Household vinegar advances the fight against crown of thorns starfish threat on great barrier reef abc north qld by kathleen calderwood and isobel roe crown of thorns starfish (cots) is a pest which eats coral tissues, posing a huge threat to the reef. australian institute of marine science research showed coral cover on surveyed reefs had declined by about 50% over the past 30 years, with cots responsible for almost half of that decline. james cook university scientist lisa boström-einarsson searched for an eradication method for cots that was cheap, easily available and safe for everything other than the starfish themselves. her method involved injecting the cots with 20 milliliters of household vinegar. the trial saw a 100% kill rate within 48 hours of injection. "i tried alcohol [first] and that did not work very well, and then i heard some rumors that some people had used vinegar but had not had very good results," ms boström-einarsson said. "so i refined