Conservation Minnesota

Zebra Mussels – Let’s Not Become Complacent

Zebra mussels are in the news.  While much has been accomplished recently, zebra mussels and other aquatic invasive species (AIS) remainDick-Osgood-bio serious threats and our prevention and control efforts remain insufficient.

When we hear stories involving control methods, many tend not to read past the headlines.  When we hear that it was only one mussel discovered, we want to hope and believe it was the only one.  There are also the stories we do not hear of or relate to zebra mussels’ impacts – how can zebra mussels facilitate blue-green algae toxins?

Read past the headlines.  I have never heard of only one zebra mussel in a lake.  Zebra mussels and many other AIS undermine the integrity of lake ecosystems.

Zebra mussels will continue to impact our lakes with the status quo.  It is important to keep this in perspective and not become complacent.

I provide three points that emphasize we have a long way to go.  Namely, one of our best prevention programs has come up short, zebra mussels’ total impact will likely keep increasing and controls are not quite ready for prime time.  Most critically, prevention must be Plan A and effective prevention will require structural changes to our management systems.

Here are some eye-openers:

Zebra Mussels in Green Lake (MN).  This should not be a surprise.  Even though the Green Lake Association, with great support from the state and local communities, has one of the most aggressive, comprehensive, expensive and intensive inspection and prevention programs in place, zebra mussels were discovered recently.

I know they just found a single animal, but guess what, there is no such thing as one zebra mussel.  More will be found.

What does this mean?  More lakes will become infested.  The reason is simple – our total prevention system is leaky (very leaky).  Despite greatly increased funding, stronger laws and more enforcement, the underlying system that allows free movement between lakes and unfettered commerce of unwanted plants and animals has not changed.  Until we are willing to address this, we will have more (many more) lakes with zebra mussels and other AIS.

Blue-Green Algae Shuts Down Toledo’s Drinking Water Supply.  The City of Toledo gets its drinking water from Lake Erie.  Lake Erie has been producing toxic blue-green algae with greater regularity and recently these toxins became so concentrated as to become a public health issue.

What does this have to do with zebra mussels?  Plenty.

Zebra mussels are filter-feeders, meaning they filter particles from lake water.  Many of these particles are algae.  Zebra mussels shun toxin-forming blue-green algae – so they do not eat stuff that would make them ill or even kill them (would you?).  In this manner, zebra mussels perform a service to toxic-forming algae by preferentially eating other algae competitors and leaving the bad ones.  Zebra mussels are a key element of the phenomenon of facilitating toxic blue-green algae blooms.

Lake Erie is not an outlier.  We can expect an increased prevalence of toxic algae blooms in zebra mussel lakes.

Zequanox is Approved for Lake Use.  Zequanox is the trade name for a bacterial product that kills zebra (and quagga) mussels, but does not harm fish or other aquatic plants and animals.  Zequanox has recently been approved for use in open water systems (like lakes) by the US Environmental Protection Agency.  This means that when used appropriately, it is safe for fish, wildlife and humans.  It does not provide any assurance of efficacy.

Will this mean we can eradicate zebra mussels from lakes?  Nope.

Here is what we do not know.  We do not know Zequanox’s efficacy in controlling zebra mussels – how much control, how long, etc.  It is hoped that Zequanox may be useful for controlling zebra mussels in small areas, such as around docks and field evaluations have just begun.  We also do not know the price tag for these treatments.

What Does This Mean?  Zebra mussels are now a fact of life.  Many lakes have them, many more will get them and, sadly, there is not much we can do about that (given our current policies and priorities).  We are finding out that the increased attention and investment in prevention programs may slow the spread (although there is no objective way to know this for sure), but probably not much.

Many argue that we must change boaters’ and others’ behavior to really solve the AIS problems.  This sounds good, but we don’t just wave a magic wand for this to happen.  Social and behavioral researchers know that changing behavior is difficult, requires a long time and involves structural changes.  For example, smoking kills people, yet per capital consumption of cigarettes did not decline for four or five decades following intensive public education campaigns.  Only following the implementation of structural solutions did per capita smoking rates decrease.  There is a lesson here – education, awareness and even scare tactics did not work.  Only when cigarette smoking was banned in buildings, public places, etc. (structural change) did behavior change in an objectively measurable way.

What Should We Do?

1. Confront and recognize the real, underlying mechanisms of zebra mussel and other aquatic AIS movement and address these systematically.  Zebra mussels are moved by boaters.  Relying on behavioral changes is ineffectual.  To change the system, structural changes, such as quarantine, are needed.

2. If your lake has zebra mussels, don’t waste much time, effort or expense on controlling them.  Solutions may be coming, but for now they are not here.  Hope is not a game plan.  Focus on keeping additional AIS out.

3. If your lake does not have zebra mussels, focus on keeping them out, but only as part of a comprehensive AIS prevention plan.  Be realistic.  Unless this plan is truly comprehensive (covering all accesses all the time as well as all other pathways), re-think your commitment and investment.

About Dick Osgood

Dick Osgood
Dick Osgood has authored numerous scientific journal papers, made hundreds of presentations at professional meetings, and recently co-authored his first book.  Now he’s working on his second book titled A Lake Manager’s Notebook.  Dick is a Certified Lake Manager and offers lake management consulting services through his business Osgood Consulting LLC.
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