不同摄食环境下夜光藻的生物-光学特性与定量反演研究

夜光藻是广泛分布于全球近岸海洋的主要赤潮生物之一，在海洋生态系统的能量传递和碳源流动等过程中发挥着重要作用。近年来我国近海夜光藻赤潮频发，给海洋生态环境带来多方面的危害。使用光学遥感技术开展夜光藻的识别与量化工作，准确评估夜光藻赤潮的爆发范围与强度，并追踪其动态变化过程与驱动因素，已成为目前亟待解决的问题。和其它常见赤潮藻种不同，夜光藻具有异养特性，主要靠摄食周围环境中的浮游植物来获取营养，因此夜光藻的生物-光学性质可随细胞内食物组分而改变，从而影响其光学响应关系。面对对夜光藻生物-光学特性与光学响应机理认识不足的科学难题，本项目拟通过开展室内外受控实验，明晰夜光藻在不同摄食环境下的生物-光学特性，在此基础上解析夜光藻丰度在不同海洋光学环境下对遥感反射光谱的调制作用，构建和检验夜光藻丰度遥感反演模型，结合多源遥感数据分析不同夜光藻赤潮过程中夜光藻丰度动态变化特征及其环境驱动因素。

Widely distributed in world’s coastal oceans, Noctiluca scintillas (NS) is one of the major phytoplankton species causing red tides, which also plays an important role in trophic energy transport and carbon cycling. In recent years, frequent NS red tides have been reported in Chinese marginal seas, causing detrimental impacts to marine fisheries, ecosystem, and economy. It is therefore urgent to develop optical remote sensing techniques to quantify NS abundance, to characterize intensity and evolution of NS red tides as well as to study environmental forcing behind NS red tides. Yet, this is hindered by lack of fundamental understanding of bio-optical properties of NS and bio-optical response to their various feeding conditions. The difficulty is further due to the fact that, unlike other red tide species, NS is heterotrophic without photosynthetic pigments, thus growing through feeding on other phytoplankton, making it difficult to characterize optically or to quantify remotely. This study is designed to address such challenges through fundamental research and practical applications, with the following objectives: 1) through laboratory culturing and field experiments, understand changes in NS bio-optical properties in response to NS feeding environment; 2) through radiative simulations and sensitivity analysis, design and develop bio-optical inversion algorithms to detect and quantify NS abundance under variable feeding and oceanic environments; 3) through multi-sensor remote sensing applications, assess dynamic changes of NS abundance in typical NS red tide events in Chinese marginal seas and understand the environmental forcing behind such changes.