By Sandra Olivetti Martin
Oysters are a victim in the climate crisis, by most accounts, and ours in Chesapeake Bay waters are feeling it like their bivalve brethren elsewhere.
West Coast oysters are hurting from changing ocean chemistry. In New Orleans’ French Quarter, eateries are scrambling to live up to their reputations as Gulf of Mexico oysters die, smothered by the billions of gallons of Midwestern freshwater rolling down the Mississippi River.
In Maryland and Virginia, freshwater also is the culprit, diluting the salinity oysters need. For long stretches, the Chesapeake has resembled a big farm pond absent the salt that fuels oyster growth.
Chesapeake watermen lost one day a week of work under new limits imposed by the Department of Natural Resources. Oyster farmers saw nearly a one-fourth-production decline last year — and that was before the problems this year.
Horn Point Laboratory on the Eastern Shore, one of the East Coast’s primary hatcheries, turned out just a fraction of the spat of recent years, an ominous sign for the future.
At the Smithsonian Environmental Research Center in Edgewater, Allison Tracy is researching ways to gird the Chesapeake oyster for an uncertain future in her PhD postdoctoral fellowship project called Working Land and Seascapes.
Read on for an edited discussion with Bay Weekly about her work and the fate this year of the Chesapeake’s iconic oyster.
Bay Weekly People are getting ready to eat oysters this holiday season, perhaps oyster dressing at Thanksgiving. What are we seeing out there after all those heavy rains last spring and early summer?
Allison Tracy The freshwater we had at the beginning of the summer was really tough and caused a lot of problems for scientists and the state’s efforts at management restoration and, of course, for aquaculture operations and for watermen. It was a tough year because of the low salinity, for sure. This is something to consider for the health of oysters going forward.
Bay Weekly Do we know yet how bad the season will turn out to be?
Allison Tracy They’ll have to see what the numbers are at the end of the season (which runs through next spring). There can be good parts of the season and bad parts of the season. I know that the salinity has recovered. But the problem is with the bad summer we had. It will be interesting to see how that shows up in the numbers this year. It also could show up more strongly in future years.
Bay Weekly Why do oysters need salt?
Allison Tracy They can only survive and grow at a certain level of salinity, and the water can’t be too fresh. They also need a certain level of salinity to reproduce, roughly 10 parts per thousand to happily spawn. Here in Edgewater it was as low as four parts at some points. There were levels of four, six and eight at places in the Bay usually salty enough for oysters. At the end of the summer, there wasn’t much rainfall, and some of the operations began to recover.
Bay Weekly What has the low salinity meant for restoration?
Allison Tracy The state of Maryland does a lot of planting of spat on shell, and if they don’t have it because oysters aren’t reproducing in hatcheries or in the field, they can’t proceed with restoration. They couldn’t plant as much spat on sites as they had hoped. Horn Point Laboratory had some trouble. They recovered at the end of the summer, but they got a lot less out of the summer than they were planning to.
Bay Weekly How did the Maryland Grow Oysters program — in which people living along the water work as oyster gardeners — fare in this difficult season?
Allison Tracy I talked to people who usually participate in the program who just weren’t able to do it this year because the water was too fresh. It’s a great program, but I think they had trouble getting spat to potential growers because there wasn’t enough spat for restoration.
Bay Weekly Hadn’t Crassostrea virginica (the Bay oyster) been making a nice comeback?
Allison Tracy Yes. In the records we see a really strong impact of Dermo and MSX in the past that was getting relatively better recently. And there were some particularly strong years, 2013 and 2012. It would be great to get some of those strong years soon.
Bay Weekly There was a serious push earlier this century to start planting a Chinese variety, ariakensis, in the Chesapeake. Was it good that we didn’t follow that recommendation by some politicians?
Allison Tracy There are a variety of opinions, but we think it was a good thing we didn’t do that. Ideally, we can use the toolkit we have to restore our native oyster populations.
Bay Weekly Tell us about what you’re working on …
Allison Tracy There are two main projects. I’m looking at historical data sets in Maryland and Virginia to try to combine the two and get an idea of Bay-wide trends. By looking back and trying to understand what’s happened with oysters in the last few decades and understanding why, we might be able to know more about how the system works. We can look around the Bay and see where oysters have done well. There’s a lot of variability even within Maryland and within Virginia, and we can try to see what the magic recipe for oysters might be.
We’re also surveying oyster reefs and looking at vertical habitat around the Bay. It’s important to know what these reefs look like, not just how many oysters are on them. We think that reefs with greater vertical structures are better reefs. There’s been some research that shows increased reproduction of the oysters and better persistence of reefs over time.
Bay Weekly Is it the consensus that the recent rains and so much wacky weather are related to climate change?
Allison Tracy It’s hard to pin any particular rainfall or freshwater influx on climate change. But according to climate change projections, we know that the Chesapeake Bay is expected to become warmer and wetter and have more rainfall and more of these issues with fresh water.
