Why measure chlorophyll using aircraft ocean color sensors?

The distribution of phytoplankton in estuaries and coastal waters is characterized by high spatial and temporal variability. Phytoplankton “blooms” may be short-lived and patchy, making it difficult to sample them effectively using traditional methods. Aircraft can monitor the entire Bay in less than a day, providing a rapid assessment of surface water conditions.

What is the spring “bloom”?

The annual cycle of phytoplankton in Chesapeake Bay is dominated by a spring "bloom" that constitutes the highest biomass of the year. This bloom, composed mainly of diatoms that are phytoplankton typical of rich marine systems, is the source of particulate organic material that leads to anoxia in the deep channel of the main stem Bay in summer. Chlorophyll concentrations in the spring bloom often exceed 30 mg m^-3 in a significant part of the estuary. Several characteristics of the spring chlorophyll maximum are highly variable among years, including the timing, position, and magnitude of the peak.

What happens in summer?

By late spring, concentrations of chlorophyll generally decline in the lower Bay as nutrients, particularly nitrogen, become depleted. In summer, flagellated forms of phytoplankton replace the diatoms of spring. Several dinoflagellate species often reach red-tide proportions in late spring and summer with concentrations that can reach 50-100 mg m^-3. The high densities that are attained in these blooms are extremely patchy and are often more prevalent on the western side of the main stem Bay and in the mouths of some tributaries. By late summer to fall, chlorophyll concentrations decline throughout the Bay.