USE OF ANTIBIOTICS TO REDUCE VARIABILITY IN AMPHIPOD MORTALITY AND GROWTH

The antibiotics penicillin-G and streptomycin sulfate, commonly used t o grow axenic cultures of diatoms, consistently reduce mortalities in experiments using laboratory cultures of the gammaridean amphipod Coro phium spinicorne. These antibiotics do not change average weight-speci fic growth rates of the test organisms. Applications of antibiotics ca n reduce the variability within nutritional and survival-related exper iments, and thus differences between treatments can be detected. This technique can improve the results from bioassay and toxicity tests usi ng amphipods when bacterial-induced mortalities appear to impact the q uality of test data.