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Helicobacter cetorum sp. nov. has been cultured from the stomach of Atlantic white-sided dolphins (Lagenorhynchus acutus) and the feces of Pacific white-sided (L. obliquidens) and Atlantic bottlenose (Tursiops truncatus) dolphins and a beluga whale (Delphinapterus leucas). H. cetorum has high homology to Helicobacter pylori as shown by 16S rRNA sequencing, and H. cetorum infection has been associated with gastritis and clinical signs in cetaceans. Because the prevalence of H. cetorum in wild populations is unknown, minimally invasive techniques for detecting H. cetorum were compared for 20 wild bottlenose dolphins sampled as part of a long-term health study. Fecal samples were tested for helicobacter by culture, Southern blotting, and PCR using genus-specific and H. cetorum-specific primers. An enzyme-linked immunosorbent assay (ELISA) was developed to measure H. cetorum immunoglobulin G (IgG). H. cetorum was cultured from 4 of 20 fecal samples, 7 samples were positive using Helicobacter sp. PCR, and 8 samples were positive for H. cetorum using species-specific primers. Two additional fecal samples were positive by Helicobacter sp. Southern blotting, suggesting infection with another helicobacter. All 20 sera contained high levels of IgG antibodies to H. cetorum that were significantly lowered by preabsorption of the sera with whole-cell suspensions of H. cetorum (P < 0.02). Until the specificity of the serum ELISA can be determined by testing sera from dolphins confirmed to be uninfected, PCR and Southern blot screenings of feces are the most sensitive techniques for detection of H. cetorum, and results indicate there is at least a 50% prevalence of H. cetorum infection in these dolphins.

High levels of polychlorinated biphenyls (PCBs) have been reported in the tissues of some species of marine mammals. The high concentrations are of concern because a growing body of experimental evidence links PCBs to deleterious effects on reproduction, endocrine homeostasis, and immune system function. Much of the recent research has focused on determining the exposure of marine mammal populations to PCBs, but very little effort has been devoted to the actual risk assessments that are needed to determine the expected impacts of the documented exposures. We describe a novel risk assessment approach that integrates measured tissue concentrations of PCBs with a surrogate dose-response relationship and leads to predictions of health risks for marine mammals as well as to the uncertainties associated with these predictions. Specifically, we use PCB tissue residue data from three populations of bottlenose dolphins (Tursiops truncatus), study the feasibility of published dose-response data from a surrogate species. and combine this information to estimate the risk of detrimental reproductive effects in female dolphins. Our risk analyses for dolphin populations near Beaufort (NC, USA), Sarasota (FL, USA), and Matagorda Bay (TX, USA) indicate a high likelihood that reproductive success, primarily in primiparous females, is being severely impaired by chronic exposure to PCBs. Excess risk of reproductive failure, measured in terms of stillbirth or neonatal mortality, for primiparous females was estimated as 60% (Beaufort), 79% (Sarasota), and 78% (Matagorda Bay). Females of higher parity, which have previously off-loaded a majority of their PCB burden, exhibit a much lower risk.

The dorsal fin of the bottlenose dolphin Tursiops truncatus contains blood vessels that function either to conserve or to dissipate body heat. Prior studies have demonstrated that heat flux, measured from a single position on the dorsal fin, decreases during body cooling and diving bradycardia and increases after exercise and at the termination of the dive response. While prior studies attributed changes in heat flux to changes in the pattern of blood flow, none directly investigated the influence of vascular structures on heat flux across the dorsal fin. In this study we examined whether heat flux is higher directly over a superficial vein, compared to a position away from a vein, and investigated the temporal relationship between heart rate, respiration and heat flux. Simultaneous records of heat flux and skin temperature at three positions on the dorsal fins of 19 wild bottlenose dolphins (with the fin in air and submerged) were collected, together with heart rate and respiration. When the fin was submerged, heat flux values were highest over superficial veins, usually at the distal tip, suggesting convective delivery of heat, via blood, to the skin's surface. Conversely, in air there was no relationship between heat flux and superficial vasculature. The mean difference in heat flux (48 W m(-2)) measured between the three fin positions was often equal to or greater than the heat flux that had been recorded from a single position after exercising and diving in prior studies. Tachycardia at a respiratory event was not temporally related to an increase in heat flux across the dorsal fin. This study suggests that the dorsal fin is a spatially heterogeneous thermal surface and that patterns of heat flux are strongly influenced by underlying vasculature.