The icing of external recorders during the polar winter

Recorders and transmitters are commonly attached to suitable polar species of vertebrates. When using these devices, power and memory are two of the most limiting factors in successful experiments. To conserve power and memory the units are often programmed to record or transmit at designated times. A commonly used sensor is operational only when the animal is in sea water. For this procedure to function properly, exposed electrodes close a circuit when the attached device is wet. Using satellite transmitters that were programmed to transmit only after they were dry for a prescribed time, we noted an uncommon number of failures in transmission. On later controlled experiments using captive emperor penguins, Aptenodytes forsterii, we found that mock transmitters formed a glaze of ice over their surface while the birds were diving freely into an ice hole cut in two meter thick sea ice. We concluded that the icing caused the sensor to fail in detecting when the birds had re-entered the water. Icing could be an important factor in successful use of attached recorders and transmitters on polar animals, especially in winter

Deep dives and aortic temperatures of emperor penguins: new directions for bio-logging at the isolated dive hole

In order to document deep (>100 m) dives and aortic temperature responses of emperor penguins (Aptenodytes forsteri) at an isolated dive hole, and also to evaluate a new catheterization technique, three birds were equipped with time depth recorders, temperature data loggers, and percutaneously-inserted aortic thermistors. After recovery from anesthesia, they were provided access for one day to the dive hole. The birds tolerated the experiment without complication. Mean diving duration (+ SE) of 83 dives was 5.9 + 3.1 min; 55% of dives were > 5.6 min, the previously determined aerobic dive limit; 36% were > 100 m in depth. Mean aortic temperatures during 3-h rest periods ranged from 37.3 + 0.2oC to 38.0 + 0.1oC. Mean dive temperature did not correlate with dive duration, and the grand mean of mean dive temperatures in each bird ranged from 38.3 + 0.2oC to 39.0 + 0.2oC; there was no evidence of core hypothermia during dives. Reliable, safe catheterizations, and the large percentage of deep/long dives of these birds should provide the basis both for future studies of pressure adaptation and hypoxemic tolerance in diving emperor penguins, and for investigation of deep-dive foraging behavior

Blood Oxygen Depletion Is Independent of Dive Function in a Deep Diving Vertebrate, the Northern Elephant Seal

Although energetics is fundamental to animal ecology, traditional methods of determining metabolic rate are neither direct nor instantaneous. Recently, continuous blood oxygen (O2) measurements were used to assess energy expenditure in diving elephant seals (Mirounga angustirostris), demonstrating that an exceptional hypoxemic tolerance and exquisite management of blood O2 stores underlie the extraordinary diving capability of this consummate diver. As the detailed relationship of energy expenditure and dive behavior remains unknown, we integrated behavior, ecology, and physiology to characterize the costs of different types of dives of elephant seals. Elephant seal dive profiles were analyzed and O2 utilization was classified according to dive type (overall function of dive: transit, foraging, food processing/rest). This is the first account linking behavior at this level with in vivo blood O2 measurements in an animal freely diving at sea, allowing us to assess patterns of O2 utilization and energy expenditure between various behaviors and activities in an animal in the wild. In routine dives of elephant seals, the blood O2 store was significantly depleted to a similar range irrespective of dive function, suggesting that all dive types have equal costs in terms of blood O2 depletion. Here, we present the first physiological evidence that all dive types have similarly high blood O2 demands, supporting an energy balance strategy achieved by devoting one major task to a given dive, thereby separating dive functions into distinct dive types. This strategy may optimize O2 store utilization and recovery, consequently maximizing time underwater and allowing these animals to take full advantage of their underwater resources. This approach may be important to optimizing energy expenditure throughout a dive bout or at-sea foraging trip and is well suited to the lifestyle of an elephant seal, which spends > 90% of its time at sea submerged making diving its most “natural” state

Relationship between red blood cell lifespan and endogenous carbon monoxide in the common bottlenose dolphin and beluga

Certain deep-diving marine mammals (i.e., northern elephant seal (Mirounga angustirosis), Weddell seal (Leptonychotes weddellii)) have blood carbon monoxide (CO) levels that are comparable to those of chronic cigarette smokers. Most CO produced in humans is a by-product of heme degradation, which is released when red blood cells (RBC) are destroyed. Elevated CO can occur in humans when RBC lifespan decreases. The contribution of RBC turnover to CO concentrations in marine mammals is unknown. Here, we report the first RBC lifespans in two healthy, marine mammal species with different diving capacities and heme stores, the shallow diving bottlenose dolphin (Tursiops truncatus) and deep-diving beluga (Delphinapterus leucas) and relate the lifespans to the levels of CO in blood and breath. The belugas, with high blood heme stores, had the longest mean RBC lifespan compared to humans and bottlenose dolphins. Both cetacean species were found to have three times higher blood CO content compared to humans. The estimated CO production rate from heme degradation indicates some marine mammals may have additional mechanisms for CO production, or delay CO removal from the body, potentially from long duration breath-holds

doi:10.1098/rspb.2006.0005

It is obvious, at least qualitatively, that small animals move their locomotory apparatus faster than large animals: small insects move their wings invisibly fast, while large birds flap their wings slowly. However, quantitative observations have been difficult to obtain from free-ranging swimming animals. We surveyed the swimming behaviour of animals ranging from 0.5 kg seabirds to 30 000 kg sperm whales using animalborne accelerometers. Dominant stroke cycle frequencies of swimming specialist seabirds and marine mammals were proportional to mass K0.29 (R 2 Z0.99, nZ17 groups), while propulsive swimming speeds of 1-2 m s K1 were independent of body size. This scaling relationship, obtained from breath-hold divers expected to swim optimally to conserve oxygen, does not agree with recent theoretical predictions for optimal swimming. Seabirds that use their wings for both swimming and flying stroked at a lower frequency than other swimming specialists of the same size, suggesting a morphological trade-off with wing size and stroke frequency representing a compromise. In contrast, foot-propelled diving birds such as shags had similar stroke frequencies as other swimming specialists. These results suggest that muscle characteristics may constrain swimming during cruising travel, with convergence among diving specialists in the proportions and contraction rates of propulsive muscles. Keywords: accelerometer; power spectral density; dive; free-ranging; scaling; optimal INTRODUCTION In a Friday Evening Discourse given at the Royal Institution in 1949 Direct observations have often been used to record movements of flying animals MATERIAL AND METHODS We compared the stroke frequencies and swimming speeds of a range of animals in relation to their body sizes. Owing to morphological differences among species, body mass was used as an index of body size. Morphological measurements were used to estimate mass for adult Weddell seals , leatherback turtles and sperm whales Field experiments using accelerometers were conducted from tropical to Antarctic regions. Detailed protocols of the field experiments were already published for the sperm whale (French Guiana, South America, May 2001. Study protocols followed those of the above-mentioned published studies. We used acceleration data loggers (D2GT and PD2GT, Little Leonardo Ltd, Tokyo; Dtag, the Woods Hole Oceanographic Institution; We could detect the duration of each stroke cycle from the time-series data, but our goal was to determine the dominant stroke cycle frequency for each animal. The periodic properties of the acceleration signal allowed us to apply a Fourier Transform to determine the dominant frequency. Power spectral density (PSD) was calculated from the entire acceleration dataset of each animal, or a subsample during identified foraging or migration behaviour to determine the dominant stroke cycle frequency using a Fast Fourier Transformation with a computer program package, IGOR PRO (WaveMetric, Inc., Lake Oswego, OR, USA). For the sperm whale, the bottom phase of the dive was not used as it is typified by body rotations, which can occur at similar rates to the fluking action. Stroke frequency and body size of animals K. Sato et al. 473 Proc. R. Soc. B (2007) 3. RESULTS Seals move their rear flippers side-to-side and these movements are detected as fluctuations in lateral acceleration along the transverse axis of the body (Mirounga angustirostris; with R 2 Z0.99 (nZ17, p!0.0001). The 95% confidence interval for the exponent was from K0.28 to K0.30. In contrast, the mean propulsive swim speed (U ) among these species was independent of body mass in the log-log analysis (UZ1.88 m K0.05 , R 2 Z0.18, nZ17, pZ0.09). Sperm whales of more than 30 tons, 300 kg seals and 0.5 kg seabirds all swam at mean swim speeds around 1-2 m s K1 during transit between the sea surface and the foraging depths (table 1). DISCUSSION According to experimental measurements based on respirometers in water tunnels and the doubly labelled water technique, the optimum swim speed was proportional to mass 0.27 Stroke frequency and body size of animals K. Sato et al. 475 Proc. R. Soc. B K1 ). Why these free-ranging animals did not follow the theoretical and experimental predictions for optimal swimming speed is a question we cannot answer now. The constructal model The isometric model proposed by According to the present study, swim speed (U ) was independent of body size, therefore the frequency is expected to be proportional to area divided by mass (S/m), which is expected to be proportional to the length K1 or mass K1/3 . Results of the present study were obtained from morphologically diverse animals. Nonetheless, f is inversely proportional to m K0.29 , close to the predicted value of mass K1/3 , implying that diving specialists among seabirds and marine mammals have evolved similar proportions of propulsive muscles and muscle contraction rates during cruising travel. The scaling relationship was very strong among swimming specialists during contexts when they were predicted to swim efficiently. Moreover, interesting deviations from the regression line (see Japanese flounders Paralichthys olivaceus had lower stroke frequencies than other swimming specialists (open pink circle i

Distribution of emperor penguins' dive directions under the fast sea ice

December 15-17, 2007, Royal Phuket City Hotel, Phuket, ThailandEmperor penguins Aptenodytes forsteri feed mainly on Pleurogramma antarcticum and Pagothenia borchgrevinki in the sea of Antarctica. Because these prey are not distributed uniformly, prey encounter rates during a dive change depending on where emperor penguins dive. In limited time and space, they should select areas in which prey are expected to be abundant. We hypothesized that the distribution of emperor penguins' dive directions was not uniform due to their selective dives. In order to test this hypothesis, dive paths were calculated with the data recorded by data loggers. Dive direction was obtained for each dive path, and the distribution of the dive directions was investigated. In five experiments of the total of six experiments, the dive directions were not distributed uniformly. This suggested that the emperor penguins had a preference about their dive directions. The dive directions were not related with ocean current direction, which was considered to be one of the factors affecting penguins' diving behavior. The emperor penguins may have decided where they dived according to their knowledge about prey distribution and/or the behavior of conspecific individuals

Swimming velocities in otariids

Ponganis PJ, Ponganis EP, Ponganis KV, Kooyman GL, Gentry RL, Trillmich F. Swimming velocities in otariids. Canadian journal of zoology. 1990;68(10).Velocities during surface swimming and diving were measured with microprocessor recorders in four otariid species: northern fur seals (Callorhinus ursinus), Galapagos sea lions (Zalophus californianus wollebaeki), Galapagos fur seals (Arctocephalus galapagoensis), and Hooker's sea lions (Phocarctos hookeri). Mean surface swimming velocities ranged from 0.6 to 1.9 m/s. Transit distances to feeding sites (1.2–90 km) were calculated using these velocities. Dive velocities, recorded every 15 s, ranged from 0.9 to 1.9 m/s. These velocities were consistent with calculated minimal cost of transport velocities in the smaller species. Using time partitioning, the metabolic cost of a northern fur seal foraging trip is estimated on the basis of recorded velocities and their calculated energy costs. This value is within 6% of that previously made with doubly labeled water techniques