Home | Air / Water Quality | Great Lakes Aquatic Nuisance Species | Counterattack: Great Lakes Panel Targets Aquatic Nuisance Species
Great Lakes Panel on Aquatic Nuisance Species
The Laurentian Great Lakes have been subject to invasion by exotic species since the settlement of the region by Europeans. Since the 1800s, at least 136 nonindigenous aquatic organisms have become established in the Great Lakes. The bulk of these organisms have been represented by plants (61), fish (24), algae (24), mollusks (9) and oligochaetes (7). Most of these species have come from Europe (47%), the Atlantic Coast (18%) and Eurasia (14%).
As human activity has increased in the Great Lakes watershed, the rate of introduction of exotic species has increased. More than one-third of the organisms have been introduced in the past 30 years, a surge coinciding with the opening of the Seaway. The two major entry mechanisms overall, unintentional releases (37%) and ships (32%) were responsible for all but on introduction in the periods of 1960-1990.
Approximately ten percent of the Great Lakes' nonindigensous species have had significant influence, both economic and ecological. The impacts of some of these species have been enormous. The sea lamprey has cost millions of dollars in losses to recreational and commercial fisheries and millions of dollars in control programs. Alewife littered beaches each spring and altered food webs thereby increasing water turbidity before salmonids such as chinook salmon (themselves exotic) were stocked as predators and the foundation of a new recreational fishery. Control costs associated with the zebra mussel have been estimated at $5 billion over the twentieth century's last decade. Great Lakes mangers are convinced that ruffe, which became the most abundant fish species in Lake Superior's St. Louis River within five years of first detection, has the potential to disrupt important fisheries particularly in the lower Lakes.
One likely ballast water introduction, the spiny water fleas, "Bythotrephes cederstroemi (BC)," is a tiny crustacean with a sharply barbed tail spine. The northern Europe native was first found in Lake Huron in 1984. Although researchers do not know what effect the invader will have on the ecosystem, resource managers suspect that B.C. competes directly for food with small fish (such as perch). The spiny water flea is now found throughout the Great Lakes and in some inland lakes.
The zebra mussel ("Dreissena polymorpha") is but one of these 136 established exotic species in the Great Lakes system, but played a central role in prompting passage of the federal legislation, which focuses on all exotics. For this reason, the zebra mussel infestation is highlighted below.
The zebra mussel was first discovered in Lake St. Clair in June 1988, although the age of some harvested specimens suggests that the mussel was introduced in 1985 of 1986. Native to the Black and Caspian Seas, the mussel spread throughout Eastern Europe during the late eighteenth century, aided by the construction of canals for commercial navigation purposes.
The zebra mussel had established itself throughout much of the European continent by the 1930s, with colonies found in Britain as well. The zebra mussel is believed to have been transported to the Great Lakes Basin from a transoceanic vessel. Ballast water taken on in a freshwater European port and subsequently discharged into Lake St. Clair introduced zebra mussel larvae to a new plankton-rich environment well-suited to their proliferation. A small bivalve mollusk with an elongated shell, the zebra mussel grows up to two inches in length, with an expected lifespan of five years. The adult mussel feeds on plankton by filtering water at a rate of one liter per day. The adult female can produce over 30,000 eggs per season, which can range from as long as May through October in parts of the Great Lakes Basin.
In their free-swimming larval (or "villager") stage, zebra mussel are scattered by currents over a wide area. As adults, they become stationary, anchoring with a tuft of fibers known as byssal threads to any hard, non-toxic substrate. In this stage, they can colonize in great density. Although they prefer warm temperatures, shallow water, slow currents, and a plankton-rich environment, the zebra mussel has demonstrated a tolerance for waters throughout the Great Lakes Basin. Lake Erie remains the locus of the bulk of infestations, but reports of zebra mussel colonies have come from many parts of the Basin in recent years, including Lake Superior. The entire Great Lakes system and its tributaries are believed to be vulnerable to large scale infestations, as is a substantial portion of the United States.
Economic and Environmental Impacts
The ecosystem and economic impacts of the zebra mussel are pervasive. Experts attending a March 1990 workshop sponsored by the Great Lakes Fishery Commission and the International Joint Commission agreed that "exotic aquatic organisms have the potential to transform water quality, existing plant and animal communities, and human use of the aquatic ecosystem that they invade." The potential impact on the fishery is profound. For example, the zebra mussel colonizes the rock substrate used for spawning by various fish species. The filtering capacity of the zebra mussel efficiently eliminates plankton from the water column, binding it into "pseudofeces" that are ejected from the mussel's syphons and accumulate among the shells in the colony, a condition that can create an adverse spawning environment.
Economic impacts of the zebra mussel infestation are as pervasive as the ecosystem impacts. The zebra mussel is not selective about substrates; it attaches itself to boat hulls, reefs, navigational buoys, anchors, and water intakes, to name a few. The municipal water intake in Monroe, Michigan, for example, experienced a temporary interruption of flow in December 1989 due to large concentrations of zebra mussels obstructing the intake. Emergency sources of water supply were activated until the flow could be resumed. Variations on this scenario have been seen with increasing regularity since that time at municipal water intakes, power plants, and private manufacturing operations.
Commercial and recreational vessels are also vulnerable to damage or compromised fuel efficiency. Once attached to the hull, zebra mussel colonies will create drag, lessen fuel efficiency and (on small boats), place an unnecessary strain on motors. Zebra mussels drawn into an engine's cooling water intake can occlude the system, leading to overheating and engine damage. Navigational buoys can sink under the weight of zebra mussel shells and the odors of decaying zebra mussels have been observed, with an attendant impact upon beach usage levels.
One respected Great Lakes scientist has been quoted as saying that the environmental and economic impacts over the long term could exceed those associated with the "Exxon Valdez" disaster. If the infestation is left unchecked, damages of approximately five billion dollars over the next ten years have been estimated; this is approximately the annual economic value of the entire Great Lakes sport fishing industry. Costs associated with the cleaning of municipal and industrial water intakes, the locks at the Welland Canal and other structures have already run into tens of millions of dollars. A variety of control mechanisms have been identified but a viable means to effectively manage or eradicate the zebra mussel population on a Great Lakes-wide basis has yet to be found. Protection of water intakes is possible (to varying degrees of effectiveness) through physical and mechanical controls. These include, for example, a traveling screen mesh, micro-straining fabrics, physical scraping, electrical currents, electrostatic filters and outright replacement of occluded intakes.
The environmental and economic implications of the zebra mussel infestation problem speak to the magnitude and immediacy of the issue. While this is indeed a matter of national significance, it is clear that effective control strategies within the Great Lakes Basin will have a preventive value for other regions far removed from ours.
Nonindigenous ANS Prevention and Control Act of 1990
The zebra mussel is but one of the many exotic aquatic nuisance species (ANS) in the Great Lakes system, but played a central role in prompting passage of key federal legislation. In drafting the federal Nonindigenous Aquatic Nuisance Species Prevention and Control Act of 1990 (P.L. 101-646), the Congress recognized that mitigation of the adverse impacts of all such species is dependent upon a well-coordinated research, monitoring and prevention program at the Great Lakes and national level. As enacted, the legislation has five purposes: to prevent unintentional introductions; to coordinate research, control and information dissemination; to develop and carry out environmentally sound control methods; to minimize economic and ecological impacts; and to establish a research and technology program to benefit state governments.
National Aquatic Nuisance Species Task Force
The Aquatic Nuisance Species (ANS) Task Force was established in response to the Nonindigendous Aquatic Nuisance Prevention and Control Act of 1990 (Act), to coordinate efforts, both governmental and private, related to nonindigenous aquatic species in the United States. The ANS Task Force consists of seven federal agency representatives and eight ex-officio members appointed to represent non-federal government entities. The Task Force is co-chaired by representatives from the U.S. Fish and Wildlife Service and National Oceanic and Atmospheric Administration.
The Task Force has been actively developing an ANS Program and implementing various provisions of the Act. The proposed ANS Program is being developed to: prevent the introduction and dispersal of ANS; monitor, control and study ANS; and disseminate related information. The program is currently undergoing review and is expected to be presented to Congress early in 1993. Implementation of this comprehensive program will build on existing nonindigenous activities and be a cooperative effort among Federal agencies, states, tribes, local governments, non-governmental entities, and other countries.
Additional implementation activities of the ANS Task Force include: developing a research protocol to ensure that research activities carried out under the Act do not result in an "intentional introduction policy review," developing control programs (as appropriate), and Great Lakes regional coordination.
The intentional introductions policy review is being conducted to identify and evaluate approaches for reducing the risk of adverse consequences associated with intentional introductions of aquatic organisms. The Task Force is preparing a report to Congress to summarize its findings, conclusions, and recommendations. A draft of the report should be available this fall with the final report completed in early 1993.
At its most recent meeting in April 1992, the Task Force prepared a resolution finding the ruffe (a small percid fish) to be an aquatic nuisance species, that control is warranted, and that the ruffe control program proposed by the Great Lakes Fishery Commissions Ruffe Task Force addresses the requirements of the Act for control. The ANS Task Force Ruffe Control Committee is currently refining the proposed ruffe control program and will begin implementing the procedure for proposing, authorizing and conducting a control program as outlined in the proposed ANS Program.
The Great Lakes Panel
One component of the Act (Section 1203) has particular relevance for the Great Lakes Basin: the convening of a Great Lakes Panel on Aquatic Nuisance Species. Officially convened in 1991, the Panel is directed to identify Great Lakes priorities; assist/make recommendations to the National Task Force (also established via P.L. 101-646); coordinate federal exotic species program activities; advise public and private interests on control efforts; and submit annually a report to the Task Force describing prevention, research and control activities in the Great Lakes Basin. With its membership drawn from a wide range of federal, state, provincial and regional agencies, private sector user groups, and Sea Grants Programs and environmental organizations, the Panel is a Great Lakes partnership well suited to the task at hand.
Two policy position statements, "Research and Management Needs" and "Legislative/Budget Needs," have been developed by the Panel to a) coordinate efforts of the research community and b) link them with the challenges of facing policymakers and resource managers.
The research and management policy position will help guide strategic decision-making in the scientific community by providing guidelines for interactions between researchers and managers, and compiling a list of key research needs that exist in the areas of biology and life history of nonindigenous species; ecosystem effects of the species; socio-economic costs and benefits, control and mitigation; prevention of future introductions of nonindigensous species; and finally, reducing the spread of established nonindigenous species.
Budget and legislative policy positions for ANS programs at the binational, national and regional levels target the policy community--providing an important foundation for future development and funding. Three areas are of particular interest:
Selected Accomplishments of the Great Lakes Panel
Questions and Answers about Zebra Mussels
Q: Zebra mussels have been a problem in various European waterways since the 1700s; why did it take them until 1988 to establish themselves in the Great Lakes?
A: The opening of the St. Lawrence Seaway just over 30 years ago accounted for the introduction of many nonindigenous species. Coincidentally, the spread of the zebra mussel in Europe has actually been accelerated by improving water quality in many harbors. Thriving colonies of zebra mussels have established themselves in these harbors, and increasing numbers are taken in with ballast water. Also, transcontinental trips are shorter and ballast tanks cleaner--two factors that enhance survivability. Finally, it is believed that improving water quality in the Great Lakes has provided a favorable aquatic environment for the zebra mussels.
Q: Why are zebra mussels so successful in spreading?
A: Zebra mussels are very opportunistic. They have a broad environmental tolerance and an amazing reproductive capacity. Recent studies show that a female can produce 30,000 - 1,000,000 eggs each year, which, once fertilized, have the ability to travel long distances through the water. The mussels then attach to any hard surface; they have a habit of attaching to each other, and even native mussel species, to form huge colonies.
Q: What are the best conditions for zebra mussels to survive?
A: Zebra mussels do best in water in the 54-80 degree F temperature range, which is why they are more numerous in shallow Lake Erie than in deeper, colder Lake Superior. They reproduce best in water that rises in temperature gradually, not suddenly, as in more southern waters. They need a calcium level above 28 milligrams per liter, and a pH of 7.4 or higher. Zebra mussels also need a hard surface to attach to, such as rocks, a firm lake bottom, boats an docks or other mussel colonies. A mussel villager must attach to the substrate within three weeks, which it can do only if the water current moves less than six feet per second. All this, combined with the lack of an effective natural predator, makes the Great lakes an excellent breeding ground for zebra mussels.
Q: Don't zebra mussels have any natural predators?
A: In some places in Europe, such as the Rhine River and some small lakes, predators keep the numbers in check. Some species of fish, such as the freshwater drum, feed on zebra mussels, as do diving ducks. In fact, this past winter the Ohio Department of Natural Resources counted record numbers of diving ducks on Lake Erie. However, the number of zebra mussels is too high for any predator to provide significant control over the population.
Q: What is the risk to inland waters?
A: Zebra mussel sightings in new waters take place constantly. The mussels themselves spread their colonies through rivers and other waterways, while boaters, anglers and very possibly birds transport the mussels to inland lakes. The cost to recreational lakes and municipal waters in North America will be high. However, the mussel will probably not infest agricultural drainage ditches in great density. Since these usually have soft muddy bottoms, other than the occasional rock or log, the mussels can't find a substrate to attach to.
Q: What methods of control do municipal water plants in the Great Lakes use?
A: Most plants have installed feeder lines which chlorinate the water at the point of intake. Others use potassium permanganate, which also prevents the mussels from clogging the pipes. A few plants have built sandbed filters by pouring a bank of sand down at the area of the intake, then laying filtered pipes 20 feet beneath the surface. Right now chlorination is the most inexpensive method, but as zebra mussel control becomes more sophisticated, this will change. Constant monitoring of villager levels at the intake will enable plants to use small, infrequent bursts of chlorine. New plants will have built-in systems, such as two-way pipes that can pump hot water out. Other methods now being tested include acoustics/ultrasound, UV light, anti-fouling coating and disposable substrates. Research on the environmental impacts on the immediate area must also be done to study the effects of all of these methods.
Q: When will we be able to wipe out the zebra mussel?
A: With today's technology, we are not in a position to eradicate the zebra mussel from North America. Perhaps in the future, such methods will be developed but until that time it is not possible to eliminate the zebra mussel without adversely affecting other aspects of the Great Lakes Basin ecosystem. Control and prevention, not eradication, is the direction North America is headed.
New Mussel Species Discovered
A second variety of zebra mussel has been discovered in the Great Lakes, and researchers believe it may be hardier than its prolific relative. Like the original "Dreissena polymorpha," this new mussel, named the "quagga mussel" after an extinct African zebra, likely entered the Great Lakes system via the ballast water of ships from Europe. Dr. Ellen Marsden of the Illinois Natural History Survey's Lake Michigan Biological Station and Dr. Bernie May of Cornell University recently discovered the second species of zebra mussels in Lake Ontario.
Researchers are concerned that the new species may be able tolerate a different range of environmental conditions (such as more extreme temperatures) than the zebra mussel which arrived in the Great Lakes several years ago. The quagga mussel tends to be lighter in color than the zebra mussel and can grow much larger. Since their discovery last October, the quagga mussel has spread to Lake Erie, the St. Lawrence River and Onondaga Lake. Quagga mussels seem to be as prolific as zebra mussels, which produce more than 30,000 eggs a year. They live two to three years and have no known predators.
-Northeast Midwest Congressional Coalition-
Research, Control, & Info Dissemination Efforts Around Basin The original "Counterattack!" insert includes two dozen updates from key U.S. and Canadian federal agencies, Great Lakes states and provinces, tribal authorities and university/research institutions, detailing their efforts in the region regarding exotic species. Since at the time of this posting those briefs are two years old, they have not been included in this online edition. If you would like a hard copy--a photocopy of the original--please contact the Great Lakes Commission, Eisenhower Corporate Park; 2805 S. Industrial Hwy, Suite 100; Ann Arbor, MI 48104-6791; Phone: 734-971-9135; Fax: 734-971-9150.
-W.P. Kovalac, Technical & Engineering Services, Detroit Edison-
"Zebra mussel fouling at Detroit Edison water intakes necessitated development of maintenance and control programs that would ensure unit availability and be cost-effective and environmentally acceptable. In 1991 Detroit Edison achieved record availability at all plants including Monroe where mussel infestation has been particularly acute. Monroe has used mechanical cleaning (dewatering and hydrolasing) and limited chlorination with outstanding success. The annual cost of mussel monitoring and control is approximately $100/megawatt of generating capacity. Recently small numbers of mussels have infested intakes in Lake Huron and St. Clair River. Development of control programs at these intakes have focused on deoxygenation(sodium sulfite) and heat which was used successfully at the Harbor Beach Power Plant. In the future, use of foul-release coating and improvement/development of control techniques should substantially reduce cost."
-Faith A. McGruther, Executive Director, Chippewa-Ottawa Treaty Fishery Management Authority-
"The sea lamprey has had a disastrous effect on the commercial fishery over the past several years and is still a very serious threat. Without even having sufficient funds to eradicate this species from the Great Lakes, we now face several new exotic species which threaten the fishery. The ruffe, spiny water flea, and zebra mussel are now taking their toll on the fishery.
If theory is true, that the spiny water flea is the cause of the chub recruitment problem in Lake Huron, where will the chub fishery be in four or five years? The impact the ruffe will have on the fishery, if it gets out of control in Lake Superior, is too scary to contemplate.
If funding is insufficient in sea lamprey control, where will the funding come from to do what is necessary to keep the new exotics in check? The impact of the sea lamprey on the fishery can be readily identified and is in the millions of dollars. It is yet too early to identify how severely the other new species will impact the commercial and sport fishery."
-Daniel N. Thomas, President, Great Lakes Sport Fishing Council-
"While improved water clarity has created a challenge for the angling community, concern is growing over an increasingly depressed perch fishery due to increased competition for phytoplankton in Lake Erie and possibly Lakes Michigan and Ontario, and the expansion of the European ruffe in Lake Superior. Both open water fishing and shore fishing is threatened, both Basin-wide and nationally. Increased maintenance costs are being realized by the boaters and boat fishermen, and growing restrictions are being placed on the freedom of movement by trailerable boats between different waterways."
-R.L. Eshenroder, Senior Scientist, Great Lakes Fishery Commission-
"The exotic sea lamprey and alewife clearly were most responsible for destablizing the fish community in the upper Great Lakes in the 1940s and 1950s, and they impaired the Lake Ontario community even earlier. Recovery of native species, for instance in Lake Michigan, could not proceed until sea lamprey were controlled, thereby allowing large predatory fish to survive and suppress alewife populations. Newly introduced species such as the ruffe, the spiny water flea, and the zebra mussel already appear to be a threat to the revitalized fisheries of the Great Lakes."
-W.L. LePage, Monroe Waterworks, City of Monroe, Michigan-
"The macrofouling characteristics of the zebra mussel have been felt by virtually all the drinking water utilities obtaining water from the lower Great Lakes. Intakes have been blocked, raw water transmissions mains fouled, treatment processes upset, and tastes and odor treatments compromised. Mechanical and/or chemical cleaning has in several cases been necessary and offshore treatment to preclude colonization has become advisable on all existing intakes. The presence of the mussel and the need to defend against it has changed the whole complexion of water intake structure design. Pre-treatment for mussel abatement also has, in some instances, compromised the ability of some facilities to comply with maximum contaminant levels (MCL) for certain disinfection by-products. The overall impact is one of frustration and substantial expense."
A Look to the Future: Aquatic Nuisance Species--What's next?
MONSTER SHARK TERRORIZING LAKE SUPERIOR! This is the headline of an article found in a recent issue of a supermarket tabloid making the rounds in the Great Lakes community these days. It tells of a vacationing fisherman who claims to have seen an 80- foot freshwater shark swallow a deer in a single gulp in shallow water off Whitefish Point, Michigan. It also quotes a "top scientist" as warning that "It's not alone!"
I certainly wouldn't stake my professional reputation on the scientific validity of this entertaining bit of creative writing. However, I do agree with the "top scientist;" the aquatic nuisance species her refers to, real or imagined, is indeed "not alone." In fact, over 130 organisms have invaded the Great Lakes since the 1800s; one third of them in the past 30 years. They aren't 80 foot long, and they don't swallow large mammals in a single gulp, but in their own way they are terrorizing the Great lakes. I refer, of course, to the zebra mussel, the ruffe, the lamprey, "Bythotrephes," and a number other species that are threatening to turn the aquatic ecology of the Lakes inside out while damaging public infrastructure and impairing water-based economic activity.
The headline-grabbing zebra mussel stories of recent years are largely gone, but the problem persists. The Great Lakes Panel on Aquatic Nuisance Species is "digging in" for the long term and, through the strength of its membership, will direct its energy to addressing the many unmet needs revealed on the pages of this special insert.
It is imperative that the Great Lakes Panel--and the entire Great Lakes community--focus on prevention as well as response. Somewhere on the continuum between the zebra mussel and the 80 foot freshwater shark is another aquatic nuisance species problem waiting to happen. Researchers, for example, have just found the "quagga mussel" in the depths of Lake Ontario: a larger and more adaptive cousin of the zebra mussel that is suited to the colder waters of the upper Great Lakes, and has no known predators. What's next?
This special insert was made possible by a grant from the U.S. Fish and Wildlife Service. Other funding sources supporting Great Lakes Panel activities include the Great lakes Environmental Research Lab (NOAA), the National Sea Grant Program, and the states of Illinois and Indiana through funds made available from the Interjurisdictional Fisheries Act. Material presented within will be included in the 1991-92 "Annual Report of the Great Lakes Panel on Aquatic Nuisance Species" to be released this fall.