Producing Acartia tonsa

Batch culture of A. tonsa copepods is relatively straightforward, once proper environmental and nutritional conditions are met. Start with a clean 300L tank, algae, and filtered, UV-treated seawater. Tanks can be stocked with nauplii or copepodites. Clean and feed the tank daily. Adults will begin producing eggs and sperm in 9-12 days; thereafter egg production will rise, peak, and fall. Separate eggs, nauplii, and adults from the detritus daily, using graded sieves, then return adults and nauplii to the tank. Clean the eggs and discard detritus. Prepare eggs for immediate use or storage. Once the hatching success falls below 75%, it is time to terminate the culture batch. For continuous production of nauplii, start sequential batch cultures at 5-7 day intervals. When timed correctly, one tank of a series will be at maximum productivity at any given time.

System Design Considerations

Ergonomic design	minimize wasted labor
Critical systems backups and alarms	avoid catastrophes
Clean and safe operation	avoid accidents
Site security and biosecurity	avoid contamination
Flexibility of operations	enhance opportunities
Scale of linked operations	assure success

FSU uses 300 L fiberglass tanks for meso-scale culture and we are scaling up to 1000 L tanks for full-scale production. Tanks should be maintained independently and run as batch cultures to minimize risks. Batches of nauplii are stocked, fed, regularly cleaned, and monitored. Once egg production begins, tanks are siphoned and fed everyday. Water changes per day average 15-20% of the tank volume (from siphoning and feeding) done properly. System design should address minimizing contamination, regulating water quality, algae production requirements, daily maintenance requirements, efficient use of labor, and desired level of egg production. Smaller tanks in replicate sets are more costly, but catastrophic loss impacts would be reduced by redundancy.

Tanks must be designed and arranged to be independently cleaned, filled and drained, heated and cooled, and conveniently worked. Tanks should be covered, to prevent contamination; but the cover must not impede regular siphoning of the bottom of the tank. Labor must be allotted for tank maintenance, feeding, population and egg counting, sieving, and egg storage. Many small tanks will require disproportionately more labor than a few large ones. For research, this extra labor is acceptable. For commercial scale production the higher risks of catastrophic loss may be offset by the lower labor costs fewer tanks would require.

Tanks for culturing A. tonsa should have a flat bottom for ease of egg collection and tank cleaning. Depth and width are also dependent on human ergonomics, such that no more than 1 m depth or 1 m width/diameter is recommended when tanks are arranged in pairs along their long axis. Freestanding tanks may be up to 2 m in width and still be worked effectively from both sides. Acceptable length of tanks is a function of building design, fabrication costs, and production goals. Sufficient space must be provided between tanks to allow workers to perform effectively. Tanks ideally should be elevated off the floor, to increase control of tank thermal conditions and to allow for easy plumbing of the system.