KERKENNAH ISLANDS, Tunisia, Nov 13 (Reuters) - (This Nov. 13 story has been corrected to show sea is overall 1.2C warmer than 30 years ago, not 0.4C, in 18th paragraph) A decade ago, Tunisian fisherman Ahmed Chelli's nets bulged with fish and octopus that he sold at the local market in the Kerkennah islands.Temperatures climbed higher, and the heatwave lasted longer, than any other to hit the waters west of Sicily since record-keeping began in 1982, Garrabou said, based on preliminary findings from his analysis, shared exclusively with Reuters.Measurements taken by European Space Agency satellites show that, from June through September, the waters off north Africa and southwest Europe were 2 to 5 degrees Celsius above the 1985-2005 daily averages.A 2016 marine heatwave along Chile's southern coast caused huge algae blooms that wiped out fish farms and cost the aquaculture industry some $800 million, said scientist Kathryn Smith with the Marine Biological Association of the United Kingdom.The bright yellow rabbitfish, for example, overgrazes seagrass beds, destroying plants that provide a key habitat for local species and sequester carbon."