CHRONIC TOXICITY OF A PROPOSED AQUACULTURE DRUG TO AN AQUATIC INVERTEBRATE

Jeffery R. Meinertz, Shari L. Greseth, and Theresa M. Schreier, U.S. Geological Survey, Upper Midwest Environmental Sciences Centers

U.S. Food and Drug Administration (FDA) approval is being sought for the use of hydrogen peroxide as a therapeutic aquaculture drug. Before hydrogen peroxide can be approved for use, the FDA must accept data characterizing the chemical's environmental safety. An environmental assessment describing the fate of hydrogen peroxide released from hatcheries into receiving waters was submitted to the FDA for review. Although their response was favorable, the FDA requested an additional study to determine the effects of hydrogen peroxide on a chronically exposed aquatic invertebrate. A study was designed to determine the hydrogen peroxide concentrations that have no effect on the growth, time to production of the first brood, numbers of broods, number of progeny per brood, and survival of Daphnia magna during 21 days of continuous exposure in a flow through test system. Daphnia magna was chosen for testing because it is considered a sensitive aquatic invertebrate species. The continuous exposure regimen was selected to represent a worst case exposure scenario that could occur during intensive aquaculture operations.

The experimental design included six test groups with target hydrogen peroxide concentrations of 0.0, 0.32, 0.63, 1.25, 2.5, and 5.0 mg/L. Each test group consisted of 10 test chambers. Each chamber was randomly assigned to one of 10 blocks so that each test group was represented in each block; a randomized block design in a 2 x 3 configuration. Daphnia magna were continuously exposed to hydrogen peroxide for 21-days in chambers (volume 205 mL) with continuous flow rates of about 5 mL/min (about 35 volume exchanges per 24 h). A portion of the data generated during the study is presented in Table 1.

Table 1. Length and production from daphnia continuously exposed to hydrogen peroxide for 21 days. Length data are from daphnia that survived to the end of the trial (na = not applicable).

Hydrogen peroxide concentration
(mg/L) Adults surviving for 21 days Adult mean length
(mm) Mean number of young in first brood Total young produced
0.0 10 of 10 4.616 20 1516
0.32 9 of 10 4.455 22 1564
0.63 9 of 10 4.391 16 1388
1.25 8 of 10 3.901 8 1000
2.5 0 of 10 na 1 1
5.0 0 of 10 na na 0

SUGGESTED READING

Gaikowski, M.P., J.J. Rach, J.J. Olson, and R.T. Ramsay. 1998. Toxicity of hydrogen peroxide treatments to rainbow trout eggs. Journal of Aquatic Animal Health 10:241-251.

Gaikowski, M.P., J.J. Rach, M. Drobish, J. Hamilton, T. Harder, L.A. Lee, C. Moen, and A. Moore. In press. Efficacy of hydrogen peroxide to control mortality associated with saprolegniasis on walleye, white sucker, and paddlefish eggs. North American Journal of Aquaculture.