A typical urine-diverting toilet collects solid and liquid waste, which could be processed into fertilizer, removing nitrogen from the waste stream

Considering that we all flush at least three times a day, it’s surprising how little we know about where our waste goes. Into a white bowl and then down a pipe— never to be seen, smelled, or thought of again.

But as many Cape Codders are beginning to realize, that’s not really the case. The by-products of our waste are seeping out of underground septic systems and into the groundwater, flowing finally into coastal ponds. The nutrients are harmless by themselves, but in concentrated form, throw off the ecological balance of sensitive estuarine systems.

Though there are many nutrients and “contaminants of concern” to be worried about, nitrogen is known as the culprit for changing pristine harbors into algae-filled swamps, devoid of marine life. Or so we fear.

Last night, Falmouth selectmen approved a town-wide comprehensive wastewater management plan (CWMP), developed over the course of several months last year by a panel of community members. It calls for over $300 million to install a sewer system in the neighborhoods south of Route 28 from Little Pond to Seapit Peninsula. Millions more are expected to sewer the next phases north of Route 28.

The CWMP committee and selectmen also set aside funding for the study of alternatives to sewering, which could lower the overall cost of the plan.

Several of these options were covered in a forum held earlier this month at the Waquoit Bay National Estuarine Research Reserve (WBNERR), in which four experts in various areas of wastewater treatment delivered “The Scoop on the Poop” from the perspective of traditional sewer systems, alternative systems, shellfish aquaculture, and coastal engineering.

It’s not as complicated as it sounds. In fact, it should be taught in grade schools.

The big pipe method

Falmouth's wastewater treatment plant on Blacksmith Shop Road is one of just five such facilities on Cape Cod

Michael Giggey, the senior vice president of Wright-Pierce, an engineering and consulting firm, started off the evening with an overview of the municipal treatment options, from individual “on-site” systems to cluster and satellite systems to centralized wastewater treatment facilities.

As an advisor to the Town of Orleans on its comprehensive wastewater management plan and an islandwide wastewater plan on Martha’s Vineyard, Mr. Giggey noted that each watershed has different needs, which can be met through a combination of technologies.

The simplest option, he pointed out, is to simply eliminate the main controllable source of nitrogen pollution by removing enough septic tanks to meet the TMDL and connecting those homes to a sewer system, discharging the treated effluent outside the watershed.

However, across the Cape, that strategy has proven to not be so simple, and certainly is not cheap.

In Falmouth alone, the cost of sewering homes south of Route 28 from Little Pond to Seapit Peninsula is expected to cost $310 million for the first two phases, to be paid for by a combination of taxes and homeowner betterments. Across the Cape and Islands, these figures add up to billions.

In a report compiled last April by the Barnstable County Wastewater Cost Task Force, the study found the most important factor when choosing a wastewater treatment strategy is the amount of nitrogen that each system can remove per dollar spent. Centralized wastewater treatment facilities can reduce nitrogen down to 3 milligrams per liter, whereas effluent from on-site denitrifying systems ranges from 10 to 19 mg/L, Mr. Giggey said.

Though sewer mains and wastewater treatment facilities require a large amount of capital up front, the task force found that operation and maintenance costs for a centralized sewer system were far lower than on-site denitrifying systems, cluster, or satellite systems.

“It’s not just about cost, but cost-effectiveness,” said Mr. Giggey, who served on the task force. “It would seem the most cost-effective option is with the larger systems.”

David Dow, president of the Cape and Islands chapter of the Sierra Club, asked Mr. Giggey whether wastewater managers on Cape Cod have had any experience with removing “contaminants of concern” from effluent. These chemicals are the byproducts of pharmaceuticals, personal care products, and detergents that most wastewater systems do not treat, or even monitor.

“Unfortunately, there’s not a lot of local experience. We’re just now getting our arms around what nitrogen does. Contaminants of concern are not just one compound, it’s thousands,” Mr. Giggey said.

Innovative & Alternative systems

The British-designed "Loowatt" toilet was originally built with the waste disposal needs of developing countries in mind.

Also serving on the task force was panelist George Heufelder, director of the Barnstable County Department of Health and the Environment, who established the Massachusetts Alternative Septic System Test Center at the Massachusetts Military Reservation in 1999.

Mr. Heufelder noted that every wastewater treatment option works on basically the same principle: to “manipulate the nitrogen cycle inside a black box.” Though some methods are more efficient than others, the basic idea is to break down nitrates into nitrogen gas, a major component of the air we breathe.

In over a decade of testing, Mr. Heufelder found that innovative and alternative (I/A) systems “remove about 50 percent of the nitrogen 70 percent of the time.”

Emerging membrane technologies, such as the Nitrex, is capable of removing 90 percent of nitrogen from groundwater. The Nitrex, which Mr. Heufelder referred to as “a box of proprietary cellulose material, otherwise known as wood chips,” and other membrane systems are also becoming cheaper and easier to maintain.

A composting toilet: the only difference is the pipe

Another affordable and effective option for individual homeowners is the composting toilet, which Mr. Heufelder noted has an added benefit of separating toilet waste from graywater—the shower, sink, and dishwasher water that usually goes down the drain.

In an earlier comment from North Falmouth resident Alison Robb about the need to keep drinking water from becoming wastewater, Mr. Heufeulder agreed that the tradition of defecating into potable water “is lunacy, but we do it.”

However, he said it would probably require “mass hypnosis” to get every resident to install a composting toilet and never put kitchen scraps or chemicals down the drain. Even if Town Meeting members bought into composting toilets as a nitrogen management strategy, the Department of Environmental Protection would need a way to ensure its regulations were being met, he said.

“It’s trust and verify. Not everyone’s composting nicely in the back yard. There will be some nitrogen [in the system], and we need to know what it is,” said Mr. Heufelder.

The Eco-flush urine diverting toilet can remove 90% of the nitrogen from human waste, using 80% less water than a traditional toilet

Another innovative home nitrogen removal method on the market is the urine-diverting toilet, which was on display at WBNERR, thanks to Conrad Geyser, president of Cotuit Solar.

Though Mr. Heufelder admitted that he and other men might have a problem sitting down to use the toilet, he said one day the market for phosphorus and nitrogen would put a premium on mankind’s most abundant waste product.

Because urine contains up to 90 percent of the nitrogen and 50 percent of the phosphorus in domestic wastewater, separating and collecting it is also a simple way to prevent nutrients from reaching the groundwater.

“I envision a day when someone comes to your door to write you a check for good-quality urine,” Mr. Heufelder said, estimating that there is a total of 150 more years of phosphorus left in traditional mines.

Mr. Heufelder noted that membrane systems can be “a little power hungry,” using five to eight kilowatt hours per day in a typical home. However, the Nitrex makes use of a trickling system with lower energy use, he said.

There are other costs associated with on-site systems that should be factored into their overall costs, said Mr. Heufelder, estimating that one full-time employee would be required for every 1,500 on-site systems to ensure they meet environmental standards.

Furthermore, homeowners are required by regulations to have a maintenance contract for their on-site system, and any residual waste would have to be disposed or converted into fertilizer by a private company, he said.

“I cannot imagine DEP allowing composting or urine-diverting toilets unless the residuals leave the watershed completely,” he said.

The shellfish solution

The Sippewissett oyster, a product of local aquaculture efforts

While town officials and residents tend to focus on technical solutions for wastewater treatment, local scientists are turning to Mother Nature to help reduce the nitrogen load.

Diane Murphy, an aquaculture and fisheries specialist for the WHOI Sea Grant and Cape Cod Cooperative Extension, gave an overview of the potential for shellfish aquaculture to remove nitrogen from sensitive coastal embayments.

While shellfish are becoming more accepted as a method for meeting total maximum nitrogen loads (TMDLs), Ms. Murphy emphasized that aquaculture should not be considered the only solution for reducing nitrogen loads.

“Oysters can serve a crucial role in the uptake of nitrogen. Aquaculture should not be the sole source, but should be integrated into a nitrogen management plan,” she said.

Acting as grazers on the sea floor, oysters and other shellfish consume the phytoplankton that tend to grow in the presence of elevated nitrogen levels. The more food there is, the more the oysters grow.

Though there are conflicting reports on how much water oysters are capable of filtering each day, the accepted number is about 20 gallons per day, Ms. Murphy said. Studies have found that a market-size oyster can sequester an average of 0.52 grams of nitrogen and 0.16 grams of phosphorus over its lifetime.

When harvested, all that nitrogen is removed from the ecosystem “free of charge,” she said.

Based on a study of the 2006 oyster harvest in Wellfleet, Ms. Murphy said that 20,000 bushels of oysters can assimilate 282 kilograms of nitrogen. The oyster feces become buried in the sediment, stimulating denitrifying bacteria, a process that results in nitrogen gas being released to the atmosphere. In Wellfleet that year the total nitrogen removed was 2.3 tons.

Even though oysters are good to eat, Ms. Murphy does not advocate turning every coastal pond into an aquaculture site, noting the impact on recreational users’ access to and enjoyment of the water.

A large-scale oyster aquaculture project could clean up Falmouth's coastal ponds, create jobs and increase local food production

About 2.5 million oysters would be needed to filter all the water in Waquoit Bay, Ms. Murphy said, requiring about 10,000 square meters, or about 2.5 acres, for all of the gear.

According to an estimate by Woods Hole resident and aquaculture consultant Ron Zweig, many more oysters may be necessary to adequately filter the water, covering up to 30 acres of the 825-acre bay.

The ecosystem also has a certain “carrying capacity” for aquaculture production, and even oysters have their limits before disease, predation, and lack of food inhibit their growth, she said. Because each estuary is different, she recommended a feasibility study to determine how extensive an aquaculture operation the ecosystem is capable of supporting.

Mashpee Shellfish Constable Rick York. said that conditions in the estuary also determine the type of shellfish most suitable for aquaculture. In the low salinity of the Mashpee River, he had great success in growing half a million oysters without fear of predation or disease. Since 2005, the oysters have removed over a ton of nitrogen, he said, which increased the dissolved oxygen content to the point of being safe again for fish.

However, he said the Mashpee River is unique, and in other areas he would recommend seeding quahogs instead of oysters.

“I take issue with oysters having the most potential,” he said. “Quahogs don’t filter as much water, but they consume as much nutrient.”

Flushing the bays

Another strategy to decrease the impacts of nitrogen in sensitive embayments is to increase the amount of “flushing,” or exchange, between the ocean and the estuary.

Nitrogen concentration is higher at the head of coastal ponds, but becomes diluted in areas of greater flushing

The adage, “the solution to pollution is dilution” rings true in this case, said John Ramsey, a senior coastal engineer at Applied Coastal Research and Engineering, a Mashpee firm.

If the tidal conditions are right, nitrogen concentrations can be decreased to acceptable levels, even if the load remains high, he said. Since people tend to live near the water, the nitrogen load at the head of the bay tends to be higher than that near the tidewater.

Due to coastal geology, estuary inlets tend to become filled with sand, or even become blocked by the formation of barrier beaches, he said, showing slides of such events. Unless the inlets are dredged, flushing will decrease over time, Mr. Ramsey said.

Even if the inlets are maintained, all tides are not created equal. While Cape Cod Bay has a 13-foot tide, Vineyard Sound only has a 1.5-foot fluctuation, and Buzzards Bay tides are about 4.5 feet.

“The size of the pump matters,” Mr. Ramsey said. Some towns, he said, “are at a huge disadvantage for tidal flushing.”

Green Pond, Bournes Pond, and Eel Pond in East Falmouth

In Falmouth, Bournes Pond has been cited as one area that does get a generous amount of flushing activity. Mr. Ramsey said if the inlet could be widened from 50 to 100 feet, the coastal pond’s nitrogen concentration would be reduced from 0.6 milligrams per liter to 0.46 mg/L. That reduction would mean that half as many homes in the Bournes Pond watershed would have to be connected to a sewer, he said.

Although on paper widening the inlet seems like a win-win solution, wetland protection regulations place restrictions on projects of this kind because of the impacts on barrier beaches, which protect coastal zones from storms and flooding and provide habitat for endangered species, said Mr. Ramsey.

“Widening the Bournes Pond inlet will create a bigger footprint of impact on the barrier beach system. It’s something regulators will struggle with,” he said.

Given that its now easier to find oysters from Duxbury and mussels from Prince Edward Island than it is to get locally-sourced seafood, this locovore’s dilemma begs the question: which came first? The shellfish or the septic system? The problem or the solution?

Sometimes, when overhearing discussions among wastewater experts, the idea is floated that Cape Cod should try to get back to 1619– that is, before Pilgrims landed on these shores.

Though it took until roughly 1990 for humans to load the estuaries with enough nitrogen to kill small fish, the basis for the idea is that we should limit our inputs to the environment to basically zero, just as the native Wampanoag did.

Here's what eel grass should look like

In the past three decades, we have developed our communities to the point where the nitrogen leaching from household septic systems and fertilized lawns has caused our beloved estuaries to seriously decline.

Across the entire Cape, algal blooms clog and stink up the water, leading to unpleasant swimming and boating experiences– and signaling a major ecological disaster.

A lack of eel grass is often the first sign that nitrogen loading has tipped the scales towards an unhealthy estuary. As nitrogen seeps in with the groundwater, it causes algae to grow– and infamously, bloom, when summer temperatures heat up.

Not only is it yucky to look at, algae blocks the sunlight needed by eel grass, causing a rapid decline for this aquatic plant species– as well as the shellfish that grow on its blade and stems.

Dying eel grass: a familiar sight in Falmouth harbors

As the algae dies off, it sucks up the oxygen in the water. If the die-off is extensive, it can cause dissolved oxygen levels to get so low that fish die– or swim to less suffocating areas.

The less lucky marine creatures– snails, worms, and shellfish– are not mobile, and tend to die at much greater rates than fish.

So how do we get back to the way it was in 1619? The state, through the Massachusetts Estuary Project, has set daily maximum nitrogen loading (TMDL) targets that we’ll need to achieve to restore the estuaries, but does not offer any guidance on how to get there.

We need only take a lesson from nature to understand how the nitrogen cycle has balanced itself out over millennia.

A bi-valve solution

While towns on Cape Cod brace themselves for a lengthy, costly, and energy-intensive installation of a sewer system, some residents have taken a back-to-the-Earth approach.

Drawing on his 30 years as an aquaculture consultant with the World Bank, Woods Hole resident Ron Zweig thinks that the solution to the Cape’s water woes could be staring at us from our dinner plates.

Mr. Zweig’s experience with aquaculture in Southeast Asia and at the New Alchemy Institute in Hatchville corroborate the findings of numerous studies establishing the ability of shellfish to filter and remove nutrients (mainly nitrogen and phosphorus) from water and suspended sediments.

A Falmouth Shellfish Cooperative cage, used for growing oysters in deep water.

A 2006 study of aquaculture in Waquoit Bay by WHOI’s Marine Policy Center found that 500 oysters and quahogs removed 0.1 kilograms of nitrogen per liter from the water, and an additional 0.1 kg from the sediment underneath the growing tray per year.

According to Mr. Zweig, one oyster, on average, is capable of removing 0.65 milligrams of nitrogen per year during two years of growth.

If grown on an exponential scale, aquaculture could potentially meet TMDL targets, especially if the inlets to some coastal ponds are also widened.

In a spreadsheet analysis of four coastal ponds in Falmouth facing Vineyard Sound, Mr. Zweig recommends setting aside 8-9% of Bournes Pond, Great Pond, and Green Pond for aquaculture, and about 22% of the heavily polluted Little Pond, in order to meet the state-mandated TMDL’s.

Getting Aqua into the Culture

While these studies may be little more than numbers on paper, Mr. Zweig is working with members of the Falmouth Shellfish Cooperative, four companies that hold aquaculture permits in Buzzards Bay, to turn his hypotheses into action.

The Cooperative is currently working on a proposal to start up aquaculture plots in one or several of Falmouth’s coastal ponds. Not only would a more inland location make it easier for the farmers to get to their oyster cages, the development would also serve as an experiment on the potential for shellfish to remove nitrogen.

If successful, the Cooperative estimates that expanded aquaculture operations could create or maintain 165 permanent jobs in Falmouth, while restoring 3,700 acres of shellfish habitat.

An aquaculture site in Buzzards Bay operated by the Falmouth Shellfish Cooperative.

This summer, the Cooperative plans to market their first batch of the Sippewissett Oyster, sold straight from their retail location on Coonamessett Farm. With a fledgling mechanism already in place to put Falmouth’s seafood on the map, the oyster farmers say there is much more room to expand.

In Mashpee, Shellfish Warden Richard York hopes to build on the success of an aquaculture program he started in Mashpee River. The Mashpee Enterprise reports that Mr. York is writing a $75,000 grant to purchase, propagate, and plant 10 million quahog seeds in Waquoit Bay. Quahogs, he says, are ideal for aquaculture because of their resistance to predators.

Even if only half of the quahogs survive to maturity, the initiative will generate up to $750,000 in revenue, enough money for 15 shellfishermen to make a decent living, estimates Mr. York.

It may just turn out that doing the right thing for the environment is also good for the economy– and for our appetites.

The downside of aquaculture

However, the simple solution is not always the easiest. As Cape Codders know well, changes intended to solve environmental problems (think wind turbines) often come with a serious backlash from stakeholders.

The Marine Policy Center quantified the costs and benefits to aquaculture not only from the nitrogen removal angle, but also from the point of view of recreational users of Waquoit Bay.

Due to the potential “aesthetic costs” caused by exposed aquaculture gear at low tide, as well as decreased area for boating, the Marine Policy Center estimated that 1.5% of the head of Waquoit Bay could be used for aquaculture without negative consequences.

One additional issue that aquaculture does not address is the need for a wastewater solution that removes not only nitrogen, but a range of “contaminants of concern” from products consumed and eliminated by humans, now concentrated in your drinking water.

A typical composting toilet: the only difference is the pipe.

Even if shellfish were capable of filtering and sequestering aspirin, Viagra, and shampoo chemical residues from the water, would that solve the problem? (And would you want to eat them?) Or does it just point to a larger question: why are we contaminating fresh drinking water with our waste?

In my humble opinion, we need a variety of options to deal with our wastewater worries. If it is not conceivable to place aquaculture operations in coastal ponds on the scale necessary to remove the entire nitrogen load, it would be wise to eliminate the main cause of the contamination: septic tanks.

Even on a small scale, aquaculture can likely eliminate nitrogen released from non-point sources, namely fertilizer and road run-off. And by installing household composting toilets, we would eliminate at least half of the nitrogen load, while also pre-empting contamination by other, potentially very harmful, chemicals.

Earle Barnhart and Hilde Maingay, whose nonprofit organization, The Green Center, is the successor to the New Alchemy Institute, is concerned that the “big pipe” solutions being discussed by a town committee are inefficient and expensive ways to reduce nitrogen loading to Falmouth’s coastal ponds.

The husband and wife team have compiled nine options that residents can undertake to eliminate nutrients from wastewater. They suggest that a feasibility study be conducted to see how much nitrogen would be eliminated, and at what cost, under each scenario.
“With a great variety of options available right now, home-based systems can be designed to respond to the specific needs of each individual residence or area of concern, require very little design time or costs, can be installed immediately, and have a great degree of inherent flexibility,” wrote the couple in a five-page handout they e-mailed yesterday to Town Meeting members.

• Residents can reduce their nitrogen contribution by using low-nitrogen and phosphorus-free soaps, cleaners, and detergents.
• Eliminating the use of chemical fertilizers and garbage disposals would also reduce the amount of nitrogen in the waste stream.
• Noting that car exhaust and road runoff is a significant source of nitrogen deposition to estuaries, residents can reduce their mileage or switch to a hybrid vehicle.
• On a townwide level,  Falmouth could collect food waste separately from garbage to make compost, thereby using the nitrogen and other nutrients in food as fertilizer.

For those who think it is too hard to incorporate these tips into their lives, Hilde and Earle are living examples. They own a composting toilet, which they say is inexpensive and easy to maintain. As professional landscapers, they use compost and organic fertilizers, and at home they feed food scraps to their chickens and use plant-based cleaning products.

The Bigger Picture

A large-scale oyster aquaculture project could clean up Falmouth's coastal ponds, create jobs and increase local food production

Drawing from the expertise of farmer and aquaculture researcher Ronald J. Smolowitz and Woods Hole resident Ronald D. Zweig, an aquaculture specialist for the World Bank, Hilde and Earle recommend using oysters as  natural filters for nitrogen, and widening the inlets of coastal ponds to increase tidal exchange.

A centralized sewer system, while effective at removing nitrogen, comes with a high cost and long lead time to design, construct, and operate, the authors wrote. In terms of water and energy consumption, it is also inefficient.

Purifying water for drinking, then polluting it with human waste, and cleaning it again is inefficient. Transporting large volumes of water from a supply source to a pumping station, to homes, to a sewage treatment plant, and finally to a discharge area is inefficient.

A variety of sources contribute nitrogen to groundwater, but a majority leaches from underground septic tanks

If wastewater treatment was viewed as a “closed-loop” system, the nutrients it contains could be recovered, treated, and used as organic fertilizer, say Hilde and Earle.

Composting toilets

A composting toilet: the only difference is the pipe

The waterless composting toilet is one of the options Hilde and Earle propose for further study.

It looks like a regular toilet, without a pipe. A fan ensures that odors are released through a pipe in the roof, requiring as much energy as a 60-watt bulb.

“The lower the technology, the less likely it is to fail,” said Hilde.

“That’s right,” said Earle. “Gravity never breaks down.”

The holding tank of a Clivus composting toilet

Collection requires a basement storage tank for solid waste, which is typically removed four times a year.

Though current health codes require off-site disposal, the sterilized waste could be used as commercial fertilizer or at home for non-food crops.

Urine-diverting & packaging toilets

Another option is a urine-diverting toilet with an optional waterless urinal.

With this technology, naturally sterile urine is collected in a basement storage unit, where it can be collected for fertilizer, or be processed in a septic or sewer system.

Hilde and Earle also propose a few options for using waterless packaging toilets and urinals. These options would require a commercial contractor to collect waste “packets,” which can be sterilized and composted to create fertilizer.

The British-designed "Loowatt" toilet was originally built with the waste disposal needs of developing countries in mind.

Alternatively, the packets may be incinerated, either at home or off-site—not unlike throwing out diapers, Hilde noted.

The waste packets can be used in a bio-gas digester, which produces methane gas while killing off pathogens.

The result is a potent fertilizer suitable for edible crops.

Alternative Cost-Benefits

Based on each of these options, traditional toilets do not necessarily have to be replaced. With each of these options, a home would have to keep its septic tank in order to process the “gray water” from the kitchen and laundry.

They suggest studying the costs and benefits of maintaining the current septic treatment at most homes, with the addition of aquaculture and the widening of coastal inlets.

Jobs, food, and fertilizers could be created from this endeavor, whereby not only the oysters, but also the wastes and the macro-algae that grows around them could be harvested as fertilizer.

“Why don’t we try it  and see how much [nitrogen] is removed by reducing our inputs, then we can go to the next step?” asked Earle.

An Ecological Treatment System

This schematic by Ron Zweig proposes a centralized treatment system based on John Todd's ecological design principles

Another option is to install a centralized treatment plant with ecological principles in mind.

In this design, wastewater is treated with a biogas digester that releases methane, which can be used as energy to run the system– or cook food or heat a home.

The primary-treated water is then filtered through aquatic plants and wetlands, where the nitrates decompose and are consumed by beneficial bacteria. These aquatic plants may be composted, and the treated water can be reused to irrigate trees and non-edible plants.

Recognizing that not all residents would be comfortable installing an alternative toilet in their homes, Hilde noted that it will take serious study, modeling, and public outreach for people to understand that the systems are safe and just as effective as traditional toilets.

“We assume that we’re incapable of handling our own waste. That’s a really bad assumption,” she said.

According to scientists at the Woods Hole Oceanographic Institution, 30% of the world’s carbon dioxide (CO2) emissions, known to be a leading cause of global warming, are being absorbed by the ocean. Small coincidence that over the past 50 years of global  industrialization, rising CO2 emissions have also led to a 30% increase in the average acidity of ocean surface water.

This phenomenon is just starting to attract the attention– and alarm– of policymakers and the shellfish industry.  I talked to Scott Doney and Sarah Cooley at WHOI to find out why.

How does ocean acidification happen?

When CO2 in the atmosphere combines with seawater (H2O), the molecules combine to form carbonic acid (H2CO3). This acid is weak and dissociates rapidly in basic seawater, releasing hydrogen ions. When these ions combine with the carbonate ions already present in the water to form bicarbonate, they rob coral and shellfish of the materials they need to grow their shells and skeletons.

Scientists estimate that the pH of seawater has decreased by about 0.1 units– a 30 % decline on the logarithmic pH scale– and could decline by 0.3-0.5 units more in the next 100 years, as CO2 levels rise. Over time, they warn, the ocean’s ability to absorb CO2 could diminish the development of coral reefs and marine organisms with calcium carbonate shells, with side effects reverberating throughout the ecosystem.

Scott Doney, of WHOI, explains the connection between CO2 and your favorite seafood dinner

The question is when, and where, said Dr. Doney. Using carbon emissions projections from the Intergovernmental Panel on Climate Change, he predicted that acidity levels in the ocean will double by mid-century, and carbonate ions could decline by half.

Carbon dioxide, if you look at it as a pollutant, is very long-lived, lasting from hundreds to thousands of years. It will also continue to grow through the mid-century, with no good indication that we’ll be able to stabilize it.  We’ve now increased atmospheric carbon dioxide to a range that hasn’t been seen since 800,000 years ago,  judging from ice cores.

-Scott Doney

In a 2008 paper, Drs. Cooley and Doney indicate that bivalves, such as scallops and oysters, would feel the effects of acidification more heavily than sea urchins or crustaceans, such as lobsters, shrimp, and crabs, due to their use of a more soluble form of calcium carbonate in their shells. The effects of acidification on fish is not known, but should be studied, Dr. Doney said.

“There’s no indication that this will destroy sea life, but it certainly will diminish and dislocate some species,” he said.

Calling for additional research into the socio-economic, as well as biological and political ramifications of ocean acidification, Drs. Doney and Cooley, with WHOI marine policy specialist Hauke Kite-Powell, are investigating the impacts on the shellfish industry in the Northeast.

The economic effects of ocean acidification will be felt locally, the scientists say. In New Bedford, the top American port for shellfish, they found:

• By 2060, a 25 % loss in shellfish populations would decrease landing revenues by $67 million a year, or $2.2 billion
• Losses in primary revenue from commercial harvests—or the money that fishermen receive for their catch—could add up to as much as $1.4 billion within 50 years
• In comparison, a 25 % decrease in the seafood employment sector contributed to a dramatic economic decline from in New Bedford from 1992 to 1999, when 20 % of residents were living below the federal poverty level

The Bigger Picture

Dr. Doney’s research also takes a look at the global picture, especially at areas of the developing world that are dependent on viable fisheries.

“As with so many aspects of environmental degradation, the Third World is often hit hardest, and is the least resilient,” he said. “We want to make the connections with fishing communities and how they can adapt.”

Acidification could be the death blow for coral reefs, which are already impacted by pollution and overfishing, Dr. Doney said, which will have an impact on coastal erosion, fish habitat, and tourism.

Regions that are impacted by acid rain and nutrient runoff might already be experiencing the effects of acidification, he added. While a connection between nitrogen loading and acidity has not been thoroughly studied, Dr. Doney warned that algal blooms from excess nitrogen release CO2, “an unfortunate synergy” that could occur on Cape Cod.