Temporal variability in food availability to natural oyster populations

Productivity in oyster populations is partially determined by food availability, which is dependent on the amount of food resources in the water and characteristics of the water flow making that food available to the population. Micro-current meters were used to measure flow at locations important to oysters, such as 1 to 3 cm above the bottom and at the surface. Flow measurements were made every 3 min for 24 hr, monthly, for 1 yr at Confederate Reef (Galveston Bay, Texas, USA). Water was sampled every 3 hr to determine the amount of food resources available. Fluxes of food were calculated and indicate high variability in available food on short temporal scales, depending on time of day and season. Important differences in food resources exist throughout the water column in x - y as well as z space. These results indicate that the flux of food, rather than filtration rate, limits oyster growth and reproduction in natural populations under certain water flow conditions and food resource availabilities