MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14837

ABSTRACT: In northern Gulf of Mexico, eastern oyster (Crassostrea virginica) populations live in areas with mean annual salinities from ~ 5 to over 40 psu. They differ in salinity tolerance in a pattern consistent with their local salinity range, but the mechanisms responsible are mostly unknown. The physiological rates of four F1 populations from the highest to lowest salinity estuaries: Packery Channel (PC), Aransas Bay (AB), Calcasieu Lake (CL), Vermilion Bay (VB) were compared under a combination of four salinities (6, 12, 24, and 36 psu) and two temperatures (25 and 32°C). Clearance rate and oxygen consumption rates were first measured in all populations at all salinities at 25°C (study 1). Clearance rate, absorption efficiency %, oxygen consumption rate, ammonia excretion rate, and scope for growth (SFG) were then measured in populations from the highest (PC) and lowest (VB) salinity estuaries at 25°C (study 2) and 32°C (study 3). In study 1, clearance rates were greatest at 24 psu for the three populations from the higher-medium salinity estuaries but extended to 12 and 24 psu for the population from the lowest salinity estuary. In study 2, clearance rate and SFG tended to be greater in VB at 6 psu, but at 24 and 36 psu were greater for PC. SFG became negative at 6 psu for PC and at 36 psu for VB. At 32°C, SFG was negative or low in both populations, overriding the effects of salinity on oyster physiology. At 25°C, salinity impacted all the physiological rates and oyster populations showed variations in their physiological profiles consistent with their local salinity range.