Meeting Abstract

P3.173  Friday, Jan. 6  Ontogeny of bone buffers in two species of anoxia-intolerant turtles STEELE, Harmen*; HARNER, Andrew; BLACK, Patrick; ADAIR, Beth; KOETHER, Marina; REESE, Scott; Kennesaw State Univ.; Kennesaw State Univ.; Kennesaw State Univ.; Kennesaw State Univ.; Kennesaw State Univ.; Kennesaw State Univ.

Adult aquatic turtles use one of 2 strategies for surviving prolonged submergence depending on whether they are anoxia tolerant or anoxia intolerant. While hatchling aquatic turtles use several strategies for surviving their first winter, all are considered anoxia intolerant, even those whose adult forms are tolerant. The ontological sequence for this transition is poorly understood, so we raised two species, Trachemys scripta and Grapemys geographica, both considered anoxia-intolerant as adults, under controlled conditions measuring bone characteristics known to provide acid buffering in adults over a span of 240+ d. Shell and skeleton water, organic and ash content along with [Ca2+], [Mg2+], [K+], [Na+] and [CO2] were measured. While the animals were able to thermoregulate at summer temperatures, they did not start to feed until 157 d and the percent that was shell and skeleton did not change. The water, organic and ash composition of these elements did change slightly, but never reached the composition seen in the adult animal. The [Na+] and [Ca2+] of the T. scripta shell and the [Mg2+] of the G. geographica shell increased over the first four months and then remained unchanged through the remaining months. The shell [CO2] increased from 1.5-3 fold over 260 d. We suggest that hatchling turtles are unable to attain adult levels of anoxia tolerance in their first year even if their environment is favorable for such accumulation and this may restrict yearling overwintering strategies.