Comparative growth, condition, and survival of juvenile Crassostrea gigas and C. corteziensis oysters cultivated in summer and winter

Abstract

We report differences in growth, condition, and survival of the Pacific oyster Crassostrea gigas and the Cortez oyster C. corteziensis cultivated in a semi-arid lagoon in northwestern Mexico (Las Guásimas, Sonora) during summer and winter, periods corresponding to juvenile development at the production sites. Three sampling stations were established to determine variations in temperature, salinity, seston, chlorophyll a content, oxygen concentration, and pH at the coastal system. Growth rates and condition indices were higher during winter and cumulative mortality was higher in summer. This was the pattern for both species though significant differences were noted only for C. gigas. The Pacific oyster showed faster growth in winter and slower in summer than the Cortez oyster. While food availability was not a limiting factor in any season, differences in growth, condition, and survival were related to temperature, which ranged from a maximum of 32.7°C in summer to a minimum of 12.7°C in winter. Low temperatures are propitious for C. gigas, since high temperatures cause physiological stress. The Cortez oyster has the ability to adapt its metabolic functions to variations in temperature with no differences in growth and condition during the extreme seasons. The Pacific oyster exhibited better adaptation to variations in conditions at sites like Las Guásimas, but high temperature is a limiting factor for cultivation. Autumn is a propitious period to begin cultivating C. gigas, while the native C. corteziensis can be cultivated year-round.