Zebra Mussels

Matt Altstiel
5/05/05
Lab Sec#5

Clogging the Great Lakes

Zebra Mussels pose one of the largest ecological problems in the United States today and represent one of the most dangerous invasive species to arrive in the Great Lakes region. To understand the complex problem that Zebra Mussels pose, it is crucial to know the biological advantages in reproduction and environmental adaptations that have allowed it spread so quickly. It is also important to know where it came from, why it is here, and what can be done to combat its expansion. Ecological questions pertaining to: natural competition, selection of habitat, natural predators, and the role of humans in aiding or inhibiting population growth must be addressed as well. Only after answering such questions can proper discussion of control and reclamation take place.

The Zebra Mussel’s biology includes several traits that allow it to thrive and infest the Great Lakes region. Unlike most mussels which, brood their eggs within specialized gill brood pouches, Zebra Mussels “release sperm and eggs directly into the surrounding waters for external fertilization,” (Mackie et al., 1989). This allows Zebra Mussels to develop into free swimming larva in safe, nutrient rich water. After only eight to ten days, the larva are fully grown Zebra Mussels which can attach themselves to any thing if there is a current less than two meters a second, (Lyakhov, 1968). A single mature Zebra Mussel can produce anywhere from 30,000 to over 1,600,000 eggs per year! This natural reproductive advantage allows for the development of enormous colonies very quickly. Another natural advantage is the Zebra Mussel’s ability to produce dense clusters of population that crowd out any competition. The nail sized mollusk can pack a square meter under average conditions with between 5,000 to 30,000 individuals, (Griffiths et al., 1989). The Zebra Mussel tolerates most temperate waterways provided the water has low salinity content. Such natural advantages make controlling the pest a formidable task.

The Zebra Mussel has not always clogged North American waterways and has only been a part of the Great Lakes ecosystem for the last fifteen to twenty years. The original home for the Zebra Mussel is the Caspian and Black Sea regions of West and Central Asia. The species ability to attach themselves onto nearly every underwater surface allowed it to enter the ballast of ships and emerge in the freshwater harbors of the Great Lakes when ballast water was released. Fishing activities, fresh water plant imports and recreational equipment have also been credited to its introduction to the United States, (Kinzelbach, 1992; Morton, 1993). In 1988, Zebra Mussels were first sighted in sizeable numbers in Lake Saint Clare near Detroit. Since then, it has spread through the Great Lakes and into the Mississippi River, its tributaries and numerous smaller lakes and bodies of water. No natural barriers really exist to counter its invasion and only human control and caution prevents it spread. The Zebra Mussels steady expansion throughout the United States suggests a general pattern of dispersion; gaining a foothold and expanding where ever possible, (Ram and McMahon, 1996).

In little more than fifteen years, the Zebra Mussel has gone from an unknown Mussel that did not exist in North American water ways, to a one of the biggest menaces to fresh water fisheries and underwater infrastructure today. Such a rapid expansion, suggests that the Zebra Mussel population and extensity is increasing at a faster rate than every before. As a species, the mussel can thrive nearly anywhere there is temperate fresh water and therefore has no preference for either disturbed or undisturbed habitats. The Zebra Mussels rapid reproductive and high concentrations allow them out compete native Mussels, fishes and plants because it eats all the tiny plankton that feed and supports other links in the food chain. The species has not encountered any noteworthy resistance in terms of native predators or competing native mussel species. However, the “round goby, Neogobius melanostomus, itself a native of the Black and Caspian seas and also introduced into the Great Lakes via ship ballast, tends to feed preferentially on zebra mussels,” (Ghedotti, Smihula and Smith, 1995). Humans have by and large aided the expansion of the species through shipping and recreation boating that brings boats carrying Zebra Mussels into new bodies of water. Recent prevention methods and the emergence of a predatory species have not slowed the spread as quickly or as effectively as hoped.

Therefore, the Zebra Mussel poses significant environmental problems. Its reproductive advantages and huge densities allow for quick colonization of new areas very rapidly. The absence of a major predator as well as viable competition has permitted the Zebra Mussel travel from the ballast water in ships from the Caspian Sea region of central Asia, to the Great Lakes and Mississippi Basin in the United States. The problem is wide spread environmental problem that has only been worsened by human activities, and in order to effectively combat the growing problem of Zebra Mussels, human awareness and intervention are crucial.

Works Cited

Ghedotti, M. J., J. C. Smihula, and G. R. Smith. 1995. Zebra Mussel Predation By Round Gobies In The Laboratory. J. Great Lakes Res. 21(4):665-669. International Assoc. Great Lakes Research.

Griffiths, R.W., W.P. Kovalak, and D.W. Schloesser. 1989. The Zebra Mussel, Dreissena Polymorpha (Pallas, 1997), In North America: Impact On Raw Water Users. In: EPRI Service Water System Reliability Improvement Seminar: Papers. Electric Power Research Institute, Palo Alto, California. Pp. 11-27.

Kinzelbach, R. 1992. The Main Features Of The Phylogeny And Dispersal Of The Zebra Mussel Dreissena Polymorpha. In D. Neumann And H.A. Jenner Eds., The Zebra Mussel Dreissena Polymorpha. Pp. 5-17. Gustav Fisher Verlag, New York, NY.

Lyakhov, S.M. 1968. Work Of The Institute Of Biology Of Inland Waters, Academy Of Sciences Of The USSR. In B.K. Shtegman Ed., Biology And Control Of Dreissena. Israel Program For Scientific Translations Ltd., IPST Cat. No. 1774, Jerusalem, Israel. Available From The United States Department Of Commerce, National Technical Information Service, Springfield, V

Mackie, G. L., Gibbons, W. N., Muncaster, B. W., and Gray, I. M. 1989. The zebra mussel, Dreissena polymorpha: A synthesis of European experiences and a preview for North America. Toronto: Queens Printer for Ontario.

Pallas. “Fact Sheet for Dreissena Polymorpha.” http://nis.gsmfc.org/nis_factsheet.php?toc_id=131

Ram, J.L. And R.F. McMahon. 1996. Introduction: The Biology, Ecology, and Physiology Of Zebra Mussels. American Zoologist 36(3):239-243.

Was Darwin Wrong?

Matt Altstiel
5/05/05
Kenny #5

Darwin and Scientific Truth

In his essay in National Geographic, David Quammen makes an emphatic case for the validity of Darwin’s Evolutionary Theory. The author even goes so far as to state, “The evidence of evolution is overwhelming,” (Quammen 4). He goes in depth to provide numerous instances of modern scientific discovery to defend his support for Darwin and his theory and in the process debunk creationist convictions. In sum, the essay shows the reader that the Evolutionary theory has become even more convincing and pertinent in recent years.

Despite the overwhelming evidence supporting Evolution many Americans and people world wide dismiss Evolution in favor of Creationism, or a literal interpretation of religious text concerning the creation of the world and its organisms. Part of this belief results from ignorance in biological knowledge or overly religious backgrounds that do not allow for the duality of religion and evolution. Evolution challenges the literal interpretation of the Book of Genesis as well as the 6 Day Creation theory in the Koran. Evolution unlike many other scientific theories draws ire from many people and is constantly under attack.

Quammen defends Evolution citing numerous examples throughout the article that offer definitive proof. Recent examples show evolution in action as a powerful force that shapes modern life. Among these examples is the evolution of disease causing pathogens that have produced drug resistant strains. Another compelling example occurs within the laboratory where scientists have successfully created a new species of fly by selecting certain genes for reproduction, yielding a type of fly that can no longer mate with its original species. Human induced evolution such as the wide variation seen in today’s pet dog’s show a relatively rapid transformation from a common ancestor. Still other examples in the field of morphology show that many insects had a common ancestor, one that is still present in simplified larval form.

Crucial to Darwin’s theory of Evolution is the concept of natural selection. Natural selection tells the reader that successful species will reproduce and have competitive offspring that will over the course of many generations adapt special traits to help them best survive in an environment. Species which do not adapt to the environment will be unsuccessful and will die out without producing a new species carrying many of the traits of the old. New environments encountered in the expansion of a particular species impose particular constraints which must be adapted too in order to survive. Furthermore, species that are particularly symbiotic with another may even adapt together, such as an orchid in Madagascar and the moth which pollinates it in “Convergent Evolution,” which aids both species. Another important concept in Natural Selection is “Island Biogeography”, the effects of isolation; time and competition create new species. As a result many different localized species will share very similar characteristics due to evolution from a common ancestor. Evolution therefore has a powerful and plausible mechanism which gives credibility to the argument that all species on earth today evolved from a common ancestor.

This explanation allows seemingly disparate species such as modern whales and modern antelopes to be closely related. Moreover, fossilized evidence shows the stages in the progression from a four legged, land dwelling herbivore to the ocean dwelling, krill eating baleen whale with fins. Fossilized evidence of the intermediate species displays several traits of each, among them a more dog shaped head similar to an antelope, as well weak vestigial legs. Fossilized evidence is beneficial to scientists since it gives them a window into the past to glimpse how a species evolved in an otherwise unobservable, long time period. However, every fossilized species uncovered represents just one in a thousand possible evolutionary species and links that may never be uncovered. Intermediate species do however help show the continuous adaptation and evolution from a common ancestor. Along the same lines as fossilized evidence, recent genetic evidence lends even more credibility to the theory of evolution. Scientific researchers have determined that humans and mice have more than 30,000 DNA similarities between them. Such similarities can’t help but point to a common ancestor for the source of all genetic material.

Although the author David Quammen wrote an article entitled: “was Darwin wrong?” per Quammen, the answer is a resounding no. He refutes the claims of Creationists and skeptics by citing concrete evidence to support Darwin’s theory of Evolution. Modern examples such as disease mutation and laboratory tests show how evolution can be proven in the short term. Quammen also shows how long term evidence such a DNA modeling and Paleontology reinforce his argument. He further backs up his position by using important concepts and terminology that explain not only the theory, but plausible explanations of central themes such as natural selection. Darwin was indeed right concerning his theory of evolution, and more scientific proof exists than ever before to back him up.

Alien Invaders

Matt Altstiel
4/20/05
BioGeog

Attack of the Alien Invaders

The March 2005 National Geographic Article entitled “Attack of the Alien Invaders,” sheds light on one of the largest ecological problems threatening native wildlife in the world today. The author even refers to the phenomenon of non-native invasive species spreading to new areas as a “giant biology experiment with no one in charge, (McGrath 96). While invasive species are not a new occurrence, the rate of spread and the negative economic impact of these dangerous new plants and animals is. Each year the United States loses more than “140 Billion dollars to invasive species,” (McGrath 98). The increased rate of spread of these non-native species, whether intentional or unintentional is partially explained by three factors: more widespread and faster transfer of goods, the release of ballast water in different ports and harbors, and the emergence of a billion dollar global exotic pet, nursery specie, and Aquarium industry. One of these species, the Red Eared Slider Turtle, has spread from North America to Europe and Asia, “devouring native frogs, mollusks and even birds,” and threatening traditional wetland environments. These and other species have been “responsible for an extraordinary restructuring of wildlife around the planet,” (McGrath 102).

However governments, finally realizing the threat of non-native species and their ecological and financial impact have begun taking steps towards limiting the growth of existing invasive species, and preventing the emergence of new species. One of these methods is bio-control, a method which has yielded some impressive results but some utters failures as well. Bio-control fights the spread of invasive species by counteracting it with another species that feeds upon it. Many times bio-control can be effective with a minimum impact upon the environment because it does not use potentially polluting poisons and pesticides. However, there is often no guarantee of success and certain elements present in nature may limit the effectiveness of bio-control. Also, as a solution, bio-control is very expensive and often results in the introduction of one invasive species to control another.

Another problem that requires a viable solution is the increased spread of invasive marine life that comes from further and further away. Often these marine species enter ships as they take on water, as ballast to balance the ship. Since ships are constantly moving around the world because of international travel, there can be many species coming along for the ride within a single ship. When ships reach their destination in ports across the world, they dump out the ballast water which often contains invasive species. This process allows marine invasive species to spread exponentially quicker than they would have otherwise done. Devastating new species have reached bodies of water that contain no natural predators to stop the spread of invasives and the result can be catastrophic on the marine eco systems. The Zebra Mussel that has decimated fish populations across the Great Lakes is a prime example. Originally from the lakes and bodies of water of Eurasia, the Zebra Mussel made its way to Lake Michigan aboard a ship in the late 1980’s. Since then, Zebra Mussels have clogged pipes leading to infrastructural problems, have depleted the lake of oxygen, and killed off fish and other native mussels by consuming the same food. Several countries have taken steps to prevent similar situations such as requiring cargo ships to release ballast water before entering ports, but clearly more needs to be done.

While some alien species are beneficial and produced positive outcomes, all invasive species must be limited. One can never know when a potentially beneficial species will spread and eventually become and invasive pest species. Combating the spread of all invasive species requires a change in attitudes, and a change in policy. The article uses the phrase, “foolish and unforgivable,” if one sits back and watches ecosystems change forever. One must take the time to learn which species are invasive, and then as a local task force, go into the wild and remove and destroy native species. Such efforts of a population volunteering only once a month or week would be significant improvements and quite effective. Similarly, governments have the responsibility to prevent invasive species like Australia has, and by that is meant, publishing not a list of invasive species that must be kept out, but rather a list of organisms that may be brought in. Ballast must not be dumped in ports, and preventive measures must be put into place. Where invasive species already exist, bio-control coupled with herbicides and pest controlling agents should be used. A lot may be done to prevent the spread of invasive species; however it requires the persistent effort of the individual and the state. The author for one will find out about programs in the local area to help combat the problem of invasive species. After all, invasive species not only threaten our ecosystems, but they threaten our livelihoods and way of life.