Spatial and seasonal variability of chlorophyll a in different-sized lakes across eastern China

Chlorophyll a (Chl-a) in lakes is an indicator of phytoplankton biomass and widely employed in lake management. Here, we used Chl-a data from 586 lakes ≥1 km2 in eastern China from 2013 to 2018 derived from the Operational Land Imager (OLI) onboard the Landsat-8 satellite to examine influences of climatic and anthropogenic factors on Chl-a variations among these lakes, partitioned into groups of different sizes. The results indicate that Chl-a values in small lakes (1–50 km2) were higher than those in large lakes (>50 km2), and the mean Chl-a in summer and autumn was higher than in spring and winter. Air temperature was positively correlated with the seasonal mean Chl-a in all sizes of lakes. Small lakes had a larger cropland proportion in their watersheds than large lakes, suggesting that the higher cropland proportion of the land cover contributed to the high Chl-a of these lakes. This research highlights the merit of high spatial resolution remote sensing for monitoring lakes in a regional context and indicates that the management of lakes could benefit from controlling agricultural activities in their watersheds.