Ag. Heath et al., PHYSIOLOGICAL-RESPONSES OF FATHEAD MINNOW LARVAE TO RICE PESTICIDES, Ecotoxicology and environmental safety, 37(3), 1997, pp. 280-288
Newly hatched fathead minnow (Pimephales promelas) larvae were exposed
for 4 days to two pesticides and ambient receiving waters to simulate
conditions in the Sacramento River, California, during the striped ba
ss spawning season which coincides with pesticide use in adjacent rice
culture, Carbofuran and molinate were tested at two concentrations: a
higher level approximating one-half the LC50 and a level much lower t
hat is similar to that seen in the receiving waters of Colusa Basin Dr
ain, Physiological measurements were made immediately after the exposu
res and again after a 10-day recovery period in noncontaminated waters
, These included growth rate, swimming capacity, response to a mild el
ectric shock, upper and lower lethal temperatures, and activity of ace
tylcholinesterase in whole-body homogenates. The higher concentrations
of carbofuran and molinate caused reductions in swimming capacity, an
increased sensitivity to the electric shock, and a reduction in upper
lethal temperature, Acetylcholinesterase was reduced in those larvae
exposed to the higher levels of carbofuran, In general, the lower leve
ls of pesticide exposure caused no measureable effects nor did exposur
e to water from Colusa Basin Drain. (C) 1997 Academic Press.