A steady supply of unicellular phytoplankton is a prerequisite to the culture of shellfish. Algal species generally agreed to be good food for developing shellfish are cultured. All these larger cultures are grown under a fluctuating light and temperature regime in the greenhouse and are aerated with filtered air enriched with CO 2 . Fluorescent and metal halide lamps provide backup lighting during cloudy periods. Using sterile technique, the cultures are inoculated into the next larger vessel on about a weekly schedule.
Larval food is harvested from the carboys.
The larger Kalwall cultures are generally used for conditioning broodstock and feeding juveniles. Wild plankton is collected by flowing raw seawater through a 5 micron bag filter for several hours. The bag is then turned inside out and the collected plankton washed from the bag to obtain a 10 liter concentrate. This concentrate is then filtered through a 20 micron sieve to remove zooplankton. This procedure usually results in a mixed diatom culture that can be harvested between for and seven days after inoculation for feeding juveniles and broodstock.