Following heavy precipitation, we observed an intense algal bloom in the St. Lawrence Estuary (SLE) that coincided with an unusually high mortality of several species of marine fish, birds and mammals, including species designated at risk. The algal species was identified as Alexandrium tamarense and was determined to contain a potent mixture of paralytic shellfish toxins (PST). Significant levels of PST were found in the liver and/or gastrointestinal contents of several carcasses tested as well as in live planktivorous fish, molluscs and plankton samples collected during the bloom. This provided strong evidence for the trophic transfer of PST resulting in mortalities of multiple wildlife species. This conclusion was strengthened by the sequence of mortalities, which followed the drift of the bloom along the coast of the St. Lawrence Estuary. No other cause of mortality was identified in the majority of animals examined at necropsy. Reports of marine fauna presenting signs of neurological dysfunction were also supportive of exposure to these neurotoxins. The event reported here represents the first well-documented case of multispecies mass mortality of marine fish, birds and mammals linked to a PST-producing algal bloom.
Abstract-Knowledge is limited regarding methylsulfone (MeSO 2 )-polychlorinated biphenyl (PCB), and especially MeSO 2 -2,2-bis(chlorophenyl)-1,1-dichloroethylene (DDE), metabolites in cetacean species. We hypothesized that the ability of beluga whale (Delphinapterus leucas) to biotransform PCB and DDE compounds, and to form and degrade their MeSO 2 -PCB and -DDE metabolites, is related to the capacity for xenobiotic metabolism. Adipose biopsies were collected from male and female beluga whale from distinct populations in the St. Lawrence River estuary (STL) and western Hudson Bay (WHB), Canada, which are contrasted by the exposure to different levels of cytochrome P450 enzyme-inducing, chlorinated hydrocarbon contaminants. The PCBs, DDTs, DDEs, 28 MeSO 2 metabolites of 14 meta-para chlorine-unsubstituted PCBs, and four MeSO 2 metabolites of 4,4Ј-and 2,4Ј-DDE were determined. The mean concentrations of total (⌺-) MeSO 2 -PCB in male STL beluga (230 ng/g), and ratios of ⌺-MeSO 2 -PCB to ⌺-PCB (0.05) and ⌺-precursor-PCB (0.17) were approximately twofold higher, whereas the ⌺-precursor-PCB to ⌺-PCB ratio was approximately twofold lower, than in male WHB beluga. Both populations had a low formation capacity for MeSO 2 -PCBs with Նsix chlorines (Ͻ4% of ⌺-MeSO 2 -PCBs). The congener patterns were dominated by trichloro-and tetrachloro-MeSO 2 -PCBs, and tetrachloro-and pentachloro-MeSO 2 -PCBs in WHB and STL animals, respectively. In addition to 2-and 3-MeSO 2 -4,4Ј-DDE, two unknown MeSO 2 -2,4Ј-DDEs were detected. The mean 3-MeSO 2 -4,4Ј-DDE concentration in STL beluga (1.2 ng/g) was much greater than in WHB (Ͻ0.01 ng/g) animals. The concentrations of 4,4Ј-DDE, and not 3-MeSO 2 -4,4Ј-DDE, increased with age in male STL animals. We demonstrated that sulfone formation and clearance is related to metabolic capacity, and thus PCB, DDE, and MeSO 2 -PCB and -DDE toxicokinetics differ for STL and WHB beluga. In the past, the capacity of odontocetes for PCB and DDE biotransformation leading to persistent sulfone metabolites has been underestimated. More information is needed for other cetacean species and marine mammals. The results of this study indicate that MeSO 2 -PCBs and -DDEs need to be included in the toxicologic risk assessment of PCB and DDT exposure in odontocetes, and perhaps for cetaceans in general.
Contact calls are ubiquitous in social birds and mammals. Belugas are among the most vocal of cetaceans, but the function of their calls is poorly understood. In a previous study we hypothesized that a broad band pulsed call type labeled "Type A," serves as a contact call between mothers and their calves. Here we examined context-specific use of call types recorded from a captive beluga social group at the Vancouver Aquarium, and found that the Type A call comprised 24% to 97% of the vocalizations during isolation, births, death of a calf, presence of external stressors, and re-union of animals after separation. In contrast it comprised 4.4% of the vocalizations produced during regular sessions. We grouped 2835 Type A calls into five variants, A1 to A5. A discriminant function analysis classified 87% of calls in the same groupings that we assigned them to by ear and visual examination of spectrograms. The variants do not represent individual signatures. One variant, A1, was used by three related individuals: an adult female, her male calf and his juvenile half-sister. Our previous research documented the gradual development of the A1 variant by the male calf, until at 20 months he was producing stereotyped renditions of his mother and sister's A1. We used our findings to generate testable predictions about the usage of these signals by wild belugas. We verified the existence of signals with the same distinctive features as the contact calls found in captivity in the repertoire of St. Lawrence Estuary herds, and documented their usage by two wild individuals from different populations. In the St. Lawrence, these were emitted by a female calling after a dead-calf. In Hudson Bay, by a temporarily restrained juvenile. We propose that these calls function in nature, as in captivity, to maintain group cohesion, and that the variants shared by related animals are used for mother-calf recognition.Belugas (Delphinapterus leucas), nicknamed "sea canaries," are among the most soniferous cetaceans, producing what has been suitably described as a bewildering array of sounds (Finley, Miller, Davis, & Greene, 1990). These resemble the predominant sounds used by other toothed whales, and fall into two acoustic categories: whistles, or narrow band frequency modulated vocalizations, and pulsed sounds, or trains of broad band pulses. The latter can in turn be divided into two functional categories: click trains, used largely for echolocation, and burst pulse sounds (bursts of pulses with rapid pulse repetition rates), believed to be Animal Wild-caught or captive born? Year Age and Sex Observed and Recorded Aurora Wild caught 1990
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