Toxicity tests evaluated chronic and sublethal effects of fog oil (FO) on a freshwater endangered fish. FO is released during military training as an obscurant smoke that can drift into aquatic habitats. Fountain darters, Etheostoma fonticola, of four distinct life stages were exposed under laboratory conditions to three forms of FO. FO was vaporized into smoke and allowed to settle onto water, violently agitated with water, and dosed onto water followed by photo-oxidization by ultraviolet irradiation. Single smoke exposures of spawning adult fish did not affect egg production, egg viability, or adult fish survival in 21-day tests. Multiple daily smoke exposures induced mortality after 5 days for larvae fish. Larvae and juvenile fish were more sensitive than eggs in 96-h lethal concentration (LC50) tests with FO–water mixtures and photo-oxidized FO. Water-soluble FO components photo-modified by ultraviolet radiation were the most toxic, thus indicating the value of examining weathering and aging of chemicals for the best determination of environmental impact.

We designed an inexpensive (US$35), easy-tobuild apparatus that separates live freshwater amphipods Hyalella azteca from debris. In 2 d of unattended operation, the separator provided an average of 2,700 amphipods from debris per square meter of raceway bottom (range ¼ 1,600-4,000/m 2 ; n ¼ 3). Amphipod-containing debris collection, apparatus setup, and salt treatment of amphipods to kill hydras and flatworms took about 10 min.