Modeling oyster populations. 3. Critical feeding periods, growth and reproduction




Hofmann EE
Powell EN
Klinck JM
Wilson EA

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A time-dependent population dynamics model for oyster (Crassostrea virginica) populations is used to test the hypothesis that variations in the seasonal sequence in temperature and food supply are responsible for observed variations in oyster reproductive effort. Simulations show that a few degrees change in temperature or a small shift in timing of the spring or fall bloom can considerably alter the duration of spawning and the seasonal spawning patterns. Furthermore, the timing of the spring and fall plankton blooms relative to the spring increase and fall decrease in temperature is crucial in determining reproductive effort over a spawning season. Delay of the spring bloom with respect to the spring temperature rise increases reproductive effort and affects the number and timing of spawning pulses. Simulations using environmental conditions appropriate for Laguna Madre, Galveston Bay and Chesapeake Bay show that reproductive effort decreases with increasing latitude and that the timing of increases in food supply relative to rising temperature becomes more important. Other environmental factors such as low salinity events and turbidity have a lesser effect on population growth and reproduction than do changes in temperature and food supply. The model results suggest that oyster reproductive patterns at higher latitudes (e.g. Chesapeake Bay) are characterized by discrete spawning pulses; continuous spawning becomes more frequent at lower latitudes. The results of this modeling study suggest that the characteristically-wide range of oyster reproductive efforts recorded in the literature may result from seemingly minor changes in the environment




Crassostrea, Crassostrea virginica, DO, environmental conditions, environmental factors, feeding, food availability, Galveston Bay, growth, mathematical models, O 5020 Fisheries and Fishery Biology, Plankton, population dynamics, Population growth, Populations, Q1 01442 Population dynamics, Q3 01583 Shellfish culture, Reproduction, Salinity, simulation, spawning, spring, Temperature, Temperature effects, Timing, Turbidity, USA