Invasive Species

                            Overview
As globalization and worldwide trade markets continue to open and expand, so too does the potential for the spread of non-native organisms. In our group project we will delve into the issues of habitat loss and its correlation to the establishment of invasive species. As humans continue to disrupt ecosystems for resource consumption and human expansion, niches open up for new species to enter. Our subgroup will specifically investigate the relationship between invasive species and their environment; where did they come from, how are they introduced, and what effects do they have on their environment? These questions will be addressed with respect to terrestrial and aquatic environments.

Interview with Dr.  J. Ellen Marsden

Dr. J. Ellen Marsden is a professor of fisheries under the Rubenstein School at the University of Vermont. Her particular areas of concern lie with the restoration of native species along with studying the impacts of exotic species. Some of her work with invasive species was conducted in the Great Lakes region focusing on the introduction of round gobies and zebra mussels. Her work has dealt with the biology and management of these species for the betterment of the environment in which they live. We asked her a few questions to gain her perspective and her thoughts on Vermont's future with respect to invasives. This is what she had to say:

Q1) “In your own opinion, what do you think the major invasive species are in Vermont, both terrestrial and aquatic.”

A1) “Briefly in terrestrial, and again I’m less informed than someone working specifically with them, the big ones are the insect pest coming into the state; Asian longhorn beetle, it’s not only our trees which are the heart of Vermont, it’s a massive part of our industry, and this is when things start to get bad ash borer, which are so scary because it’s not only our trees which are the heart of Vermont, it’s a massive part of our industry, and this is when things start to get bad. In terms of Aquatic pests alewife is up there in the top…they are in the lake…the first ones showed up in 2003, and didn’t start to take off until a couple of years later, then we had the first mass die off in 2008. It’s a species I’ve dealt with extensively. They’re in the great lakes and go through a sort of boom and bust style life cycle, where they reproduce like crazy and get out of control, exhausting the resources [planktonic; favoring zooplankton to phytoplankton], and then there will be a huge die off and there will be dead alewife littering the beaches…yes they are a filter feeder…eating mainly zooplankton…competing directly with our main native filter feeder smelt, which we have been monitoring for about 20 years now. We’re now starting to see that smelt population are not as strong as they once were. Now lots of other factors can affect a population but the worry is alewife will be the cause of the collapse of the native smelt…alewife are essentially replacing smelt as the important food source for our native trout and salmon which we like to fish for. Alewife have an enzyme in their body, thiaminase, which destroys thiamin in trout and salmon. And so fish that eat to many alewife don’t allocate sufficient thiamin into their eggs, and then once they hatch the fry in the first few couple of weeks go through cronic thiamin deficiency, and in the worst case they die. So, you have alewife competing with the native species and suppressing them, you have them essentially poisoning the species we’re trying to restore; trout and salmon, and they’re also predators of the fry of the lake trout, yellow perch fry, and walleye larvae. They found in the great lakes they’ve seen that if alewife are up then yellow perch tend to be suppressed, if alewife crash were yellow perch’s do as well. They’re hitting us on a whole bunch of different fronts simultaneously.”

Q2) “Are alewife filling in for species as a potential food source?”

A2) “Somewhat, they don’t. Very few niches, if any completely overlap, so there’s a similarity in terms of their filling that planktovore niche, and many fish seem to enjoy eating them it’s just the thiaminase in them. Which breaks down that vitamin b…Zebra mussels you probably know about, we’re kind of getting used to them now, they’ve been here for about 20 years, but again they’re attacking the food web at the base, by sucking down the algal plankton and smaller zooplankton which would have been useful to other parts of the food web, and they’re now locking it down into the benthos instead of having it be available in the water column and in the great lakes they’ve seen cascading events of, [British mumble], as I said they take the energy and the nutrients out of the pelagic food web, and put it into the benthic food web, benthic species now do great in this, there is lots of habitat and organic material for insect larvae and planarians and snails, but this depletes the food web higher up, shifting whole food webs, from pelagic to the benthic zone. They’ve had algal outbreaks because now there’s all this phosphorus at the bottom of the lake, seeing huge growths of things like chledophora, which is exotic plankton, and now suddenly we’re seeing what was rocky looking like plush carpets, because there’s so many zebra mussels and so much of this exotic algae, it’s just completely changed the nature of systems.

Q3) “Is there ever a point you reach when there are simply too many individuals, and there’s nothing you can do about it? And what’s the mentality behind it?”

A3) “I think, on an individual basis, once something’s established in something as big as Lake Champlain, or as huge as the great lakes it’s there, and people say; well what are you going to do about zebra mussels? Well we can’t. All the work to figure out ways of killing, getting rid of, dislodging zebra mussels. A huge amount of research went into zebra mussels, we’re really talking about intake lines. We’re not talking about lake removal, we’re saying can we stop them fouling navigation buoys, can we stop them fouling water intakes for municipal water and so the key to invasive species has come down to prevent them from ever establishing. Rapid response, and monitoring is done, see them coming and stop them right there before things get bad. Then if you talk about the multi-species perspective, the ecological perspective, we got 49 possibly 50 exotic species in Lake Champlain; plants, bacterium’s, worms, fish, mussels, snails. In the great lakes they have got close to 200, so four times, bigger system but still considerably more. And so the whole system is changing, zebra mussels I mentioned the whole trophic food web is changing. Alewife invaded the great lakes around 1939, started showing dead on beaches until in 1959 there was a mass die off on the shores of capl. They had hundreds of tons of dead alewife, so they said we got to have a control here so they decided to introduce pacific salmon, they eat alewife. So they had an invasive species to suppress an invasive species, it worked. Populations of alewife decreased, and die offs didn’t occur. Then the anglers realized they could fish for pacific salmon in the great lakes, so now we’re managing to sustain alewife so they will sustain exotic salmon, we’ve changed the system into a massive fish farm. So the system changes again and the alewife collapse because of zebra mussels and algae, those changes probably contributed to, we think, an alewife collapse. And so now the major fishery is collapsing. The system is unbalanced, one thing that doesn’t belong there now cascades to other systems with things that don’t belong there and there’s no sort of integration of the ecosystem connections.”

Q4) “Would you say this is an example of integrated pest management?”

A4) “It’s more like bio-control, integrated pest management believes that you don’t put in any more control than you receive in return benefit. It’s like if you had a million dollars controlling it, you want to get more than a million dollars in benefit. One of the biggest precepts is to not look for a silver bullet, the control is going to a multitude of different strategies, and some of the might be chemical as with sea lamprey control, but look for biological solutions as well, and look for mechanical solutions. Kids literally picking potato beetles off plants turned out to be remarkably effective. Better than the chemical used. Pacific salmon was a bio-control, which is a tool, but the trouble with bio-control is that we’ve learned very early on is that then the thing you use for bio-control gets out of control. But it’s not that we couldn’t stop stocking pacific salmon, there is now this political pressure to maintain the fishery. So would there be other integrated management way to control alewife, we might have done a better job restoring native picovores. In Lake Champlain pacific salmon have not been introduced because its believed that the lake trout can handle the alewife. The system itself will be resilient to incoming alewife.

Q5) Have there been any successful invasive removal stories? And are there any invasives that have had a positive influence?

A5) In insect pest management, there have only been six success stories for full removal in the hundreds of cases of invasive species. It’s been done with things like pheromone trapping. eradication, not possible. To be able to get the last 3 individuals. The snake head, down in Maryland, is a great example of this concerted effort to poison the fish. Not many success stories. They did, in Lake George they got Asian clam by placing benthic Matts down. Having to put more down each year. You have to have a point at which you give in, but they won’t, which made you admire them. Are any of them good…well I’m going to dodge that, because if you’re an angler an Atlantic salmon is pretty great. But if you’re the ecosystem the salmon isn’t so great. Then you have to ask the question, that any invasive species coming in is using resources formerly used by the native species. Alewife eat plankton that used to be eaten by smelt. You can’t live and not use resources, so at best the relationship would be neutral. Silversides in the lake are a great example of a neutral species in the lake. They popped up a few years ago and are now schooling in the hundreds of thousands. But they’re a food source that wasn’t there so they aren’t hurting anything and many species eat them. This neutrality is dangerous though because it is innocence until proven guilty. An example of this is when tubed nosed goby’s followed round goby. Everyone watched round goby’s and tube nosed ended up being worse…gobys cause problems in freshwater systems by displacing native sculpin and serving as a chemical contaminant absorbers [PCB’s, mercury, dioxin].”

Q6) “Is there a commonality between many of the exotics?”

A6) To be an exotic, in order to be effective you have to be a generalist. You want to have something that has wide temperature, food, and habitat preferences in order to survive. They tend to be genetically diverse and have high fecundity this makes it easy for them to spread. They also tend to have an easily spread propagule. Two examples of this are zebra mussels and alewifes. They also tend to be aggressive. Commonalities in terms of how they get here… we know what the vectors are: boats, bait transport, horticulture, aquaria, aquaculture (legal or illegal), canal systems (specifically the Hudson; now we are trying to close canals and use locks instead, lift boats out of the water and place them back in the water on the other side, or create barriers to their transport).

Q7) “Where are humans in all of this, and as a species, are we more of a solution or a cause?”

A7) We are a cause, we are a cause frantically looking for a solution. Human migrations are the cause. They are coming in because we are carrying them physically or they are a consequence of our transport. There is no question that this is all because of us. If it weren’t because of us we would call it a range expansion. Sometimes it is hard to tell the difference between a range expansion and an invasion. An example of this is cormorants. We don’t want them here, but we have facilitated their ability to live here. So it’s all human.

Q8) If we let 100,000 years go by, and we assume humans are still around and they are doing everything you mentioned. They are still doing resource extraction, still farming fish, how long do you think before these invasives are maybe not considered invasives anymore? Or will they always be considered invasives?

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A8) I think some species will shift down and find their niche. We will have to accept that that sytem has changed. There are areas where there are invasive salmonids such as lake trout that are deemed “wild,” meaning invasive but established. It’s a deceptive term calling them wild. Naturalized is another term that also means established and self-sustaining. So what is exotic now? If you leave it long enough to the point where it becomes established do you call it native?

Q9) Do you think a species could come here, such as the asian long horned beetle, and establish itself in a period over a thousand years slightly change their genetic make up, and be brought to where it came from and be considered a new invasive?

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A9) Oh yes definitely, they can become locally adapted, eventually speciate until they are something unique to the system. They could become invasive then native which is a bitter irony.

Q10) Is there anything you would like to add that we have not added?

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A10) We need to control our own population. With conservation biology in mind, what is the ultimate problem? Too many people, you cannot possibly conserve with a limited resource. Malthus was right. As we are globally more mobile, invasive will become a bigger and more serious problem.

Q11) Do you think for you, and for other people, that the main reason for control of invasive species come’s back to benefiting humans or benefiting the environment in general?

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A11) As I biologist, I would love to say that we have this deep need to keep the ecosystems intact for their own sake, honestly the driving function is self interest. There is a thing called ecosystem collapse, which can occur if you keep adding things to an ecosystem, and taking things away, the system could eventually fall apart. We are terrified of this happening, and we are getting there, especially with oceans. There is this deep philosophy that we don’t have the right to trash ecosystems. The National Audobon used to have these posters that said, “Extinctions are forever” driving this point home that conservation is important. When zebra mussels invaded we wanted another poster saying, “Invasions are forever,” there is no cure, and there is no going back.

-Taylor and Rachael
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A Quick Analysis of Zebra Mussel Habits

It is no secret that the zebra mussel has shown its presence within waters that it is non-native to. But how does it manage to spread so quickly? A study headed by James Stoeckel looked into this ability to determine what allows for a rapid expansion of population.

Mass distribution is the key factor. The offspring of the zebra mussels is a larva form growth that is a free floating being. Once this larva is in the water coloumn it takes very little for it to move from place to place where it will attach it self and start a population.

The easiest way for the zebra mussels to spread within bodies of water is with the flow of the water system that they are in. Traveling within a single body/water system allows for observed travel in excess of 190 miles (Stoeckle).

Feeding is the other way that the zebra mussel forces its presence on an area. Its pray is zooplankton that also live within the water coloum that it travels in. Being that there are so many zebra mussels/larva constantly bombarding these untouched areas it pushes out other forms of life by attacking the fod chain at its base.

Cited:

Larval Dynamics of a Riverine Metapopulation: Implications for Zebra Mussel Recruitment, Dispersal, and Control in a Large-River System

James A. Stoeckel, Daniel W. Schneider, Lori A. Soeken, K. Douglas Blodgett and Richard E. Sparks

Journal of the North American Benthological Society , Vol. 16, No. 3 (Sep., 1997), pp. 586-601

Published by: Society for Freshwater Science

Article Stable URL: http://www.jstor.org/stable/1468146
-Adrien

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A video explaining the effects of zebra mussels in aquatic habitats.

http://www.youtube.com/watch?v=MtUnVMGpTFs
Courtesy of the American Museum of Natural History
-Adrien
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The zebra mussel is not the only species currently invading Vermont's waters. A few others include:

- Water Chestnut: A plant with sharply spined fruit. It causes problems due to the immense amounts of oxygen it draws from the water that other biota need.

- Eurasian Watermilfoil: A perennial plant that grows faster than most natives it competes with. Grows very densely and causes many problems for recreation in the waters.

- Alewife: A small fish with the capability to consume mass quantities of zooplankton thus out competing other species.

- Didymo: Commonly referred to as 'rock snot' this nuisance algae forms in thick mats on the bottom of waterways reducing the amount of habitat available to other species.

This information taken from:

Aquatic invasive species in vermont. (2003). Retrieved from

http://www.vtwaterquality.org/lakes/htm/ans/lp_ans-index.htm

Other information about Vermont's invasives can be found at:

http://www.northeastans.org/aquatic-nuisance-species-in-the-northeast/species-mapper.html
http://www.anr.state.vt.us/dec/waterq/lakes/htm/ans/lp_VIP.htm
http://www.vtinvasives.org/
-Adrien

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Extra! Extra! Read All About It!! 
      Zebra Mussels are already in Vermont, and there isn't much that can be done now that they are established, but there are other species that have not arrived but are threatening invasion. The news article titled, “Beware Marauding Carp,” was recently published in the New York Times. It warns of the dangers of the introduction of the Eurasian grass carp to the greater New York area and the Hudson River. With the Hudson River so close to Vermont, the introduction of this species could have devastating impacts for Vermont as well. This species is already in Lake Erie, and could be traveling East through the Erie Canal very soon if action is not taken. This species is comparable to “an underwater lawn mower,” can reach huge sizes, and is capable of eating everything in site. In the past they been stocked as a means of biocontrol, but their population numbers have grown out of control and their geographic range has expanded. The Hudson River, specifically, has aquatic vegetation that facilitates in its food chain along with providing habitat for other species. However, it is possible that these invaders can be stopped. It is suggested that barriers be constructed between the Lake Erie and the Erie Canal, and the Erie Canal and the Hudson River. With careful management and inspection, it is possible to avoid this introduction and save the aquatic ecosystems of New York and Vermont from this destructive invasive species. The next section about Skaneateles Lake looks closer at invasive species management techniques with the hope of habitat restoration.

To read the full length article follow the link bellow:

 Strayer, D., & Waldman, J. (2013). Beware Marauding Carp. The New York Times. Retrieved from http://www.nytimes.com/2013/11/20/opinion/beware-marauding-carp.html

-Rachael 

Skaneateles Lake Association Invasive Combating Efforts

 

         Throughout my high school summers, I worked with an organization called the Skaneateles Lake Association. I worked solely with Skaneateles Lake, which is located in the Finger Lakes of New York. This association’s goals are to protect Skaneateles Lake, NY, from invasive species and preserve its pristine condition. This organization focuses on prevention of the introduction of invasive species along with removal of species that have already been established in the lake (Skaneateles Lake Association, Inc). I worked with this association for three summers and I served as a volunteer for five years.

A current invasive species that is threatening our lake is Eurasian Watermilfoil. It is characterized as forming large dense mats of vegetation that are known to outcompete native aquatic macrophytes. The mats of milfoil block out light and take up benthic habitat resulting in habitat loss of native species.

The first summer I was in charge of circling the lake in search of invasive Eurasian Watermilfoil patches. If I found milfoil from the surface, I snorkeled to describe the patch in terms of size and density. We then plotted the GPS coordinates of the patch so that scuba divers could re-locate the patch and remove the milfoil and its rhizomes to prevent further spreading. The scuba divers pull up the root ball of the Eurasian Watermilfoil. It is then sucked up a tube to the boat where the milfoil is then bagged for removal. After a large patch of milfoil is removed, benthic mats are laid down over top of where the patch used to exist. These mats block sunlight and help to ensure the death of the rhizomes that are left behind. These removal efforts are imperative; however, invasive species prevention is most important (Skaneateles Lake Association, Inc).

Eurasian Watermilfoil and the bagging process

The second and third summer that I worked for the Skaneateles Lake Association I was an invasive species-monitoring steward in charge of organizing and scheduling approximately ten other stewards. My crew and I manned boat ramps and inspected boats before they were launched, and after they were removed from the water.

My fellow stewards and I were trained by Cornell University Cooperative Extension (CUCE) to identify invasive aquatic hitchhikers and their "look-alike" native species. CUCE is an extension of Cornell University. It is their outreach and education program that puts “knowledge to work in pursuit of economic vitality, ecological sustainability and social well-being”(Invasive Species). Each of the summer we would have a training session where CUCE would instruct us mainly on prevention techniques which included invasive species identification, the correct way to inspect a boat for invasive species, and effective ways to educate the public and fishermen.

Rachael DeWitt inspecting a boat before it is launched into Skaneateles Lake

            We took this knowledge and applied what we had learned to our lake. We manned major public boat launches around the lake and inspected boats before they entered and after they left the water. The boaters were asked a series of questions such as, in what body of water was your boat last? How many days has your boat been immersed? Where is your boat registered? Is the excursion for recreational or fishing purposes? These questions would give the Skaneateles Lake Association (SLA) a good idea of who needs to be targeted, on which boats invasives are typically found, and from where the invasives are coming. We now know that there are Asian Clams that cause toxic algae growth in neighboring Otisco and Owasco Lakes and there is a macrophyte called hydrilla in nearby Cayuga Lake that can grow a foot a day, matting the water’s surface. These invasives are threatening intrusion to Skaneateles Lake (Skaneateles Lake Association, Inc). In this regard, the stewards have greatly helped SLA in their look out for invasives.

Asian Clam and Hydrilla

            Though Skaneateles Lake is not located in Vermont, it is still a great case study for aquatic invasive species. It is a pristine lake that is reliant on a booming tourist industry, similar to Burlington, Vermont. It is paramount that the lake is kept as close to this condition as possible. Therefore, great efforts were put into place to remove/control the present invasive species along with preventing the introduction of other invasives that could cause further harm to the lake. Since it began its efforts, the Skaneateles Lake Association has been quite successful. Other Finger Lakes, such as Canandaigua Lake, have looked to Skaneateles as a model for combating invasive species. Skaneateles has developed an effective system that should be used by future aquatic ecosystems facing invasive species issues.  

References (and for further information about these organizations visit):

Invasive Species. Cornell University Cooperative Extension. Retrieved from http://www.cce.cornell.edu/Environment/Pages/InvasiveSpecies.aspx

Skaneateles Lake Association, Inc. Retrieved from http://www.skaneateleslake.org/steward.html

 -Rachael

A Social Implication for Vermont
        Vermont may benefit from examining Skaneateles Lake’s eradication practices. Similar to Skaneateles Lake, Vermont has had to deal with the effects of Eurasian Watermilfoil. This environmental issue has developed into a deeper social issue. Vermont is currently dealing with depreciating property values because of milfoil. The scientific article titled, “The effect of an aquatic invasive species (Eurasian watermilfoil) on lakefront property values,” examined just that. The study used the hedonic property-value method to estimate the impacts of this particular species on property values. The intent of the study was to determine if there actually was an influence of Eurasian watermilfoil on property values. They proved that there was a negative impact and that property values can diminish in the range of 1-16% depending on the level of infestation. This study could have huge implications for not only Vermont but also any waterfront region facing the threat of aquatic invasive species.

To view this scientific article follow the link below:

Zhang, C. Boyle, K. J. (2010). The effect of an aquatic invasive species (Eurasian watermilfoil) on lakefront property values. Ecological Economics, 70 (2). Retrieved from http://www.sciencedirect.com/science/article/pii/S0921800910003708

-Rachael

Aquatic Summation
        In this portion of habitat loss, we discovered that invasive species play a destructive role. Dr. J. Ellen Marsden informed us that humans are the source of invasive introductions, and she also informed us about the dangers placed upon the ecosystem once the invasives are introduced. After speaking with her, we decided we needed to do some digging on our own to determine what the implications are for Vermont. We delved into the topic of Zebra Mussels examining why they are so successful. We also looked at other potential invasive threats for Vermont. Prevention of introduction is the only hope keeping out these species, so we looked into a case study in the Finger Lakes, NY that was taking action against invasives. We also examined a social implication, property values, that Vermont is already dealing with due to invasive introductions. These social implications will only multiply as more and more invasives out compete native species for their habitat. Overtime we may find that invasives become common place while many of the native species become species of the past for our Vermont ecosystems.  It won't be an easy task, but it is going to take active public awareness and involvement to keep invasive species out, along with dealing with the ones that are already present.

About the Authors


Rachael DeWitt
       Rachael is an Environmental Science major concentrating in Fisheries at the University of Vermont. She is a second year student there. She grew up in the Finger Lakes region of Central New York, Skaneateles specifically. Her environmental resume includes working for the Skaneateles Lake Association doing invasive species removal and prevention, interning with the State University of New York Environmental Science and Forestry school doing fisheries research, and conducting research at the Rubenstein Ecosystem Science Laboratory at the University of Vermont. She ultimately envisions herself going on to graduate school to pursue a degree in Marine Biology. Outside of academics, she is the president of the Club Swimming Team and enjoys singing and dancing.


Adrien Plouffe

Adrien Plouffe is a second year student at the University of Vermont currently persueing studies in the Rubenstein School of Environment and Natural Resources. A native Vermonter, he possesses knowledge of the greater Champlain Valley area through his background in farming and growing up on the lake. Currently he has no plans for where he intends to go with his studies.
In his free time he can be found playing football for the Vermont Ice Storm or cheering on the varsity sports teams of UVM as a member of the Fighting Catamount Pep Band.



Taylor Swanson