Meeting Abstract

S2-2.1  Wednesday, Jan. 4  Environmental Physiology WRIGHT, Patricia A; University of Guelph, Guelph, ON Canada

Mangrove rivulus (Kryptolebias marmoratus) are hardy amphibious fish, unique for their reproductive behaviour, as well as their ability to survive > 1 month out of water relying solely on the cutaneous surface for respiration. As water quality deteriorates (eg. hypoxia), neuroepithelial cells in the gills and skin respond to low oxygen levels and trigger a ventilatory response, while more severe or prolonged hypoxia induces emersion. Over the first week of air exposure, metabolic rate increases, cutaneous angiogenesis occurs and effective gill surface area is reduced as a consequence of gill remodeling. The skin is a key site of nitrogenous waste excretion and iono/osmoregulation in air-exposed K. marmoratus. Mangrove rivulus are ammoniotelic and volatilize a significant amount of ammonia as the gas NH3 across the cutaneous surface when out of water. Ion transporting cells (ionocytes) are present in both gills and skin, but in air-exposed K. marmoratus skin ionocytes enlarge when fish are in contact with a moist hypersaline solution. These findings indicate that reversible cellular and morphological changes to the skin and gills during air exposure probably enhance the cutaneous contribution to ion, nitrogen and water balance.