Water Quality Effects of Hydraulic Dredging and Microbial Autochthon Population, a Case Study in Kochi (Kerala) India

Bacteriological effects of hydraulically dredging polluted surface water in the navigational channel of the Cochin port were investigated. Results indicated extraordinary high indicator bacterial population, nutrients and total suspended solid (TSS) concentrations in the Cochin estuary when the approach channel was being dredged. The maximum viable bacterial population reported before and after dredging event was 8200CFU/ml and 37000CFU/ml respectively. 4 6 times increase was observed for all the indicator bacteria after dredging which obviously indicates water quality deterioration. PCA reveals significant positive relationship of all indicator organisms with TSS and negative relationship with transparency, indicating the intensive dredging activity may lead to the resuspension of sediments and with that the release of sediment bound indicator bacteria. Further, the drastic reduction in benthic population after dredging suggests the disruption of benthic habitats and which also provides an advisory tool for potential ecological health risk.