The red tides that frequently haunt Guangdong waters are threatening the province's marine ecology and aquatic product cultivation.

Li Lei, a deputy inspector at the Guangdong Provincial Administration of Ocean and Fisheries, said large-scale red tides struck the province 16 times in 2012, covering an area of more than 741 square kilometers.

"Both the number of red tides that struck the province last year and the scale of the affected water were the largest in five years," Li told a news conference on Wednesday.