Impact of benzyl butyl phthalate on shoaling behavior in Fundulus heteroclitus (mummichog) populations.

Fundulus heteroclitus preference for association with familiar conspecifics of similar body length was impacted by benzyl butyl phthalate (BBP); this was found to be a statically significant result with a p < 0.0001. When presented with equally sized shoals consisting of either large or small fish, the majority of unexposed (84%) and acetone exposed control (82%) fish selected the shoal of large fish. A small number of control fish chose either the shoal of small fish (6% and 10%) or the neutral zone (10% and 8%) where they were clear morphological outliers. Fish exposed to 0.1 mg/L BBP exposure daily for four weeks selected the shoal of small fish more often than unexposed or acetone controls (7.5- and 4.5-fold respectively). They also remained in the neutral zone and displayed agitation at levels more than twice that of control. Agitation and shoal choice disruption are quantifiable behavioral responses that support the use of F. heteroclitus as a model for detecting sub-lethal BBP exposure.