Spiny water flea confirmed in Rainy Lake: MNR

Spiny water flea (Bythotrephes longimanus), a predacious zooplankton species introduced to the Great Lakes from Europe, has been confirmed in U.S. waters of Rainy Lake, the local Ministry of Natural Resources revealed yesterday.
It has not yet been confirmed in Ontario waters of the lake, the MNR added.
Even so, the ministry would like boaters to be vigilant, especially with all the anglers competing in the Fort Frances Canadian Bass Championship later this week.
The spiny water flea belongs to the group of organisms known as crustaceans. Shrimp, crayfish, and lobster also belong to this group.
It is believed that spiny water flea first arrived in North America in the
ballast water of ocean-crossing ships.
Spiny water flea is about 1-1.5 cm long. The colours orange, blue, and green may appear on its body and a large black eye can be seen. As its common name suggests, it has a long tail spine with barb-like projections.
A red stripe runs about half the length of the tail.
This organism can produce resting eggs, which are capable of over-wintering on the lake bottom until spring or early summer, when they hatch into juvenile fleas.
The first recorded occurrence of this animal in North America was in Lake
Ontario in 1982. By 1987, it was present in all of the Great Lakes.
Its known range in Ontario now includes more than 80 inland lakes.
Spiny water flea may prefer deep, cool lakes, however, it has been found in warmer lakes where surface water temperatures can exceed 25 degrees C.
Although this flea can swim up and down in the water column, it relies on
current and wind to carry it any great distance.
Unfortunately, these organisms also can be easily transferred to new areas by human activity.
Spiny water flea is a predator that feeds on smaller zooplankton (or small animal life). One may eat 20 of these prey organisms per day.
When populations of spiny water flea are large, consumption of zooplankton prey can be significant, limiting the amount available for important fish species.
With less zooplankton to feed on algae, algal populations can bloom, making lake water less clear.
< *c>What are the impacts?
There are a number of ways in which spiny water flea may impact Ontario waters.
Compared to other zooplankton species, it can eat up to three times more food, competing directly with native zooplankton and fish, and reducing both the amount and kinds of prey available.
Also, although some native fish species feed on spiny water flea as an alternative food source, smaller fish (under 10 cm long) that attempt to eat these fleas cough them up because of their long tail spine.
The resulting lack of food or prey for small fish may affect their growth and survival, and contribute to a decline in their numbers.
Adding spiny water flea to the food web in Ontario lakes may also affect biomagnification of contaminants such as mercury (Hg).
Currently, research is emerging on the impact of this species to contaminant burdens, which may build through the food web, affecting top predatory fish like lake trout.
Spiny water flea can affect fishing activity, as well, becoming entangled in fishing lines and downrigger cables. The animals look like straight pins along the downrigger or line, and may sometimes raise and lower their tails.
The Ontario Federation of Anglers and Hunters and the MNR have set up a toll-free Invading Species hotline (1-800-563-7711) and website (www.invadingspecies.com) for you to obtain information on, and report sightings of, spiny water flea and other invading species.
If you find spiny water flea in a new area, preserve the organism in rubbing alcohol, then call the Invading Species hotline or contact your local MNR office to report your finding and confirm your sample as spiny water flea.
Spiny water flea can hitchhike to other waters by boats, boat trailers, and other equipment such as fishing gear or snorkeling/scuba gear.
Although it cannot be eradicated from a lake once established there, it is extremely important to restrict the animal’s movement.
To protect your lake and prevent the spread of spiny water flea and other invading species, take the following precautions before leaving a water body and entering another:
•Inspect your boat, trailer, and equipment. Remove all plants, animals, and mud, and dispose of them on dry land or in the garbage.
•Drain water from motor, live well, bilge, and transom wells while on land.
•Do not release live bait! Empty your bait bucket on dry land, or freeze or salt the bait for later use (it is illegal to release live baitfish from one water body into another).
•Remove organisms you can’t see on your boat, trailer, and equipment by:
—rinsing them with hot water (more than 40 degrees C); or
—spraying with high-pressure water (250 p.s.i.); or
—drying them in the sun for at least five days.

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