an expensive invasion: carp and zebra mussels: economic threats to the great lakes
Post on 02-Jan-2016
Embed Size (px)
DESCRIPTIONAn Expensive Invasion: Carp and Zebra Mussels: Economic Threats to the Great Lakes. Kate Gardiner December 1, 2005. Lake Michigan. What are The Great Lakes?. H: Lake Huron O: Ontario M: Mich. E: Erie S: Superior. - PowerPoint PPT Presentation
An Expensive Invasion:Carp and Zebra Mussels: Economic Threats to theGreat LakesKate GardinerDecember 1, 2005Lake Michigan
What are The Great Lakes?H: Lake HuronO: OntarioM: Mich.E: ErieS: Superior
Lake Superior is the largest and deepest freshwater lake in the world. More than 50,000 square miles of land drain into it. It is surrounded by less-tillable soils and sparse population. The water has a reddish tint near Superior, Minn., because of high concentrations of iron in the area.
One of Lake Eries tributaries, the Cuyahoga River, burned in 1969 because of pollution. Lake Erie is the smallest of the Great Lakes.
Lake Ontario has about the same surface area as Lake Erie. It is much deeper.
Lake Huron is hydrologically the same as Lake Michigan via the Straits of Mackinac to the north. It has many shallow, sandy beaches as well as the rocky Georgian Bay.
The EnemiesSea LampreysBighead carp & Asian grass carp Zebra Mussels& the other 197 or so invasive species already in the Great Lakes
The Asian Bighead Carp is a filter-feeding carp that was introduced to fight algae blooms in southern fish farms. Through the floods of 1994, the fish escaped into the Mississippi River and have been trekking north ever since. They have reached the Illinois River, which connects the Mississippi and the Great Lakes at the bottom of Lake Michigan
Grass Carp Entry Points
Domestic Koi, show championValue: +$30,000 if a national champion (to Japanese)24-30, 15-20 pounds; larger but usually in captivity. Generally revert to olive color in the wild. Asian Grass CarpValue: Primarily Negative47 long, 65 pounds
Carp? Bad? Why?Unlike goldfish (also carp) these wild Asian grass carp can grow to 4 feet and weigh 100 pounds. Fishermen on rivers inhabited by the carp routinely carry carp-bashing baseball bats to combat startled fish that leap into their boats.
Domesticated carp have reached 3 feet and 50 pounds, but their coloration is a distinct disadvantage in the wild.
Grass carp disrupt the natural ecosystem from the bottom up, consuming most native vegetation. Pharyngeal teeth of the grass carp; adaptation to the carps preferred vegetation.
What would happen?If the carp get into the Great Lakes, they will severely disrupt the lake ecosystem. The bighead carp are filter feeders, dependent on plankton. They can eat up to 40% of their body weight per day in food. Their most obvious impact would be on the multi-billion dollar sport-fishing industry in the Great Lakes.
Barrier issuesAccidental CrossingEasily done, hard to reverseBallast WaterEggs can be transported in ships ballast water and then flow through; eggs on vegetation that travels through the barrier unaffected. Funding: cost $9.1 million; who pays?
ButThe system, which has been paid for primarily by the federal government thus far (75%), is finally installed, it should cost just over $9 million. The issue is the electric bill; because the consequences of not paying it affect multiple states, it should probably be paid for by the Federal government. The Army Corps of Engineers, who built it, are looking to the state of Ill., which is disinclined to pay because of budget issues. The economic consequences of not installing the barriers are far greater. The sport-fishing, and the commercial harvest would both be affected as larvae. Their combined worth is around $4.5 billion annually.
Australia is presently fighting the European Carp, which has been established there since at least 1845.
The Australian Department of Natural Resources and the Environment has used fish-specific poisons, where practical, but this is not possible in larger, connected aquatic systems. Rotenone, for example, has been applied to small dams and ponds.
Both Australia and the E.U. are presently creating a genetically modified fish for introduction. Mutations presently under consideration are either daughterless (unable to produce female offspring) or early death where genetic anomalies hasten death. Either is practical, however the latter is perhaps better; mature female fish can produce 1 million eggs per kilogram multiple times per summer.
It would be far easier to fight the fish in the U.S. by preventing its entry into the Great Lakes.
Sea LampreysSea Lampreys are an invasive parasite present in Lake Huron since the mid 19th Century, and in all five Great Lakes since 1947. They are considered a native species in Lake Ontario, however after the Welland Canal connected the lake to Erie, the rest of the lakes were quickly colonized. The population of lampreys in Huron is equal to that of the other four lakes.Each individual lamprey is capable of destroying at least 40 pounds of fish stock during its lifetime; this directly affects lake trout and other large fish when they are most valuable to fishermen. Lamprey populations have been fairly constant in the Great Lakes for the past 50 years, however improving water quality may change that.
Scientists are worried that the lampricide commonly used (TFM, discovered in 1958) will eventually yield a population that is resistant and the parasites population will once again explode to their 1950s levels.
Harvest the fish as a delicacyContinue to use TFM and add Bayer 73, another chemical to control or destrory individual lamprey spawning grounds every three to ten years
TFMNo known consequences for peopleFew insects, mayflies are sensitive Amphibians are sensitive, but not usually present in streams when larvae are present; most fish can process it without issueLow-head barriers; lampreys rarely jump higher than two feet when swimming upstream to spawn (anadromous fish)Best solution at the moment, however weaknesses suggest alternatives should be in the offing.
The Zebra Mussel
Physical Characteristics:Small, fingernail sized mussels Native to the Caspian SeaBlack and grey stripes, very sharp outer edge that cuts the feet of anyone who comes into contact with it; especially annoying when the mussel attaches to vascular plants. Doesnt mind being crowdedTo-be-published study by Geneva Lakes Environmental Association suggests that some varieties may be photosensitive.
HabitsAttach to anything under water in enormous quantities (as dense as 627,000 per square yard, and in some cases up to 2 feet thick)Filter water around them, removing and discarded phosphorous in the water column as well as plankton; clarifies water to the benefit of sight-predators and to the detriment of fish fryBreeding is facilitated by colonic behavior of adults; both males and females produce large numbers of gametes; females can produce 100,000 eggs per year (adult size, 1 inch)
ConsequencesZebra mussels congregate on essential pipelines, such as water intake tubes, resulting in the clogging of the pipes; they also have consequences on residential water systems, though these have not been observed as frequently, yet.Congregations also occur on the shells of other mollusks, which then suffocate and die; virtually any surface is susceptible.Costs are expected to exceed $10 billion over the next 10 years for controlMussel excrement contains concentrated PCBs and PAHs
PrecautionsResidential systems should use filtration systems for lake waterCommercial systems jury-rig a hot water set up, sending water nearing 140F through the pipes to kill the mussels; it is much more difficult to dislodge the putrifying shells.
How to Kill emChlorineBoilingHigh Pressure washToxic coatings on pipesUV raysSuffocationElectrocution
Will it work?Perhaps, but its expensive. Scientists are working on a mussel-specific bacteria and breeding controls, but its still in the planning stages. Meanwhile, the mussels are expected to be present in most inland bodies of fresh water in the next 20 years.
SolutionsEnforce the Ballast water initiatives of the international organizations and encourage the same for individuals transporting boats domesticallyPrevent new species from joining us.