2. Invasive Alien Species
Here is a list of some key invasive species that are threatening the ecological integrity of the Ottawa River watershed.
Invasive Plants
Millfoil: Invasive (left) & native (right). Photo: Dept. of Ecology, State of Washington
Eurasian Water-Milfoil
(Myriophyllum spicatum)
Submerged leaf, each with 12 or more thread-like segments.
Note: native species have fewer than 12 thread-like segments (right on photo).
Photo: Ontario Federation of Anglers and Hunters
European Water Chestnut
(Trapa natans)
Floating leaves with sharply toothed edges, flower is white with four petals. Seeds are hard with sharp barbed spines.
Photo: Ontario Federation of Anglers and Hunters
European Frogbit
(Hydrocharis morsus-ranae)
Floating leaf 2-5 cm wide with a spongy coating on only a portion of the leaf underside.
Note: The native species has a spongy coating covering the entire leaf bottom.
Invasive Invertebrates
Photo: Ontario Federation of Anglers and Hunters
Zebra Mussels
(Dreissena polymorpha)
Triangular in shape and sits flat on underside. Black or brown in colour with white to yellow zig-zag pattern.
Note: Unlike native mussels which burrow in sediment, zebra mussels can attach to docks, boats and moorings and are much smaller (<2.5 cm).
Photo: Minnesota Sea Grant
Rusty Crayfish
(Orconectes rusticus)
Claws have black bands at tips and form an oval gap when closed; body has a pair of dark, rust coloured spots.
Note: they look similar to the native species so make sure to take a photo so that it can be verified.
Invasive Fish
Illustration: Joe Tomelleri
Asian Carp
(Hypophthalmichthys nobilis, Hypophthalmichthys molitrix, Ctenopharyngodon idella, Mylopharyngodon piceus)
There are four species of Asian carp of concern. However, the bighead and silver carp pose the biggest threat. Both have large heads and toothless mouths with eyes that sit below the mouth.
This is a page from the online Riverwatch handbook.