Coping Cat Study Video
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They had been drifting for 20 days. After being shipwrecked, they had escaped in a seven-meter-long lifeboat. They survived exposure, the blazing sun and a failed motor by drinking rainwater and eating bream that they fished from the sea with harpoons. Every year, stories emerge of people who manage to endure weeks or months onboard a simple craft. After a French Frigate called the Medusa ran aground on a sandbank off of what is now Mauritania in , nearly survivors crammed onto an improvised raft. Only 10 survived. Between mid-November and late January —a period of days and a distance of 9, kilometers—Alvarenga drifted across the Pacific. For the first four months, he was accompanied by a co-worker, who later died. Coping Cat StudyThe Trauma of the Castaway
Advanced Search SUMMARY River otters Lontra canadensis are highly active, semi-aquatic mammals http://pinsoftek.com/wp-content/custom/human-swimming/persuasive-essay-on-dog-grooming.php to a range of elevations and represent an appropriate model for assessing the physiological responses to diving at altitude. In this study, we performed blood gas analyses and compared blood chemistry of river otters from a high-elevation m population at Yellowstone Lake with a sea-level population along the Pacific coast. Comparisons of oxygen dissociation curves ODC revealed no significant difference Coping Cat Study hemoglobin-oxygen Hb-O2 binding affinity between the two populations - potentially because of demands for tissue oxygenation.
Instead, high-elevation otters had greater Hb concentrations Yellowstone otters displayed higher levels of the vasodilator nitric oxide NOand half the concentration of the serum protein albumin, possibly to compensate for increased blood viscosity.
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Despite compensation in several hematological and serological parameters, theoretical aerobic dive limits ADL were similar between high-elevation and sea-level otters because of the lower availability of O2 at altitude. Our results suggest that recent disruptions to the Yellowstone Lake food web could be detrimental to otters because at this high elevation, constraints on diving may limit their ability to switch to prey in a deep-water environment.
Animals diving at high elevation, however, are faced Coping Cat Study with both of these article source conditions, and their physiological responses to low O2 availability may be unique. For example, many species native to high elevation have hemoglobin Hb with increased O2-binding affinity, which enhances the uptake of O2 at the lungs Lenfant et Coping Cat Study.
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In most mammals, Hb-O2 affinity is modulated by the allosteric effector 2,3-bisphosphoglycerate 2,3-BPG Lenfant et al. Although increased Hb-O2 affinities have been reported for some diving species as well MacArthur, ; Snyder,sea-level divers generally encounter well-oxygenated conditions during surface breathing, thereby reducing their need to modulate Hb-O2 affinity Kooyman, ; Ramirez et al. Instead, dive duration of these animals often depends on O2 stores in the lungs, blood and muscles Kanatous et al.
Both diving and high-altitude species can enhance O2 storage via an increase in Catt concentration achieved by higher red blood cell RBC counts and increased hematocrit See more. However, erythrocytosis can increase blood viscosity, placing additional demands on the Coping Cat Study Hedrick and Duffield, ; Ramirez et al.
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Consequently, many shallow-diving species have Hct values similar to those of terrestrial animals MacArthur, ; Nieminen et al. The combined constraints of diving and altitude hypoxia may be complicated because hypoxic hyperventilation in air leads to the loss of CO2 in the blood alkalosis while breath-hold diving usually results in CO2 accumulation acidosis Giardina et al. Alkalosis decreases the P50 of Coping Cat Study, which facilitates O2 loading from a hypoxic environment but also requires the tissues to function at a lower PO2 to create the necessary diffusion gradient for O2 transport to the capillaries Jensen, ; Lenfant et al.
A diving animal, however, may reap a benefit at altitude because the accumulation of CO2 while breath holding increases the P50, thereby improving O2 delivery to the tissues Butler and Jones, ; Snyder, The extent to which these effects collectively benefit or limit an animal may depend on the blood's electrochemical environment. Animals with a large chloride shift may be able to transport more CO2 in the blood with a smaller change in the plasma acid-base status Westen and Prange, To investigate O2 delivery in a diving just click for source indigenous to a range of elevations we studied river otters, Lontra canadensis Schreber This species occurs across much of North America and performs foraging dives along coastal shorelines Coping Cat Study well as at high-elevation lakes and streams Melquist et al.
As semi-aquatic piscivores, foraging otters exert themselves during submerged chases and rely on their limbs and tail for propulsion rather than solely on body undulation Fish, Thus, muscle O2 demands can be high for diving otters and could limit the duration and depth of Coping Cat Study dives Davis et al. Moreover, the cold temperatures of high-latitude marine systems and high-elevation lakes increase an animal's energetic demands Kruuk et al.
Thus, the capacity of river otters to dive at altitudes with low PO2 and cold water temperatures may depend on enhancing Hb delivery of O2 to tissues. One of the few native high-altitude populations of river otters occurs at Yellowstone Lake, in Yellowstone Coping Cat Study Park. However, for otters in Yellowstone Lake, the challenge of successfully foraging at altitude has been heightened by a recent population decline in the native cutthroat trout, Oncorhynchus clarki bouvieri Go here et al. Cutthroat trout are important prey Coping Cat Study otters in Yellowstone Lake, and during the spawning season provide an accessible and lipid-rich food source Crait and Ben-David, ]
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