Abstract
Tsunami is a serious form of natural disasters that affects the coastal ecosystem. The present paper gives a comparative account of selected hydrobiological parameters of the tsunami affected Kudankulam coast for a period of 32 months from May 2003 to December 2005. The concentration of nitrates, nitrites, and phosphates and phytoplankton density showed higher values immediately after the tsunami. The dissolved oxygen content and the zooplankton abundance decreased considerably. Post-tsunami data indicated that the coastal ecosystem recovered from the impact within five months.