Meeting Abstract

P2.56  Monday, Jan. 5  Developmental physiology of the gut as an air breathing organ during hypoxia-rearing in the suckermouth catfish, Hypostomus plecostomus FOSHA, K. R.*; DZIALOWSKI, E. M.; University of North Texas, Denton ; University of Norh Texas, Denton katie.fosha@gmail.com

Hypostomus plecostomus are facultative air breathers, switching to aerial breathing when exposed to the low oxygen conditions (hypoxia) that commonly occur in their habitat. Digestive tract modifications, such as a thin blood-air barrier associated with numerous capillaries running close to the stomach lining, allow the gut of these fish to be used as an efficient accessory respiratory organ. While much is known regarding adult H. plecostomus, little is known about the maturation of this air-breathing organ (ABO) in juveniles throughout early development. Initial hypoxia tolerance tests determined that loss of righting occurred at approximately 20mmHg in juvenile H. plecostomus without access to air. In response to acute hypoxia (60 and 98 mmHg O2), adult fish relied almost entirely on aquatic respiration. In contrast, juvenile H. plecostomus took between 10 and 40% more aerial breaths per hour during hypoxic exposure than did adult fish. Due to these observed differences in breathing rates per hour based on H. plecostomus mass, fish have been evaluated for simultaneous oxygen uptake across the gills, stomach and skin. Eggs were allowed to develop in hypoxia and normoxia and aerial and aquatic respiration was measured. The information gained from this study aids in the understanding of the development and evolution of air breathing in fishes.