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<br />C) <br />c., <br /> <br />l'~ <br /> <br />~;:'1I <br /> <br />I-~ <br />ij) <br /> <br />using the gravimetric method for enumeration (Piper et aL 1982), Briefly, the entire lot of eggs <br /> <br />was blotted with cloth towels to remove most of the excess water and then weighed (nearest g), <br /> <br />Three subsamples of eggs (about 300-700 eggs) were counted and weighed (nearest 0,001 g) to <br /> <br />determine average egg weight. Total number of eggs expressed was calculated by dividing the <br /> <br />total weight of the spawn by the average egg weight. The eggs used to detem1ine average egg <br /> <br />weight were placed in Whirl-Pak bags and frozen until analysis for whole-egg selenium residues. <br /> <br />Egg diameters (long axis, nearest 0.01 rom) were measured on groups of25 eggs collected from <br /> <br />each spawn using an ocular micrometer (Reichert model 426C filar micrometer eyepiece, <br /> <br />Reichert Scientific Instruments, Buffalo, NY) and stereoscope. <br /> <br />;"" <br /> <br />The remaining eggs from each spawn were transferred to three acrylic standard hatching <br /> <br />jars placed in a glass aquarium (73-cm long, 3D-cm wide, 3D-cm deep) with a water depth of <br /> <br />about 21 cm (about 46 L of water), The aquaria were placed in a water bath maintained at 21 <br /> <br />j: I DC and recei ved test water from an intermittent flow-through diluter at a rate of I L every 15 <br /> <br />minutes. A small submersible pump (1.1 amp, Little Giant) fitted with latex tubing, glass tees, <br /> <br />and glass pipets was used to deliver water from the aquaria to the three hatching jars. Water <br /> <br />flow to the jars was regulated by clamps on the latex tubing and was adjusted to gently roll the <br /> <br />eggs. Water in each aquaria was aerated using air stones supplied with compressed air. <br /> <br />Progeny Tests <br /> <br />~ <br /> <br />For the hatch.ability study, a sample of 100 fertilized eggs was collected from each spawn <br /> <br />at 1 day postspawn and stocked into egg incubation cups. Tb facilitate daily observations on the <br /> <br />condition ofthe embryos, only 25 eggs were placed in an incubation cup and four incubation <br /> <br />cups were used. Fertilized eggs were considered as those undergoing active embryological <br /> <br />16 <br />