Mosquitofish, the only fish species inhabiting a drainage system that received high coal ash concentration at one end and thermal discharges at the other, appeared to successfully function in this environment with no apparent detrimental effects. Temperature conditions (44.5 C) were more limiting to the species' functional capacity than was coal ash turbidity (275 JTU) with high metal concentrations.Laboratory preference, avoidance, and lethal temperature trials supported the field observations. Mosquitofish had a final temperature preferendum at 34.7-35.1 C (both individual and group response), an upper temperature avoidance at 39 C when acclimated at 30 and 36 C, and an upper lethal temperature limit at 38 C. The species survived in this aquatic system in which elemental concentrations, determined by neutron activation analysis, were sufficiently high to be lethal to other fish species according to values from the literature and by in situ toxicity tests. Of the 40 elements measured, five (calcium, chlorine, selenium, zinc, and bromine) appeared to be concentrated by the mosquitofish, while the others were most highly accumulated in the benthic sediments. |
