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treatment); and cooling occurred at a constant rate from 1900 to 0100 h. Water temperatures in the constant and diel fluctuating regimes were maintained close to the desired nominal or nominal + 2.5°C diel range (Table 1). Head reservoirs provided uniformly heated water to each incubation chamber. Flow-through conditions in each incubation chamber (complete exchange rate every 7.6 min) maintained dissolved oxygen at 5-6 mg/L, and prevented accumulation of waste products. Photoperiod was 14 h light: l0 h dark. Some embryos became infected with fungus in the first 16 h after tests began and embryos in all test chambers were immediately treated with 1 % formalin for 5 min and, 2 h later, with 5 mg/L malachite green for 30 min. A few embryos (< 5%), died early in the study, perhaps from fungus or developmental deficiencies. They were replaced with viable embryos from the appropriate fifth incubation chamber. After the first 16 h, no embryos were replaced. Fungus was not noted after treatment with malachite green and all subsequent egg mortality was attributed to treatment effect. Treatment of embryos with fungicide was not seen as a confounding factor because all embryos were treated similarly. Embryos with an opaque, irregularly-shaped chorion were pronounced dead; mortality was verified under a dissecting microscope (30x). Embryos were monitored 6-12 times daily and first, 50%, and 100% hatch were recorded. Immediately after hatching, each larva was measured (total length, TL, to the nearest 0.1 mm) with a dissecting microscope fitted with a calibrated ocular micrometer. Measured larvae were counted and placed in 0.5 L jars in water baths at treatment temperature until hatching was completed. Surviving larvae were then counted and returned to their incubation chambers. 12