FIG. 4.

Bioassay in aquarium format with an activated biofilter. Hyrock Farm (Maryland) pond 10 sediments (A) or clonal P. piscicida culture (B) and Neuse River (North Carolina) sediments (not shown) were inoculated into bioassay aquaria. Fish mortality was recorded for 240 days. Shaded areas indicate phases I and II of ichthyocidal activity. Water samples from all three aquaria tested positive for P. piscicida, and water quality remained compatible with fish health throughout the experimental period. Samples for analysis of microbial assemblage by ALH and denaturing gradient gel electrophoresis were taken from assay aquaria P10 and CPP.