Williamsburg Sun

Mollusks — dead and alive — can help predict future shellfish extinction

Rowan Lockwood and Emily Rivest are studying mollusks both dead and alive as part of a multi-university initiative to predict the extinction risk of various species as casualties of global warming.

The live mollusks in their study are a diverse set of species representing important environmental niches. The dead mollusks are long dead, and are, in fact, fossils.

Species of concern in the shadow of rising ocean temperatures and increasing acidification include many commercially important shellfish such as oysters, clams, mussels and scallops. Lockwood, a professor in the Department of Geology at William & Mary, is a conservation paleontologist who studies fossil specimens in the context of their relevance to present-day ecological concerns. She is collaborating with Rivest, an assistant professor at William & Mary’s Virginia Institute of Marine Science, who heads a lab that examines living mollusks under various environmental conditions.

“I like to think of my specimens as pre-fossils,” Rivest says dryly.

Rivest and Lockwood will assemble a team that is expected to include post-doctoral researchers and more than a dozen William & Mary undergraduates and graduate students. Their work is an important component of a National Science Foundation program called Biodiversity on a Changing Planet. Funded by the NSF at $2.4 million, the collaborative project, titled “Using the Past to Predict the Future: How Physiology and other Functional Traits Determine Survival/Extinction in Western Atlantic Mollusks,” is led by Bruce Lieberman of the University of Kansas. Other collaborators are at Cornell University and the University of Oxford.

“One of the things that I hear a lot is that climate change is natural, and the Earth has always changed its climate. And that’s absolutely true,” Lockwood said. “I think this is a good opportunity to emphasize the fact that it’s just never changed this quickly.”

For example, she said many mollusk species went extinct during the Mid Pliocene Warm Period, in which the Atlantic Ocean heated up following the formation of the Isthmus of Panama. Lockwood explained that the waters of the Atlantic originally had an outlet to the Pacific, the currents flowing through a gap between North and South America.

“About 3 million years ago, the land bridge formed that connected North and South America,” she said. “That had all sorts of implications for the organisms living on land, but also for the organisms living in the ocean.”

Lockwood said the creation of the Panama land bridge shut off the outlet to the Pacific, creating the Gulf Stream, “this warm water current that just kind of circles up the western Atlantic, hits Cape Hatteras, and then kind of wiggles and jiggles across the Atlantic Ocean, making it possible to grow coconuts in Ireland.”

Deprived of its vent to the Pacific, the Atlantic waters warmed up, thanks to the new Gulf Stream and a couple of other geological events. The point, Lockwood says, is that a few decades of human activity is causing a similar degree of Atlantic warming that took the Isthmus of Panama thousands of years.

“This is not the first time we’ve seen climate warming. It’s certainly not the first time we’ve seen ocean acidification, or anoxia,” Lockwood said. “It’s not even the first time that we’ve seen human alteration of landscapes.”

She went on to say that while the scientific record only goes back a century or two, the fossil record goes back thousands to millions of years: “And that history gives us an opportunity to see how organisms in the past have responded to these exact same drivers.”

The fossil record shows that a significant number of mollusk species became extinct during the Mid Pliocene Warm Period. Lockwood and Rivest are combining their research areas to figure out how select members of phylum Mollusca will fare in the Anthropocene as compared to the Mid Pliocene Warm Period.

Rivest explained that they are focusing on 15 species within two classes of mollusks. There are bivalves such as clams, scallops and oysters, and then there are gastropods, such as conchs and whelks. Rivest added that the selection was assembled with an eye to diversity of species. The mollusks show a surprising amount of diversity beyond the bivalve/gastropod divide, she added.

“Some are carnivores, and some are suspension feeders. Diversity is important for ecosystem function when you consider the stability of our environments,” Rivest said. “Each species will have its own sensitivity to environmental change.”

She noted their list of target species includes Urosalpinx cinerea, the eastern oyster drill, a predator of oysters. Invasive on the West Coast, this species has become a serious pest on Olympia oysters in some California estuaries, she added.

“Climate change will likely tip the balance in different species interactions,” Rivest said. “Warming temperatures and sea level rise could affect microbial diseases and parasites of oysters and also the relationship of the oysters in Chesapeake Bay with this predator.”

She examines oyster drills and other target species in her lab at VIMS, a facility in which she can simulate past, present and anticipated future ocean conditions.

“We’ll be able to bring in these animals from various locations along the Atlantic coast,” Rivest explained. “We’ll hold them for a period of time under different temperatures and water chemistry that are representative not only of present-day conditions that they experienced in the habitats where we collected them, but also of projected future conditions under our current period of climate change.”

Rivest takes careful notice of responses to changes in water conditions, notably temperature and acidification. The lab will measure rates of oxygen consumption as well as rates of shell calcification, metrics that will then be combined with data on abundance and geographic distribution from mollusks in the fossil record.

The team will conduct statistical analyses to compare the responses to simulated warming/acidification of Rivest’s living specimens with closely related extinct species from the fossil record. Rivest says the team will assemble a predictive compendium of shellfish survival and extinction. She likens their project’s deliverable to a stock portfolio.

“And just like your stock portfolio, you want to have a diversity of investments, so that if one crashes, your entire retirement isn’t down the tank.” Rivest said. “Similarly, with the environment, we need a diversity of mollusks in order to have robust health and growth of our environmental quality and to have a properly functioning ecosystem.”

The five-year project has a significant outreach component as well. It includes participating in mentoring programs at the University of Kansas as well as partnering with the environmental non-profit Bridging the Gap, which works with K-12 schools in the Kansas City area.

Closer to home, the project will partner with W&M School of Education’s Mihyeon Kim to expand the STEM-oriented Camp Launch program for Virginia students in grades 7-10.

“Right now, there is a gap between where Camp Launch ends at 10th grade and William & Mary starts at 13th grade,” Lockwood explained. “So, we’re proposing to bridge this gap with a two-week residential program at William & Mary called Camp Orbit.”

She said Camp Orbit will provide mentored research experiences at both the Williamsburg campus of William & Mary as well as at VIMS. VIMS is also the site of another related outreach initiative started by Rivest: CSI Oyster.

Rivest said the CSI stands for Citizen Science Initiative. This program —which includes an oyster-raising component —is aimed at high school students and is being extended to community college students.

“It has a focus on ocean acidification,” she said. “And one of the really cool things about it is that it teaches students how to collect data on ocean acidification. As a result we have all this data about water chemistry from around the Chesapeake Bay that we wouldn’t have otherwise.”

Original source can be found here