What Are Invasive Species? More Than Just Weeds In the Garden.
by Sheila Grother
Apr 12, 2012 | 4953 views | 0 0 comments | 12 12 recommendations | email to a friend | print
PURPLE LOOSESTRIFE is an invasive  plant that can be found along regional waterways. (Courtesy photo)
PURPLE LOOSESTRIFE is an invasive plant that can be found along regional waterways. (Courtesy photo)
We hear more all the time about invasive species from all around this country and indeed around the world. Pick up any nature magazine, news magazines or open an Internet news site and you are apt to see an article on some invasive species or other. Just for the fun of it, type “invasive species” into your web browser and see how many sites pop up. I got 27 million and change!

We have been fortunate locally to have, thus far, limited our known invasive species to numerous noxious weeds, European starlings and most recently the Eurasian collared doves that are becoming more common than our native doves. It is probably a matter of time before we are overrun with some other species that have become problems in other places in the U.S., and more particularly for this story – in Colorado. It is hard to guess the next invader, but it’s necessary to assume that it is probably already here.

So, are invasive species really that big of a problem? The answer is a resounding YES! They are arriving and proliferating on our land and sea, in rivers, lakes and grasslands, forests and roadsides, and they are having wide-ranging effects on our environment and even our health. The effects are sometimes as noticeable as the decrease in native cottonwoods on the lower Dolores River as the tamarisk invaded, but other effects are not so apparent and may include decreases in native species from trees and grasses to changes in native fish in our streams and birds at our feeders. Sometimes they get our attention, like the West Nile virus did a few years ago when people became ill and died – viruses can be invasive species too.

According to the National Invasive Species Council, 42 percent of the native species on the endangered species list are at risk primarily because of invasive species – that’s almost half of an ever growing number of species that may shortly be absent from our world.

Recently we have started to hear the term ANS (Aquatic Nuisance Species), referring to water-dwelling species, from New Zealand mud snails and quagga muscles to invasive fish and plants like purple loosestrife. The Colorado Division of Parks and Wildlife is so concerned about ANS species that they have established boat checking/cleaning stations at all of Colorado’s major lakes and reservoirs in an attempt to reduce their spread in Colorado; other states are doing the same. Minor water bodies – like our own Miramonte Reservoir and Trout Lake, have signs posted that request boaters inspect their crafts before launching. The inspections and signs have slowed the spread of these species but not halted them. As of 2011, several Colorado water bodies have tested positive for one or more invaders. These species generally began their spread in the eastern half of the U.S. and within a few years crossed the Mississippi river and headed west, jumping from water body to water body. ANS currently threaten the water we drink and the delivery systems that get that water from place to place. (Look up aquatic nuisance species on that web browser if you want to lose some sleep!)

You are encouraged to learn more about invasive species, the threat they represent, and what you can do to slow the spread of these invaders. A few suggestions include:

• Clean your hiking boots, waders, boats, trailers and off-road vehicles between uses;

• Use certified “weed-free” forage, firewood, hay, mulch and soil;

• Don’t dump live bait or unwanted fish into waterways;

• Remove invasive plants from your property and plant non-invasives in their place;

• Learn to recognize invasive species and discourage their reproduction;

• Report newly noticed invaders to the local authorities – County Weed Advisory Programs, Division of Parks and Wildlife or USFS.

We have not yet seen our first New Zealand mudsnail in the San Miguel or Uncompahgre rivers, but all it takes is one infested pair of waders on a fisherman who recently visited an infested site like Boulder’s Boulder Creek. Many discoveries of snails in North America have been associated with popular fly fishing streams, so all anglers are being encouraged to take strong measures to clean their equipment, especially boots and waders. 

– Sheila Grother is Weed Program Manager for San Miguel County.
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