Pseudoalteromonas and Fusobacterium displayed a decrease in relative abundance within all samples treated with atrazine. A subsequent increase in the relative abundance of Nocardia, a genus known for containing oyster pathogens, coincided with the decrease of Pseudoalteromonas and Fusobacterium. Directly following the 30-day treatment period, Nocardia was not detected within any of the samples except for Atrazine3.5(NR),  where it retained a minimal percent of relative abundance (<1%). However, after the 30-day rest period, Nocardia was found within the majority of the atrazine treated samples, with a relative abundance percentages ranging from 5-13% (Fig 2). Conversely, acetone and control samples never displayed an association with Nocardia either before or after the 30-day rest period. The only samples where Nocardia was detected were those treated with atrazine. All three concentrations gave rise to Nocardia colonization, with the highest relative abundance seen in sample Atrazine30.2(R) (Fig 1). Clostridium was found to be highly reduced in terms of relative abundance within all atrazine treated samples. After the 30-day recovery period clostridium dropped to <2% relative abundance in all sequenced experimental groups. 
    Clostridium, Psuedoalternamons and Fusobacterium were found to be highly reduced in terms of relative abundance within all atrazine treated samples. Clostridium dropped to <2% relative abundance in all experimental groups both directly after the treatment period and after the 30-day recovery period. Psudoalteromonas and Fusobacterium were also found to undergo a large reduction in relative abundance, However, the effects were more pronounced after the 30-day recovery period (Fig 1). The observed trends of a reduced relative abundance of Clostridium, Fusobacterium and Psudoaltermonas held true for both of the control groups as well, but to a lesser degree. 
    A Principal Coordinates Analysis (PCoA) (Fig. 3) performed using unweighted UniFrac distances allowed to further analyse the factors responsible for significant differences between groups of samples. Fig 4 shows a clear separation along the x-axis (PC1 = 23.40% of variability) between control samples (Ace_, Con_) from the remaining atrazine treated samples. Conversely, along the y-axis (PC2 = 10.97%) all post 30-day recovery period atrazine treated groups form a small cluster on the upper left quadrant of the graph, indicating bacterial composition similarities. 
    Prokaryotic diversity varied most between oysters treated with 3 μg/L atrazine without rest and the non-exposed control groups (Fig. 2). Notably, Vibrio was found to be absent in all but one of the atrazine treated groups (Atrazine10.2(NR)) (Fig. 1).  Arcobacter was present in all non-exposed control groups, but not present in the experimental groups exposed to only to acetone.