Phytoplankton and water chemistry (chemistry can be and is fun!)

Who: The most excellent Van Mooy group from the Woods Hole Oceanographic Institution – with friends and collaborators from three other institutions!

When: November 22^nd to December 15^th

Where: We take samples from the top of the ocean to the bottom, to look at how phytoplankton are changing the water they live in and being changed by it.

Why? While algae might seem tiny and like they are not as important as animals like whales, seals, or penguins, they are actually what cause many of the changes in the world’s oceans! Even more than that, they are the food all those bigger animals eat!

My team looks at the ways that phytoplankton, which are tiny algae (a lot like plants), grow in the ocean. They need sunlight, so they are concentrated in the surface. However, they also need food, or nutrients, which they can use up quickly when there is enough light. My lab looks at the balance between things like nutrients and light, to see how phytoplankton change when those factors change.

Putting bottles of seawater into the filter rigs. This is how we filter the water to find out how much phytoplankton and particulate organic carbon there is inside one to two liters of seawater.

Not only can a single algal cell change how it’s growing, but the types of cells often change as they each are fairly particular in what they like. Think of them as picky eaters – they don’t stick around when their favorite dish isn’t at the table, or there isn’t enough of it – because someone else has pushed them out! This is what we refer to as a “niche”.

My favorite thing about phytoplankton is that they are not only impacted by the water around them, but they also change that water, in a really beautiful circle. To understand how these tiny organisms function, you have to understand the chemistry of the water. And, you have to understand how they are changing that chemistry as they grow, live, and eventually die and sink, or are eaten. What happens to algae when they die is almost as important as how they live.

Together, phytoplankton and the water they live in make up an ecosystem all on their own, which is beautiful all by itself. Then, you can add in how they are food for animals like krill, which feed penguins, seals, and whales. But really, it all starts at the most microscopic levels, and my goal with this research in Antarctica is to understand how phytoplankton are changing as the chemistry of the oceans change, and then how that might make a difference to those larger animals too.

About the author: Shavonna Bent is a graduate student at Woods Hole Oceanographic Institution. This is her third research cruise.