Improving the use of satellite imagery through the use of previous water column measurements

By Ben Gustafson

Phytoplankton are tiny organisms that are important to everything living in our oceans, including here in the Gulf of Maine. They get their energy from photosynthesis, provide oxygen for the oceans, and become food for many other ocean animals, and are the base of the ocean food web. They also deliver particles to the bottom of the ocean that can help limit climate change.

As the Gulf of Maine warms rapidly due to climate change, it’s vital to know how this affects those making food for the entire ocean.  To measure the amount of phytoplankton, we use shipboard measurements to continuously collect water samples while traveling across the Gulf of Maine. We can use these water samples to measure how many phytoplankton there are in the water — near the surface and as you move deeper into the ocean. But, traveling on these ships costs lots of money and so there are only a limited number of trips each year to collect samples.

To help with measuring phytoplankton more frequently, we also use satellites to take pictures of the ocean on any clear day. The color of the ocean can tell us how many there are at that time. It’s like looking at pictures rather than having to pay for an expensive trip to a foreign country– the next best thing, but something’s missing. Like a 2-dimensional picture, satellites can only see the surface concentrations of phytoplankton.

We aim to find the percentage of them that are living at the surface during all four seasons. The amount of phytoplankton at the surface is different in each season. For example, as the water warms up in the summer and it gets sunnier, they like to hang out deeper in the water where it’s not too hot or bright for them– just like how you don’t want to go into a hot tub on a sunny summer day.  If we find the percentage of phytoplankton that is at the surface for each season, we can use this factor to find the total concentration. That way, scientists can find the amount of phytoplankton in the Gulf of Maine for any clear day from the comfort of their homes, allowing them to track the concentrations of these important organisms more frequently.

Ben Gustafson is a Colby College student in the 2020 Sea Change Semester Program at Bigelow Laboratory. This intensive experience provides an immersion in ocean research with an emphasis on hands-on, state-of-the-art methods and technologies.

Improving the use of satellite imagery through the use of previous water column measurements