Program

Chesapeake Bay has long been studied on eutrophication, ecology and hydrodynamics. However, the understanding on the biological activities are limited by sampling sizes and incubation times, and little attention has been given to the efficiency of biological carbon uptake in this region. This study investigated the large scale changes of net ecosystem production (NEP), the difference of photosynthesis and community respiration, to evaluate the biological contribution on carbon cycles using a novel underway O2/Ar method. Because argon has similar physical property of oxygen, the saturation level of O2/Ar reflects biological activities.  During the late spring and early summer, high organic matter input associated with strong spring river inflow, oxygen consumption due to organic matter decomposition are dominant in the turbid upper estuaries. NEP was reversely related to salinity (0-10%). As the consequence of inorganic nutrient availability and light attenuation became deeper because of stratification. A series of large dinoflagellate blooms occurs in the mid-bay, with large variation in phytoplankton distribution over time. Thus, this region turned into autotrophy by photosynthetic oxygen production. The scale integrated NEP are closed related to CO2 release in the upper estuary and fully interpret biological pump in carbon uptake into the productive mid-bay.