Volume 6, No. 1

Promoting Cooperation to Maintain and Enhance
Environmental Quality in the Gulf of Maine

By Andi Rierden, Editor

Meet Joe Rocker. The shiny interloper, identified by its V-shaped body and five spines behind the eyes loves to eat plants, insects, clams, oysters, worms, snails, urchins, sea stars, fish, crabs and more. And what a traveler. Known formally as the European green crab or Carcinus maenas, it was first recorded in Long Island Sound in the early-1800s and has been feasting its way north ever since. Marine biologists were shocked when the crab reached the cold waters of Maine, then in the 1950s it appeared in the Bay of Fundy, before shimmying up to the Gulf of St. Lawrence. Today, Joe Rocker, a nickname coined by New England fishermen in the early 1900s, has the distinction of being one of the most prolific crabs in the Gulf of Maine.

But a more recent arrival may cramp the crab's style. The Asian shore crab, Hemigrapsus sanguineus, was discovered in New Jersey in 1988. Measuring two to three inches wide, it has spread as far north as Maine and as far south as North Carolina. Like the green crab, this Japanese import reproduces in far greater numbers than native species. The crab dines on worms, barnacles, shellfish seedlings, algae - just about anything it can get its claws on. It has even been known to eat green crabs.

With their voracious appetites and tolerance for low and high salinity and a wide-range of temperatures, the two aquatic intruders are every marine biologist's nightmare. Like unwanted houseguests, crabs and other marine life introduced outside their native range can become major pests in their adopted ecosystems.

The long-settled European green crab has been blamed partly for the demise of the softshell clam industry in New England and Nova Scotia, destroying commercial shellfish beds and preying on large numbers of native oysters and crabs. Meanwhile scientists like Dr. Nancy O'Connor, a professor of biology at the University of Massachusetts Dartmouth, have observed declines in native crab populations that share the same habitat as the Asian shore crab.

While the Gulf of Maine has not experienced the high profile incursions seen in places like San Francisco Bay, where scientists have recorded 175 non-native species, or the North American Great Lakes, where zebra mussels and sea lampreys have severely disrupted freshwater habitats, its waters are just as vulnerable.

"The Atlantic coast has been quietly invaded by dozens of non-native plants, animals and microbes," said Dr. Anthony Ricciardi, an aquatic biologist at McGill University. "And their joint impact may be greater than the effect of species acting separately. Therefore, as invaders continue to arrive, our coastal resources will become increasingly difficult to manage."

A report released last fall by the Pew Oceans Commission states that the rate of non-native species invading U.S. coastal waters has risen exponentially over the past 200 years and shows no sign of leveling off. Once they take hold, the intruders can crowd out native species, alter habitats, disrupt ecosystems and impose substantial economic burdens on coastal communities. The report entitled Introduced Species in U.S. Coastal Waters, highlights the loss of coastal habitat and biodiversity and the millions of dollars spent each year to research and control introduced species.

At left; Non-native and highly predacious lionfish, with their venomous spines, have been found off the coast of North Carolina and in Long Island Sound. Prime discharge suspect: home aquarium owners. Photo: Paula Whitfield (NOAA Beaufort Laboratory).

Dr. James T. Carlton, a leading expert on aquatic intruders and author of the report, details why introductions occur and the factors that allow species to take hold such as climate, food resources and the presence or absence of predators, competitors and parasites. Carlton notes that the more than 45,000 commercial cargo vessels and hundreds of thousands of recreational vessels that ply the oceans are transplanting marine life around the world at unprecedented levels. "At least 7,000 species of marine life are likely transported each day around the world," he wrote.

In a recent telephone conversation, Carlton, a professor of marine science at Williams College and Mystic Seaport in Connecticut, pointed out that climate change is shifting more southern water species to northern latitudes. "Many of them are not the type that would move the man on the street to passion-worms, arthropods, sea squirts and sponges-but it is an important environmental signal," he said.

"In the Gulf of Maine," Carlton continued, "the waters are getting warmer so we will see non-native species coming to Cape Cod and beyond. And we will be seeing species coming in from other parts of the world that used to find the Gulf of Maine too cold, find it that much warmer. We're not talking about huge jumps in temperature. A one to one and a half degree change makes all the difference to aquatic species and whether or not they can reproduce."

How they arrive

Ballast water used to stabilize ships is the number one carrier of non-native species. When a vessel unloads or picks up cargo, the operator often empties the ballast tanks, thus introducing a myriad of marine life from bacteria to adult fish. In addition, barnacles, mussels, seaweeds and an abundance of other marine life attach to hulls, rudders, propellers and piping systems. Once in port, the organisms can reproduce or become dislodged and swim away.

At left; Ballast water on an oil tanker. Photo courtesy of Smithsonian Environmental Research Center.

The United Nations International Maritime Organization (IMO) instituted voluntary guidelines in 1991 calling for ships to release their ballast water on the high seas and refill the tanks with mid-ocean water, based on the assumption that species from coastal zones will not survive in the open ocean. Both Canada and the United States have established voluntary guidelines for ballast water exchange and require that all vessels entering their 200 mile Exclusive Economic Zones (EEZ) file a ballast water management report.

Mihai Balaban, a Transport Canada-Marine Safety spokesman, says there has been a steady increase of ships complying with the reporting requirements, since the agency established the guidelines in 2000. Most transatlantic ships coming into Canadian waters exchange their ballast waters at sea, he said. "But in the north-south route from the U.S. to Canada the percentage of ships exchanging ballast water at sea, prior to entering Canadian EEZ, is low. There is a high volume of un-exchanged ballast water discharged directly at the port of destination."

A U.S. Coast Guard survey of ballast water management practices reported that only 20.8 percent of the ships arriving in United States ports submitted their ballast water treatment forms during the period beginning July 1, 1999 and ending June 30, 2000.

"The small amount of data present does not provide good news with regards to voluntary ballast water management practices," the report states. "Only one third of the water discharged...in New England ports has undergone any sort of at-sea exchange, leaving the majority of the water full of animal and plant life that could potentially invade new ecosystems."

Trying to solve the ballast water problem by requiring or encouraging ships to exchange water out on the high seas is far from ideal and not likely to meet with high compliance. "It's a good stop gap measure, but intermediate," Carlton said. Instead, Carlton and other scientists are pushing for more financing to study the potentials of treating ballast water with filtration, ultra-violet light, deoxygenation and other methods still in the experimental stages to kill marine life lodged in the tanks.

"I'm very much looking forward to the day when we have our first ships coming into the Gulf of Maine that have installed ballast water treatment plants," Carlton said.

But ballast water is only part of an increasingly complex problem, according to the Pew report. A diversity of other vectors, or ways non-native species are released, are linked to a global and ever-so-mobile world. Marina floats towed from New Jersey to Massachusetts in 2000 brought with them a population of Asian shore crabs. Atlantic salmon are reproducing in the Pacific Northwest after escaping from fish farms in 1998. Seaweed crusted with small invertebrates and used as packing for bait worms in Maine was discarded in San Francisco Bay in 1989, releasing the European green crab, which has invaded the U.S. Pacific Coast.

And the list goes on. Live marine animal and plant imports, live seafood from specialty markets or sushi bars, exotic plants or fish from water garden stores or home aquariums can easily end up in a lake, estuary, river or coastal waters and begin a chain of disturbing events.

"There are staggering numbers of vectors and a whole range of exotic species falling into the hands of the public," Carlton said. "And what they do with them afterward is pretty scary. What we've learned is that a seemingly minor vector can lead to major invasions."

What to do?

Experts on both sides of the border agree that regulating coastal invasive species has been slow and poorly coordinated. Massachusetts has completed the first comprehensive plan in New England to assess the impacts and threats of freshwater and coastal aquatic invasive species. Developed by the Aquatic Invasive Species Working Group (AIS) comprised of 18 representatives from government and non-government entities, the five-year plan calls for coordinating management efforts, monitoring new introductions, controlling the spread of non-native species, research and education programs. (The U.S. National Invasive Species Act of 1996 calls for the development of state aquatic nuisance species management plans).

Jason Baker, an analyst with the Massachusetts Office of Coastal Zone Management (CZM) who wrote the document, says a survey conducted by Massachusetts Institute of Technology Sea Grant in the summer of 2000, helped to set the priorities for the management plan. The survey recorded 10 nonindigenous species and 20 species of unknown origin found on floating docks and piers along the Massachusetts coast.

He added: "On the marine side we just don't know enough about invasive species to know what the impact has been."

Although focused on Massachusetts, the management plan serves as a window to non-native species that threaten the Gulf of Maine and those that have already invaded its waters. Lace Bryozoan (Membranipora membranacea), for example, has killed large areas of kelp forests by encrusting the algae. Another invader, Codium fragile, an algae of the intertidal region, has replaced native eelgrass beds in some areas and displaced other native species dependent on the beds.

The document also lists marine species that have not invaded the area but may in time like the Chinese mitten crab, Pacific oyster and veined rapa whelk.

The CZM and the AIS working group recently organized the first Gulf-wide effort, the Northeast Aquatic Nuisance Species Panel, to study the issue on a regional level and create strategies to manage the problem. The panel, which is being hosted by the Gulf of Maine Council, met in November for the first time in Rye, New Hampshire and included representatives from Maryland to Quebec. "There is a huge recognition regionally that we have to start coordinating our efforts," said Susan Snow-Cotter, the assistant director of CZM and panel co-chair. "No matter how thorough a state management plan might be, if we get an invasion in one state or province, it's only a matter of time before it reaches a neighboring region."

She said the panel will coordinate their efforts with ballast water management experts, but will serve primarily as a vehicle to educate the public about the array of exotic species at their fingertips through the Internet, bait shops or local malls. "Even if you are an informed consumer, there is no way of knowing when you walk into a water garden shop what may or may not be invasive," she said. "For a start, plants should be labeled and fact sheets handed out."

Another target will be the aquarium trade, which is loosely regulated and imports marine life from around the world. "A lot of people do not have a clue about the impact on the environment of introducing these species," Snow-Cotter says, "How do you dispose of fish you don't want anymore? The vast majority of consumers would be open to changing their behaviors if they knew how deleterious their actions could be."

Carlton, who is a member of the Northeast regional panel, concludes the Pew report with a review of efforts to prevent, reduce and control introductions and offers several recommendations for action. The report calls for a national program to eradicate new populations through an early-warning system, education programs to help people understand the harm marine bioinvasions can cause and a substantial increase of federal funding for research.

In closing he wrote, "Industries that play a fundamental role as vectors transporting non-native species should bear more of the costs of prevention, control and research," through a bioinvasions reparation fee to help recoup government costs.

Carlton's report is the third in a series that includes reports on marine pollution and aquaculture. Introduced Species in U.S. Coastal Waters: Environmental Impacts and Management Priorities is available at: http://www.pewoceans.org/reports/introduced_species.pdf.

A draft file in pdf format of the Massachusetts Aquatic Invasive Species Management Plan is available on the CZM Web site at: www.state.ma.us/czm/invasivemanagementplan.htm.