Great Lakes Article:

Exotic spiny waterflea found infesting Saganaga
By Steve Foss
The Timberjay News
10/10/03

The DNR and Minnesota Sea Grant Program have confirmed that a very small exotic - which could become a big problem - has been found in Lake Saganaga in the BWCAW along the Minnesota-Canadian border.
Biologists identified the harmful exotic spiny waterflea in Saganaga after studying samples collected by a summer resident.

Saganaga, located at the end of the Gunflint Trail in northern Cook County, is the third inland water body in the state to be infested with the tiny exotic zooplankton, which may disrupt local food chains and outcompete native species.

The spiny waterflea takes its name from the barbs on a long tail filament, which can catch on fishing lines, aquatic vegetation and downrigger cables. These tiny barbs can also stop small fish from eating this animal.

The infestation danger is in transporting the adult females and the eggs, which cling to lines and cables and look like gelatinous or cottony strings. While adult fleas taken from water die quickly, the eggs can dry out completely and remain viable. Once introduced again to water, they reconstitute and hatch into female fleas. The females, which reproduce asexually, will form their own eggs and infest the new lake, said Doug Jensen, exotic species specialist with Sea Grant.

How it happened

The waterflea is native to cold climates in eastern Europe and western Russia and Siberia, and made its way into Lake Ontario in 1982 through the shipping industry, according to Jensen. It likely spread through the great lakes in the same way as several other exotics, when ships picked up infested ballast water and discharged it in other lakes.

Shortly after its discovery in Lake Superior, it was also found in Island and Fish lakes, about 20 miles northwest of Duluth and popular destinations for anglers who also fish Lake Superior.

Jensen believes the flea came to Saganaga by hitchhiking on fishing equipment of Lake Superior anglers from the Grand Marais area.

Biologists hope to monitor the lake to see if the tiny (less than ½ inch long) exotic affects fish populations or other aquatic life in the lake.

What’s the problem?

There is strong, but not conclusive, evidence the species is damaging to local food chains.

In southern Lake Michigan, infestation was followed by the loss of several small species of plankton. In Harp Lake in southern Ontario, no small zooplankton species remain after infestation.

Smaller fish can’t eat spiny waterfleas, so large numbers could impact the food chain, according to Gary Montz, DNR aquatic invertebrate biologist. And Jensen said that the loss of smaller zooplankton species may create a bottleneck in the food chain, since some fish depend on small zooplankton.

However, larger fish can eat the water flea, so the impacts from the infestation are difficult to predict.

Biologists aren’t ready to say waterfleas have directly caused the changes in lakes Michigan and Harp - though they suspect it - because ecosystems are complex, and their components can vary widely because of other factors, Jensen said.

How to stop it

Montz says it is important that people visiting infested waters take time to avoid spreading this species.

Clumps of spiny waterflea can become entangled in fishing lines, downrigger cable or other gear. Montz said it is important to clean off any equipment that may have spiny waterflea attached to prevent moving eggs.

In Minnesota, the spiny water flea is a regulated exotic species and may not be introduced in state waters. State regulations require that anglers drain all lake water from their boats, including live wells, bait buckets and bilge areas before leaving the access of waters infested with spiny waterfleas.

Signs reminding anglers and boaters of these preventive actions will be posted at public access areas, Montz said.

It’s important not to lose heart and believe the war against invaders is being lost, Jensen said.

"We’re actually protecting these lakes," he said. "Less than 1 percent of Minnesota’s 15,000 lakes are infested."

Jensen said that, once Minnesota boaters are aware of a problem with exotics, they respond quickly and in large numbers.

More than 95 percent of the state’s boaters are taking steps at accesses to protect against zebra mussel and Eurasian milfoil infestation, which Jensen said has dramatically decreased the rate of milfoil infestation and probably accounts for the fact the Lake Zumbro, near Rochester, is the only inland lake known to contain the mussels.

"But they need to know what to look for," he said. "Our charge is to get the identification info out there and tell people how to take action."

The agencies have worked together to produce spiny waterflea identification cards similar to those warning against, milfoil, zebra mussels and rusty crayfish.

Not only do state wildlife agencies have the cards available, but bait shops, resorts and convenience stores that sell licenses and bait can get them for free by contacting either agency. Individuals can get single cards free by contacting the agencies.

Contact the DNR Information Center at (888) MINNDNR (646-6367) and the Minnesota Sea Grant Program at (218) 726-8712. More information on the species is available through Sea Grant’s Web site at www.seagrant.mnu.edu.