Primary Production and Satellite Remote Sensing Nastassia Patin Summer Workshop in Marine Science at Georgia Tech June 27 2017

Phytoplankton are primary producers ~50% of all oxygen in the atmosphere is produced by single-celled photosynthetic algae known as phytoplankton

Primary production regulates climate and forms the foundation of the marine food web Herndl and Reinthaler 2013 Nat. Geosci.

Types of phytoplankton Coccolithophores “brussels sprouts covered in chalk” Diatoms “brussels sprouts covered in glass” Dinoflagellates “brussels sprouts covered in wood” Cyanobacteria “bacteria”

Photosynthesis relies on chlorophyll

Chlorophyll a reflects green light (500-600 nm)

Satellite remote sensing Aqua and Terra satellites use the Moderate Resolution Imaging Spectroradiometer (MODIS) to look at irradiance of Earth’s surface MODIS views the entire planet every 1-2 days and covers a swath of 2330 km podaac.jpl.nasa.gov/Terra

Satellite remote sensing MODIS scans for irradiance at the wavelengths emitted by chlorophyll a We can use those readings as a proxy for phytoplankton population density en.wikipedia.org/wiki/Moderate-resolution_imaging_spectroradiometer

What causes phytoplankton blooms? Limiting nutrients (eg nitrogen and phosphorous) What are some nutrient sources? Coastal runoff, upwelling oceanservice.noaa.gov

Harmful Algal Blooms (HABs) Gulf of Mexico dead zone Phytoplankton blooms like this “red tide” can produce toxins that harm fish, birds, humans

Algal blooms precede dead zones High nutrient loads can lead to algal blooms These blooms are then consumed by heterotrophic bacteria that deplete the water of oxygen Gulf of Mexico dead zone

Exercises Part A: Chlorophyll and Sea Surface Temperature (SST) neo.sci.gsfc.nasa.gov Under “Ocean” navigate to “Chlorophyll Concentration” and “Sea Surface Temperature 2002+ (MODIS)” Part B: MODIS Chlorophyll a Printout has wrong URL! Instead use: giovanni.gsfc.nasa.gov