Photo taken on May 7, 2012 through an optical microscope shows round-shaped Noctilucas taken from the waters near Rizhao, a city of East China's Shandong province. Five blocks of red tide have been detected in waters near Rizhao, according to a notice issued Saturday by the State Oceanic Administration (SOA). The SOA said the red tide was caused by a bloom of Noctiluca scintillan, a species of algae. The SOA will use satellite remote-sensing technology, patrol vessels and helicopters to monitor any changes in the red tide. (Xinhua/Li Ziheng)