Three-spined sticklebacks do not respond behaviorally to environmentally relevant concentrations of the toxic explosive 2,4,6-trinitrotoluene

Approximately 1.6 million tons of conventional munitions were dumped in German coastal waters. Corrosion of munition shells facilitates the leakage of explosives, such as the toxic and carcinogenic 2,4,6-trinitrotoluene (TNT), into the marine environment. Consequently, TNT contamination was detected in seawater, sediments, and marine organisms near munition dump sites, and is known to cause adverse effects in marine organisms. Accordingly, avoidance of contaminated areas would be advantageous for fish. We therefore hypothesized that fish respond to dissolved TNT and exhibit an avoidance reaction. To test this, we exposed three-spined sticklebacks (Gasterosteus aculeatus) to environmentally relevant TNT concentrations and evaluated their behavioral response. Individual fish were placed in a behavioral test tank equipped with two hideout zones composed of artificial plants. The hideout zone occupied by the stickleback was infused with either TNT solution (100 µg/L) or control water. Behavioral readouts included the time stickleback spent in the infused hideout zone, time until the exposed hideout zone was first left, and number of transitions between hideout zones. Sticklebacks did not exhibit significant behavioral responses to environmentally relevant TNT exposure. Consequently, fish inhabiting munition dump sites may experience chronic TNT exposure, potentially increasing long-term toxicological risks.