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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />.' <br />~i <br />1'(\.................... <br />.. <br /> <br /> <br /> <br />,. <br />~:0~' <br /> <br />~.. <br /> <br />f~' <br /> <br />ti. <br /> <br />- <br /> <br />24 <br /> <br />Reclamation (USBR) facilities, Boulder City, Nevada, or Arizona State University <br /> <br /> <br />(ASU), Tempe, Arizona. Incubation trays were of2S0-,um NitexR screen on a rectangular <br /> <br />frame, floating in 38- or 7S-L aquaria half filled with aged tapwater and aerated to induce <br /> <br /> <br />slight current. Netting was about a centimeter beneath the surface and developing ova <br /> <br />arranged in a single layer. Hatching temperature was 18:tlOC (USBR) or 20:tSoC (ASU); <br /> <br /> <br />higher variations in the latter were due to cooling system malfunctions. All were on a 12 <br /> <br />: 12-hr flourescent-light photoperiod; two small windows at USBR allowed natural <br /> <br /> <br />change in day length. <br /> <br />Embryos were visible within the translucent ova a day after fertilization. Dead <br /> <br />ova were white, and opaque, and removed daily or more often. Fungi were a primary <br /> <br /> <br />agent of mortality after the second day and all eggs that appeared infected also were <br /> <br /> <br />removed. Fungi were suppressed by S- to 10-min dips in 1: ISO dilutions of formalin. <br /> <br /> <br />Hatching began in 6 d and continued for 36 hr. Newly hatched larvae were unable to <br /> <br /> <br />sustain swimming and spent most time on the substrate, from where they were pipetted <br /> <br /> <br />into aerated 38-L aquaria. Directed movement (swim-up) began a few days later. <br /> <br /> <br />In all but starvation experiments (see later), larvae were fed 3 times a day with <br /> <br /> <br />first instar brine shrimp (Artemia salina) (Arum AquacultureR) produced on-site in 2.0-L <br /> <br /> <br />jars. To harvest nauplii, hatching jars were removed from aeration and placed on a light <br /> <br /> <br />table. Negatively buoyant nauplii speeded by their positive phototaxis concentrated on <br /> <br /> <br />the bottom, from where they were siphoned to another container. A milliliter of <br /> <br /> <br />concentrated nauplii was diluted into each of 3, 10-ml sub samples and enumerated in a <br /> <br />Sedgewick-Rafter cell. The three counts were averaged to estimate total nauplii/ml, used <br />