Meeting Abstract
Carcinus maenas occurs in two color morphs: green after molting and red after prolonged intermolt. Ion regulation is well documented in green morphs at constantly low salinity, but few studies have focused on fluctuating salinity levels like that of a natural tidal environment. We investigated how the ability to ion regulate differs between the two morphs, how oscillating salinity affects both morphs, and whether these changes vary with sex. Red and green morphs were exposed to constantly low salinity (12 psu) for 72 h or to oscillating salinity ranging from 12 to 32 psu every 6 h. Whole animal performance was measured by reaction time, treadmill running endurance, and hemolymph osmolarity. Expression of key ion regulators was measured by western blots and qPCR. Our results reveal green morphs as better ion regulators accomplished not by changing the ion transporters, but by enhancing the driving force for the transporters through increased mRNA expression of cytosolic and membrane bound carbonic anhydrase along with Na+K+ATPase. Exposure to constantly low salinity results in greater mRNA expression of these ion regulators demonstrating that constantly low salinity is more stressful than oscillating salinity. Little difference was noted between sexes. An analysis of the full transcriptome by Roche 454 RNA sequencing is currently ongoing. Our data show that the well-documented ion regulatory capabilities of C. maenas need to be viewed in a color morph specific context. Oscillating salinity being less strenuous than constantly low salinity is in agreement with the conditions in the crabs’ natural habitat as they are rarely exposed to constantly low salinity.
