Physiology Abstracts
Pending Publishing Permission
Anatomy of the sense of touch in sea otters Sarah McKay Strobel, UC Santa Cruz Full Abstract
A combination of approaches can be used to interpret underwater foraging behavior of sea otters. Previous research in our laboratory has focused primarily on behavioral assessments of sensory abilities that sea otters likely use to detect and acquire prey. For example, we have worked cooperatively with trained otters to learn about texture discrimination using touch in air and under water. Our understanding of sensory biology in this species can be supplemented through fine scale histological analyses of sensory tissue. Here, we provide results from our recent efforts to link skin structure and touch function using anatomical approaches. We obtained freshly harvested hairless skin samples from the paws, nose, lips, and flipper pads of euthanized sea otters (n=4) through collaboration with the Monterey Bay Aquarium. After fixing the tissues in 10% neutral buffered formalin and processing them for histochemical staining with H&E, we imaged each tissue sample with light microscopy. In addition to gross descriptions of skin morphology, we report density of multiple mechanoreceptor types (including Pacinian corpuscles, Merkel cells, Meissner corpuscles, and unidentified lamellar corpuscles) responsible for different touch sensations. We compare these data across skin structures and within paw regions (digit pads, palmar pads, carpal pads) to test the hypothesis that different structures contribute to different tactile functions of skin regions in sea otters. |
Beyond morbidity: an integrated approach to sea otter intestinal parasitism Kyle Shanebeck, Univeristy of Alberta Watch Video (Login required) Full Abstract
Food webs are often more complex than biology textbook figures let on. Sea otters are charismatic animals at the centre of considerable conservation efforts. They are also keystone species in their ecosystems and play a vital role in kelp forest ecosystem structure and functioning. Potential variations in their breeding success and population dynamics following perturbations can have dramatic effects on the whole ecosystem. The only parasite that exclusively uses sea otters as a definitive host, Corynosoma enhydri if often dismissed as insignificant for otter and ecosystem health. We argue here that the dismissal of this widespread, prevalent and abundant parasite of sea otters is premature, and potentially negligent. Parasites are increasingly recognized as an integral part of food webs in marine ecosystems. Many species affect host behavior, influencing rates of predation and prey preference. Some parasites suppress immune response, and may increase rates of polyparasitism or secondary bacterial infection. Parasites can also affect energetics and metabolic success of hosts, a limiting factor for sea otter population success. Furthermore, little is known about how increasing ocean temperatures and climate change may influence infection levels and how this could affect sea otters and kelp forest ecosystem health. |
Sea otter toxicology research: what can we learn about toxic compounds in sea otters using non-invasively collected fecal samples?
Amy Olsen, The Seattle Aquarium Watch Video (Login required) Full Abstract
Pollutants and other toxic contaminant compounds are found in ecosystems throughout the world, from the Arctic to the Mariana Trench. These chemicals have been associated with negative health effects in wildlife, including those that live in the marine environment. Sea otters are a marine predator with a high metabolism, and extensive consumption of contaminated prey may result in biomagnification of these toxic compounds. The Seattle Aquarium houses four Northern sea otters, and their diet includes a variety of restaurant quality seafood. The Aquarium measured three chemicals for trial testing, all known to cause adverse health effects in high concentrations: polybrominated diphenyl ethers (PBDEs, a flame-retardant used in furniture and electronics), polychlorinated biphenyls (PCBs, a coolant and lubricant), and pyrethroids (a common synthetic insecticide). Seafood diet items and non-invasively collected fecal samples were tested. Overall, values of the three chemicals were found to be below the threshold for concern in humans for all sample types. There is no known threshold for concern in sea otters, so human concern values were used as a proxy. Seattle Aquarium sea otters were ingesting levels below the daily oral limits set by the EPA and World Health Organization. Pyrethroids were the highest measured chemical overall, most likely because PCBs and PBDEs have been managed or fully banned in Washington for 40 and 10 years, respectively, while pyrethroids are still permitted for use both residentially and commercially. The Seattle Aquarium will use these data to improve our animal care by providing our animals with the cleanest sources of food and water, and to serve as a foundation for understanding sea otter toxicology. |
Investigating the energetic cost of anthropogenic disturbance on the southern sea otter
(Enhydra lutris nereis) Heather E. Barrett, Moss Landing Marine Laboratories, California State University Watch Video (Login required) Full Abstract
As coastal populations and tourism increase, there is an increase in human-wildlife conflicts. The impacts of these conflicts are not well understood for many coastal species, and of particular concern is the southern sea otter (Enhydra lutris nereis). Sea otters have high metabolic costs and are at risk of increased energetic costs due to human disturbance. To investigate the effects of human disturbance, behavioral scans were conducted over three years to record sea otter activity in response to potential disturbance stimuli at three locations in California (Monterey, Moss Landing, Morro Bay). We developed a hidden Markov model to predict the level of increased activity based on location, disturbance stimuli, and distance. We then paired previously recorded metabolic rates to the observed activity changes to calculate expected energetic cost. Our data indicate that disturbance to sea otters and consequent change in activity is location and distance specific. This activity change correlates to energetic costs that increase with disturbance stimuli proximity and frequency. The coupling of metabolics to activity change in response to a disturbance furthers our understanding of the true energetic cost to sea otters, while providing a sound scientific basis for management. |
Pending Publishing Permission
Investigating microplastic ingestion in sea otters through scat analysis Jennifer Van Brocklin, Oregon State University Full Abstract
The presence of microplastics in marine environments is becoming an increasing concern due to their potential impacts on marine species. As part of a master’s thesis project to investigate how sea otters may be exposed to these pollutants, we will be assessing the number and type of microplastics ingested by sea otters by analyzing diet and scat samples in ex- and in-situ individuals. We will also be exploring the possible change in microplastic load sea otters have experienced over time by observing microplastic presence in archived samples. |
Using behavioral and physiological data to evaluate animal welfare in marine mammals: a case study on sea otters Megan Hagedorn, Oregon Zoo Watch Video (Login required) Full Abstract
In recent years, zoos and aquariums have increased their efforts to systematically evaluate and improve animal welfare. One tool that can be used for objective assessment of physiological state is the monitoring of adrenal hormones in fecal samples. Since 2015, animal care staff at the Oregon Zoo have been collecting fecal samples from various animals for hormone analyses in our on-site endocrinology lab. The lab uses enzymeimmunoassay (EIA) techniques to track reproductive hormones like estrogen, progesterone and their metabolites, as well as adrenal hormones like cortisol, corticosterone and glucocorticoid metabolites (GMs). Temporary increases in GMs can occur in response to negative or positive events and can be used to identify acute stressors and responses to novel stimuli, such as a new enrichment item. Long-term elevations of GMs may indicate the existence of a chronic stressor, such as an on-going health issue. When paired with detailed behavior data, hormone data can be used to evaluate animal welfare, investigate responses to specific events or management decisions as well as facilitate end of life discussions. The following presentation discusses several examples in which paired hormone data and behavioral data were used to monitor animal welfare in 2.1 southern sea otters (Enhydra lutris). |