Evaluation of Erythrocyte δ-amino Levulinic Acid Dehydratase Activity as a Short-Term Indicator in Fish of a Harmful Exposure to Lead

Abstract

The activity of erythrocyte .delta.-amino levulinic acid dehydratase (ALA-D) of fish is easily measured under a variety of experimental conditions. Exposure of rainbow trout (Salmo gairdneri), brook trout (Salvelinus fontinalis), goldfish (Carassius auratus) and pumpkinseeds (Lepomis gibbosus) to Pb consistently inhibited ALA-D within 2 wk at concentrations as low as 10, 90, 470 and 90 .mu.g/l, respectively. In rainbow and brook trout, these concentrations were closely related to the published minimum effective concentrations causing sublethal harm. There was a significant linear relationship between ALA-D activity and log of blood Pb concentration, between ALA-D activity and log of Pb in water, and between blood Pb and Pb in water. Near lethal exposures to Cd, Cu, Zn and Hg did not significantly inhibit ALA-D activity. Recovery of ALA-D activity of rainbow trout after transfer from 120 .mu.g/l Pb to clean water occurred in 8 wk. This enzyme provides fast, consistent, specific and sensitive estimates of Pb concentrations causing sublethal harm to fish and may help to relate sources of Pb to degree of exposure of fish populations in the field.