Abstract |
A fully enclosed test system was developed to assess both potential adverse effects of microbial pest control agents on nontarget aquatic invertebrates and monitor their fate and survival. Eastern oysters, Crassostrea virginica, were exposed to various microbial pest control agents including the vegetative bacterium, Pseudomonas fluorescens, bacterial spores of Bacillus sphaericus, and fungal spores of Colletotrichum gloeosporioides f. sp. aeschynomene. After an exposure of 3 days for the fungus, 14 days for the bacterial spores, and 7 days for the vegetative bacterial cells, half the oysters were placed into a fully enclosed 60 liter aquarium equipped with a recirculating water system which passed water through an ultraviolet-irradiation sterilizer at a rate of 1 liter per minute. The remaining oysters were placed into wire cages maintained in Santa Rosa Sound, Pensacola, Florida. Plate counts performed on homogenized oyster tissue, revealed that all of the microbial pest control agents were found in the oyster after exposure. None of the agents colonized the animals. Oysters depurated each microorganism at a different rate. For all microbes tested, their rates of clearance from the oysters in the enclosed UV light depuration system was similar to the rate of clearance from the oysters in Santa Rosa Sound. (Copyright (c) Inter-Research 1993.) |