Long-term variation of phytoplankton biomass and physiology in Taihu lake as observed via MODIS satellite

Changchun Huang; Yunlin Zhang; Tao Huang; Hao Yang; Yunmei Li; Zhigang Zhang; Mengying He; Zhujun Hu; Ting Song; A-Xing Zhu

doi:10.1016/j.watres.2019.01.017

Long-term variation of phytoplankton biomass and physiology in Taihu lake as observed via MODIS satellite

Water Res. 2019 Apr 15:153:187-199. doi: 10.1016/j.watres.2019.01.017. Epub 2019 Jan 25.

Authors

Changchun Huang¹, Yunlin Zhang², Tao Huang³, Hao Yang³, Yunmei Li³, Zhigang Zhang³, Mengying He³, Zhujun Hu³, Ting Song⁴, A-Xing Zhu⁵

Affiliations

¹ Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing, 210023, China; Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing, 210023, China; School of Geography Science, Nanjing Normal University, Nanjing, 210023, China. Electronic address: huangchangchun@njnu.edu.cn.
² State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
³ Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing, 210023, China; School of Geography Science, Nanjing Normal University, Nanjing, 210023, China.
⁴ Environmental Monitoring Center, Wuxi, 214000, China.
⁵ Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing, 210023, China; School of Geography Science, Nanjing Normal University, Nanjing, 210023, China; Department of Geography, University of Wisconsin, Madison, WI, 53706, USA.

PMID: 30711794
DOI: 10.1016/j.watres.2019.01.017

Abstract

Estimation of phytoplankton biomass (noted as phytoplankton carbon, C_phyto) and evaluation of phytoplankton physiology is central to the estimation of primary productivity and the carbon cycle. This issue has been widely considered in oceans but not in inland water. Here, we develop experiential and semi-analytical models, which validated by independent in situ measurement data, respectively, to derive C_phyto and phytoplankton absorption coefficient at 675 nm (a_ph(675)) from MODIS. The effects of nutrients and temperature on the seasonal variation of phytoplankton physiology were assessed through a novel proxy of C_phyto to a_ph(675) ratio (C_phyto/a_ph(675)) over the Lake Taihu, the third largest lake in China. Significant seasonal climatological cycles of C_phyto, a_ph(675) and C_phyto/a_ph(675) were observed in Lake Taihu, especially in Meiliang Bay and Zhushan Bay, where algal blooms occur frequently. The highest C_phyto and a_ph(675) values were observed in summer due to the growth of phytoplankton biomass and chlorophyll-a concentration. Lower values were observed in winter and spring, which are characterized by relatively high total nitrogen levels and low irradiance, owing to the low temperature astricts the algae growth. However, the C_phyto/a_ph(675) shows an opposite trend compared to C_phyto and a_ph(675), which have high values in winter and low values in summer. The analysis of C_phyto, a_ph(675) and C_phyto/a_ph(675) with total phosphorus (TP) levels and temperature indicates that TP are the main positive driver of the increase in C_phyto and a_ph(675) and negatively regulate C_phyto/a_ph(675). Warming promotes an increase in C_phyto and a_ph(675) and restricts C_phyto/a_ph(675) in summer. Biomass and nutrient levels are the primary drivers of the decrease of C_phyto/a_ph(675) in such a typical eutrophic lake. The results present some new findings compared to previous oceanic studies and expand our knowledge in the study of phytoplankton biomass and physiology in eutrophic lakes.

Keywords: Eutrophic lake; Phytoplankton absorption coefficient; Retrieval algorithms; Satellite data.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biomass
China
Eutrophication
Lakes*
Phytoplankton*