The Effects of Pheophytin a on Absorption Properties of Phytoplankton in Dalian Bay, China

Abstract

Abstract We examined the effects of pheophytin a (Phe-a) on absorption properties of phytoplankton obtained from the red tide prone area of Dalian Bay in the North Yellow Sea, China, in June 2007 and July 2011. When the proportion of Phe-a relative to chlorophyll-a (Chl-a) increased, the absorption peak in the blue-violet region shifted from 438nm to 409nm. The relationship between blue-violet absorption maximum and Phe-a concentration is more tightly correlated than the relationship between blue-violet absorption maximum and Chl-a concentration. However, we found the opposite results for the red absorption maximum. These findings suggest that Phe-a mainly effects the blue-violet absorption maximum, while Chl-a primarily controls the red absorption maximum. Our results are determined by specific absorption coefficients of Phe-a and Chl-a in living algae cells. A multivariate linear regression analysis revealed that the specific absorption coefficients of Phe-a accounts for the absorption peaks at 407 nm and 673 nm, and specific absorption coefficient of Chl-a accounts for the absorption peaks at 440 and 673 nm, furthermore, the specific absorption coefficients of Phe-a are much larger than those of Chl-a in the blue-violet region, but they are lower in the red region.