Island Interviews: Eastern Oyster

Photo courtesy of NOAA Fisheries

If we could interview our islands’ non-human residents, what would we learn from them? In the "Island Interviews" series, we imagine that fictional scenario to help readers learn about the real-world interactions between people and ecosystems.

Our Boston Harbor Islands National and State Park ranger recently shared a conversation with an eastern oyster (Crassostrea virginica). This mollusk species is well-known for its role in our diets, but the life of an oyster is much less commonly understood. On a Spectacle Island tidal flat, this interviewer learned about eastern oyster daily life, amazing abilities, and more.

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RANGER: Thanks for meeting me here—and for being patient while I tiptoe my way over.

OYSTER: Of course. My neighbors that don’t enjoy being stepped on very much.

RANGER: So what’s it like for you intertidal zone dwellers? It must be strange switching back and forth between underwater and above water.

OYSTER: It’s not so bad. Each of us has figured it out in our own ways. We oysters close up at low tide. I like the break from feeding.

RANGER: Feeding? How does that work?

OYSTER: I’m a filter feeder. I pull water in, over my gills. I take bits of food and then spit the water back out.

RANGER: Sounds...lovely.

OYSTER: It sounds gross, but it’s actually a good thing. When we filter water, we pull out food, but we also pull out nutrients like nitrogen. There’s a sweet spot for it. Too much nitrogen can cause algae blooms, and when those blooms die, they consume a lot of oxygen in the water... or all of it.

RANGER: Oxygen is pretty important.

OYSTER: Yep. So what we do helps keep that loss from happening. And it keeps water clean for other species. On a really good day, I can filter almost 50 gallons of water. And I can tuck that nitrogen away in my shell.

RANGER: Wow. Speaking of shells, why grow one? Wouldn’t it be easier to just swim away from danger like a lot of other animals?

OYSTER: Hey, I can swim! Just not anymore.

RANGER: What do you mean?

OYSTER: We swim when we’re tiny. I think I have a picture of me as a larva somewhere.

RANGER: And then?

OYSTER: We build a tiny shell. It’s calcium carbonate. It's the stuff that people put in stomach medicine to cancel out the acid.

RANGER: I see. So... I know ocean waters are becoming more and more acidic--

OYSTER: It’s a problem for us. Water is a lot more acidic than it was before the Industrial Revolution, and it’s looking like that will continue with climate change.

RANGER: What can we do about it?

OYSTER: Cutting down on carbon emissions is important, but so is just getting to know us! If you pitch in on a participatory science project like Bivalve Quest, you’re helping scientists understand how to help us and other marine species.

RANGER: And then you can help us in return by keeping the water clean.

OYSTER: For sure. Speaking of water, it looks like the tide’s coming back in. Dinnertime.

RANGER: Enjoy your meal.

OYSTER: Thanks, and I appreciate the chat. It gave me a chance to come out of my shell a little!