Mario Acquarone

Homing Behaviour in an Atlantic Walrus (Odobenus rosmarus rosmarus)

An adult Atlantic walrus (Odobenus rosmarus rosmarus) male (31 years old in 2001) tracked by use of satellite telemetry in NE Greenland during four seasons (1989, 1990/1991, 2000/2001, 2001) revealed a remarkably high perennial tendency of homing and consistency of migration pattern. During all four inshore summering periods (August to September), the animal used only one terrestrial haul-out from which it made excursions to the same general shallow water area (i.e., likely clam beds) in western Dove Bay (ca. 76o to 77o N). In different years, the size of the inshore foraging area varied between 48 and 86 km 2 in August, and between 136 and 385 km 2 in September. The inshore foraging period lasted ca. 69 days in 1989 and 1990, but ca. 86 days in 2000 (no data for 2001). During fall 1989, 1990/1991 and 2000/2001, the walrus followed the same migration route in the Greenland Sea north to the wintering grounds in the Northeast Water polynya (ca. 79o to 81o N). Apparently, this movement pattern was relatively independent of annual variations in ice and temperature regimes. Offshore in the Greenland Sea–Fram Strait area, the walrus occurred mainly in areas with dense ice cover (> 90%). During both the inshore summer and offshore winter, the animal dived to at least 250 m (maximum depth limit of the transmitter). The tracking of this walrus, whose activity pattern was typical of male walruses in the region, shows that this stenophagous species is a creature of habit with a highly stereotypic movement pattern which apparently is influenced by the location of predictable feeding, wintering, and mating areas.

Field Metabolic Rates of Walrus (Odobenus rosmarus) Measured by the Doubly Labeled Water Method

The energy and food requirements of free-ranging pinniped species are difficult to measure and, as a consequence, are unknown for most species. They can be inferred from measures of Field Metabolic Rate (FMR) made by the Doubly Labeled Water (DLW) method, however. In this work, we confirmed our hypothesis that the FMR of pinnipeds measured by DLW can be described by an allometric relationship as a function of body weight. Although costly and difficult to apply, the DLW method is one of the few possible methods generating estimates of energy demands for unrestrained, free-living animals. The results of its application on two adult, male, freeliving Atlantic Walruses (Odobenus rosmarus rosmarus), weighing 1,370 kg and 1,250 kg, respectively, estimated from length and girth measures, are presented here. These data extend the size range of the seven pinniped species for which the DLW method has been applied by a factor of 10. The animals were measured at a site in northeast Greenland (76° N) during the summer. FMR was dependent on the pool model for estimating metabolic rate and was approximately 13% higher when using the single-pool compared with the two-pool model. The estimates using

Decrease Stress; Train Your Animals: The Effect of Handling Methods on Cortisol Levels in Harbour Porpoises (Phocoena phocoena) Under Human Care

Circulating cortisol levels are accepted as a sensitive indicator of acute stress in marine mammals, particularly in relation with capture and handling. The present study provides the first long-term monitoring of cortisol levels in four harbour porpoises held in human care—an adult male and adult female and two juvenile females. It also compares levels in blood obtained after removing the animal from the water (OWR sampling) with levels in blood obtained at poolside under voluntary husbandry behaviours (VHB sampling). Cortisol levels differed significantly between the four porpoises, although they all exhibited quite high variations in cortisol levels, with averages of 64.9 and 70.5 µg/l in the adult male and female, respectively, and 90.7 and 51.4 µg/l in the juvenile females. OWR sampling induced significantly higher cortisol levels than VHB sampling, with a dramatic threefold decrease in circulating cortisol levels obtained under VHB sampling compared to levels obtained under OWR sampling (16.6 and 20.2 µg/l compared with 64.9 and 70.5 µg/l in the adult male and female respectively). Even if the porpoises showed some habituation to handling, regular and frequent handling over several years did not suppress a significant stress response in the porpoises when they were removed from the water, pointing to the advantage of using VHB for limiting stress in husbandry practices.

Effects of Polar Bear and Killer Whale Derived Contaminant Cocktails on Marine Mammal Immunity

Most controlled toxicity studies use single chemical exposures that do not represent the real world situation of complex mixtures of known and unknown natural and anthropogenic substances. In the present study, complex contaminant cocktails derived from the blubber of polar bears (PB; Ursus maritimus) and killer whales (KW; Orcinus orca) were used for in vitro concentration-response experiments with PB, cetacean and seal spp. immune cells to evaluate the effect of realistic contaminant mixtures on various immune functions. Cytotoxic effects of the PB cocktail occurred at lower concentrations than the KW cocktail (1 vs 16 μg/mL), likely due to differences in contaminant profiles in the mixtures derived from the adipose of each species. Similarly, significant reduction of lymphocyte proliferation occurred at much lower exposures in the PB cocktail (EC50: 0.94 vs 6.06 μg/mL; P < 0.01), whereas the KW cocktail caused a much faster decline in proliferation (slope: 2.9 vs 1.7; P = 0.04). Only the KW cocktail modulated natural killer (NK) cell activity and neutrophil and monocyte phagocytosis in a concentration- and species-dependent manner. No clear sensitivity differences emerged when comparing cetaceans, seals and PB. Our results showing lower effect levels for complex mixtures relative to single compounds suggest that previous risk assessments underestimate the effects of real world contaminant exposure on immunity. Our results using blubber-derived contaminant cocktails add realism to in vitro exposure experiments and confirm the immunotoxic risk marine mammals face from exposure to complex mixtures of environmental contaminants.

Seroprevalence for Brucella spp. in Baltic ringed seals (Phoca hispida) and East Greenland harp (Pagophilus groenlandicus) and hooded (Cystophora cristata) seals

Zoonotic infections transmitted from marine mammals to humans in the Baltic and European Arctic are of unknown significance, despite given considerable potential for transmission due to local hunt. Here we present results of an initial screening for Brucella spp. in Arctic and Baltic seal species. Baltic ringed seals (Pusa hispida, n = 12) sampled in October 2015 and Greenland Sea harp seals (Pagophilus groenlandicus, n = 6) and hooded seals (Cystophora cristata, n = 3) sampled in March 2015 were serologically analysed for antibodies against Brucella spp. The serological analyses were performed using the Rose Bengal Test (RBT) followed by a confirmatory testing of RBT-positive samples by a competitive-enzyme linked immunosorbent assay (C-ELISA). Two of the Baltic ringed seals (a juvenile male and a juvenile female) were seropositive thus indicating previous exposure to a Brucella spp. The findings indicate that ringed seals in the Baltic ecosystem may be exposed to and possibly infected by Brucella spp. No seropositive individuals were detected among the Greenland harp and hooded seals. Although our initial screening shows a zoonotic hazard to Baltic locals, a more in-depth epidemiological investigation is needed in order to determine the human risk associated with this.

First Case of a Monitored Pregnancy of a Harbour Porpoise (Phocoena phocoena) Under Human Care

Most of the data collected on the reproduction of harbour porpoises (Phocoena phocoena) comes from by-caught or stranded animals and is therefore opportunistic in nature. Harbour porpoises kept in a human-controlled environment offer a unique opportunity to gather data on the same individual with a known history over a long period of time. At Fjord&Baelt in Kerteminde, Denmark, Freja, a 10-y-old female harbour porpoise, became pregnant in September 2005 and gave birth during the night between 24 and 25 July 2006. Routinely sampled parameters, such as food intake, weight, blubber-thickness, body-girth measurements, and respiration rates, did not follow the seasonal patterns observed the preceding years at the facility. These variables either increased or remained stable during the pregnancy. As the first sign of the approaching parturition, a dramatic drop in food intake occurred 8 d prior to her giving birth followed by a decrease in body temperature of 1o C at about 62 h before giving birth. Freja’s intermammary distance also increased as the date of the birth approached, although this parameter cannot be used for immediate diagnosis of impending parturition. The newborn calf was found dead a few hours after the birth and appeared to be the result of a full-term gestation. This study describes some observable changes in behavioural, physical, and physiological parameters occurring in a primiparous harbour porpoise during gestation, which could be used in animal husbandry for this species.

Estimation of water pool size, turnover rate and body composition of free-ranging Atlantic walruses ( Odobenus rosmarus rosmarus ) studied by isotope dilution

Deuterium oxide was used to measure isotope dilution space 11 times in seven free living, adult, male Atlantic walruses ( Odobenus rosmarus rosmarus ) (930–1597 kg) in north-east Greenland in the month of August 2000 and August 2001. Telemetry instruments, which were attached to the animals as part of a long term study, provided data on activity levels. Equilibration of the intravenously injected isotope was complete after 2–3 h. The application of a general correction factor developed for all pinniped species allowed the estimation of total body water content as 56.8% (range: 36.6–73.3%) of total body mass (TBM). Water turnover averaged 44.5 g kg -1 d -1 . For one animal it was possible to estimate water influx to 4.8 g kg -1 d -1 and water efflux to 21.8 g kg -1 d -1 . The estimates of body fat and body protein averaged respectively 24.7% and 18.4% of TBM. Similarly, for an ‘average’ walrus with a TBM of 1300 kg body ash was calculated to average 26 kg and body gross energy to 18,300 MJ. The assessment of body fat by isotope dilution did not differ significantly from the estimates of blubber content obtained from the dissection of walruses in the wild.

Reply to ‘Swim encounters with Killer Whales (Orcinus orca) off Northern Norway: interactive behaviours directed towards Human Divers and Snorkellers obtained from opportunistic underwater video recordings’

ABSTRACT This is a reply to the research note ‘Swim Encounters with Killer Whales (Orcinus orca) off Northern Norway: Interactive Behaviours directed towards Human Divers and Snorkellers obtained from Opportunistic Underwater Video Recordings’ by C. Pagel, M. Scheer and M. Lück published on the Journal of Ecotourism in the December 2016 issue. This research note gives us the opportunity to reflect on the following aspects: (1) the concepts of sustainability and ecotourism, (2) the researchers’ position in terms of animal ethics, (3) the relevance of the empirical context where the fieldwork occurs and the related research ethics aspect, (4) the difficulty of evaluating risk of injury. We comment on each of these aspects and discuss them in the attempt to clarify research challenges, propose some reflection points and possible alternative approaches for improving research quality in wildlife tourism.

Carbon, Nitrogen and Sulphur isotopic fractionation in captive juvenile hooded seal (Cystophora cristata): application for diet analysis

RATIONALE Intrinsic biogeochemical markers, such as stable isotope ratios of carbon, nitrogen and sulphur, are increasingly used to trace the trophic ecology of marine top predators. However, insufficient knowledge of fractionation processes in tissues continues to hamper the use of these markers. METHODS We performed a controlled feeding experiment with eight juvenile hooded seals (Cystophora cristata) that were held on a herring-based diet (Clupea harengus) for two years. Stable isotope ratios were measured via isotope ratio mass spectrometry in three of their tissues and related to values of these markers in their diet. RESULTS Diet-tissue isotope enrichment (trophic enrichment factor, TEF) values between dietary herring and seal tissues for carbon (Δ13 C) were +0.7 ‰ for red blood cells, +1.9 ‰ for hair and +1.1 ‰ for muscle. The TEFs for nitrogen trophic (Δ15 N) were +3.3 ‰ for red blood cells, +3.6 ‰ for hair and +4.3 ‰ for muscle. For sulphur, the Δ34 S values were +1.1 ‰ for red blood cells, +1.0 ‰ for hair and +0.9 ‰ for muscle. CONCLUSIONS These enrichment values were greater than those previously measured in adult seals. This increase may be related to the higher rate of protein synthesis and catabolism in growing animals. This study is the first report on sulphur isotope enrichment values for a marine mammal species.

The Nasal Geometry of the Reindeer Gives Energy-Efficient Respiration

Abstract Reindeer in the arctic region live under very harsh conditions and may face temperatures below 233 K. Therefore, efficient conservation of body heat and water is important for their survival. Alongside their insulating fur, the reindeer nasal mechanism for heat and mass exchange during respiration plays a fundamental role. We present a dynamic model to describe the heat and mass transport that takes place inside the reindeer nose, where we account for the complicated geometrical structure of the subsystems that are part of the nose. The model correctly captures the trend in experimental data for the temperature, heat and water recovery in the reindeer nose during respiration. As a reference case, we model a nose with a simple cylindrical-like geometry, where the total volume and contact area are the same as those determined in the reindeer nose. A comparison of the reindeer nose with the reference case shows that the nose geometry has a large influence on the velocity, temperature and water content of the air inside the nose. For all investigated cases, we find that the total entropy production during a breathing cycle is lower for the reindeer nose than for the reference case. The same trend is observed for the total energy consumption. The reduction in the total entropy production caused by the complicated geometry is higher (up to -20 %) at more extreme ambient conditions, when energy efficiency is presumably more important for the maintenance of energy balance in the animal. In the literature, a hypothesis has been proposed, which states that the most energy-efficient design of a system is characterized by equipartition of the entropy production. In agreement with this hypothesis, we find that the local entropy production during a breathing cycle is significantly more uniform for the reindeer nose than for the reference case. This suggests that natural selection has favored designs that give uniform entropy production when energy efficiency is an issue. Animals living in the harsh arctic climate, such as the reindeer, can therefore serve as inspiration for a novel industrial design with increased efficiency.