The Satake Pulse Counter is the only method that provided data outputs as estimated 
individuals/volume; this method tended to underestimate the concentration of individuals as 
compared to microscope counts (see Figure la, lb; most data points fall below 1:1 line), but 
precision was higher than microscopy (i.e. less variation between replicates, Figure C.l). 
Interestingly, for low concentrations, both the Satake Pulse Counter and SGS ATP (aqua-tools) 
showed a strong relationship between microscope counts and measured value (ind/ml and 
ng.cATP/ml, respectively) with one group of outlier data (Figure lb; outlier data points came 
from same trial). The Walz WATER-PAM and the Hach BW680 fluorometer also showed a fairly 
strong concordance with microscopy values at low concentrations (Figure lb). 
3.2 Results for 10-50 pm size class 
Nine methods were used to analyze water samples containing organisms in the 10-50 
pm size range: three FDA methods (epi-fluorescence microscopy using FDA stain, Satake Pulse 
Counter, MLML bulk FDA), four CFA methods (bbe lOcells, Hach BW680, Turner Designs' (TD) 
BallastCheck-2™ , Walz WATER-PAM), flow cytometry (Beckman Coulter Epics-XL-MCL), and 
MLML ATP (Table 1). Five methods/devices were able to provide estimates as 
individuals/volume: Hach BW680, bbelOcells, TD BallastCheck-2™, flow cytometry (counts the 
sum of live and dead organisms), and the Satake Pulse Counter. Most methods were sensitive 
enough to detect organisms in the ballast water at a range of concentrations, including values 
less than 10 per mL (Figure 2a,b; but see Hach BW680 where several samples from open ocean 
oligotrophic waters were below the detection limit), and all methods showed a positive 
relationship between measured values and microscope estimates (Figure 2). The Satake Pulse 
Counter underestimated organism concentrations as compared to microscope estimates (see