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Summary Fatal meningoencephalitis due to Brucella ceti infection has been described in striped dolphins (Stenella coeruleoalba), Atlantic white-sided dolphins (Lagenorhynchus acutus), short-beaked common dolphins (Delphinus delphis) and long-finned pilot whales (Globicephala melas), which are all within the family Delphinidae. We report B. ceti-associated neurobrucellosis in three juvenile male Sowerby's beaked whales (Mesoplodon bidens) that all had typical lesions of lymphocytic meningoencephalitis, which increased in severity from rostral to caudal regions of the brain. In two cases there was loss of ependymal cells lining the cerebral ventricular system, with large numbers of lymphocytes in the underlying neuropil. This finding suggests that B. ceti gains access to, and multiplies in, the cerebrospinal fluid, and confirms that this is the sample of choice for bacteriological recovery of the causative organism. These findings expand the increasing range of cetaceans susceptible to neurobrucellosis to members of the family Ziphiidae.

During Leg 1 of the MAR-ECO expedition on the R.V. G.O. Sars in June 2004 four main species of dolphins were observed along the Mid-Atlantic Ridge from Iceland to the Azores: pilot whale ( Globicephala melas ) ( n =326), short-beaked common dolphin ( Delphinus delphis ) ( n =273), white-sided dolphin ( Lagenorhynchus acutus ) ( n =103), and striped dolphin ( Stenella coeruleoalba ) ( n =86). Pilot whales and white-sided dolphins were found in cold (5–16 °C) and less-saline (34.6–35.8‰) water masses in the northern part of the study area, whereas common and striped dolphins inhabited warmer (12–22 °C) and more-saline (34.8–36.7‰) waters in the south. Dolphins tended to aggregate in areas of steep slopes, but actual bottom depth appeared to be less important. Based on spatial correlations between dolphin occurrence and candidate prey organisms recorded acoustically and by midwater trawling, mesopelagic fishes and squids were assumed to be important prey items, with Benthosema glaciale probably being the most important prey for pilot whales and white-sided dolphins, while Lampanyctus macdonaldi , Stomias boa ferox and Chauliodus sloani were probably of particular importance for common dolphins. Cephalopods, especially Gonatus sp. and Teuthowenia megalops were the most likely prey species of pilot whales and striped dolphins, respectively. The difference in physical habitat north and south of the Sub-polar Frontal Zone seemed to have important effects on prey distribution, in turn influencing dolphin distribution.

Three novel halogenated organic compounds (HOCs) have been identified in the blubber of marine mammals from coastal New England with the molecular formulae C 9 H 3 N 2 Br 6 Cl, C 9 H 3 N 2 Br 7 , and C 9 H 4 N 2 Br 5 Cl. They were identified using high and low resolution gas chromatography mass spectrometry (GCMS) and appear to be highly brominated analogues of Q1, a heptachlorinated HOC suspected to be naturally produced. These compounds were found in Atlantic white sided dolphin ( Lagenorhynchus acutus ), bottlenose dolphin ( Tursiops truncatus ), common dolphin ( Delphinus delphis ), Risso's dolphin ( Grampus griseus ), harbor porpoise ( Phocoena phocoena ), beluga whale ( Delphinapterus leucas ), fin whale ( Balaenoptera physalus ), grey seal ( Halichoerus grypus ), harp seal ( Phoca groenlandica ) and a potential food source ( Loligo pealei ) with concentrations as high as 2.7 μg/g (lipid weight). The regiospecificity of C 9 H 3 N 2 Br 6 Cl is suggestive of a biogenic origin. Debromination of C 9 H 3 N 2 Br 6 Cl may be significant in the formation of C 9 H 4 N 2 Br 5 Cl.

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.

Metallothioneins (MTs) were characterised in the kidneys of a white-sided dolphin Lagenorhynchus acutus stranded along the Belgian coast, displaying high levels of cadmium (Cd) and mercury (Hg) in liver and kidney. The protein has two isoforms: MT-1 and MT-2. MT-1 binds Cu, Zn, Hg and Cd, while MT-2 only binds Zn, Hg and Cd. This suggests different metabolic functions for the two isoforms: MT-1 is mainly involved in Cu homeostasis; MT-2, which was four-fold more abundant than MT-1, detoxifies most of the accumulated cadmium.

Marine mammal by-catch in 11 pelagic trawl fisheries operated by four different countries in the northeast Atlantic was studied. Observers accompanied commercial fishing vessels and monitored 374 tows totalling 1771 h of towing during 377 days fishing. Three species of marine mammal were identified in by-catches (white-sided dolphin, Lagenorhynchus acutus, common dolphin, Delphinus delphis and grey seal Halichoerus grypus) and a fourth, bottlenose dolphin Tursiops truncatus, was probably present. Dolphins were caught in four of the 11 fisheries and seal in one. In those fisheries with cetacean bycatch, rates varied from 0.0606 to 0.1000 per tow and 0.0107 to 0.0137 per hour of towing and were highest in the French sea bass fishery and lowest in the French tuna fishery. Grey seals were caught in the Irish Celtic Sea herring fishery at a rate of 0.0513 per tow or 0.0396 per hour of towing. The meanSD dolphin catch rate for all fisheries combined was 0.0480.013 per tow (one dolphin per 20.7 tows), or 0.01850.0019 per hour of towing (one dolphin per 98 h of towing) and, for all marine mammals, 0.0590.019 (1 per 17.0 tows) or 0.01240.0121 (1 per 80.6 h of towing). 95% confidence intervals, calculated on untransformed data, for all fisheries combined were 0.4‐1.6 dolphins per 100 h of towing. No operational factors were correlated with by-catch rates but the haul-back procedure was identified as a potentially important factor. All dolphin by-catches occurred during the night which may be a due to an association between cetaceans and trawlers at night. White-sided dolphins and grey seals were observed feeding around the net during towing and this behaviour may make them more vulnerable to capture. Operational difficulties in observing by-catch and potentially significant annual fluctuation in catch rates warrant further observer studies of these and other trawl fisheries. # 1999 Elsevier Science B.V. All rights reserved.

Chlorobiphenyls (CBs) and organochlorine pesticides (OCPs) have been determined in the blubber of 17 Atlantic white-sided dolphins stranded at Killala Bay, Co Mayo, Ireland and five from the Scottish coast. The concentrations of the contaminants measured range from 773 to 63,400 microg kg(-1) for sigmaCB and from 160 to 54,600 microg kg(-1) for sigmaDDT. The concentrations of the CBs and OCPs is highly dependent on the age, sex, reproductive state and nutritional condition of the animals in addition to the intake via the food web. Principal Components Analysis (PCA) has been used to study the variation of chemical patterns (data ratioed to CB 153). Immature animals (6 years), mature males and primogravid females, and lactating females could be distinguished on the basis of their contaminant patterns. This paper describes the different processes of bioaccumulation and metabolism of organochlorine contaminants (OCs) in this species.

Bottlenose dolphins ( Tursiops truncatus ) collected during the 1987/88 mass mortality event along the Atlantic coast of the United States have been analyzed for coplanar PCBs #77, 105, 126 and 169 in blubber, and for the metals Hg, Pb, Cd, Mn, and Cr, and the non-metallic element Se in liver. Results have been compared to two reference species, common ( Delphinus delphis ) and white-sided ( Lagenorhynchus acutus ) dolphins. The three most toxic PCB congeners (#77, 126 and 169) contributed less than 1% of the total TCDD toxic equivalent concentration (TEC) calculated for all di-, mono- and non-ortho chlorine substituted PCBs in adult male animals. The total TEC for the four PCBs was approximately 4.5 times lower in adult female bottlenose than in male. The mean concentrations of Pb, Cd, Mn and Cr in adult male bottlenose dolphins were at or below the mean concentrations in the two reference species. The mean concentration of mercury was highest in adult female bottlenose dolphins. However, mercury concentrations in all animals studied correlated with selenium concentrations (r=0.86) at a 1:1 mole ratio, indicating that selenium may protect these animals from mercury toxicity.

Bottlenose dolphins ( Tursiops truncatus ) collected during the 1987/88 mass mortality event along the Atlantic coast of the United States have been analyzed for anthropogenic chemical contaminants. Average contaminant concentrations in adult males were higher than the average concentrations measured in adult females. Females could be divided into two groups by contaminant concentrations, one with low concentrations, and another with concentrations 4.4 times (PCBs) to 8.9 times (p,p′-DDE) greater. Contaminant concentrations in bottlenose were generally greater than the concentrations measured in either common ( Delphinus delphis ) or white-sided ( Lagenorhynchus acutus ) dolphins from the western North Atlantic Ocean. A subset of animals screened for unusual chemical contaminants showed that numerous polybrominated chemicals were present, including polybrominated biphenyls and diphenyl ethers not previously found in marine mammals from U.S. coastal waters.