Impact of removal of invasive species Kappaphycus alvarezii from coral reef ecosystem in Gulf of Mannar, India.

Kappaphycus alvarezii is a commercially important red alga being intentionally introduced in marine waters worldwide for the production of kappa carrageenan. Its introduction into the Gulf of Mannar Biosphere Reserve during the 1990s and its subsequent escape from cultivation sites have paved the way for its invasion into the coral reef ecosystem of Kurusadai Island. Since the report of its invasion in 2008, removal of K. alvarezii from the reefs has been started by means of manual removal (hand plucking). This article details the unsuccessful attempt and negative impact of the eradication programme. Regrowth of K. alvarezii from removal points and drifting broken fragments resulting during removal have led to further establishment in the reef environment. Variation in the morphology of K. alvarezii populations after their removal has been observed. A significant reduction in the cover of coral and native algae due to the increase in abundance of K. alvarezii was evident from the study. The need for immediate scientific control measures to eradicate the invasive alga is discussed.