The comparative effects of three toxic substances on bluegill behavior

摘要

A behavioral bioassay was used to compare the separate toxic effects of sublethal concentrations of methyl parathion, copper sulfate and chlordane on bluegill, Lepomis macrochirus. Ten behaviors were monitored in bluegill hierarchies before and after toxicant introductions. These behaviors encompassed respiratory disruptions, changes in comfort movements and aggression. Hyperactivity and increased frequencies of s-jerks and fin flicks were significant (P (LESSTHEQ) 0.05) in fish exposed to the lowest methyl parathion concentration (0.003 mg/L) used. Respiratory disruptions were significantly (P (LESSTHEQ) 0.01) elevated in bluegill exposed to as low as 0.034 mg/L copper sulfate while chlordane (0.00015 mg/L) produced increased aggression. The most dominant and most subordinate fish were more affected in every concentration of each of the three chemicals used than intermediately ranked hierarchy members. This differential response suggests that there is a combined effect due to social stress and toxicant stress. Social hierarchies develop as mechanisms to efficiently ration limited resources among individuals of a population. Low levels of methyl parathion, copper sulfate and chlordane could affect hierarchy function which might ultimately disrupt population dynamics under natural conditions.