Recently I was contacted by a student from a local high school who was “completing a research project about the negative and positive effects that foreign invaders have on the environment”. Because I felt it might have a broader appeal than to just one student and with the student’s permission, the questions and my response follow.
1) Despite all of the negative impacts invasive species have on the environment, are you aware of any positive impacts they have as well? If so, what?
2) Can you list examples of invasive species in New York, and what roles they play in the ecosystem they have invaded?
3) What solutions or programs are being enacted to solve the problems associated with foreign invaders?
4) To what degree are invasives impacting our area/New York State as a whole?
5) Have you conducted research in this area of study? If so, what was your hypothesis (what was the subject) and what conclusions did/could you deduct from the research?
The National Invasive Species Information Center (NISIC) defines invasive species as plants, animals, or pathogens that are non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause harm. I am not an expert or researcher by any means but I have taken an interest during my retirement to advance the water quality of Sodus Bay in an effort to sustain it for future generations. I am pleased that you are interested in this subject.
In the relatively short time that this country has existed, over 200 invasives have found their way here from other parts of the world. Not all non-native, non-indigenous imports are bad. There are both good and bad imports. Invasives are like weeds. Plants are only weeds if you don’t want them where they are. Many non-indigenous plants, animals and pathogens were brought here with good intentions as was the case with Water Chestnut, Eurasian Water Milfoil, Hydrilla and Mute Swans. Each of these was brought to this country by man to beautify aquariums or garden ponds with no consideration for unintended consequences. Each has proven itself to be a net negative influence and a formidable foe costing hundreds of millions of dollars to control while none has been eradicated at this point. I’m essentially convinced that eradication, although a goal, is rarely attainable and that a level of acceptable coexistence is a more reasonable end point. This is the case with Purple Loosestrife. Biological controls proven in Southeast Asia, in part by Cornell University students and staff, have the potential to bring this invasive into harmony with indigenous species.
Others invasives arrived here unintentionally by other vectors or pathways. As residents of the Great Lakes Basin, we have been subjected to a major vector since the opening of the St. Lawrence Seaway. We have become victims of the contents of ballast water discharged into the Great Lakes by ships from around the world. With that ballast water come potential invasives. There is much talk currently regarding the treatment of ballast and bilge water prior to discharge to prevent the introduction of invasives into Great Lakes waters. This will serve to slow the influx of new threats.
Many imports are not perceived as harmful and are part of our daily diets. The tomato comes from the South American Andes via Mexico. Bananas are native to Indomalaya and Australia. Others, although harmful to the aquatic food chain, are perceived as beneficial. Quagga and Zebra muscles are in this category in the eyes of some. They have filtered algae from the water column creating clear water to greater depths than previously experienced. To the casual observer this would appear to be an improvement. The unintended consequence is that now the macrophite community (weeds) can flourish at greater water depths increasing the total biomass of the water body, diminishing recreational opportunities. These small bivalves also serve to restrict water flow wherever there is an intake to a power plant, municipal water system or boat as they inhabit intake screens restricting water flow.
Monolithic stands of Water Chestnut have choked the southern waterways of Lake Champlain for over 100 years. They have also destroyed previously thriving fishery habitat across the state. Presently we are faced with an even more formidable aquatic plant, Hydrilla. As this invasive attempts a foothold at the southern end of Cayuga Lake at the Ithaca Inlet, at Fall Creek and in Tonawanda Creek that forms part of the Erie Canal, the State is expending great effort and money to contain and eradicate this plant. Hydrilla has the ability to render a water body unusable as it has in the Florida everglades.
The “cost/(invasive) life cycle” curve quickly points out the cost benefit and comparison of prevention, early detection, control and reduction/eradication. Many invasives arrive in a new environment with an ecological advantage. They lack natural enemies and controls and may fill a niche not being served by their indigenous cohorts. Consequently they thrive at the expense of native indigenous species until they come into balance or dominance over those with which they compete. Other invasives that you may have heard of or be familiar with are Emerald Ash Borer that will kill most of New York’s ash trees, Japanese Knotweed, Giant Hogweed (phototoxic) and Phragmites Australis which are spreading along our roadsides at an alarming rate. Their propagation mechanism is roadside mowing. The Round Goby is here to stay and the Asian Carp is threatening the Great Lakes at the Chicago sanitary and shipping canal that connects to the upper Mississippi basin at the Illinois River.
New York State has passed legislation to restrict the sale of some known invasives and recently passed legislation governing the transportation of aquatic invasive species via the vector of boats, trailers and motors. This “Clean, Drain, Dry” campaign targets the spread of invasives and has spawned the advent of the Launch Steward Program around the state. It targets macrophytes, baitfish and bilge water. Lumber, wood product and firewood restrictions are also in place.
I suggest that you poke around on the internet for a plethora of additional information. The New York State Department of Environmental Conservation would be a good place to start. We are fortunate to be located in an area rich in academic resources that specialize in these and related subject areas.
I wish you well in your studies and encourage you to continue in this vein. It is flush with opportunities.
Dave Scudder, President, SOS