|
|
 |
|||||
|
Volume 13, Issue 41 ~ October 13 - October 19, 2005
|
|||||||
 Putting Nature to WorkCan a tiny clam save a dying lake? Aquaculture pioneers launch a bold scientific experiment to clean a community’s lake. by B.C. Phillips There’s always something to do in Chesapeake Ranch Estates. From the main entrance off Rousby Hall Road, turning to the right will take you to Seahorse Beach, the horse stables and the community clubhouse, host to parties and celebrations year round. To the left is Driftwood Beach, the ball field, and the 30-acre, non-commercial airport — the only paved airport in Calvert County. A Maryland State Police emergency medevac helicopter, which averages 40 to 50 evacuations per year, calls it home. A number of privately owned planes keep the helicopter company. There are also campgrounds, horseshoe pits and a substantial community garden that sells produce and plants to residents. The two beaches are the best places outside of Calvert Cliffs State Park to see the county’s famous Bayside cliffs. But the residents get their cliffs all to themselves. More than 12,000 people, many of them military families, share these amenities. That makes Chesapeake Ranch Estates the most populous community in Calvert County, with more people than Chesapeake Beach, North Beach, Prince Frederick and Solomons combined. Lake Lariat, which came into being after the damming of Mill Creek in 1965, occupies the center of the Ranch Estates’ nearly six square miles. At 90 acres of surface area and over a mile in length, it is no small pond. Residents flock to the bath and boat houses during the summer months, then head down the wooden walkway to the lake shore, where they swim and boat under the watchful eyes of community lifeguards. But the lake doesn’t look the same as it did in the early days of the community, and there may be dangers in the water the lifeguards can’t see. The waters of Lake Lariat are dangerously polluted.
Citizens at Lusby’s Chesapeake Ranch Estates thought they didn’t have the money to have their lake cleaned. Then along came the founders of the Clam Project, with what they believe is a cheap, safe and revolutionary alternative. In the project, residents and scientists and eco-entrepreneurs have joined together to try something never done before. As of September, three floating reefs of Asiatic clams went to work in the troubled waters of Lake Lariat. The hope is that these tiny, bronze-hued bivalves will purify the waters of the lake and restore balance to its ecosystem. Project planners envision more than a clean Lake Lariat. They aim to quantify and publish the results of their efforts, putting their shellfish-based pollution control technologies on the scientific map. “Once the system has been tested and perfected, it is natural that the technology will be exported throughout the state, the nation and the world,” says Don Statter, president of the Lake Lariat Clam Project Inc., now a non-profit corporation. “To bridge the gap between basic research and commercial engineering: That’s why we’re here.” Betting the Farm The three brains behind the Lake Lariat Clam Project are Don Statter and Sandi Sullivan — both long-time residents of Chesapeake Ranch Estates — and aquaculture pioneer Richard Pelz, of Circle C Oyster Ranch in St. Mary’s County (see “Wrangling Oysters Out of Trouble,” Vol. XI, No. 2: Jan. 9). Statter is a partner in Circle C and a director of the Chesapeake Water Association, the public water system of the Ranch Estates community. There may be more than clean recreation riding on Lake Lariat; with competition emerging over Southern Maryland’s already low aquifers, Statter envisions the lake as a potential source of drinking water. Aquaculture has interested Sullivan since her college days. She studied marine biology and animal science at Wesley College and the University of Delaware. She put this interest to the side to homeschool her three children. In the fall of 2001, she met Pelz at the Patuxent River Appreciation Days festival. The success of his surface water technologies, designed specifically for use in the Chesapeake Bay, reminded Sullivan of what she missed. “Rich and I had almost the same outlook on the potential of aquaculture,” she recalls. With her children now in public school, Sullivan has time to put her old passion to work in cleaning her community’s cherished lake. As for Pelz, the technologies he developed farming oysters form the core of the clam project’s system. He invented the floating reefs and patented them for two innovative uses: to control water levels of biological nutrients (nitrogen and phosphorus), and to rid waters of infectious agents (Cryptosporidium). That’s right: These floaters aren’t just for farming. As part of a carefully engineered process, the shellfish reefs filter a variety of unwanted materials from the water. Pelz, Statter and Sullivan are betting the technology will translate well from oysters to freshwater clams. The comparatively small, enclosed nature of Lake Lariat makes it an excellent test site. Pelz doesn’t yet have hard data to back up his observations, but he’s seen what his floating oyster reefs have done for the water of St. Jerome’s Creek, where he farms at Circle C Oyster Ranch. “Rich has the visual,” Sullivan says. “He knows what’s happening. He just needs to quantify it.” “When I first started growing oysters at our dock,” Pelz explains, “I sunk to my knees in black smelly ooze. Much of the carbon is gone now, leaving brown sand and clay behind. When I walk, I only leave footprints, and the water is a foot deeper over much of the bottom.”  Troubled LakeThe bottom of Lake Lariat is full of similar muck, carbon matter mostly made up of decomposing plants and animals. In a healthy freshwater ecosystem, aerobic and anaerobic bacteria at the bottom of the lake would break down this carbon matter into harmless gases. But after decades of agricultural runoff and septic leakage, the water in Lake Lariat is stratified and stagnant. Excess nutrients flowing into the lake have bred dense algal blooms. Now little sunlight can reach the lake floor. Without sun, aquatic grasses starve. Deprived of the oxygen these plants give off, deep waters become dead zones. Dead aquatic matter collects on lake bottom, as does surface material like fallen leaves. But the low oxygen content of the water hinders the decomposition of this material by aerobic bacteria. The carbon matter continues to accumulate. This is what members of the Clam Project believe has happened in Lake Lariat, where the lower portion of the lake is too anoxic and acidic for new life to grow. The stratification of the waters below is not easy to see from above, unless you happened to take a walk in September down to the pond just below Lake Lariat’s dam. A recent leak in the bottom of the dam let the muck from the lake’s floor seep into the pond, turning it a putrid, oily brown. Dead carp floated at water’s edge. “The water has to be very filthy to kill a carp,” Statter said. The leak wiped out any doubt about what was happening below the surface of the lake. This muck isn’t the end of Lake Lariat’s troubles. The lake is one of the recreational hubs of the Ranch Estates community, but it may be unsafe to swim in its waters or eat its fish. Subsurface water samples have detected elevated levels of fecal coliform bacteria, indicating the presence of sewage. Worse, the lake may harbor the water-borne parasite Cryptosporidium, dangerous not only because of the serious illness it causes in humans but also because of its resistance to most forms of water purification, including chlorine bleach. In 1993 in Milwaukee, Wisconsin, 400,000 people became ill after drinking municipal water contaminated with Cryptosporidium. Finally, Lake Lariat’s fish have the highest recorded levels of mercury of any lake in the state, according to a 2004 report from the Maryland Department of the Environment. The Food and Drug Administration recommends that pregnant women and young children refrain from eating fish with high levels of mercury. This toxic metal accumulates in the tissues of humans and wildlife. Too much may cause neurological impairments. Especially at risk are fetuses and young children, on whom the effects can be severe and permanent. Most mercury pollution comes from coal-burning power plants. Despite all these troubles, on a warm day you may still spy swimmers in Lake Lariat.  Moving at the Speed of GovernmentThe muck below Lake Lariat’s dam dismays Richard Bohn, of the Maryland Department of Natural Resources, who issued the permits that allowed the clam project to proceed. Bohn is a believer, in both aquaculture and environmental cleanup. He earned his M.A. in fisheries from the University of Washington and began his career farming oysters on the West Coast. Before joining DNR, he was an associate professor for the Sea Grant College at the University of Maryland. Still, permits took some three years to acquire, and Bohn has been accused, somewhat jokingly, of “moving at the speed of government.” But like his department, Bohn needs to assure the safety of what he’s permitting. Bohn and the DNR were mainly concerned about the species of clam the Lake Lariat Clam Project intended to use. Corbicula fluminea are a freshwater species native to southeast Asia, first introduced to North America at the end of the 19th century. The clams are now widespread, but they are still considered invasive pests. They compete with native clam species for food and space, and their tendency to lodge in intake pipes and irrigation canals has caused millions of dollars worth of damage to public and private industry. The Clam Project needed two permits: one authorizing collection of the Corbicula clams from the northern Potomac River, another authorizing the stocking of clams in the lake. Before these could be issued, Bohn and others had to be convinced that the clams would be unlikely to spread beyond Lake Lariat. They also wanted to make sure that the clams would not be eaten as food or used as fish bait. Given the toxic nature of the clam’s work, they represent a potential health hazard. Bohn takes his job seriously and defends the concerns of his agency, but he, too, is frustrated by the lack of progress made in over thirty years of efforts to clean up the Bay. He is cautious about casting blame. “It takes a great deal of cooperation between very many groups,” he explains. To get the Lake Lariat permits, he had to meet with the Food and Drug Administration, the U.S. Department of Agriculture, the Maryland Department of the Environment, the Maryland Department of Health and Mental Hygiene, private environmental groups and university scientists, each with its own agenda and concerns. Del. Anthony O’Donnell isn’t satisfied, either. “We dump millions of dollars in the Bay each year on oyster restoration efforts,” O’Donnell said at the ribbon-cutting of the Lake Lariat Clam Project on September 15. “The results of those efforts have been not good, at best.” Enter the aquaculture revolution. The Ultimate Cleaning Machine “I grew up in the 1960s, when we were just starting to become conscious of what we were doing to the planet,” recalls Statter, the project’s main spokesperson. “I remember thinking as a young child, why don’t we invent a cleaning machine? But the realities are, most machines run on electricity and you end up with waste-products. We need smarter ways to clean the environment.” Smarter means safe, efficient and cheap. The Lake Lariat Clam Project’s system is contending to be all three, making it Statter’s “Ultimate Cleaning Machine.” Here is how it will work: 100 floating reefs of Corbicula clams will be distributed in shallow coves throughout Lake Lariat. The clams will float just below the surface of the water, in what Pelz discovered is the ideal placement for greatest metabolic efficiency: plenty of oxygen for the clams, plenty of sunlight for the algae consumed by the clams. The clams will eat a lot, grow fast, then eat even more. But because of the severe stratification of the lake, the clam reefs themselves are not enough to do a thorough cleaning job. If the reefs alone were used, the clams would only filter the top half of the water column, leaving the dense carbon matter and anoxic waters in the deeper portion. That is why solar-powered water pumps will be installed, one for every 10 clam reefs by current estimates. These pumps serve two purposes. First, they’ll bring the nutritious carbon matter and nitrogen up from the bottom of the lake to feed the algae and clams. Second, they’ll bring oxygen from the top of the lake down to the bottom of the lake to fuel the aerobic bacteria. The algae will eat the nitrogen and proliferate. The clams will fill up on algae. Whatever the clams don’t eat, they will spit out in the form of pellets known as pseudofeces. The pseudofeces and other waste products will sink to the bottom of the lake, where they will be feasted upon by oxygen-invigorated aerobic bacteria. The anaerobic bacteria in the deepest portion of the lake will consume any nitrogen left over by the aerobic bacteria, transforming it into inert nitrogen gas. Once this cycle gets in full swing, it should both destratify and clean the waters of Lake Lariat. With all 100 reefs deployed, the system is expected to be capable of cleaning 5.5 million gallons of water per day. Lake Lariat has an estimated capacity of 250 million gallons. Put another way, one reef alone could remove 210 pounds of nitrogen from the lake each year. That’s a good trick, but these clams are not a one-trick act. Bohn speaks enthusiastically about their ability to pull very low concentrations of metals out of the water to use in constructing their shells. Clams will use any metals they can find, including mercury, even plutonium, according to Bohn. Remember our friend Cryptosporidium? Pelz has based his second patented technology on the clams’ ability to filter and destroy the tough little protozoa, and possibly other parasites. He used the discovery of Thaddeus Graczyk, of the Department of Environmental Health Sciences at Johns Hopkins University, that Corbicula clams’ white blood cells would eat Cryptosporidium. These clams will not be fit for human consumption.
The Lake Lariat Clam Project finally received its permits from DNR this past May, on the condition that it first test the survival of the clams by placing a few reefs in the pond below the dam. “It was an easy way to get some quantitative data without impacting the environment you want to clean,” said Sullivan. “If they can live there,” remarked Bohn, “they can live anywhere.” The clams did live, and not only that, they grew. At the end of the summer, Statter, Sullivan and Pelz found the survival rate of the control group clams was 96 percent, with measurably increased biomass. During a ceremony on September 15 — attended by state delegates, county commissioners, DNR officials and the press — the three reefs were moved from below the dam into the lake proper. On September 30, Statter, Sullivan and Pelz checked on the clams a second time to see how they were faring in the lake. The survival rate of the control group remained high at 94 percent. The project needs additional funding to install the first solar pump. Compared to other water purification methods, Lake Lariat Clam Project’s system is cheap — but not cost-free. So far, Statter, Sullivan and Pelz have been footing the bill themselves, with the help of some donations from Ranch Estates residents. With their new non-profit status, they are seeking public grants and private, tax-deductible gifts to fund the next phase of the project. Statter estimates $10,000 is needed to install a total of 10 floating reefs and a solar-powered pump. The fully envisioned project, with 100 reefs and 10 pumps, would require an estimated $260,000 over two years. This figure includes scientific studies to quantify results. Even if money comes soon, Statter does not believe the lake will be completely clean in two years. But, he says, “I do believe the lake will be trending toward clean, and that there will be enough information to understand the science and engineering aspects well enough to duplicate results at other locations.” If Statter is right, there are still plenty of questions to answer, questions that the project’s researchers plan to address. What conditions are necessary for the clams’ survival? Is there a better clam than the Corbicula? Where are the best locations for clams in the lake? Must the clams be replaced every year, or will they reproduce? What is the economic value of the project? Is the Clam Project’s system truly a low-cost solution?
“This project is bigger than Lake Lariat. It’s bigger than the Chesapeake Bay region. From California to Maine, we need this,” Statter says. It’s hard to argue with him. Although Bohn has been the symbol of bureaucracy for the gung-ho Lake Lariat aquaculturists, he, too, would love to see the project succeed. Unlike many Bay Country natives, Bohn is in the enviable position of having seen locally initiated clean-ups work. He speaks excitedly about Lake Washington, in King County, Washington state. In that case, metropolitan Seattle formed a council in the late 1950s devoted to ridding the nation’s second largest natural lake of pollution. At first, the pollution continued to get worse. By 1994, the lake water was clearer than it had been in 50 years. Pelz has witnessed his own little miracle around St. Jerome’s Creek, and in this he places his faith. All indicators are good. “The plants and animals tell you how the clean-up is going. When we started, we had a seagull-fouled dock and an eroding shoreline,” Pelz said. “Now, fat crabs are everywhere, healthy fish abound in large schools, shore grasses have come back thick throughout our cove. Clam holes dot the bottom under our oyster floats, and a pair of osprey raise their young at the far end of the dock each year. Green and blue herons fish from the floats. From overhead can be heard the cries of terns fishing. These birds have all but replaced the dock-fouling garbage-hunting seagulls of 10 years ago. “All in all,” he says, “it is a pleasant and pleasing change.” Let’s hope something similar is in store for Lake Lariat, our Chesapeake Bay and all this wide world. The Lake Lariat Clam Project has a new website: www.clamproject.com. Or call Don Statter: (410-326-6958) Sandi Sullivan (410-326-0150).
|
|||||||
|
|
|||||||
|
© COPYRIGHT 2004 by New Bay Enterprises, Inc. All rights reserved. |
About the Author