AN APPARATUS FOR TESTING THE EFFECTS OF EPISODIC STRESSORS ON JUVENILE AND ADULT FISHES

We describe an apparatus designed to deliver pulsed changes in water q uality with variable (and controlled) magnitudes, rates and durations. The apparatus combines both standard flow-through and recirculating s ystems, and it is designed for use with six 114 l aquaria. All compone nts are of standard materials and sizes, and customizing to fit existi ng systems is easily accomplished. The apparatus has been used to simu late the dramatic changes in salinity associated with freshwater canal discharge into Biscayne Bay, Florida. An example of its application o n juvenile bluestriped grunts (Haemulon sciurus) is presented. Althoug h we focus here on salinity fluctuations, the apparatus could also be used to examine the effects of other variables (e.g., temperature, tur bidity, and contaminants) with little or no modification to the system .