Appendix 2: Details on the functioning of the Ciona system
(numbers referred to in brackets [n] are those in Fig. 10)
Aquaria
1.Each experimental aquarium [1] of 35 liters contains two holding supports.
2. Seawater flow rate through the aquaria ranges between 10 and 15 l/h, corresponding to 7 - 10 turnovers of seawater per day.
3. Before entering the aquaria, the seawater passes through a series of three cartridge filters (20; 10; 5 microns) [2] and through a U.V. sterilizer [3] to reduce the amount of introduced hosts (zooplankton eggs and larvae; possible pathogens), which could endanger early stages of growth of ascidians or compete with them.
Food1.Food is introduced into the aquaria continuously, mixed with the seawater. In our systems we have sets of 10 tanks supplied by a centralized "food tank" [4], which collects the incoming seawater. This is where we introduce the food mixture through peristaltic pumps [5].
2. From the food tank the enriched water is distributed to the aquaria (Fig. 14). See Appendix 4 for the schedule of animals' diet and details of food preparation; food solutions [6] are continuously stirred.
3. Food is maintained in suspension by airstones, both in the food tank and in the aquaria.
Physico-Chemical ConditionsSee Appendix 3 for notes on the physico-chemical conditions applied to the system.