The potential of high-fidelity spatial, spectral, temporal, and radiometric sensors to advance aquatic remote sensing beyond chlorophyll
The coastal zone, or transition between land and ocean biomes, is the largest ecotone on Earth, contributing an estimated $12.5 trillion to the global economy annually. There is an urgent need to better monitor, manage, and protect our global coastal ecosystems, which are showing signs of stress leading to declining fisheries, reduced biodiversity, increasing harmful algal blooms and hypoxia, and the potential for catastrophic collapse of key ecosystems such as kelp forests, which provide a mediating influence on ocean acidification and the increasing burden of CO2 in the atmosphere. NASA’s historical emphasis on measuring chlorophyll globally has been and remains important, but it does not address our mandate to understand, protect, and manage critical coastal regions. NASA’s recent (2018) Decadal Survey calls for development of a UV-NIR hyperspectral sensor with high spatial (30-60m) resolution for application to land and coastal systems. This will allow us, for the first time, to routinely estimate ocean “health” at relevant scales by developing Phytoplankton Functional Type (PFT) models that can be used with existing algorithms such as the Phytoplankton Food Quality Index. While a global sensor is not yet available, multiple datasets (e.g. HICO, HyspIRI) allow us to simulate what a future satellite might provide, paving the way to effectively move beyond chlorophyll as the primary biotic metric of coastal ecosystem health and productivity.