Invasive species cause harm to humans directly as pathways for disease, indirectly as pathways for species that harm quality of life such as food resources. Invasive species also harm the environment, or ecosystems, that provide support for human activities such as atmospheric gas regulation, storm water management and erosion control, and habitat for biodiversity that in turn supplies the genetic material we need for the Big Six “F’s”: Food, Feed, Fuel, Fibers, Flowers and Forests (also known as agriculture). And on top of this, invasive species harm human aesthetic well being damaging recreational activities such as hunting, birding, boating or swimming. Invasive species also drain resources needed to maintain open space for human activities such as hiking and running. The problem is expansive and complex; as an example, invasive species damage will eliminate the wood used to make baseball bats with the death of ash trees which are being destroyed by the emerald ash borer (EAB), Agrilus planipennis. Another example is the alteration of the natural resource regime of the southwest US that will allow for more intense and more frequent wild fires which will claim more building as buffelgrass, Pennisetum ciliare, changes the desert to an African grassland.
So how much damage can we allow or do we want? The cost of prevention is expensive and immediate, but it is hard to measure effectiveness. For how do you measure and convince economically society to incur the cost of the possibility of something that has not actually occurred? Meanwhile the monetary and resource outlay of control and management follows after the damage is apparent and out of control. The costs of this after the fact control and management most often exceeds available resources and elimination is usually impossible. Zebra, Dreissena polymorpha, and quagga, Dreissena rostiformis bugensis, mussels as well as kudzu, Pueraria montana var. lobata, come to mind of examples of invasive species that are severely impacting ecosystems and the resources they provide to humanity - that is us.
Do we or should we therefore seek a 100 percent interdiction rate for the importation and denial of commerce and distribution of invasive species at our borders? Is there a rational tolerance for invasive species themselves or some acceptable level of tolerance for invasive species contaminants which hitch-hike in on trade goods and human traffic, that is achievable and affordable by the industry? If a pest species is regulated because of standards, observations, research or past experience that strongly predict negative environmental impacts and damage to ecosystem services, should there be any leeway in the zero risk metric? If we let a few invasive species enter in order to lessen the economic burden or benefit for the business and to the end user, who then should pay to control and manage the ecosystem damage at a later date?
The wickedly inconvenient answer is in part a function of how you ask the question. Do you want to know how little harm is possible? Or is your focus on how much harm is allowable? These two questions divide us in two large philosophic camps at war with one another, even while we agree that we must protect our resources. And then to this muddled, murky mess we mix in individual rights versus the common good and public value. We, the end users cherish to various degrees the right to do what we want in that little area we call our own. We want to have lythrum and lionfish with our homes under our care and in our control so that we can enjoy the beauty no matter how dangerous to the general good. We claim the right to decide without the obligation to understand the potential or real harm that certain few invasive species may bring to the ecosystem that our gardens and homes are part. It is the failure to recognize that all our activities, both individual and communal are linked.
So we look for goods and services from those who can supply us with our wants of the moment with little consideration of the impact in space and time that these demands may have. And because we want, businesses supply and seek to do so at a profit that is measured in the present, accounted for in the past and debited against the future.