What are clam gardens? Join us on Spark Science’s first research field trip up the coast of Vancouver Island, BC. Dr. Marco Hatch answers this question by showing us a day in the life of a marine ecologist. We learn about clam habitat and how people have been managing these beaches for thousands of years.
Photo of clam garden rock wall located in Fulfod Harbor B.C. courtesy of Dr. Marco Hatch. For more information on his research, go to his website https://wp.wwu.edu/hatchlab/
If you would like to learn more about the garden in the image and other efforts to manage these historical gardens, check out the Clam Garden Network.
[Calm instrumental music.]
REGINA BARBER DEGRAAFF: Welcome to Spark Science. I’m your host, Regina Barber DeGraaff. I teach astronomy and physics at Western Washington University.
This episode is a little different from any of the shows we’ve made before because, well, it’s a road trip. It involves scenic ferry rides and traveling up the coast of Vancouver Island in British Columbia. We conducted research on the beaches of Quadra Island with my colleague, Doctor Marco Hatch.
He’s an assistant professor at WWU and a marine ecologist. Marco studies clam gardens. I’d actually never heard of clam gardens before I met him, even though clams are one of my favorite foods, and I love digging for clams on cold, rocky beaches in the Pacific Northwest. So, you can imagine how excited I was when Marco invited me to tag along with him and his research team.
But let’s start from the beginning. What are clam gardens? I’ll let Marco answer that question.
MARCO HATCH: My name is Marco Hatch. I’m an assistant professor in environmental science at the Huxley College of the Environment at Western Washington University. And we’re here today to study clam gardens.
Clam gardens are special spots in the intertidal where, for thousands of years, up and down the coast, from Washington to southeast Alaska, indigenous people have modified the environment, have modified the intertidal and nearshore environment, for the purpose of growing more clams.
So, many of these clam gardens exist on what were formerly steep beaches. And you can roll rocks to the low tide line and take that steep beach and flatten it out. And that creates more clam habitat, and these flat beaches are right in what we call the “Goldilocks Zone” for clams. If clams live too high in the tideline, they dry up and die. If they live too low, the sea starts to eat them.
So, for thousands of years, people have modified the environment to open up more space for clams in the ideal habitat, in the ideal zone that these clams like to live.
There’s been identified clam gardens in the southern gulf islands, just across from the Washington/Canada border. And there’s ethnographic evidence of clam gardens in Washington State, mixed in all the way through Southeast Alaska.
So, these are really numerous. We have no idea how many there are. There’s likely thousands and thousands of these features up and down the coast, often in really high densities. So, here on Quadra, within just one small bay, there’s probably 20+ clam gardens, so it’s a really intensely managed ecosystem with a lot of effort put into figuring out how to grow the most number of clams in a small area.
DEGRAAFF: One of the amazing things about the technology used in clam gardens is they don’t only produce clams of one variety but create a system that supports different types of clams with very specific needs.
HATCH: So, clam gardens offer us a really interesting opportunity to look at sea level rise because of what I mentioned, that they’re built on a really narrow part of the intertidal, that they’re really, really specific down to just a few centimeters of where they’re placed.
So, we can look at and date these rock wall features and understand that, when that rock wall was built, the proper clam habitat was built at that sea level. And now, depending on where you are, you’ll see clam gardens that are way too deep for clams now, and you’ll see some that are way up high on the shore. And that gives us an idea of how sea levels change in that local environment.
Some area sea level has risen quite a lot over the past five or six thousand years. And in other areas, sea level has actually dropped over five or six thousand years. So, clam gardens follow that tideline up or down depending on what’s happening locally.
So, every clam has its own unique habitat—certain kind of flow, certain kind of temperature, certain kind of sediment. And so, there’s a lot of engineering that goes into—and a lot of ecological knowledge that goes into—trying to propagate or create good habitats for these areas.
And one thing you notice right away when you walk around on clam garden versus a non-clam garden is that clam garden sediments, the actual sand within the beach, tends to be quite a lot different from what you see in other areas.
Clam gardens tend to have a lot more shell—shell hash, it’ll be white, kind of flaky—and it turns out that clams really, really like that sort of sediment, that that white calcium carbonate shells and barnacles let water flow through more easily, and clams just really, really like that area compared to maybe like a mud beach or kind of a muckier beach.
So, that’s a big part of it, as is turning the sediments over to help wash away some of the fine-grained organic matter and keep the sediment healthy.
So, and the other big thing is water flow. So, clams eat phytoplankton. So, they need lots of water swishing back and forth provided in food every day. And so, you can think of it like hamburgers on a conveyer belt, right? So, some areas, that conveyer belt’s real slow. In other areas, that current’s real fast, and it’s just force-feeding them hamburgers, hamburgers, hamburgers. In this case, phytoplankton.
So, when you start to look at where these clam gardens are placed, and look at the currents, and look at the habitat, you find out that these are always the ideal spots for clams, that it’s more than just, “Well, here’s a beach. Let’s make a clam garden.”
You’re thinking about where the current’s like, what is the wave energy like, what does the water quality look like, and what tide height, where do we build this wall to within centimeters to be the perfect spot for clams? And so, there’s actually tons and tons of different pieces that go into that.
DEGRAAFF: Standing on the shore, I could immediately see the clam garden and the rock wall. I had never taken part in field work before. Astrophysicists don’t usually take samples. Before we could start extracting small portions of the beach, Marco helped me understand what I was looking at.
That is a big clam. What kind of clam is that?
HATCH: That’s a butter clam.
DEGRAAFF: That’s a butter clam. That’s a big butter clam.
HATCH: That’s a big butter clam, yep.
DEGRAAFF: Whoa.
HATCH: So, one way to figure out what kind of clams live on the beaches is exactly what you just did, is look at the shells on top of the beach.
DEGRAAFF: Mm-hmm.
HATCH: And that’s a good indication of what’s below the sediment, right?
DEGRAAFF: Right. So, you can see a lot of butter clams out here.
HATCH: Yeah, you see butter clams—
DEGRAAFF: The more elongated ones, those are the horse ones? I don’t know.
HATCH: Yeah, horse clams are quite large. That’s a soft shell.
DEGRAAFF: That’s a soft shell.
HATCH: And that’s a cockle. That’s a butter clam.
DEGRAAFF: Okay.
HATCH: And that’s a littleneck, which is what you had for dinner.
DEGRAAFF: Yes, that’s what we had the other night!
HATCH: So right there, without doing any digging, you know, there’s at least four species.
DEGRAAFF: Clam gardens serve more than one purpose. And they tell us the history of people engineering the land.
HATCH: We talked about clam gardens being at the “Goldilocks Zone” for clams?
DEGRAAFF: Yeah.
HATCH: And this is now too high for clams. This whole beach behind us is no longer clam habitat.
DEGRAAFF: Right.
HATCH: It’s too high. And what happened in Quadra is, unlike some areas, in Quadra, sea level has been falling. During the last glaciation, when there was about a kilometer and a half of ice just over this whole area that pushed the land down, so depressed the land, pushed it down, when that ice melted, two things happened. One, all that waste lifted off the land, and two, those glaciers melted, and the water went into the sea.
So, the glaciers melting putting the water in the sea is raising the bathtub up, right?
DEGRAAFF: Right.
HATCH: It’s raising sea level. But at that same time, Quadra had been depressed for quite a while. The ice went away. And now, it starts to bounce back.
DEGRAAFF: Mm-hmm.
HATCH: And it turns out, Quadra bounced back faster than that sea level rise. You can see that there’s this, like, nice flat spot right here.
DEGRAAFF: Yeah.
HATCH: And it extends out to another rock wall that’s recent, that’s new.
DEGRAAFF: What do you mean by “new”?
[Both laugh.]
HATCH: It’s probably about 1,200 years old.
DEGRAAFF: Okay.
HATCH: So, there’s this second rock wall that extends around.
DEGRAAFF: Yeah, you can see the dipping right here.
HATCH: You can see the dipping. You can see the fucus, the rock weed, that’s growing along the rock.
DEGRAAFF: Okay.
HATCH: That’s a good indication that there’s rocks here instead of sand. And so, this is forming a second rock wall, a lower rock wall, that’s quite a lot newer.
So, you can see these multiple walls as an adaptation to local sea level change. In this case, sea level dropping.
And in certain areas where sea level’s been rising, you’ll find features that are way underwater now.
DEGRAAFF: Mmkay.
HATCH: So, you can see them, like, on your bottom sounder and your sonar, where these rock walls that are now a few meters below water.
So, we’re looking at clams here, which is an important part of the food system. I also had another student look at the rock wall back here. ‘Cause we think of clam gardens as clams, right? It’s in the name, clam garden.
DEGRAAFF: Yeah.
HATCH: And I often say I spent years with my head in the sand, just looking for clams. And often, when we come out, we’re just in such a rush.
DEGRAAFF: Mm-hmm.
HATCH: Like, we don’t stop and look around and kind of take it all in and think about what it means. It’s hit the beach, put some sediment in the baggie, get some clams, throw ’em in a bag, get on a boat, zip to the next one.
So, like, it’s pretty rate to like stop and really think about, like… this clam garden versus the ones we’re gonna see over there, and all the ones around the bay. The fact that this bay had between 7 and 8 winter villages, right?
DEGRAAFF: Right. Yeah, we were talking about that.
HATCH: This is a massively populated area. The people that come together in the winter, because it’s a relatively protected cove. These sorts of resources become really
important, right, having known spots that you can go to and get good amounts of clams, are really vital. And also, this rock wall is full of a lot of other traditional foods.
DEGRAAFF: Mmm. Like, like—
HATCH: Snails, limpets, red rock crab, maybe octopus. Um, red sea cucumber.
DEGRAAFF: What are limpets?
HATCH: Limpets are the little flat gastropods. Um.
[Rustling.]
DEGRAAFF: Aha!
HATCH: So, that’s a little limpet.
DEGRAAFF: Ah! So, what do you— Oh, there is meat on it!
[Hatch laughs.]
Ah! Yeah!
HATCH: So, they’re grazers. So, it’s a mollusk related to clams and snails.
DEGRAAFF: Okay.
HATCH: You see the foot, and he has a head there.
DEGRAAFF: Yeah.
HATCH: You have two antenna that stick out.
DEGRAAFF: Should we put it back?
HATCH: Yeah, we’ll put it back when we’re done.
DEGRAAFF: Okay.
[DeGraaff laughs.]
HATCH: It has a radula, which is like, a little scraper?
DEGRAAFF: Mm!
HATCH: It goes around and scrapes the algae off rocks.
DEGRAAFF: Okay, and that’s what it wants to eat?
HATCH: Mm-hmm.
DEGRAAFF: There’s a lot of them. That’s a little hat!
HATCH: Yeah, yeah. So, this habitat of, like, all these big rocks, provides a three-dimensional habitat, right? So, if we think about a plane, like this, like a big, flat plane, there’s not that much surface area.
DEGRAAFF: Mm-hmm.
HATCH: But you start in adding rocks that are probably on top of each other with holes in between.
DEGRAAFF: Right.
HATCH: Way more surface area. Way more area for little guys to crawl around and graze, right? ‘Cause they car—
DEGRAAFF: And also to hide!
HATCH: Exactly! Exactly. Little hiding holes so they don’t get eaten by things. And also—
DEGRAAFF: There’s crabs everywhere.
HATCH: There’s crabs everywhere, and then also, when it’s hot and sunny out, spots for them to hide out of the heat.
DEGRAAFF: Mm. I’m terrified of ocean creatures!
[Hatch laughs.]
But that’s another show! So, what you’re telling me, so in the winter, we both grew up in the Northwest. But I remember clam digging when it was really cold and wet ’cause that was the time we could eat the clams, right? ‘Cause you don’t really want to eat them in the summer with the algae blooms.
So, you’re talking about wintering—
HATCH: Yep.
DEGRAAFF: —um, people coming here from various villages to stay here in the winter and just have an abundance of food, so these clam gardens are not only good for clams, but, like, everything else.
HATCH: Mm-hmm.
DEGRAAFF: Like, it’s just… but you have to manage it!
HATCH: Yes.
DEGRAAFF: Otherwise, it’s not gonna work out.
HATCH: Yeah. It’s not by accident.
DEGRAAFF: It’s not by accident! Yeah.
HATCH: Um, yeah, it required a lot of careful care, cooperation, right, to build this wall. You can’t do it by yourself. And a system of governance and management to figure out, you know, if you spend a whole bunch of time, if your family spends a bunch of time building this wall, like, who gets to access to it?
DEGRAAFF: Mmm.
HATCH: There’s a governance structure associated with it.
DEGRAAFF: Mmm, yeah. And with all the villages that are coming in, like, yeah.
HATCH: Yeah. Okay.
DEGRAAFF: Let’s dig for clams!
HATCH: Dig for clams!
[Stepping through the water.]
So, what we’re trying to do here is get a good idea of what clams are living here. We’re doing this pretty methodologically. We’re just gonna scrape a bit down and just kind of remove and keep going until we get to some clams. And we’ll set those aside.
And this first part, in the very upper surface, is usually where you’ll see your baby clams. And so, once we get this kind of gravel out of the way, uh, keep an eye out for real tiny clams.
DEGRAAFF: Big ones have a [inaudible] first.
HATCH: Yeah.
DEGRAAFF: What is that?
HATCH: A worm.
DEGRAAFF: Okay. Just a normal worm?
HATCH: Just a normal—yes.
DEGRAAFF: Okay.
You could use a… clam bakes and stuff, you see like, a baby crab in your clam?
HATCH: Oh, yeah.
DEGRAAFF: That happens a lot, right?
HATCH: Yeah.
DEGRAAFF: Why? How does it get in there? Like, what’s happening?
HATCH: So, it’s called a pea crab or [inaudible] crab.
DEGRAAFF: Okay.
HATCH: And the only place they live is in a clamshell.
DEGRAAFF: Really?
HATCH: Yeah!
DEGRAAFF: Oh!
HATCH: Yeah.
DEGRAAFF: That’s, like, a certain crab, okay.
HATCH: Yeah.
DEGRAAFF: Oh, here’s another one!
HATCH: Nice.
[DeGraaff laughs.]
DEGRAAFF: They’re all the same kind, the ones that I’m finding. Seem, like, the same color. What’s the white ones that we have been finding?
HATCH: So, these are—um, they’re all sandy. We’ll have to watch them. These are juvenile littleneck clams.
DEGRAAFF: Okay. Like, the ones we ate?
HATCH: Yep! And that’s some of the butter clam. The littleneck, you have the same rings, but you also have this crosshatching.
DEGRAAFF: Right.
HATCH: It’s like a hashtag.
DEGRAAFF: Yeah! Your undergrad student and I were talking about how this very much looks like hashtag littlenecks, right?
HATCH: Hashtag littlenecks, nice.
DEGRAAFF: Hashtag littlenecks, yeah.
HATCH: And littlenecks are interesting ’cause they can look a whole variety of different ways.
DEGRAAFF: Mm, okay.
HATCH: So, if we look at just the littlenecks—
DEGRAAFF: Yeah, the comparison of the littlenecks—
HATCH: Yeah, it’s crazy, right? So…
DEGRAAFF: Huh!
HATCH: Those look kind of the same, but then we start to get all these different color patterns here.
DEGRAAFF: Oh, wow!
HATCH: Yeah!
DEGRAAFF: These are very leopard-y kind of—
HATCH: Yep!
DEGRAAFF: —or like a lionfish.
HATCH: A lionfish?
DEGRAAFF: That’s what it kind of looks like.
HATCH: A lionfish clam?
DEGRAAFF: A lionfish littleneck.
HATCH: These little ones are probably two years old.
DEGRAAFF: Oh! Okay, I was not gonna expect that. Okay.
HATCH: They have growth increments on them.
DEGRAAFF: Oh!
HATCH: And so, that is probably Year 1, from here to here. And then, it’s grown up.
DEGRAAFF: Oh, wow! So, like, like trees!
HATCH: Yep!
DEGRAAFF: Like, the rings of a tree!
HATCH: Yeah, so, and that’s actually one of the things that I’ve done. In trees, it’s called dendrochronology. Dendro, tree, and chronology, time.
DEGRAAFF: Okay.
HATCH: In clams and other hard parts, it’s called sclerochronology—scelero, like skeleton, and chronology, like time.
DEGRAAFF: Okay, cool!
HATCH: So, you can cut these in half and measure both the annual growth increments. And they also have tidal or daily growth increments as well.
DEGRAAFF: Oh, wow. Okay.
HATCH: So, you can reconstruct the chronology of the shell, and based on the chemistry in the shell, it’ll tell you about ocean conditions: what the temperature was, what the salinity was, and how much nitrogen was in the water.
DEGRAAFF: Mm-hmm.
HATCH: So, we can actually use them as proxies to figure out what past ocean conditions look like as well.
So, a littleneck like this might be… sort of, like, 1, 2, 3, like, 4 or 5 years old.
DEGRAAFF: Oh, wow! And then, when we get to these, these are like, 6 , 7.
HATCH: Yeah, they kind of max out around 10.
DEGRAAFF: Oh, then, okay. And then, they’re just like…
HATCH: They call it, in the clam literature, they call it senile. They become senile.
DEGRAAFF: Okay.
[Hatch laughs.]
Like, the sea?
HATCH: No.
[Hatch laughs.]
DEGRAAFF: No?
[Hatch laughs.]
No?
HATCH: They call it—
DEGRAAFF: Senility. “Coping with senility.” That’s my favorite line from the census.
HATCH: So, when they get to a certain age, they just grow really, really slow.
DEGRAAFF: Oh, okay.
HATCH: So, a butter clam can be 20-25 years old.
DEGRAAFF: Okay, and then those lines get closer and closer together.
HATCH: Yep, yep.
DEGRAAFF: Ohhh.
As a new field assistant, there were a few experimental methods I had to learn, like plotting a transect. This is a straight line along the beach where core samples were taken using various long tubes. I was slowly getting the hang of it.
HATCH: If you look at this sediment, this is that shell hash. Really, a lot of broken clams, a lot of broken barnacles. This is kind of typical clam garden sediment.
So, we go around the corner, there’s a non-walled beach that’s very, very mucky and muddy. And so, you couldn’t just pull up a hand of sand or sediment. It would look like this, right?
And so, when we run this through the sieves, that’s a quantitative way of measuring that, right?
DEGRAAFF: Mmkay.
HATCH: And then, we can also take that same sample, and we can measure the amount of shell, of calcium carbonate, in a couple different ways. One, you could heat it up a whole bunch, and all the shell will burn off.
DEGRAAFF: Uh-huh.
HATCH: So, you can weigh it, burn off all the shell, calcium carbonate, and weigh it again.
DEGRAAFF: Okay.
HATCH: And that gives you a percent calcium carbonate at the beach.
There’s a traditional teaching in that after you eat clams, you return them to the beach—that you take the shells, and you dump them back on the beach. And so, that’s one of the thoughts around looking at a beach like this—is that, over time, people are dumping all their clams back on the beach, which helps fill in the beach but also helps give a lot of this kind of shell hash-type sediment.
DEGRAAFF: Right. I mean, I liked when you were talking about earlier about, like, these clam gardens are very similar to the gardens in, like, your backyard and how you’re kind of making sure you manage them constantly. But I’m thinking about this idea of, like, fertilizer. You’re making more nutritious soil, right?
HATCH: Yeah.
DEGRAAFF: So, you’re like putting the shells back in so you can make sure that the sediment is good for the clams, right, instead of that muckiness?
HATCH: Yep. Yep. So, we do 2 transects per beach, 3 samples per transect. So, 6 samples per beach.
DEGRAAFF: Okay.
HATCH: And we have 10 beaches. So, 60 per trip. We did 60 samples in July and 60 in May.
DEGRAAFF: How long does it take— Up to 4 millimeters, right?
HATCH: 5.
DEGRAAFF: 5!
HATCH: Yeah.
DEGRAAFF: Come on, Gina. You can do this.
HATCH: 20 times 360….
DEGRAAFF: This is the most field work I’ve ever done!
[Hatch laughs.]
‘Cause when you study, you know, galaxies, you don’t really go out.
HATCH: You don’t go to quorum?
DEGRAAFF: No, you don’t quorum.
[Hatch laughs.]
HATCH: Ask them how they’re doing?
DEGRAAFF: Yeah, you don’t…
HATCH: Look for critters?
DEGRAAFF: You don’t do any analysis on algae.
PERSON: Sorry.
HATCH: Uh, TO2.
DEGRAAFF: Ugh! It seriously is stopped! Okay, let’s keep on going!
Is that about good?
HATCH: Yeah, there you go.
PERSON: Yeah!
DEGRAAFF: Okay, I’m ready!
HATCH: She’s labelling. A lot of what we do is write with Sharpies on things. Probably half of our—
DEGRAAFF: We’re really finding out what the clams are eating.
HATCH: Yeah.
DEGRAAFF: And we’re like, coring for the environment, like, the sediment and—
HATCH: So, what we’re doing right now is we’re taking a very small sediment core—
DEGRAAFF: Okay.
HATCH: —which is just a modified syringe, to take a small plug of the sediment. And what we’re looking for is on top of the sediment, there could be little phytoplankton that live here called benthic diatoms that are clam food. So, we want to see how much of the benthic diatoms are contributing to the diet of the clams.
DEGRAAFF: What are the benthic diatoms look like, like under a microscope?
HATCH: Diatoms have a glass house. So, they’re in a silica shell. So, they’re often, like, really, really pretty.
DEGRAAFF: Oh.
HATCH: They’re typically kind of round, they’ll have like little impressions in them. But you can do SEM imagery of them, and they’re really pretty.
So, you’ll take the glass vial.
DEGRAAFF: Okay.
HATCH: The sample will go into that.
DEGRAAFF: All right. And I’ll just be ready to take the sample, right?
HATCH: Yeah.
DEGRAAFF: All right. We’re gonna core this.
HATCH: Label it really quick.
DEGRAAFF: Ah, yes. That’s important. It’s always good to label your mater—like, your samples. I’ve heard that.
[DeGraaff laughs.]
And there’s all these little baby crabs! Like, they want to be involved!
PERSON: Oh, yeah?
DEGRAAFF: Yeah, they’re like all over this! Sweet!
HATCH: And then you cap that.
DEGRAAFF: Close it up. I just did some science.
[Laughter.]
Feel great!
HATCH: Do you want to core one?
DEGRAAFF: Yeah, sure! Let’s do it!
HATCH: Don’t want to do that!
DEGRAAFF: Don’t want to do that! I’m not gonna touch that area!
[Hatch laughs.]
But I can move this.
HATCH: No, he’s— He’s part of the beach.
DEGRAAFF: What do I want to do, then? I touched him, but that’s okay, right?
HATCH: Yeah.
DEGRAAFF: No, that’s not okay? Should I go here?
[DeGraaff laughs.]
HATCH: Sure.
DEGRAAFF: Let’s go here! Okay, and then I go all the way down to the top.
HATCH: Yep.
DEGRAAFF: So, about here?
HATCH: About there, yep. And then, so, normally, you kinda dig some of this out with your hand.
DEGRAAFF: So, I can touch that?
HATCH: Yeah, yeah, yeah.
DEGRAAFF: Okay.
HATCH: Everything in the can is what we want.
DEGRAAFF: Everything in the can, don’t touch, okay.
HATCH: Do that. And then slide that under, yeah.
DEGRAAFF: I’m gonna try to make it as flat as possible around here.
HATCH: There you go. Yep. That’s the move.
DEGRAAFF: Okay. That’s the move!
HATCH: Yeah.
DEGRAAFF: People go to college for this!
[Hatch laughs.]
I didn’t! I’m like, really thorough here. There we go.
HATCH: ‘Kay.
DEGRAAFF: And then I go like that.
HATCH: Yeah. Stuff upside down. Make sure all the sediment stays in the can.
DEGRAAFF: All right! And then I put it around that?
HATCH: Yeah.
DEGRAAFF: Okay. And then I flip.
HATCH: Yeah, and hang on to the whirl pack.
DEGRAAFF: I’m, like, worried I’m gonna ruin your science here! It’s like, ugh! All right, cool! We learned from our mistakes. Oh my God. I am not good at this! Okay! Okay! There we go. That looks like way more than you want. Like, way more.
HATCH: You’re just making more work for the student, Regina.
DEGRAAFF: I am, I am! How long does it take to do a few digs in one beach? When you, like, core, you do this?
HATCH: Mm-hmm. Yep.
DEGRAAFF: Like, what’s an average day?
HATCH: Um.
[Hatch laughs.]
Uh, an average day… for this trip, our low tides start off at, say, 7:30.
DEGRAAFF: Mm-hmm.
HATCH: A.M. We want to be on station, ready to work, two hours before that. So, we want to be here with all of our stuff ready to go by 5:30 A.M., which is about when the sun comes out. So—
DEGRAAFF: So, you’ve been really nice to us today.
HATCH: Yeah. So, we leave town— There’s an 8-day trip when we’ve been camping. So, we’ll leave camp at 4:30 in the morning, in the dark with our head lamps on, drive to the dock, get in the boat, come out here, unload everybody, and then, just about 5:30, our first transect will be exposed as the tide’s receding.
DEGRAAFF: Right.
HATCH: And we get straight on that, lay out our transect tape, start sampling like mad, try to finish that transect before the second one’s exposed, go and sample that one. Collect all of our data. Get our clams, our sediment cores, any other measurements we need. Load up everybody in the boat. Go to our second beach. And we try to get to that second beach before low tide.
DEGRAAFF: Okay.
HATCH: So, we have two hours to work before low tide and two hours to work after low tide—
DEGRAAFF: Okay.
HATCH: —before our sites are underwater.
DEGRAAFF: Okay.
HATCH: Once our sites are underwater, then, and only then, we take lunch breaks.
[DeGraaff laughs.]
DEGRAAFF: Right! We took those early today!
[Hatch laughs.]
HATCH: Not until two hours after low!
DEGRAAFF: Sorry!
HATCH: Then, we take a lunch break. And then we go— Our next operation is to go out and sample the phytoplankton populations in the water.
DEGRAAFF: Right.
HATCH: So, we actually filter the water through a small filter that collects all the phytoplankton, and then we can measure the fatty acids within that filter, and we can also measure the chlorophyll.
DEGRAAFF: Yeah.
HATCH: And then we’ll come back when there’s about 3 to 4 feet of water right on top of us now.
DEGRAAFF: Okay.
HATCH: And then we do the same thing here—we sample the water right above our transects.
DEGRAAFF: Oooh, okay!
HATCH: So, we work from below low tide, through low tide, all the way to the next high tide.
DEGRAAFF: Right.
HATCH: And so, in those days, if we leave camp at 4:30, we’ll get back to camp around maybe 6:00 or 6:30 P.M. And then we take all of our samples, put ’em in the freezer, make sure everything’s correct, image all of our data sheets in case the paper gets lost.
DEGRAAFF: Yeah.
HATCH: And then we make sure. And then we date and label everything for the following day, so that’s ready to go.
DEGRAAFF: Doctor Hatch has been studying these clam gardens for years. And he’s one of the many who are part of a movement to bring back the active management of clam gardens. These ancient clam gardens can help nourish the local indigenous people, both physically and culturally.
A lot of these clam gardens haven’t been managed in a long time. Is there a movement to kind of go back to those areas? Have people been talking about that?
HATCH: So, what happens in some of these instances… that former open-access beaches, beaches where people can go dig clams, became part of federal parks.
DEGRAAFF: Mm, okay.
HATCH: And the park system was trying to keep nature natural by keeping people out of it. And the people at the time, the indigenous groups at the time, said, “Well, if we don’t dig these beaches, they’re going to die.”
DEGRAAFF: Mm-hmm.
HATCH: Um, and that’s what happened. Those beaches weren’t dug. The sediments became compacted, and clam populations went way down.
Now that that’s being reactivated, the species are being dug again and being re-managed, the hope is that those clam populations are gonna come back. It takes time for that to happen, right? It doesn’t happen overnight. These are, like, we talked about animals that can live to be 20+ years old. So, to be able to measure an impact on that takes a while.
But everybody involved in that sort of work is really optimistic that by being back out on the landscape, by digging clams, by turning over the sediment, by managing beaches, following indigenous protocols, that’s gonna improve the health of these beaches.
DEGRAAFF: Right.
HATCH: So, there’s an environmental benefit, as well a benefit for those communities by getting back out, practicing traditional practices, being youth involved, reconnection to these spaces that they’ve been excluded from due to federal policy.
DEGRAAFF: So, we have these different rock walls. The indigenous people here were dealing with sea level change, but at much slower rate than what we’re dealing with now. So, how can we use this technology currently?
HATCH: So, I think clam gardens are a great technology that have been in continuous use for thousands of years. And today, we’re seeing clam gardens used in a few areas to stabilize the shoreline, and we start to see the rock wall being rebuilt over time. You know, these rocks are kind of spread out now. Over time, the waves kind of knocked them down and spread them out.
So, what folks are doing now is starting to put the rocks back in the wall, which also raises it. So, clam gardens can be used as one tool to help stabilize shorelines in a rising sea.
Now, it’s not the cure for everywhere.
DEGRAAFF: Yeah.
HATCH: It’s not appropriate everywhere. But where it is, I think it’s a good way to mitigate some of these changes that we’re seeing and use this as a form of adaptation.
However, there’s lots of other issues that are going on with global climate change. But clam gardens are still this really good technology that is adaptable to changing seas.
As we lose the ability to dig clams due to either sea level change, other anthropogenic issues like toxins or biotoxins, we also lose that connection between particularly elders and youth, who go out on the land together and dig clams. We lose that knowledge transfer from one generation to the next.
And it also changes our view of the environment, right? Like, if things that come out of the sea are viewed as being toxic, then how does that work as an indigenous person, where going out and harvesting from the sea is part of who you are?
DEGRAAFF: Right.
HATCH: People put amazing amounts of effort and knowledge and technology into creating this landscape and seascape. You know, almost 4,000 years ago.
And so, this idea that people shouldn’t be out on the beaches, they shouldn’t be digging clams, they shouldn’t be doing traditional management, actually makes a very unnatural system, right? Having folks out on the landscape, you know, practicing sustainable
harvest practices, practicing culture, I think it builds a more resilient environment, and it helps keep people connected to the land.
DEGRAAFF: Yeah.
We’d like to thank Doctor Marco Hatch and WWU undergraduate student Sienna Reid for showing us a day in the life of ecology research on the banks of Quadra Island.
If you’d like to know more about Doctor Hatch’s research lab, you can visit wp.wwu.edu/hatchlab.
Spark Science is produced in collaboration with kmarie and Western Washington University. Today’s episode was recorded on Quadra Island in British Columbia, Canada. Our producers are Suzanne Blais, Faith Haney [sp?], and myself, Regina Barber DeGraaff. Our audio engineers are Zerach Coakley and Julia Thorpe. Script support by Ariel Shiley.
If you missed any of the show, go to our website, sparksciencenow.com. If there’s a science idea you’re curious about, send us a message on Twitter or Facebook at Spark Science Now.
Thank you for listening to Spark Science.
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