Invasives

Invasives, also often called exotic species, are plants and animals that evolved elsewhere but thrive in their new environment. They can feed on native species, or take over their habitat and cause local extirpations. Not only do invasives affect native flora and fauna, but they can have economic costs. For example, crops may require expensive applications of herbicides to kill invasive weeds. Herbicide use also increases the risk of contaminated waterways. Governments and stewardship organizations monitor and control invasives, but it is a challenging task, and data are sparse.

This section addresses only invasive species in waterways, wetlands and riparian areas. Findings from stewardship groups and government monitoring agencies are included. However, given the size of the watershed and the lack of coordination among monitoring programs, these findings are not comprehensive. Invasive plants are introduced by vegetative means, seeds and spores which may be transported by birds, animals, wind, water and human activities including agriculture, forestry, and recreation to name a few. Aquatic species are often introduced through the release of exotic baitfish and worms, and non-inspected boat transfer.

Aquatic Invasive Species
Brown trout and brook trout are not native to the Mighty Peace watershed. However, they are not considered an invasive species as they are stocked by the Government of Alberta to provide public angling opportunities. The northern crayfish (Orconectes virilis) has been observed in the Peace River, likely due to illegal introductions.

Wetland Invasive Species
Wetland surveys conducted by the ABMI found no invasive plants. An invasive aquatic macrophyte, the Eurasian milfoil (Myriophyllum spicatum), has only been reported at one location in the watershed so far, the Wapiti River watershed.¹⁶

Status of Species of Particular Concern
Zebra and quagga mussels, invasives that pose problems in many areas in Canada, have not been detected in any Alberta lakes to date. The spiny water flea has not been reported in any rivers, streams, lakes or wetlands in the watershed. The invasive algae Didymosphenia geminata has not been reported in the watershed, but it has been reported in Saskatchewan, BC, and the southern Albertan foothills, so it is possible that it is already present.

Invasive Plant Species in Riparian Areas