Lake Perry Zebra mussles

[DenOz]

This lake, sadly, had the infestation of the Zebra mussles a few years back. The lower end of the lake appeared to have a much larger amount than the upper end. Up until about 2 years ago, these mussles where clustered to any structure that you looked at on the shoreline. The "spuds", or steel uprights, at the marinas, were absolutely coated with mussles.

About a year ago, I noticed that I was not seeing as many. A good thing. Just this past summer, the lake was held about 8 ft. above normal, for approx. 3 months due to the Missouri flooding problems. When the lake was returned to near normal pool there wasn't any new Zebra mussles on the flooded shorelin. Again, a good thing. The marina has no new mussles clustered to the spuds. OK, this is still good.

From all that I have heard, and read, I have not seen that they completely die out. Appears that we have at least a 98 % reduction. Just in my observation.

My questions. Do they cycle? Have there ups and downs once they in these waters? Will they completely die naturally without the body of water chemically treated? Any info. will be greatly appreciated.

[Craig Johnson]

This lake, sadly, had the infestation of the Zebra mussles a few years back. The lower end of the lake appeared to have a much larger amount than the upper end. Up until about 2 years ago, these mussles where clustered to any structure that you looked at on the shoreline. The "spuds", or steel uprights, at the marinas, were absolutely coated with mussles.

About a year ago, I noticed that I was not seeing as many. A good thing. Just this past summer, the lake was held about 8 ft. above normal, for approx. 3 months due to the Missouri flooding problems. When the lake was returned to near normal pool there wasn't any new Zebra mussles on the flooded shorelin. Again, a good thing. The marina has no new mussles clustered to the spuds. OK, this is still good.

From all that I have heard, and read, I have not seen that they completely die out. Appears that we have at least a 98 % reduction. Just in my observation.

My questions. Do they cycle? Have there ups and downs once they in these waters? Will they completely die naturally without the body of water chemically treated? Any info. will be greatly appreciated.

DenOz,

1.) Do they cycle? Yes. Zebra mussels are a boom and bust species meaning that they can increase in numbers exponentially until carrying capacity is exceeded and then their numbers crash.

2). Have their ups and downs once they are in these waters? Yes. Once the population crashes they will begin to build their population density again. This is where it gets a little tricky. We really don't know how long it takes the species to reach a level for the first crash or how long it will take for the population to start rebuilding in numbers. For example, zebra mussels were discovered at El Dorado in 2003. The population peaked in 2006. The first 'crash'/large die-off occurred in 2007. During the 2008, 2009, and 2010 growing seasons the zebra mussels remained at very low densities with very few young of the year zebra mussels (veligers) produced. But during 2011, shoreline encrustation by adults increased as veliger densities increased to over 100 veligers per liter of lake water over the 4-6 veligers per liter of lake water that was seen during 2008-2010. The big question now is will we reach the densities we saw in 2006, will the population crash as it did before, will a higher population density be maintained for a longer period? There are many factors that can influence the zebra mussel populations so it is difficult to predict what the outcome will be.

3). Will they completely die naturally without the body of water chemically treated? No. As stated above we expect the zebra mussel populations to naturally cycle from very high levels to low levels. Even when at their lowest levels after infestation there will still be adequate numbers of mussels to sustain the species and continue the 'boom and bust' population cycling so they will never die out completely. Predicting the cycle is the tricky part as each water body and the factors affecting them vary each year. Researchers continue to look for ways to control zebra mussels in open water systems but right now there is no feasible way to apply treatment to kill zebra mussels over 1,000's of acres of open water found in our reservoirs.

[Fish Taxi]

How deep underwater do they live? Can they survive below the thermocline in a deep lake? I have always wondered if the corps couldn't help control the population with a system of raising and lowering the lake levels. For instance, if they normally only live above the thermocline in the water with higher oxygen content, then couldn't the corps draw the lake down extra low in the winter to kill the ones near shore, and then keep the lake up in the summer to suffocate the deep ones?

I'm sure they have probably tried that before somewhere... Maybe they can survive low levels of dissolved oxygen.

I also wondered if blue-green algae killed them, since it seems to be toxic to everything else.

[Craig Johnson]

How deep underwater do they live? Can they survive below the thermocline in a deep lake? I have always wondered if the corps couldn't help control the population with a system of raising and lowering the lake levels. For instance, if they normally only live above the thermocline in the water with higher oxygen content, then couldn't the corps draw the lake down extra low in the winter to kill the ones near shore, and then keep the lake up in the summer to suffocate the deep ones?

I'm sure they have probably tried that before somewhere... Maybe they can survive low levels of dissolved oxygen.

I also wondered if blue-green algae killed them, since it seems to be toxic to everything else.

Fish Taxi,

Zebra mussels require oxygen so they will occur as deep in a lake where oxygen levels are sufficient. For those lakes that don't thermally stratify, zebra mussels will be found all the way to the bottom. Since it is impossible to completely kill zebra mussels with water level manipulations, it usually isn't feasible to attempt such dramatic water level fluctuations. Although water level fluctuations can kill millions and millions of zebra mussels in exposed areas, enough zebra mussels will remain just under the water line to quickly repopulate vacated areas.

Zebra mussels are selective in their feeding activities and do not consume blue-green algae. They can actually make conditions better for blue-green algae by removing other beneficial algae causing elevated blue-green algae densities.

[kingfish387]

Hey Craig just want to say thanks for all the info you provide us with.I believe it helps bring awareness to some of these things.I know it has made me more conscious of what/what not to do.I wish all the state boards had a biologist to call on.Thanks again.

[Kansasoutdoorsman]

Thanks craig,

We pulled a branch out of Melvern this fall in 20 ft of water and it had 20+ little musclues on it. Going to choke those piles out at some point I am afraid of.

[Craig Johnson]

Thanks craig,

We pulled a branch out of Melvern this fall in 20 ft of water and it had 20+ little musclues on it. Going to choke those piles out at some point I am afraid of.

Below is a picture of a brushpile at El Dorado Reservoir during 2006. Nearly all of the branches under the water line were completely encrusted with zebra mussels. The 'big blobs' right at the water line are the zebra mussels. Looking deeper in to the water, you can see the majority of the branches were covered with the mussels.

[DenOz]

Thank you, Craig.