The acute sublethal effects of the pesticides carbaryl and malathion on partial ethograms of the yellow bullhead : (Ictalurus natalis (Lesueur)) after exposure to the pesticide carbaryl and malathion

"The acute sublethal effects of the pesticides carbaryl and malathion on partial ethograms of the yellow bullhead, Ictalurus natalis (Lesueur).

The dominant fish of pair colonies of adult yellow bullheads, Ictalurus natalis (Lesueur) were acutely exposed (48 hours) to sublethal levels 1, 2, and 4 mg 1^-1 of carbaryl and 1, 2, and 4 mg 1^-1 malathion. The alterations of social behaviors in a partial ethogram (reproductive behaviors were excluded) were recorded in a geometric time series and analyzed. Analyses of Variance and Multiple Classification Analyses of transformed data demonstrated clear alterations of field substantiated social behaviors with both chemicals. Carbaryl altered abilities to maintain dominance temporarily. In some malathion exposed animals dominance was apparently not maintained over approximately 10 days, when compared with untreated yellow bullheads. An interference with feeding (ingestion) reactions by carbaryl was not accompanied by a corresponding inhibition of sensory ability in detecting food. Social behaviors in non-treated bullheads were generally "opposite" to the treated fish. Social behavior alterations provided more sensitive indications to toxicants than physiological reactions.

The ethological methods employed revealed a level of damage and extent of risk to a species heretofore generally unappreciated. The exposure levels of these short-lived common pesticides were reasonably close to detected ambient levels in forested watersheds, estuaries and agroecosystems.

The implications of alterations of social behavior and structure on short-term adaptive ability of species are hot known; however, these effects may be much more profound than acute large scale mortalities.

The hypothesis that possible ambient environmental levels of two pesticides altered social behavior was substantiated.