Toxin concentration Toxin analyses recorded the presence of low concentrations of various variants of microcystins (MCs) on a number of occasions To evaluate the potential threat posed by microcystins to different animals that utilize the pond water, toxin values are provided in ug L highlight the threat posed to pond water drinkers or those living in the water). Additionally toxin content was calculated as ug mg DW of the total phytoplankton biomass (to illustrate the potential assimilation by filter feeders) and in ug mg DW of the total cyanobacteria biomass (Table 3), overall the presence of microcystins in the pond water was found to be a highly irregular event with total microcystin concentration (sum of microcystins) ranging from below the of detection to 1.66 pug L of pond water (Fig. 2) Expressed in terms of phytoplankton biomass, the highest microcystin content was 0.28 ug mg phytoplankton DW. Based on the total cyanobacteria biomass, the maximum toxin content was 551.08 ug mg cyanobacteria DW (Table 3). The dominant MC