Physiology of Fish in Extreme Environments

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My area of research is environmental physiology. Aquatic animals can live in environments that vary in terms of oxygen concentrations, salinity, temperature and even water availability on a daily or seasonal basis. My research program focuses on how these environmental factors disturb physiological systems and the mechanisms that aquatic animals employ to compensate for these perturbations. Over the next granting cycle my objectives are to determine 1) the mechanisms of nitrogenous waste excretion in amphibious fishes during early life and later stages under variable environmental conditions, 2) the strategies that amphibious fishes use to osmoregulate, respire and physically support themselves in air and 3) the role of ammonia transporting proteins (Rhesus glycoproteins) in ammonia transport in the kidney of teleost and elasmobranch fishes. For example, we have proposed a novel hypothesis that stronger gravitational forces on land relative to water remodel tissues and organs of active amphibious fishes to increase strength, rigidity and performance in air. We will study the amphibious mangrove rivulus Kryptolebias marmoratus (as well as other species) that survive up to 2 months out of water. We will also study the regulation of Rhesus glycoproteins in the kidney of bony (goldfish) versus cartilaginous fishes (shark) in response to severely acidic water to test the hypothesis that renal ammonia excretion is coupled with Na+ transport. Our approach is to study the mechanisms from the molecular to whole animal level. The insights gained from this research will provide a more comprehensive understanding of the plasticity of key physiological systems and the cellular mechanisms that vertebrates utilize to maintain homeostasis in the face of extreme environmental perturbations.