Weijun Jian1, 2 and Jay-Chung Chen1, 1Center for Coastal and Atmospheric Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, 2South China Sea Institute of Oceanology, Chinese Academy of Science, 164#, Xingangxi Road, Guangzhou, China
Abstract
A survey of bio-optical characteristics was carried out during four cruises in the coastal waters near Hong Kong, including Peal River Estuary & Lamma Channel, Port Shelter, Tolo Harbor and Mirs Bay, from March to May 2001. Two red tides, the dominating species of which were Chattonella ovata and Prorocentrum dentatum, were captured in Port Shelter and Tolo Harbor, respectively. The samples were analyzed for Chlorophyll-a and other pigment concentrations, phytoplankton species composition and abundance. Optical property profiles at the sampling stations were taken by the Biosphericals PRR800 instrument. Together with the laboratory analysis, the relationship among the absorption coefficients of particulates, phytoplankton, detritus and soluble materials, reflectance and water leaving radiance were obtained. It is found that there were spatial and temporal differences of optical properties in coastal waters. The bio-optical properties varied clearly during the algal blooms. Especially both these two red tide causative species had high absorption characteristics in the UV region. Based on the results, the application feasibility of using the bio-optical properties in the UV region to monitor red tide in case 2 waters is discussed.