Abstract
An automated, flow-through, multi-aquarium system with precise temperature control and dosed inputs of water soluble toxicants has been built from biologically inert materials for long term effect-studies on aquatic organisms. Although especially constructed for effect-studies of oil (water soluble fraction) on eggs and larvae of marine fishes, the biotest system holds the potential of testing other water soluble toxicants on aquatic animals within a size range from 1 mg to 1 kg. In its current form, the biotest system has a capacity of about 120.000 eggs or 60.000 yolk-sac larvae of cod (Gadus morhua L.), divided between two test groups and one control group, each of four parallel aquaria. Special consideration has been given to essential steps and components in order to maximize continuity of operation, safety, and ease of handling of the system. The long term temperature variation of the system is within 0.05° C, and the temperature difference between the experimental groups within 0.005° C. The stability of the dosage pumps is within 2 per cent. Two days of extraction are sufficient for a partial stabilization of the stock solution which then can be used for biotest purposes for at least a following week. The stirring of the stock solution and its subsequent dilution is adequate to deliver homogeneous test water of the programmed concentrations. No loss of oil components occurs in the pipelines between the stock solution tank and the test aquaria.