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52 HAMILTON ET AL end of each chamber. Mter all four fish stopped swim- ming, their total length and weight were recorded and linked to the appropriate fish based on fish markings, color, size, or shape as observed at the start of the swimming test. Swimming capacity was calculated by the equation: swimming capacity (cm/s) = A + 6.2 (B/180), which integrates water velocity and swimming time: A is the water velocity (cm/s) during the last successfully completed interval, and B is the time (s) that the fish spent swimming at the highest water velocity reached (Beamish, 1978; Little et aI., 1985). Inorganic Analysis Water samples were collected from the residue cham- ber of each replicate exposure aquaria at 15 day inter- vals for analysis of copper, selenium, and zinc. These three elements were selected because they have been identified as the major toxic components in toxicity tests with endangered fish exposed to inorganic mix- tures (Buhl and Hamilton, 1996; Hamilton and Buhl, 1997a; 1997b). Water samples were filtered through a 0.45 p.m polycarbonate filter before preservation. Polyethylene bottles (125 mL) were used as containers for water samples and, before use, were soaked in an acid solution (40% nitric and 20% hydrochloric) for 3 days and in deionized water for at least 1 day. Immedi- ately after filtration, one set of 100 mL water samples were acidified with 1 mL HCI for selenium analysis and a second set of samples was acidified with 1 mL HN03 for copper and zinc analysis. Preserved water samples were stored frozen at - 250C until analysis. Copper and zinc concentrations in water were determined with a Perkin-Elmer model 2280 atomic absorption spec- trophotometer equipped with a model HGA-400 graph- ite furnace. Selenium concentrations were determined with the same instrument equipped with a MHS-lO hydride generator. The spectrophotometer was stan- dardized with National Institute of Standards and Technology (NIST) standard reference solutions. Cop- per and zinc samples were analyzed directly using the graphite furnace. Samples for total selenium were di- gested using a persulfate digestion technique deter- mined by a modification of the method of Presser and Barnes (1984). Each sample was analyzed in duplicate and the mean concentration recorded. Quality con- trol/ quality assurance measures included determina- tion of limit of detection, procedural blanks for back- ground equivalent concentration, percent relative standard deviation for triplicate sample preparation and analysis, recovery of inorganics from reference material, and recovery of digested sample spike solu- tions and analysis spiked samples. Recovery of copper was measured in NIST reference material 1643c water, selenium in NIST reference material 1643b and 1643c water, and zinc in U.S. Environmental Protection Agency reference material Trace Metal 1 water. Re- coveries of copper, selenium, and zinc from water sam- ples were within the recommended range of concentra- tions. Measures of quality control and quality assurance showed good recovery of the spiked samples before and after digestion for selenium and prior to analysis for copper and zinc, which suggested that the digestion procedure did not alter the amount of spike inorganic in the sample and matrix interferences were minimal (Table II). The low percent relative standard deviation of triplicate sample preparation and analysis showed consistent sample handling during preparation, diges- tion, and analysis. Results of analysis of reference materials were within recommended ranges, which showed that the digestion and analysis procedures ac- curately measured inorganic concentrations. A composite sample of larvae was collected after 30 day intervals from the residue chamber of each repli- cate exposure aquaria for analysis of whole-body con- centrations of copper, selenium, and zinc. For razor- back sucker, the composites were 15-16 larvae at 30 days, 10-14 at 60 days, and 7-12 at 90 days, and for bony tail were 15, 10, and 10-11 larvae, respectively. A sample of Biodiet was collected and analyzed for cop- per, selenium, and zinc concentrations. A sample of brine shrimp nauplii was collected and analyzed for selenium concentration. A sample of fish eggs from Dexter NFH was collected for analysis of selenium concentrations. Larvae, eggs, Biodiet, and brine shrimp samples were stored at - 250C until analysis. All fish, diet, and brine shrimp samples were prepared for anal- yses by first lyophilizing to a constant dry weight and then homogenizing with a food processor. Eggs were not dried before homogenization. Dried, homogenized samples were prepared for copper and zinc analyses with a nitric acid solubilization procedure (May and McKinney, 1981).. Dried, homogenized samples of fish, diet, and brine shrimp and wet samples of eggs were prepared for selenium analysis with a combination ni- tric acid wet digestion and magnesium nitrate dry ash technique (Pettersson et aI., 1986). The dry ash proce- dure was accomplished in Thermolyne model FA1730 muffle furnace at 500ae. Copper concentrations in tissue samples were determined by graphite furnace atomic absorption, selenium by hydride generation atomic absorption, and zinc by flame spectroscopy. Quality control measures included those given previ- ously. Recovery of copper was measured in National Research Council of Canada (NRCC) reference mate- rial DORM-l (dogfish muscle). Recovery of selenium and zinc was measured in NBS research material 50A T , (tuna) and NRCC DORM-I. Measured concentrations of copper, selenium, and zinc from reference tissues