coast in relation to stable nitrogen and carbon isotope ratios (delta15N and delta13C). The presence of FOCs in top predators such as marine mammals would indicate a potential biomagnification of these compounds and their widespread occurrence. Liver and kidney tissues of nine marine mammal species have been sampled. Among all the measured FOCs compounds, PFOS (perfluorooctane sulfonate) was predominant in terms of concentration. The highest PFOS concentrations were found in the liver of harbor seal compared to white-beaked dolphin, harbor porpoise, gray seal, sperm whale, white-sided dolphin, striped dolphin, fin whale, and hooded seal. PFOS concentrations differed significantly between sexes and age classes in harbor porpoises. Stable isotope measurements (delta13C and delta15N) were used in this study to describe the behavior of contaminants in food webs. We found a significant (p < 0.05) linear relationship between PFOS concentrations in livers of harbor porpoises and both muscle delta13C and delta15N measurements. Harbor and gray seals and white-beaked dolphin, which displayed the highest trophic position, contained the highest PFOS levels, while offshore feeders such as sperm whales, fin whales, striped dolphin, and white-sided dolphin showed lower PFOS concentrations than inshore species.

Summer distribution and relative abundance of cetacean populations off north-west Scotland

A line transect survey was conducted in July/August 1998 to investigate the distribution and abundance of cetaceans off north-west Scotland. Over 2156.5 km of survey effort, 304 sightings were recorded of which 184 were identified to species. Nine species were identified: Atlantic white-sided dolphin Lagenorhynchus acutus, fin whale Balaenoptera physalus, sei whale Balaenoptera borealis, long-finned pilot whale Globicephala melas, sperm whale Physeter macrocephalus, common dolphin Delphinus delphis, harbour porpoise Phocoena phocoena, white beaked dolphin Lagenorhynchus albirostris and Risso's dolphin Grampus griseus. The Atlantic white-sided dolphin was the most relatively abundant species. The relative abundance of large whales and dolphins was greatest in the Faroe–Shetland Channel. The continental slopes of this area are undergoing development by oil industries and concerns have been raised about the potential impacts of these activities on cetaceans. These waters are used year-round by cetaceans and provide feeding and breeding grounds and are a migration route for large whales.

Marine mammals from northeast Atlantic: relationship between their trophic status as determined by delta13C and delta15N measurements and their trace metal concentrations.

The relationship between trophic position through delta13C and delta15N and trace metal concentrations (Zn, Cd, Cu and Hg) was investigated in the tissues of six marine mammal species from the Northeast Atlantic: striped dolphin Stenella coeruleoalba, common dolphin, Delphinus delphis, Atlantic white-sided dolphin Lagenorhynchus acutus, harbour porpoise Phocoena phocoena, white beaked-dolphin Lagenorhynchus albirostris, grey seal Halichoerus grypus stranded on French Channel and Irish coasts. White-beaked dolphins, harbour porpoises, white-sided dolphins, common and striped dolphins display the same relative and decreasing trophic position, as measured by delta15N values, along both the Irish and French channel coasts, reflecting conservative trophic habits between these two places. Hepatic and renal Cd concentrations were significantly correlated to muscle delta13C and delta15N values while Hg, Zn and Cu did not. These results suggest that Cd accumulation is partly linked to the diet while other factors such as age or body condition might explain Hg, Zn or Cu variability in marine mammals. Combined stable isotope and trace metal analyses appear to be useful tools for the study of marine mammal ecology.

Marine mammals from the southern North Sea: feeding ecology data from δ13C and δ15N measurements

The harbour porpoise Phocoena phocoena, grey seal Halichoerus grypus, harbour seal Phoca vitulina and white-beaked dolphin Lagenorhynchus albirostris are regularly found stranded along southern North Sea coasts. Occasionally, offshore species such as the fin whale Balaenoptera physalus, the white-sided dolphin L. acutus and the sperm whale Physeter macrocephalus are also found stranded. In order to trace their diet, we measured δ 13 C and δ 15 N in their muscles as well as in 49 invertebrate and fish species collected from the southern North Sea. The δ 15 N data indicate that the harbour seal, grey seal and white-beaked dolphin occupy the highest trophic position, along with ichtyophageous fishes such as the cod Gadus morhua (mean muscle values of 18.7, 17.9, 18.8 and 19.2‰ respectively). The harbour porpoise occupies a slightly lower trophic position (mean δ 15 N value of 16.2 ‰), reflecting a higher amount of zooplanktivorous fishes in its diet (mean δ 15 N of 14.7‰); 2 suckling harbour porpoises displayed a significant δ 15 N enrichment of 2.2‰ compared to adult females. Adult females are δ 15 N-enriched compared to adult male harbour porpoises. Fin whales, sperm whales and white-sided dolphins are 13 C-depleted compared to southern North Sea particulate organic matter and species, suggesting that despite regular sightings, they do not feed within the southern North Sea area.

Mammals of the Sea in Science and Culture

Encyclopedia of Marine Mammals . William F. Perrin, Bernd Würsig, and J. G. M. Thewissen, Eds. Academic Press, San Diego, 2002. 1452 pp. $139.95, £90. ISBN 0-12-551340-2. Marine mammals-cetaceans, pinnipeds, sirens, sea otter, and polar bear-and their interactions with humans are covered in 283 entries, which range from "Abundance Estimation" to "White-Beaked Dolphin."

Abundance of harbour porpoise and other cetaceans in the North Sea and adjacent waters

Summary The status of small cetaceans in the North Sea and adjacent waters has been of concern for many years. Shipboard and aerial line transect surveys were conducted to provide accurate and precise estimates of abundance as a basis for conservation strategy in European waters. The survey, known as SCANS (Small Cetacean Abundance in the North Sea), was conducted in summer 1994 and designed to generate precise and unbiased abundance estimates. Thus the intensity of survey was high, and data collection and analysis methods allowed for the probability of detection of animals on the transect line being less than unity and, for shipboard surveys, also allowed for animal movement in response to the survey platform. Shipboard transects covered 20 000 km in an area of 890 000 km2. Aerial transects covered 7000 km in an area of 150 000 km2. Three species dominated the data. Harbour porpoise Phocoena phocoena were encountered throughout the survey area except in the Channel and the southern North Sea. Whitebeaked dolphin Lagenorhynchus albirostris and minke whale Balaenoptera acutorostrata were found mainly in the north‐western North Sea. Phocoena phocoena abundance for the entire survey area was estimated as 341 366 [coefficient of variation (CV) = 0·14; 95% confidence interval (CI) = 260 000–449 000]. The estimated number of B. acutorostrata was 8445 (CV = 0·24; 95% CI 5000–13 500). The estimate for L. albirostris based on confirmed sightings of this species was 7856 (CV = 0·30; 95% CI = 4000–13 000). When Atlantic whitesided dolphin Lagenorhynchusacutus and Lagenorhynchus spp. sightings were included, this estimate increased to 11 760 (CV = 0·26; 95% CI 5900–18 500). Shortbeaked common dolphin Delphinus delphis were found almost exclusively in the Celtic Sea. Abundance was estimated as 75 450 (CV = 0·67; 95% CI = 23 000–149 000). Current assessments and recommendations by international fora concerning the impact on P. phocoena of bycatch in gillnet fisheries in the North Sea and adjacent waters are based on these estimates.

Source levels of clicks from free-ranging white-beaked dolphins (Lagenorhynchus albirostris Gray 1846) recorded in Icelandic waters.

This study reports the source levels of clicks recorded from free-ranging white-beaked dolphins (Lagenorhynchus albirostris Gray 1846). A four-hydrophone array was used to obtain sound recordings. The hydrophone signals were digitized on-line and stored in a portable computer. An underwater video camera was used to visualize dolphins to help identify on-axis recordings. The range to a dolphin was calculated from differences in arrival times of clicks at the four hydrophones, allowing for calculations of source levels. Source levels in a single click train varied from 194 to 211 dB peak-to-peak (p-p) re: 1 microPa. The source levels varied linearly with the log of range. The maximum source levels recorded were 219 dB (p-p) re: 1 microPa.

Cetaceans of the Atlantic Frontier, north and west of Scotland

Surveys carried out to the north and west of Scotland have recorded 15 species of cetacean between 1979 and 1998. These were fin whale ( Balaenoptera physalus) , sei whale ( B. borealis) , minke whale ( B. acutorostrata) , humpback whale ( Megaptera novaeangliae) , sperm whale ( Physeter macrocephalus) , northern bottlenose whale ( Hyperoodon ampullatus) , Sowerby's beaked whale ( Mesoplodon bidens) , killer whale ( Orcinus orca) , long-finned pilot whale ( Globicephala melas) , Atlantic white-sided dolphin ( Lagenorhynchus acutus) , white-beaked dolphin ( L. albirostris) , Risso's dolphin ( Grampus griseus) , bottlenose dolphin ( Tursiops truncatus) , common dolphin ( Delphinus delphis) and harbour porpoise ( Phocoena phocoena) . Atlantic white-sided dolphin was the most abundant species in the region with a total of 6317 animals recorded. Harbour porpoise was the most frequently sighted cetacean species. The geographical distribution of sightings indicate that cetacean species have varying ecological requirements, with species such as sperm whale, pilot whale and white-sided dolphin favouring deep water off the continental shelf edge, while minke whale, white-beaked dolphin and harbour porpoise were apparently limited to the continental shelf. The diversity of species recorded in the region suggests that the Atlantic Frontier is an important habitat for cetaceans.

Accounting for responsive movement in line transect estimates of abundance

A method is developed to account for effects of animal movement in response to sighting platforms in line transect density estimates using data on animal orientation. Models of expected distributions of animal orientation show that presence of responsive movement is determined by the ratio of animal sightings with angles of orientation in the third quadrant relative to the first quadrant. The distance at which response began is estimated using logistic generalized additive models of the relationship between radial distance and orientation. Density corrected for responsive movement is estimated by applying the Buckland and Turnock two-team analysis method to data poststratified into regions "close" to and "far" from (beyond the distance that responsive movement began) the observation platform instead of the original stratification by observation team. For data collected in the North Atlantic, white-sided dolphins, harbor porpoises, and minke whales responded by avoiding the survey ship, and white-beaked dolphins were attracted to the ship. For these populations, our method to correct for responsive movement gave significantly higher estimates, from 1.4 to 2.7 times the uncorrected estimates.

Echolocation signals of wild white beaked dolphins measured with a four-hydrophone short base line array in real-time

The echolocation signals of Lagenorhynchus albirostris were measured in the waters off Keflavik, Icelend during 22–26 August 1998. A four-hydrophone array was used with each hydrophone located at the tip of an equilateral triangle and one located at the center of the triangle. Each of the outer three hydrophones was spaced 0.61 m from the center hydrophone and the separation angle between outer hydrophones was 120 deg. An underwater video camera was attached 10 cm from the center hydrophone. The array was mounted on a long pole that was lowered to a depth of about 2 m from the side of a 10-m diesel driven boat. The hydrophones were connected to two GAGA-1210 data acquisition boards operating at a 500-kHz sample rate. The computer clock was synchronized with the clock on portable video recorder. Two-hundred pretrigger and 200 posttrigger points per channel with four channels of data were acquired simultaneously and stored in the memory of a transportable computer. The results indicate that the white beaked dolphins emitted high-frequency clicks with peak frequencies close to 120 kHz. The maximum source level of the echolocation signals was 219 dB and the source levels increased with range from the array.

Ingestion of Plastic and Unusual Prey by a Juvenile Harbour Porpoise

Considerable quantities of plastic debris are found throughout the world’s oceans (e.g., Dufault and Whitehead, 1994), and may impact a diversity of species, including marine turtles, birds and mammals (Laist, 1997). Since many species of whales and dolphins live in waters far from shore, and may sink upon death, opportunities to record instances of ingestion of marine debris by cetaceans are infrequent. Despite this, there are several cases where ingestion of plastic or other marine debris has been documented for cetaceans, with published reports existing for 21 species of odontocetes (Laist, 1997). We know of an additional five species of odontocetes for which marine debris ingestion has been documented: the killer whale (Orcinus orca; K. Evans, pers. comm.), northern bottlenose whale (Hyperoodon ampullatus; R. Michaud, pers. comm..), finless porpoise (Neophocoena phocoenoides; C. Parsons, pers. comm.), white-beaked dolphin (Lagenorhynchus albirostris; R. Kastelein, pers. comm.), and pantropical spotted dolphin (Stenella attenuata; K. Robertson, pers. comm.). For most species of odontocetes, only one or a few records have been reported. Here we document the third reported case of plastic ingestion by a harbour porpoise (Phocoena phocoena), and discuss factors that might have contributed to its ingestion.

NEW HOST RECORD FOR THE WHALE LOUSE ISOCYAMUS DELPHINII (AMPHIPODA, CYAMIDAE)

Isocyamus delphinii (Gu?rin-M?neville, 1836) was described from the com mon dolphin, Delphinus delphis L., 1758. It has subsequently been recorded from Risso's dolphin, Grampus griseus (G. Cuvier, 1812), the long-finned pilot whale, Globicephala melas (Traill, 1809), the short-finned pilot whale, Globi cephala macrorhynchus Gray, 1846, the white-beaked dolphin, Lagenorhynchus albirostris (Gray, 1846), the false killer whale, Pseudorca crassidens (Owen, 1846), the rough-toothed dolphin, Steno bredanensis (Lesson, 1828), the harbor porpoise, Phocoena phocoena (L., 1758), the bottlenose dolphin, Tursiops trunca tus (Montagu, 1821), and the Antillian beaked whale, Mesoplodon europaeus Ger vais, 1855. For documentation of the above host records, the reader is referred to Martin & Heyning, 1999 (their table 1 and Literature Cited section) and to Haney (unpubl.). The killer whale, Orcinus orea (L., 1758), is also listed as a host for /. delphinii in Sedlak-Weinstein (1992), who cites Best (1969) for the host record. One of the present authors (Haney), however, found no such reference in Best's report, so the record of this cyamid species from the killer whale is considered doubtful. Although Isocyamus delphinii has been reported on the aforementioned ceta cean hosts from various localities in the North Atlantic and Pacific oceans, it has only once been previously recorded from a cetacean in the Gulf of Mexico (Bowman, 1955).

Quantitative analysis of tonal calls from five odontocete species, examining interspecific and intraspecific variation

Whistle vocalizations of five odontocete cetaceans, the false killer whale P. crassidens, short-finned pilot whale G. macrorhynchus, long-finned pilot whale G. melas, white-beaked dolphin L. albirostris and Risso's dolphin G. griseus, were analysed and summarized quantitatively. Recordings were acquired from a number of locations and encounters. Significant differences were found between species and, to a lesser extent, between locations. The calls of the two pilot whale species are distinct despite their close relatedness, and similar size and morphology. This may be due to selection pressures to maintain distinctiveness. The variance was partitioned into between-species, between-location (within species) and within-location factors. For the frequency variables, variation between-species is high relative to variation between locations. Thus geographic variation is a relatively minor effect, compared to the many processes which cause interspecific differences. The within-location component includes such factors as social context, behaviour and group composition. This component is of a similar magnitude to the between-species component, indicating that whistles vary considerably with these factors. Significant between-location differences may be attributable to these confounding factors. For whistle duration, most of the variation occurred within location. There is less significant variation in duration across species compared with the frequency measures. This study highlights the need to collect samples across all potential strata whenever possible, and provides a framework for future, more comprehensive work.