Jodie Wennemer, MS CandidateConservation Biology
Chase down the term charismatic megafauna, and most likely you’ll come across references to the rock stars of the conservation world; giant pandas, blue whales, whooping cranes and the like. You’re unlikely to find clams in the mix, unless you happen to be chatting with Jodie Wennemer, a second year AUNE student who found herself up to her neck this past summer researching the re-establishment of quahogs and other mollusks in a once pristine tidal estuary.
The locale Wennemer researched was known until recently as Pilgrim Lake. Up through the late 1800s the locals called it East Harbor, since it was a large tidal body that connected directly with Cape Cod bay and with the village of Provincetown’s own harbor. In 1868, the commonwealth of Massachusetts built a 1,400 foot-long dike clear across the mouth of the harbor. The construction provided a new overland route to Provincetown, but at the cost of tidal flow into and out of East Harbor. Over the next 130 years, what had been a thriving tidal estuary became in essence a stagnant fresh water lake known as Pilgrim Lake. The harbor that once hosted a healthy saltwater marsh ecosystem devolved into a nightmarish breeding ground for midges, mosquitoes, and ever-expanding swaths of the invasive marsh grass Phragmites australis. Fish populations crashed (40,000 herring died in 2001 from chronic oxygen depletion), as did bi-valve populations. To reverse further degradation, the Cape Cod National Seashore in 2002 opened a set of tidal gates in the dike and reestablished modest tidal flow into Pilgrim Lake.
Wennemer’s study of mollusk restoration is just one facet of an ongoing research and monitoring effort at the 700-acre lake that has relevance in many coastal areas. “There’s a lot of attention paid right now to restoring salt marshes and restoring estuaries, restoring systems that were once salt water or brackish systems back to their natural state,” she notes. “We need to know how long it takes for the system to become a healthy natural system again. And the bivalve reestablishment or mollusk reestablishment within that system is one piece of the puzzle.”
Absorbed by Her Work
During her field work, Wennemer found herself wading through waters sometimes waist high, sometimes chin high with a GPS unit in one hand and the tow rope of a small skiff loaded with equipment in the other. Over the course of the summer she sampled some sixty-five randomly selected points in the lake. At each sampling site she took five sediment cores, sieving each sample for two minutes and pulling out any bivalve over one millimeter in size to record its species and size. She also took notes on water temperature and salinity, collected sediment samples for later analysis, and, with the help of a grid, a diving mask and a good set of lungs, took note of aquatic vegetation density.
That sounds like a fair amount of work-and she allows that it was-but having grown up not far from the Cape, Wennemer knew entering AUNE that she would be interested in working on coastal processes, on something that was close to home and meaningful. Knowing that helped her focus and inform her choices of classes and program direction.
As for the status of clams on Cape Cod, Wennnemer quotes fellow AUNE student Brett Thelen’s quip that the clam is the charismatic megafauna of the Cape. “The shellfish industry is so huge there,” she says. “The economy is dependent on the clams. Soft shell clams, quahogs, blue mussels ! these are all edible bivalves that were in East Harbor.” Her work tracking the re-emergence and health of quahogs and their cousins will help restore the area not just to what it once was but, as she says, “to what it’s supposed to be.” Perhaps in that spirit, locals have once again begun calling the lake East Harbor.