banner.gif (2557 bytes)

Attack of the Zebra Mussels?
Controversies about Dreissena polymorpha in North America

(Version I:  By S. P. Currie)

zebramap.gif (30898 bytes)On June 1st, 1988 (Hebert et. al. 1989), Paul Hebert and students from the University of Windsor were collecting samples in Lake St. Clair. They found a mussel they had never seen before: it was striped black and white, and was between 25 and 35 millimetres long (Ludyanskiy et al. 1993). They soon identified it as a zebra mussel, Dreissena polymorpha. Zebra mussels are from the Black, Caspian, and Azov seas of Russia. However, since the 19th century, they have spread throughout Europe (Hebert et al. 1989). Able to filter a litre of water a day, zebra mussels remove phytoplankton from the water, leaving less food for organisms such as juvenile fish (Hebert et. al. 1991). They also attach to hard surfaces, and can clog pipes (Sea Grant 2000c). Although these mussels had caused problems throughout Europe, the 1988 discovery of them in Lake St. Clair was the first sighting in North America.

Ironically, in 1981, a Cassandra figure had warned of the possibility of zebra mussels invading North America. Joe Schormann of Environment Canada had examined the ballast water of foreign ships entering the Great Lakes. He found many species of organisms in the ballast water, and warned in his report that zebra mussels, which had caused problems in European waters, could be transported in the same manner (Roberts 1990). However, the government did nothing, and his report was shelved and not dusted off until 1988.

The introduction of non-indigenous species to North America is not a new problem. Scientists estimate that there are 139 non-indigenous aquatic species in the Great Lakes, including the Sea Lamprey, introduced in the 1830's. Most of the non-indigenous species entered the Great Lakes after the St. Lawrence Seaway opened in 1959 (Sea Grant 2000b). Non- indigenous species may out-compete native species for resources, or may cause conditions that the native species cannot tolerate, so that the native species are at risk of extinction. In the case of the zebra mussels, they attached to native bivalves, and the native species could not feed (Sea Grant 2000c), in addition to reducing the phytoplankton available to young fish. But, North Americans had not learned their lessons from the introduction of other non-native species in the past, and the government failed to act on Joe Schormann's 1981 report. So, by 1989, the mussels had spread to Lake Erie.

In 1989, the government finally addressed the ballast water issue. The Canadian Coast Guard began asking all foreign ships to exchange their ballast water at sea. In this process, the ship exchanges the fresh water in its ballast tanks for salt water. The organisms from the freshwater European port cannot live in the ocean water, and the salt water organisms will die when released into the freshwater Great Lakes, so non-native species cannot be transported to a new location. However, this does not work if both ports are salt water ports, and the process can be dangerous to the ship during a storm (Sea Grant 2000d). The Canadian Coast Guard's program was criticized by Ronald Griffiths, of the Ontario Ministry of the Environment, because it was only voluntary (Banks 1990).

By 1990, the zebra mussels had spread to the other Great Lakes. In an article in Audubon, Frank Graham Jr. voiced concerns that the zebra mussels, attached to the hulls of boats, would travel from Lake Michigan into the Mississippi. Also, some engineers predicted the cost of the zebra mussel invasion would be over five billion dollars. However, R. Warren Flint of the State University of New York said that the mussels would provide food for ducks and bottom feeders such as catfish and suckers, and that the zebra mussel population would eventually crash. Griffiths agreed that the population would crash (Banks 1990), since female zebra mussels produce more than one million eggs two to five times a year (Hebert et. al. 1991) and the population would soon run out of food. However, Gerald Mackie of the University of Guelph argued that since there were plenty of nutrients in the Great Lakes, the zebra mussel populations would not crash (Banks 1990).

James Carlton, from Williams College, explained in 1990 (Roberts 1990) why zebra mussels established in the Great Lakes in the 1980's but not before. Ships in the 1980's had ballast tanks with a greater volume than previous ships, so had more chance of transporting enough individuals of a species to establish a North American population. Also, ships were much faster, allowing the organisms to survive the trip. In addition, when polluted European ports were cleaned, the zebra mussels thrived there, and could be picked up and transported by ships. Also in 1990, the United States Congress considered a bill requiring foreign ships coming to the Great Lakes to exchange their ballast water in the ocean, much like the Canadian Coast Guard program but mandatory, and passed the Non-indigenous Species Control Act (Sea Grant 2000a).

In 1991, Discover magazine named the zebra mussel its 1990 "pest of the year" (Reynolds 1991). Clarence Reynolds wrote: "The plot could be from a hokey science fiction story: a colony of marauding shellfish swarms into freshwater lakes, multiplies by the millions, and generates a wave of mayhem. This past year fiction became fact when the pesky zebra mussel overran all five Great Lakes and showed every sign of spreading farther." The zebra mussel problem had gained the public's attention, as well as its imagination.

boathull.jpg (13786 bytes)Tim Walker (1991) discussed ways that industry dealt with the zebra mussel problem. Having a diver scrape zebra mussels from pipes and other surfaces was expensive and only offered a temporary solution. Although chlorine controlled the zebra mussels, it could be harmful to other organisms, so it was only used in contained spaces such as power plant pipes. Chemicals in zebra mussel-repellant paints were also harmful to other organisms. Scientists searched for other ways to control the zebra mussels, such as inducing them to spawn at inappropriate times, or finding a microorganism that is harmful to the zebra mussels but not to other species. However, in 1992 (Hamilton 1992), the Bush Administration seemed disinterested in the zebra mussel problem, and funding for studies of aquatic biological invaders was threatened.

In 1993 (Banks 1993), Joe Leach of the Ontario Ministry of Natural Resources and Mackie reported that zebra mussel populations in Lake Erie and Lake St. Clair, respectively, had decreased. However, they warned that the zebra mussels would still be a problem for industrial pipes, and that scientists were still unsure about the mussels' ecological impact. Boat show attendees (Lichtkoppler et. al. 1993) also saw zebra mussels as a threat to the Lake Erie boating and fishing industry. Meanwhile, Ludyanskiy et. al. (1993) reported their ideas of how the zebra mussel came to North America. Although scientists agreed that the mussel had probably been transported in the ballast water of a foreign ship in 1985 or 1986, they had different ideas on what port they had come from. Carlton claimed he had proof that the zebra mussels were transported to North America from a European port. However, Ludyanskiy compared shell morphology to determine the mussel had been transported from the Black Sea and Caspian Sea region of Russia. Ludyanskiy compared the invasion of the zebra mussels to an invasion of Russian soldiers when he wrote: "Just when the threat of a Russian invasion of North America seemed to have disappeared with the end of the Cold War, an invasion has been found to be not only under way but proving to be successful. Rather than missiles, a naval force of hordes of zebra mussels has secured beach-heads in many US and Canadian lakes and rivers. One could call it biological warfare, but not directed by any human admiral." So, the zebra mussels were as much of a threat to North America as the Cold War had been.

However, Ludyanskiy also pointed out some of the zebra mussel's positive qualities. It could be used as a biomonitor since it is sensitive to water contamination. Also, some scientists had suggested using the zebra mussel's filtering capabilities to remove algae and restore lakes. This was actually done in the Netherlands by 1996 (MacIsaac 1996), and some divers in North America were suspected of introducing zebra mussels to an area to improve the water clarity for diving (Sea Grant 2000d).

In 1994, Timothy Stewart and James Haynes reported that zebra mussels had not negatively affected other benthic macroinvertebrates in Lake Ontario, and benthic macroinvertebrate populations were even greater following zebra mussel establishment. In 1996 (no author 1996) David Moore reported that eight native species of aquatic plants in Lake Erie had reestablished. By filtering the water, the zebra mussels had increased the water clarity, allowing light to reach the plants. The zebra mussels were not as much of a disaster as originally predicted, with control costing industry much less than expected (Zorpette 1996). In addition, about half of the contaminants in Lake St. Clair had been taken up by zebra mussels. However, this had only concentrated the contaminants in zebra mussel tissue, risking bioaccumulation in any organisms that ate the mussels. Also, contaminants were excreted by the zebra mussels as pseudofeces, exposing organisms that feed on the pseudofeces to high concentrations of contaminants. MacIsaac (1996) also reported on the negative effects of zebra mussels. The commercial harvest had decreased in Lake Erie, unionid mollusks had decreased, and food chains had switched from planktonic to benthic. Susan Fisher from Ohio State University warned that "Every little benefit you get out of them . . . is not worth the problems" (Zorpette 1996).

Also in 1996, Ladd and Padilla pointed out some "mussel myths" that were used to justify not controlling the zebra mussels' spread. Some claimed that zebra mussels would eventually be dispersed to all habitable waters by waterfowl, so there was no use controlling their spread by boaters. Also, some claimed that "it only takes two mussels to establish a population" although this is unlikely.

By 2000 (Sea Grant 2000c), native aquatic plants had recolonized Lake Erie and the lake's walleye spawning was not affected. However, native species of mollusks had been reduced in Lake Erie and Lake St. Clair, and Yellow Perch in the Great Lakes had declined drastically (Sea Grant 2000d). Industry had spent over 120 million dollars on zebra mussel control, and even though this was less than the 5 billion dollars damage predicted in 1990, it was still a lot of money. The zebra mussel has spread throughout the Great Lakes, St. Lawrence Seaway, Mississippi River, other locations throughout Eastern North America, and even California (USGS 2000).

It turns out that the introduction of zebra mussels to the great lakes had advantages, like making the water clearer and benefitting plants and benthic macroinvertebrates, but it had many disadvantages including decreasing fish and native mussel populations, costing industry much money in zebra mussel control, and concentrating pollutants present in the Great Lakes. Scientists such as Susan Fisher point out that the problems of zebra mussels greatly outweigh any advantages. So, were the many problems zebra mussels have caused in North America preventable? Apparently they were. Scientists already knew that non-indigenous species could cause problems in North American ecosystems, since organisms such as the Sea Lamprey had been introduced long ago and their negative effects had been observed. Joe Schormann had found in 1981 that organisms could be transported, alive and well, by the ballast water of ships. Although he reported this to Environment Canada, and warned that zebra mussels could be transported this way, the report was ignored. No action was taken by the Canadian government until the zebra mussels were found in Lake St. Clair in 1988. By that time, zebra mussel populations had already established in North American waters, so the Coast Guard's voluntary ballast exchange program could not reduce the zebra mussel's impact. Although it could potentially prevent other organisms from being introduced to the Great Lakes by ballast water transport, since the program was voluntary, any ship that did not comply could still introduce other exotic species.

Because North Americans did not learn from past mistakes, zebra mussels invaded their waters, causing much damage. One can only hope that, finally, we have learned our lesson, and a non-indigenous species problem like this will not happen again. But as bigger and faster ships transport goods throughout the world, only time will tell.

 

REFERENCES

(1996) "Zebra Mussels - the Bright Side," Discover, 17 (August): 18-19.

Banks, Brian (1990) "Alien Onslaught," Equinox, 53: 69-75.

Banks, Brian (1993) "March of the Zebra Mussel," Equinox, 70: 97.

Graham, Frank, Jr. (1990) "Musseling In," Audubon, 92: 8-9.

Hamilton, David P. (editor) (1992) "Funding Squeeze Threatens Zebra Mussel Research," Science, 255: 1343.

Hebert, Paul D. N., B. W. Muncaster, and G. L. Mackie (1989) "Ecological and Genetic Studies on Dreissena polymorpha (Pallas): a New Mollusc in the Great Lakes," Canadian Journal of Fisheries and Aquatic Science, 46: 1587-1591.

Hebert, Paul D. N., Christopher C. Wilson, Mary H. Murdoch, and R. Lazar (1991) "Demography and ecological impacts of the invading mollusc Dreissena polymorpha," Canadian Journal of Zoology, 69: 405-409.

Johnson, Ladd E. and Dianna K. Padilla (1996) "Geographic spread of exotic species: ecological lessons and opportunities from the invasion of the zebra mussel Dreissena polymorpha," Biological Conservation, 78: 23-33.

Lichtkoppler, Frank R., David O. Kelch, and M. Annie Berry (1993) "Attitudes of 1990, 1991, and 1992 Mid-America Boat Show and 1991 Fairport Fishing Symposium Patrons Concerning the Zebra Mussel (Dreissena polymorpha), Lake Erie, and Great Lakes Pollution," Journal of Great Lakes Research, 19(1): 129-135.

Ludyanskiy, Michael L., Derek McDonald, and David MacNeill (1993) "Impact of the Zebra Mussel, a Bivalve Invader," BioScience, 43 (8): 533-541.

MacIsaac, Hugh J. (1996) "Potential Abiotic and Biotic Impacts of Zebra Mussels on the Inland Waters of North America," American Zoology, 36: 287-299.

Reynolds, Clarence V. (1991) "Invasion of the Zebra Mussels," Discover, 12 (January): 44.

Roberts, Leslie (1990) "Zebra Mussel Invasion Threatens U.S. Waters," Science, 249: 1370-1372.

Sea Grant (2000, January 19 a) "Sea Grant Zebra Mussel Update: A 1995 Report of Research," (http://www.sg.ohio-state.edu/publications/nuisances/zebras/tb-030.html)

Sea Grant (2000, January 19 b) "Zebra Mussels and Other Nonindigenous Species," (http://www.seagrant.wisc.edu/greatlakes/glnetwork/exotics.html)

Sea Grant (2000, January 19 c) "Zebra Mussels in North America," (http://www.sg.ohio-state.edu/publications/nuisances/zebras/fs-045.html)

Sea Grant (2000, January 19 d) "Zebra Mussel Update: Summary of Research Results," (http://www.sg.ohio-state.edu/publications/nuisances/zebras/update/results.html)

Stewart, Timothy W. and James M. Haynes (1994) "Benthic Macroinvertebrate Communities of Southwestern Lake Ontario Following Invasion of Dreissena," Journal of Great Lakes Research, 20(2): 479-493.

USGS Biological Resources (2000, January 19) "Zebra Mussels Hitchhike to California," (http://www.nbs.gov/pr/newsrelease/1995/8-16.html)

Walker, Tim (1991) "Dreissena disaster: scientists battle an invasion of zebra mussels," Science News, 139 (18): 282-283.

Zorpette, Glenn (1996) "Mussel Mayhem, Continued," Scientific American, 275 (August): 22-23.

 

VERSION II (With B. Madeira)

On June 1st, 1988 (Hebert et. al. 1989), Paul Hebert and his students from the University of Windsor were collecting samples in Lake St. Clair. They came across a mussel they had never seen before: it was striped black and white, and was between 25 and 35 millimetres long (Ludyanskiy et al. 1993). They soon came to realise that it was the zebra mussel, Dreissena polymorpha; Zebra mussels are native to the Black, Caspian, and Azov seas of Russia. Since the 19th century, they have spread quickly throughout Europe (Hebert et al. 1989), being quite a nuisance to aquatic conditions by attaching to hard surfaces like boat hulls and fishing nets, and clogging industrial pipes. Being highly efficient filter feeders with an incredible ability to reproduce, they multiply and can quickly remove phytoplankton from the water, leaving less food for organisms at the base of the food chain such as juvenile fish. Headlines in the following year reveal that Canada was forewarned years ago about this organism becoming a domestic problem and chose to do nothing about it. In 1981, a Cassandra figure had warned of the possibility of zebra mussels invading North America. Joe Schormann of Environment Canada had examined the ballast water of foreign ships entering the Great Lakes. He found many species of organisms in the ballast water, and warned in his report that zebra mussels, which had caused problems in European waters, could be transported in the same manner (Roberts 1990). However, the government ignored the zebra mussel warning and his report was shelved and not dusted off until 1988. The introduction of non-indigenous species to North America is not a new problem. Scientists estimate that there are 139 non-indigenous aquatic species in the Great Lakes, including the Sea Lamprey, Chinook salmon, brown trout, white perch, introduced in the 1830's. Most of the non-indigenous species entered the Great Lakes after the St. Lawrence Seaway opened in 1959 (Sea Grant 2000b). "Based on our samples, nonnative individuals outnumbered natives in an estimated 31.5% (11%) of lakes. Without quantitative historical data, it was not possible to demonstrate a homogenizing effect of introductions on lake fish assemblages."(Whittier, Thomas R., Thomas M. Kincaid, 1999). While most established non-indigenous are not pests some invaders species may out-compete native species for resources, or may cause conditions that the native species cannot tolerate, so that the native species are at risk of extinction. They attached to native bivalves, and the native species could not feed (Sea Grant 2000c), in addition to reducing the phytoplankton available to young fish. But, North Americans had not learned their lessons from the introduction of other non-native species in the past, and the government failed to act on Joe Schormann's 1981 report. So, by 1989, the mussels had spread to Lake Erie.In 1989, the Canadian government finally addressed the ballast water issue. The Canadian Coast Guard began requesting all foreign ships to voluntarily exchange their ballast water at sea. In this process, the ship exchanges the fresh water in its ballast tanks for salt water. The organisms from the freshwater European port cannot live in the ocean water, and the salt-water organisms will die when released into the freshwater Great Lakes, so non-native species cannot be transported to a new location. This solution works only for fresh water to fresh water ports and does not work if both ports are salt-water ports. Furthermore the process can be dangerous for the transport ships during a storm (Sea Grant 2000d). The Canadian Coast Guard's program was criticized by Ronald Griffiths, of the Ontario Ministry of the Environment, because it was only voluntary (Banks 1990). By 1990, the zebra mussels had spread to the other Great Lakes and the importance of the issue was becoming realised. Ontario Natural Resource minister Joe Leach and Ohio State senator both considered this to be an "ecological disaster of oil spill proportions" (Toronto Star Mar. 12 90). In an article in Audubon, Frank Graham Jr. voiced concerns that the zebra mussels attached to the hulls of boats, would travel from Lake Michigan into the Mississippi. Other concerns of zebra mussels affecting cottage country were at hand and boaters and fishermen were advised to spray their hulls with chlorinated water to kill any veligers that were stuck to it and to empty their live wells. If the expanding population entered the Moskokas and Haliberton highlands, thousands of people would have to spend hundreds of dollars on water intake pipe repairfor their cottages. This process had already cost Ontario Hydro and Metro Works commission $3.2 million( Toronto Star 1991); some engineers predicted the cost of the zebra mussel invasion would be over five billion dollars by the year 2000. U.S. President, George Bush singed legislation to provide $11 million in research grants (New York Times Dec, 3 1990.) which helped establish the OHIO Sea Grant.James Carlton, from Williams College, explained in 1990 (Roberts 1990) why zebra mussels established in the Great Lakes in the 1980's but not before. Ships in the 1980's had ballast tanks with a greater volume than previous ships, so had more chance of transporting enough individuals of a species to establish a North American population. Also, ships were much faster, allowing the organisms to survive the trip. In addition, when Ships entered polluted European ports and their ballast water cleaned, the zebra mussels thrived there, and could be picked up and transported by ships. Also in 1990, the United States Congress considered a bill requiring foreign ships coming to the Great Lakes to exchange their ballast water in the ocean, much like the Canadian Coast Guard program but mandatory, and passed the Non-indigenous Species Control Act (Sea Grant 2000a). Tim Walker (1991) discussed ways that industry dealt with the zebra mussel problem. Having a diver scrape zebra mussels from pipes and other surfaces was expensive and only offered a temporary solution. Although chlorine controlled the zebra mussels, it could be harmful to other organisms, so it was only used in contained spaces such as power plant pipes. Chemicals in zebra mussel-repellent paints were also harmful to other organisms. Scientists searched for other ways to control the zebra mussels, such as inducing them to spawn at inappropriate times, or finding a micro organism that is harmful to the zebra mussels but not to other species. However, by 1992 (Hamilton 1992), the Bush Administration seemed disinterested in the zebra mussel problem, and funding for studies of aquatic biological invaders was threatened. In 1993 (Banks 1993), Joe Leach of the Ontario Ministry of Natural Resources and Mackie reported that zebra mussel populations in Lake Erie and Lake St. Clair, respectively, had decreased. However, they warned that the zebra mussels would still be a problem for industrial pipes, and that scientists were still unsure about the mussels' ecological impact. Meanwhile, Ludyanskiy et. al. (1993) reported their ideas of how the zebra mussel came to North America. Although scientists agreed that the mussels had probably been transported in the ballast water of a foreign ship between 1985 and 1988, they had different ideas on what port they had come from. Carlton claimed he had proof that the zebra mussels were transported to North America from a European port. However, Ludyanskiy compared shell morphology to determine the mussel had been transported from the Black Sea and Caspian Sea region of Russia. Ludyanskiy compared the invasion of the zebra mussels to an invasion of Russian soldiers when he wrote: "Just when the threat of a Russian invasion of North America seemed to have disappeared with the end of the Cold War, an invasion has been found to be not only under way but proving to be successful. Rather than missiles, a naval force of hordes of zebra mussels has secured beach-heads in many US and Canadian lakes and rivers. One could call it biological warfare, but not directed by any human admiral." So, the zebra mussels were seen as much of a threat to North America as the Cold War had been.The zebra mussel problem had gained the public's attention, as well as its imagination. Publications professed predictions of gloom and doom:"Like creatures from a dark science fiction fantasy tiny creatures, capable of reproducing by the millions Almost as if you can hear the music from jaws in the background Steven King would love this thing."New York Times, Dec 3, 1990"1990 pest of the year The plot could be from a hokey science fiction story: a colony of marauding shellfish swarms into freshwater lakes, multiplies by the millions, and generates a wave of mayhem. This past year fiction became fact when the pesky zebra mussel overran all five Great Lakes and showed every sign of spreading farther. "Clarence Reynolds, Discover magazine And it seemed to some that there were more Zebra Mussel Conferences than AIDS conferences (Toronto Star 1996). Claims of zebra mussel problems ranged from encrusting live fish to clogging sprinkler systems and fire hydrants began to spout (Toronto Star Feb. 22, 95). In Lake Erie officials pulled a sports car from the water covered in a crust, one foot thick, of zebra mussels which they called the mussel car.The ever prevalent North American apathy was taking hold of opinions. Some argued what were called "mussel myths"- misbeliefs that were used to justify not controlling the zebra mussels' spread (Ladd and Padilla1996). Claims that zebra mussels would eventually be dispersed to all habitable waters by waterfowl were addressed, so there was no use controlling their spread by boaters. Also, others argued, "it only takes two mussels to establish a population". In time, as the effects of the zebra mussel in were studied, several positive phenomenon were discovered (Knapton 1994). Off the coast of several bird observatories, bird watchers reported a tremendous increase in numbers. Upon analysing these birds' diet it was discovered that 85-100% of the diet was zebra mussel. The increased clarity in the water had caused the mussel itself to be easy prey for water foul and bottom feeders such as catfish and suckers. The once told major ecological disaster had proven not as explosive. The initial hope that zebra mussels would eat themselves through a boom and bust seemed to be valid to some researchers; that the zebra mussel population would eventually crash. By 1992, the rate of increase had dropped dramatically (James 1992) Griffiths agreed that the population would crash (Banks 1990), since female zebra mussels produce more than one million eggs two to five times a year (Hebert et. al. 1991) and the population would soon run out of food. However, Gerald Mackie of the University of Guelph argued that since there were plenty of nutrients in the Great Lakes and surrounding lakes, the zebra mussel populations would not crash (Banks 1990) and would still continue to spread across North America. Ludyanskiy also pointed out some of the zebra mussel's other positive qualities. It could be used as a biomonitor since it is sensitive to water contamination, Also, some scientists had suggested using the zebra mussel's filtering capabilities to remove algae and restore lakes. This was actually intentionally done in the Netherlands by 1996 (MacIsaac 1996), and some divers in North America were suspected of introducing zebra mussels to an area to improve the water clarity for diving (Sea Grant 2000d). By 1994, Timothy Stewart and James Haynes reported that zebra mussels had failed to negatively affect other benthic macroinvertebrates in Lake Ontario and that they were reported to even greater following zebra mussel establishment. Reports of at least eight rare native species of aquatic plants in Lake Erie had re-established their numbers. By filtering the water, the zebra mussels had increased the water clarity, allowing light to reach the plants at the bottom of these huge water bodies. The zebra mussels were not as much of a disaster as originally predicted, with control costing industry much less than expected (Zorpette 1996). In Canada’s cottage country, the waters proved to be too cold and lacked the necessary calcium to proliferate. In addition, about half of the contaminants in Lake St. Clair and many of the phosphorous, and nitrates had been ingested by zebra mussels. The is not to say that these substances are eliminated, they only become concentrated in zebra mussel tissue, risking bioaccumulation in any organisms that ate the mussels or excreted by the zebra mussels as pseudofeces. This poses a bigger problem because it exposes organisms that feed on the pseudofeces to higher concentrations of contaminants. The commercial harvest had decreased in Lake Erie, unionid mollusks had decreased, and food chains had switched from planktonic to benthic MacIsaac (1996). Susan Fisher from Ohio State University concluded "Every little benefit you get out of them . . . is not worth the problems" (Zorpette 1996)..By 2000 (Sea Grant 2000c), native species of molluscs had been reduced in Lake Erie and Lake St. Clair, and Yellow Perch populations in the Great Lakes had declined drastically (Sea Grant 2000d) while native aquatic plants had actually recolonized Lake Erie due to increased clarity and the lake's walleye spawning was not drastically affected. Industry had spent over 120 million dollars on zebra mussel control, and even though this was less than the 5 billion dollars damage predicted in 1990, it was still a lot of money. The zebra mussel has spread throughout the Great Lakes, St. Lawrence Seaway, Mississippi River, other locations throughout Eastern North America, and even California (USGS 2000).The introduction of zebra mussels to the great lakes may have had advantages, like making the water clearer and benefitting plants and benthic macroinvertebrates, but it also had disadvantages including decreasing fish and native mussel populations, costing industry much money in zebra mussel control, and concentrating pollutants present in the Great Lakes. As Susan Fisher points out that the problems of zebra mussels greatly outweigh any advantages. So, were the many problems zebra mussels have caused in North America preventable? The answer is obvious. Yes. When scientists already knew that non-indigenous species could cause problems in North American ecosystems, organisms such as the Sea Lamprey had been introduced long before and their negative effects had been observed. Joe Schormann had found in 1981 that organisms could be transported, alive and well, by the ballast water of ships. Although he reported this to Environment Canada, and warned that zebra mussels could be transported this way, the report was ignored. The Canadian government took no action. The zebra mussels were subsequently discovered in Lake St. Clair in 1988 indicating that zebra mussel populations had already been established in North American waters. The Coast Guard's voluntary ballast exchange program could not reduce the zebra mussel's impact. Although it could potentially prevent other organisms from being introduced to the Great Lakes by ballast water transport, since the program was voluntary, any ship that did not comply could still introduce other exotic species. While the scientific data presents one story, there still lies a deeper issue at hand; for the zebra mussel affects people at many different levels. It is obvious that the issue presents environmental concerns, yet the fundamental heart and soul, which Canada prides itself on its natural landscape and environment (canada.com) was also at risk. Invasive species require a national defense strategy, one that does not presently exist in Canada. With actions such as warnings rather than threats or laws and suggestions rather than policies, Canada’s concerns to respect the international world often leave more debate than action. Canadian politics have been the focus of countless TV shows like Royal Canadian Air Farce, cartoons satires and books such as Unfulfilled Union. This stereotype is strengthened in light of the lack of an official position in ballast water dumping. Where the United States made it a law to exchange ballast water prior to entering the great lakes in 1993 the Canadian government has yet to follow suite.People were threatened directly as this affects their hydro and water supply. Throughout the 1990's, Ontario Hydro was the only industrial company researching the scientific control the zebra mussels. (Globe and Mail 1997) Why? Because they had the most to lose. Ontario hydro relies tremendously on the Great Lakes for its source of power, power that the entire area is dependent on. Moreover, the water cools nuclear reactor chambers and if this process is hindered, it could be catastrophic. So while the zebra mussels themselves have not directly caused the estimated $120 million in damage, control measures to protect our society have. Hydro affects everyone and it is in everyone’s best interest to secure it. On a more personal level, at one point the people who owned cottages and fishing boats were threatened. Not only was the zebra mussel affecting the nations Great Lakes, and all the power supplying their surrounding residents but it affected their leisure time too. Because North Americans did not learn from past mistakes, zebra mussels invaded their waters, causing much damage. One can only hope that in the future, we learn lessons from our mistakes, and invasive species problems due to anthropogenic actions like this are avoided. But only time will tell, as bigger and faster ships transport goods throughout the world, our world grows ever smaller. The environment is forces to deals with our negligence. The warning sign are all available for us to see, we just have to learn how to read them properly and act appropriately. References"Action Urged to Stem Invasion of Species From Ships' Ballast." The New York Times. July 23, 1996.(1996) "Zebra Mussels - the Bright Side," Discover, 17 (August): 18-19.Banks, Brian (1990) "Alien Onslaught," Equinox, 53: 69-75.Banks, Brian (1993) "March of the Zebra Mussel," Equinox, 70: 97.Byers, Jim. "Corralling tiny mussels could cost $3.2 million". The Toronto Star. August 1, 1991.Duncanson, John. "Onslaught of mussels creating lake havoc 'worse than oil Spill'". The Toronto Star. March 12, 1990.Faber, Harold. "Aquatic Pest Turns Up Early in Hudson". The New York Times. November 29, 1990.Graham, Frank, Jr. (1990) "Musseling In," Audubon, 92: 8-9.Gorrie, Peter. "Pesky zebra mussels infest Toronto harbor". The Toronto Star. November 7, 1990. Gorrie, Peter. "A dead end for zebra mussels?" The Toronto Star. December 8, 1990. Gorrie, Peter. "Mussels battle to cost billions delegates told". The Toronto Star. February 12, 1991.Gorrie, Peter. "Mussels edge into cottage country". The Toronto Star. July 14, 1991.Gorrie, Peter. "Zebra mussel colonies taking hold in Muskoka". The Toronto Star. Februay 20, 1992.Gorrie, Peter. "Cousin of zebra mussel in lakes". The Toronto Star. August 19, 1992.Gorrie, Peter. "Zebra mussels fail to take Muskoka". The Toronto Star. August 22, 1992.Grossi, Fiorella. "Company wages war on tiny zebra mussels". Globe and Mail. Hamilton, David P. (editor) (1992) "Funding Squeeze Threatens Zebra Mussel Research," Science, 255: 1343.Hebert, Paul D. N., B. W. Muncaster, and G. L. Mackie (1989) "Ecological and Genetic Studies on Dreissena polymorpha (Pallas): a New Mollusc in the Great Lakes," Canadian Journal of Fisheries and Aquatic Science, 46: 1587-1591.Hebert, Paul D. N., Christopher C. Wilson, Mary H. Murdoch, and R. Lazar (1991) "Demography and ecological impacts of the invading mollusc Dreissena polymorpha," Canadian Journal of Zoology, 69: 405-409.Hengeveld, Rob. Dynamics of Biological Invasions. New York: Chapman and Hall

March 2000

zebramus.txt

 

Sierra Club

 

| Home | Chemistry | Physics | Astronomy | Biology | Ecology |
| Geography | Medicine | Mathematics | Technology |
| Issues | Scientists | General | Reference |

 

Counter

 

Last Updated Monday, August 27, 2007 01:00 -0400

Suzanne P. Currie 1999 sciencelives@hotmail.com