The Gulf of Mexico—like many elements of the world—has misplaced a lot of its historic oyster reefs. In June 2022, a crew of conservationists from The Nature Conservancy and the Dauphin Island Sea Lab constructed an oyster reef close to Bayou la Batre, Alabama. (If the city sounds acquainted, that could be as a result of it’s the place Forrest Gump began his profession as a fictitious shrimp-boat captain.)
The challenge was half of a bigger effort to guard the group’s eroding shoreline by putting in breakwaters and restoring marshes, together with oyster reefs. However for Lee Smee, a marine scientist concerned within the challenge, it was about finding out one thing evolutionary too: Are you able to scare the oysters into being stronger and extra resilient?
Q: Earlier than you delivered the oysters to Bayou la Batre final June, you first uncovered them to blue crabs. Why would you try this?
Plenty of earlier work has discovered that oysters reply to blue crabs (and different predators like oyster drills) by constructing heavier, stronger shells. We knew that some sort of chemical from the crab triggered the oyster response, and we thought that it was seemingly within the urine.
Q: Why would the oysters want stronger shells?
Effectively, the outdated strategy to restore oysters was placing out some shells, and the oyster [larvae] would land on it and begin to construct a reef. However right here [in Alabama], the pure populations have gotten so low that there are areas the place there’s not sufficient oyster larvae within the water to get the reef going. So we develop them in a nursery and put this stuff out, however then all of them get eaten. So, we mentioned, can we pre-adapt them in a roundabout way?
Q: In order that’s the place these predator crabs, which eat oysters, are available. You mentioned you raised the oysters in tanks with caged crabs in them. Why not simply add crab urine to the tanks?
Crabs have a gap on their face close to every eye that they launch urine from. They really squirt it at one another throughout fights. However it takes us like half of a day to get 20 milliliters of crab urine. And we’d like 600 or 700 milliliters for a two-month challenge to get them to develop. Now, if we will work out what the molecules are [that affect the oysters], then we may make these things, probably. Then it’s simply, “Right here’s the scary juice!” Roll this into your [oyster-growing] tank every single day. However proper now, we’re simply not there but.
Q: You’re engaged on figuring out these molecules although with a few researchers from Georgia Tech. How is that analysis coming alongside?
We’ve recognized two molecules which might be concerned, however they’re not the entire story. We all know that as a result of the best way you do that is you expose oysters to this urine and also you see the best way that the oysters modified. However, there’s all the time variation. A few of them change loads, a few of them change just a little a few of them don’t actually change. There’s all this pure variability. So, we give the urine samples to Georgia Tech they usually analyze them. We’ve pulled two issues from that after which we check them in isolation. And in isolation they form of work but it surely’s not as clear as you’d suppose. So there’s most likely another issues in there that [the oysters] are smelling, not simply these two—however we’re closing in on it.
Q: That is smart.
What’s actually attention-grabbing is once we’re finished we’ll have the ability to ask—that is an evolutionary query—however do oysters odor concern? Or do they odor particular predators?
Do fish odor like fish and crabs odor like crabs? Do blue crabs and stone crabs odor otherwise or are they only crabs? We don’t know. We form of know this: Should you feed [crabs] oysters, they’re scarier than for those who don’t feed them one thing. So it could possibly be that there’s one thing within the food regimen.
Q: You imply for those who feed oysters to a blue crab, then different oysters have a stronger response to that blue crab?
It will get wilder than that. After we first did this experiment, we had been feeding blue crabs oysters or clams. And we acquired the strongest response when blue crabs had been consuming clams. Effectively, that doesn’t actually make any sense, proper? After which my PhD scholar on the time, she mentioned, “You recognize, we all the time feed them contemporary clams. However once we’re out within the discipline, to avoid wasting area within the cooler I am going forward and shuck the oyster and I put them on ice after which it’s like three or 4 days later after I really feed them to the crab.”
So then we did a separate experiment the place we [fed crabs] contemporary oysters versus oysters that had been useless for a number of days. And [the oysters] reply extra to the contemporary ones. So, they will additionally distinguish between a blue crab that’s scavenging versus one which’s an energetic predator.
Q: What’s the way forward for the challenge going ahead? I assume you’ll preserve monitoring how properly these oysters planted final June survive. What’s subsequent?
We’re going to attempt it once more this summer time—[build a reef] adjoining to the one in Bayou la Batre. So long as we will get the manpower to do the experiments, we will simply preserve constructing reefs each summer time, doing them barely totally different to check one thing new. Over time, we’ll even have constructed a bunch of reef habitat.
A model of this interview ran in Nature Conservancy journal’s summer time concern. You possibly can learn extra tales from that concern right here together with options on California’s kelp forests, a gaggle advocating for equitable entry in searching and an effort to make the worldwide tuna trade a bit extra sustainable.
