Meeting Abstract
P1.96 Jan. 4 Cardiac temperature sensitivity in the grass shrimp (Palaemonetes pugio): Physiological limits to temperature extremes REIBER, Carl L.*; MIKA, Teresa; Univ. of Nevada, Las Vegas; Univ. of Nevada, Las Vegas reiber@ccmail.nevada.edu
Environmental temperature plays a significant role in determining species spatial distributions. In aquatic environments temperature can be a primary influencing factor behind latitudinal distributions over large geographic regions as well as determining species distribution patterns observed over more local intertidal regions. The thermal sensitivity of critical physiological systems will determine a species minimal and maximal temperature range. The cardiovascular system of Crustacea can be very sensitive to temperature extremes and may be the limiting physiological system that establishes the temperature range within which a defined crustacean species may inhabit. Critical thermal minimum/maximum temperatures, LT50�s and metabolic rates were established for Grass shrimp (Palaemonetes pugio) acclimated to 25° C (temp range 5° � 40° C) and compared to values established for animals acclimated to 15° and 35° C. Cardiac functions (heart rate, stroke volume and cardiac output) and energetics were assessed using P-A loops generated at various temperatures to determine when and how the system failed. The area enclosed by the P-A loop provides a measure of stroke work and when multiplied by heart rate allows for the calculation of cardiac work and an estimate of myocardial oxygen consumption. Given the sensitivity of the crustacean heart to both oxygen and temperature, these data support the hypothesis that the cardiovascular system maybe a primary factor in determining distributions for some species.
