Water Quality Assessment and Genetic Insights into Cyanobacterial Toxin Presence in Gyeonggi Province Reservoirs

This study aimed to examine the water quality of and presence of genes linked to cyanobacterial toxins in 17 reservoirs in Gyeonggi Province, South Korea. The levels of TN, TP, and chlorophyll-a indicated nutrient conditions ranging from eutrophic to hypereutrophic, consistent with international standards. Most reservoirs were found to be vulnerable to algal blooms beyond the eutrophication stage. Chlorophyll-a correlated positively with TP and TOC but negatively with TN in most reservoirs. The mcyA gene for microcystin was detected in 14 reservoirs, with a 64.9% detection rate. The toxin was detected in 47.2% of these cases, with increased concentrations in summer. The dominant microcystin variants were MC-LR>MC-RR>MC-YR. The anaC gene for anatoxin-a was detected in 11 reservoirs at an 18.9% rate, with a toxin detection rate of 9.5%. The aoaB gene for cylindrospermopsin was detected in six reservoirs at a 12.6% rate, although the toxin itself was not detected. This study emphasizes the ongoing presence of cyanobacterial toxin genes and their toxins in Gyeonggi Province reservoirs. The potentially increasing adverse impact of these toxins, because of climate change, needs to be addressed via continuous monitoring and management.