Meeting Abstract
6.9 Jan. 4 Balancing the demands of physiological systems in the Dungeness crab, Cancer magister and the blue crab, Callinectes sapidus CURTIS, DL*; MCGAW, IJ; University of Nevada, Las Vegas; Bamfield Marine Sciences Centre; University of Nevada, Las Vegas; Bamfield Marine Scienes Centre curtisd4@unlv.nevada.edu
Decapod crustaceans inhabiting estuaries are often subjected to salinity fluctuations that occur on varying spatial and temporal scales. The osmoregulatory ability of a given species may dictate the energetic demands associated with salinity changes. The Dungeness crab, Cancer magister, is classed as a weak osmoregulator and unfed crabs showed no change in oxygen uptake when exposed to low salinity. In contrast, an efficient osmoregulator, the blue crab, Callinectes sapidus, which is highly tolerant of low salinity exhibits an increase in oxygen uptake in low salinity. Feeding and digestion causes a general increase in metabolic parameters, commonly referred to as specific dynamic action (SDA). When postprandial animals are exposed to environmental challenges the added cost of digestive processes may result in different physiological responses. We hypothesized that less efficient osmoregulators may not be able to balance the demands of osmoregulation and digestion concurrently; therefore a prioritization of events will be seen. For efficient osmoregulators, it was hypothesized that the crabs would be able to sum the demands of these two systems. In this study, when Cancer magister fed in seawater, there was an increase in oxygen consumption. However, when 1 h postprandial crabs were exposed to 50% or 75% SW, a dose dependant decrease in oxygen uptake occurred. In Callinectes sapidus, feeding and exposure to low salinity both resulted in an increase in oxygen uptake. The results of this study suggest that osmoregulatory ability may dictate the metabolic responses to feeding and digestion in low salinity, and has important implications for modeling the energetics of crustaceans inhabiting estuaries.
