Interannual and seasonal variation of chlorophyll-a off the Yellow River Mouth (1997–2012): Dominance of river inputs and coastal dynamics

Abstract The temporal variations of sea surface chlorophyll- a concentration off the Yellow River Mouth were investigated using SeaWiFS and MODIS data over the period of 1997–2012. And the complex interplay of different dominant factors (e.g. river inputs and coastal dynamics) on the phytoplankton dynamics in different seasons was discussed. High concentration of nutrients from the Yellow River inputs plays a significant role in sustaining phytoplankton growth. Approximately 59% of the interannual variations of the chlorophyll- a concentration off the Yellow River Mouth were attributed to river inputs (water discharge, sediment load and median grain size of sediment particles). On seasonal time scale, the Yellow River discharge of water and nutrients is a major factor that influences the increased chlorophyll- a concentration from August to October (summer and autumn). From February to May, the stronger winds and enhanced wave actions resuspend and vertically mix the previously deposited riverine sediment and the associated nutrient, thus possibly contributing to higher chlorophyll- a concentration.