Plankton form the basis of the food web in oceans and new research shows that the level of phytoplankton in Rhode Island’s Narragansett Bay has dropped by half in the past 60 years. We wondered why.
Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall.
The ocean is full of life, big and small. Today, we’re going to talk about some of the little guys – specifically, a type of plankton. These tiny organisms play a big role in the health of Rhode Island’s Narragansett Bay, and there’s new research out about how they’re changing.
Possibly reporters Will Malloy and Nat Hardy are here to explain. Hi guys!
Will Malloy: Hi Megan!
Nat Hardy: Hi!
Megan Hall: So, before we talk about this new research, can we just back up a bit? What are plankton and why do we care about how they’re doing?
Will Malloy: There are tons of different kinds of plankton, but this big study looked at the amount of phytoplankton in Narragansett Bay.
Megan Hall: And what are phytoplankton?
Nat Hardy: They’re essentially microscopic algae that drift through the water/
Will Malloy: And they are super important.
Megan Hall: Why?
Will Malloy: For one, they’re the bottom of the food chain for all kinds of creatures in the ocean – the same way plants are on land.
Tatiana Rynearson: Zooplankton, the animal plankton, eat the phytoplankton, and then fish and other organisms eat the zooplankton. Also filter feeders, all those great oysters that people love, mussels, quahogs, they all filter feed phytoplankton
Nat Hardy: That’s Tatiana Rynearson, a professor at the University of Rhode Island.
Will Malloy: Even if you don’t like quahogs, you still rely on phytoplankton. They create oxygen the same way trees and plants do on land.
Tricia Thibodeau: Every time you take a breath, you can thank the ocean, because phytoplankton produce about 50% of the oxygen that we breathe.
Nat Hardy: That’s Tricia Thibodeau, a professor at the University of New England who works with Tatiana to study these little creatures.
Will Malloy: For 60 years, they’ve been taking weekly samples to measure the amount of plankton in the Bay.
Nat Hardy: And a 60 year study can show you things that you might miss in a shorter one, which is super valuable, especially for understanding long-term things like climate change.
Will Malloy: For example –
Tatiana Rynearson: We found that phytoplankton are decreasing
Megan Hall: By how much?
Will Malloy: Between the 1960s and 2010’s, the amount of phytoplankton in the water fell by half.
Megan Hall: That sounds like a lot. Why is this happening?
Will Malloy: Tricia and Tatiana say they weren’t able to pinpoint just one cause –
Tricia Thibodeau: We found that this long-term decline was connected to many different factors, including long-term temperature increases in Narragansett Bay
Nat Hardy: So it seems to be climate change related. But lots of things were changing at once, so it’s hard to figure out the exact reason we’re seeing this decrease.
Will Malloy: But this drop is happening in other places, too, like the Gulf of Maine and even as far away as Australia.
Nat Hardy: The authors wondered if this decline had anything to do with the way Rhode Island has reduced the amount of wastewater running into the bay.
Megan Hall: What would that have to do with it?
Will Malloy: Wastewater can carry nutrients like lawn fertilizer into bodies of water, which in turn, can cause algae to grow.
Nat Hardy: But this study found that improved sewage treatment probably wasn’t the main cause of the decrease in plankton –
Tricia Thibodeau: we found that there’s been a long-term decline in phytoplankton occurring since before the time when a lot of this wastewater treatment was induced
Megan Hall: Okay, so we’re not exactly sure why we’re seeing fewer phytoplankton in Narragansett Bay. But should we be worried?
Will Malloy: I don’t think that’s the message here. The Bay is changing in lots of ways – it’s cleaner now and the water’s warmer.
Nat Hardy: And the more the climate warms up, the less we can predict about how these living systems will respond.
Will Malloy: That’s part of why studies like this are crucial. This one is one of the longest-running of its kind.
Tricia Thibodeau: It allows Narragansett Bay to really be a model ecosystem, to understand how changes here could affect or look in other ecosystems as well
Will Malloy: Long-term studies like this help paint a better picture of how places like Narragansett Bay are changing over time.
Megan Hall: Got it! That’s it for today. You can find more information, or ask a question about the way your choices affect our planet, at askpossibly.org. You can also subscribe to Possibly wherever you get your podcasts or follow us on Instagram, Facebook, LinkedIn or X at “askpossibly”
Possibly is a co-production of The Public’s Radio, Brown University’s Institute for Environment and Society and Brown’s Climate Solutions Initiative.
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