Evaluation of a battery of toxicity tests for use in the assessment of water quality in a Costa Rican laboratory

Abstract

The Laboratory for Ecotoxicological Studies (ECOTOX) of IRET evaluated the following toxicity tests: Daphnia magna (daphnia test), Hydra attenuata (hydra test), Allium sp. (onion test), Panagrellus redivivus (nematode test), Lactuca sativa (seed test), and the Fluctuation kit. Selection criteria were that the tests should be sensitive to a range of different toxicants, reliable, and preferably of low cost. The tests were evaluated for their reproducibility and sensitivity with 24 blind samples which contained metals, pesticides, and other organic compounds. The hydra, seed, and onion tests were more reproducible when evaluated with a set of samples of a mixture of cadmium and metolachlor. Daphnia and hydra were the most sensitive organisms in our laboratory using mortality or reduction in growth as endpoints. Sublethal effects in the hydra test were useful to detect additional effects. Lettuce seeds and onions performed better than the nematode test for pesticides and other organic compounds. For metals the nematode test was more sensitive than the seed and onion tests. Environmental water samples collected in a banana plantation area were tested with the hydra and seed assays. The hydra test was more sensitive to the pollutants present in these samples. Reproduction in the hydra test was measured as an additional endpoint and differences with the control were observed. This study concluded that short-term bioassays such as daphnia, hydra, seed, and onion tests are promising for screening water quality. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 312–321, 2000