Rarely common and commonly rare, or how a super weed loses its might

Post by Jenny Seifert, UWEX Aquatic Invasive Species Outreach Specialist

It turns out an aquatic invasive plant feared by many as a lake-choking menace may not be so universally problematic after all.

The “super weed” in question is Eurasian watermilfoil, or EWM for short, and a decade’s worth of research is dismantling some commonly held beliefs about the non-native plant’s impact on lakes and how to effectively control it.

This mat of Eurasian watermilfoil may look menacing, but it’s actually a rare sight in Wisconsin.

To Michelle Nault, a water resources management specialist with the Wisconsin DNR who is among those studying the plant, one of the most surprising things they’ve found is just how much the amount of EWM can vary within one lake and across lakes in the same region.

In other words, it’s not really behaving in a way that would make an “invasion” inevitable.

“We could be on a lake with relatively dense milfoil one year, and then return to that same exact lake the following year and barely be able to find any it. We observed this even in lakes with no active management,” says Nault, explaining statewide research is important for helping them understand the extent of the problem and making wise management decisions.

But the weed hasn’t lost its might completely, cautions Nault. It can certainly become problematic in some lakes, making it still critical for lake users to always take the basic steps to prevent invasive species – that is, inspect, remove, drain and dry whenever you leave the water.

“There are still many lakes within Wisconsin that do not have Eurasian watermilfoil, and preventing its introduction is much more ecologically and economically cost-effective than dealing with the invader once it’s introduced,” says Nault.

Think you know what’s up with EWM? Read on to test your knowledge against what researchers at the WDNR and elsewhere are finding out.

True or false: EWM has invaded most of Wisconsin’s lakes.

False. The research indicates EWM is “rarely common and commonly rare.” According to Wisconsin’s statewide aquatic invasive species database, fewer than five percent of Wisconsin’s 15,000 lakes contain EWM, and the majority of lakes with public access, particulary those up north, still don’t have a shred of it.

Not only that, most lakes that do contain EWM have just a little bit of it – not even enough for most lake users to consider it a nuisance. For some of these lakes, strategic aquatic plant management helps to keep the non-native plant at bay, while natural conditions seem to be enough to keep it in check in other lakes.

The rare cases of dense EWM populations are most commonly found in reservoirs, not natural lakes, and in more southerly parts of the state, where the species began its invasion decades ago.

True or False: Herbicide treatments are the only way to control EWM effectively.

False. There are many ways to control EWM effectively, and choosing the right method depends on your specific lake and management goals. The toolbox of methods includes pulling it by hand, harvesting it with machines, diver-assisted suction harvesting (a method that entails using hoses to transport pulled plants to the water’s surface for easier removal), drawing down lake levels, and protecting shoreline habitat for weevils that eat the plants (a method called biocontrol). Since several of these methods require a permit, consult the WDNR before you make your management plan.

Can you spot the baby bug? This young weevil will grow up to be biocontrol for EWM.

As for chemical herbicides, they seem to be more effective when EWM is caught early or with purebred Eurasian watermilfoil, but they can also have unintended consequences.

Like most invasive species, EWM is clever about finding ways to claim its new territory. One of its tactics is to hybridize with a common native milfoil species, which has resulted in a variety of milfoil mutts, some of which seem to have a tolerance for herbicides or a knack for growing back quickly after treatments.

Moreover, research is showing the cure may be as bad as or worse than the disease sometimes. Large-scale or long-term herbicide control can potentially harm native plants, fish and other beneficial organisms, necessitating a balancing act between treating the problem and protecting the things we’re trying to protect in the first place.

Ultimately, there is no one size fits all solution to controlling EWM. An adaptive approach, continued research and an acceptance that total eradication may be the unobtainable pot o’ gold can help us make careful management decisions.

True or False: Once EWM invades, it quickly dominates the whole lake.

Sometimes true, but usually false. It turns out it is hard to predict what exactly EWM will do once it gets into a lake, but contrary to long-held beliefs, its population doesn’t always explode upon introduction.

A ten-year study of unmanaged lakes with EWM showed that sometimes the plant remains relatively sparse in a lake, while other lakes experienced an immediate spike in EWM that was followed by a natural drop over time. Still other lakes found equilibrium with their EWM population.

Moreover, year-to-year events like drought or lots of rain – the latter of which can lead to floods or bursts of nutrient runoff – can make annual EWM populations boom or bust.

True or False: Prevention and management are still important for keeping our lakes healthy.

True! (Just checking to make sure you’ve been reading carefully.) The best – and cheapest – way to protect your lake from becoming one of the “commonly rare” is to not allow EWM and other invasive species to get in it. Enter the Inspect, Remove, Drain and Dry mantra.

If EWM does find its way into a new lake, the second best thing is early detection, which can reduce the amount of time and effort spent on trying to control it in the long run. A lake-specific management plan with a realistic goal and an approach that integrates multiple control techniques may bring the most success to suppressing EWM’s sub-super powers.

For a deeper look into the latest WDNR research on EWM, read the article ‘The science behind the “so-called” super weed’ in the August 2016 issue of Wisconsin Natural Resources.

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Help wetlands, raise beetles!

By Jenny Seifert, UWEX Aquatic Invasive Species Outreach Specialist

Now is the time to be growing purple loosestrife, an invasive plant, in your backyard.

What, you ask? Why would you tell us to intentionally nurture an invasive species?

Good question. Normally, we shouldn’t be planting or otherwise encouraging invasive species in our gardens, ponds or properties.

But purple loosestrife is an oddball case. Tending just a couple of specimens of this otherwise unwanted wetland invasive can be beneficial if done to help their worst enemy, Cella beetles, grow and flourish.

Cella beetles are our best defense against purple loosestrife. Photo credit: Paul Skawinski

The beetles, formally called Galerucella pusilla and Galerucella calmariensis, have become heroes for wetland lovers, because they are really good at eating purple loosestrife. Their appetites prevent the plants from growing tall and producing seeds, allowing native wetland species to thrive instead.

About two decades ago, the DNR and partners first released the European-native Cella beetles in Wisconsin in an attempt to “stem the purple (loosestrife) tide,” which was consuming so many wetlands that land managers had nearly given up hope that it could be tamed. Now, the beetles are a frontline defense against this wetland-ruining (although, kinda pretty) exotic plant.

Each spring, the beetle army gets a little help from people around Wisconsin, who rear new recruits to be deployed come summer. Each cohort starts small but multiplies quickly – up to 100 times the starting population – before flying off to duty.

You can help raise an army, too! Here’s what the task entails:

  • Order a “starter kit,” containing beetles and cage netting, from the Wisconsin DNR for a $20 donation (it’s free to teachers!) by filling out this application. The DNR will mail the netting to you immediately and the beetles in May.
  • Once the netting arrives, sew it into “cages,” which you will attach to your purple loosestrife planting pots (don’t worry, instructions will be included) to protect the plants and beetles from other critters that might eat them.
  • As soon as the spring thaw hits, dig up a few of the tallest loosestrife plants from your property or, with landowner permission, a nearby infested wetland. Pot and cage them immediately, and place them in your backyard or schoolyard. Here’s how to identify purple loosestrife, if you don’t know what it looks like. (See also the pictures below.)
  • By May, your plants should be two or more feet tall, and it will be beetle time. As soon as you get your beetles, place ten of them in each cage with the plants.
  • In June or July, you will start noticing new adult beetles in the cages, which means it’s time to move the potted plants to a nearby loosestrife-infested wetland, which may or may not be the same one from which you collected them.
  • Remove the cages and release the beetles!
  • Report your release to the DNR, including the location, so we can keep track of your much-appreciated efforts.

If you really want to geek out, you can help the DNR monitor your beetles and their progress by photographing your wetland year to year and filling out this form.

This letter has more details about how to get involved in Cella beetle rearing, or you can contact the state’s purple loosestrife guy, Brock Woods, at brock.woods [at] wisconsin.gov.

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As the ice begins to melt, here are some invasive species to be on the lookout for

By Jenny Seifert, UWEX Aquatic Invasive Species Outreach Specialist

The weird spring tease we got this week – in February – got me thinking about what sorts of aquatic invasive species (AIS) water lovers could be on the lookout for as Wisconsin’s lakes begin to awaken from their icy slumber. So I had a quick chat with one of the state’s AIS gurus, Paul Skawinski, the Citizen Lake Monitoring Network Educator with UW-Extension Lakes and a self-proclaimed “dorky botanist.”

According to Skawinski, a few AIS are active during the winter, meaning they aren’t dead or dormant, but are still photosynthesizing (albeit slowly), eating plankton, and going about their usual ways. People can keep their eyes out for these species while seizing the day with some late-season ice fishing or just wandering about a thawing lakescape.

Eurasian water milfoil and curly leaf pondweed are typically still standing and readily visible under the ice,” says Skawinski, naming two of those hardy few that can tough it out through a Wisconsin winter.

The advantage these two invasive plants have is their tolerance of darkness and cold water. In the summer, they can grow in deep waters, where light and warmth are scarce, which means when ice and snow curtain lakes in the winter, it’s no big deal for them.

Another winter-resistant species is starry stonewort, an invasive alga that is relatively new to Wisconsin. While its green “planty” parts die off in the winter, its star-shaped bulbils, or its namesake reproduction centers, are still detectable, staying cozy in the lake sediment and ready to sprout come spring.

Starry stonewort’s bulbil, or reproduction center, can overwinter in lake sediments. Credit: Paul Skawinski

“These species can grow fast and tall, and quickly shade out other species, making it harder for some native species to grow back in the spring,” says Skawinski of why winter hardiness among invasive flora contributes to their potential dominance in a lake.

One more invasive critter to be on the lookout for as Wisconsin melts is the zebra mussel, that pipe-clogging filter feeder that can smother native mussels, promote algal growth and generally get all over everything.

A stubborn zebra mussel clings to an aquatic plant, even during winter’s deep freeze. Credit: Paul Skawinski

“I was out on a lake last weekend and pulled Eurasian water milfoil through the ice with several zebra mussels attached,” says Skawinski of a trip he made with some citizen lake monitors to Cedar Lake. For the past four or five years, he has done wintertime explorations around the state to see what he can find lurking under the ice.

So what should you do if find any of these or other invasive flora or fauna as winter turns to spring?

“Contact someone,” says Skawinski.

Specifically, you can choose among your regional AIS Coordinator at the DNR, your regional Tribal or County Coordinator or your regional Citizen Lake Monitoring Network Coordinator. Be sure to tell them what species you found, how much of it you saw, when you found it and whether you have a sample you could send them. This information helps them keep track of invasive populations and recommend appropriate management actions.

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Make Inspect, Remove, Drain, Never Move your 2017 intention, and some science behind that

Post by Jenny Seifert, AIS Outreach Specialist, UW-Extension

As you recover from the holiday revelry and look ahead into the New Year, full of optimistic resolve to make your life better, we suggest you add a certain intention to your 2017 game plan. You guessed it: when using Wisconsin’s lakes, rivers and wetlands, always Inspect, Remove, Drain, and Never Move to help prevent the spread of aquatic invasive species.

I know aquatic summer fun may be far from your mind right now, as you pile on the layers to protect yourself from the icy wrath of the latest polar vortex. But there’s no time like the present to set your intentions, and here’s why.

Behavioral intentions play a key role in behavior change, according to the Theory of Planned Behavior, an important theory we apply often to our AIS prevention campaigns.

Intentions are indications that you are ready to act and the immediate determinants of a behavior. Without the intention, the behavior won’t happen, so the theory goes.

Underlying our intentions are three factors: our attitude toward the behavior, perceived social norms, and our perceived ability to perform the behavior. Let’s break this down further.

Starting with attitudes, these are our feelings about a behavior – is it and its outcomes good or bad (favorable or unfavorable)? If I believe aquatic invasive species are bad and preventing them is good, I am likely to think it is good for me to try to stop them. So my attitude toward Inspect, Remove, Drain, Never Move is favorable.

Our attitudes about a behavior interact with what we think other people – particularly, people whose opinions we care about – expect of us, which includes what they think about the behavior in question and what they do themselves. This factor is called subjective norms.

In other words, if I think my friends, family and fellow boaters expect me to Inspect, Remove, Drain, and Never Move, then I am more likely to cave to that social pressure.

Finally, our attitudes and subjective norms also interact with our sense of self-efficacy, or our perceived behavioral control. If I believe I am capable of Inspecting, Removing, Draining and Never Moving and there is nothing preventing me from doing so, then my intent to act is stronger.

All three of these factors combined predict our intentions, which in turn predict our behaviors.

If you need a visual to pull all of this together, here is what the theory looks like:

Source: Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50, p. 179-211.

Of course, real-life behavior is not always as neat and tidy as a conceptual model. Our behaviors are often a mess of factors that we can’t always explain. But behavior theories do a good job of making some sense of why people do what they do and how we might change our ways for the better. (Side note: An interesting exercise is to try to dissect why you do a certain behavior – at least I geek out on that sometimes.)

Now that we understand how setting an intention to help prevent the spread of aquatic invasive species can help us actually do it, we’d love to hear how you intend to stop aquatic hitchhikers this year. Send us a comment below and/or tag @WisconsinAIS in a Tweet – we’ll share or retweet our favorites.

Happy 2017!

Posted in Education and Outreach, Invasive Species | Tagged , , | 1 Comment