Zebra Mussels Documented in Lewisville Lake

Boaters urged to clean, drain and dry

AUSTIN � Less than a year following the discovery that zebra mussels had established a population in Lake Ray Roberts, the destructive invasive species has been confirmed in Lewisville Lake by the United States Geological Survey (USGS). This is the third lake in Texas, and the second within the Trinity River basin, where zebra mussels have been discovered.

Christopher Churchill, a biologist with the USGS who has been monitoring for zebra mussels in North Texas rivers and reservoirs, discovered the live juvenile on a settlement sampler near the dam.

Churchill indicated that this latest infestation is likely the result of contaminated boats being transported to Lewisville Lake, but it could be the result of downstream transport of zebra mussels from Lake Ray Roberts via Elm Fork of the Trinity River. Also, this latest infestation appears to be relatively new as no additional specimens have been documented.

The USGS, Texas Parks and Wildlife Department, University of Texas-Arlington and others continue to closely monitor for the spread of zebra mussels in Texas.

Zebra mussels can have economic and recreational impacts in Texas reservoirs. They can clog public-water intake pipes, harm boats and motors left in infested waters by covering boat hulls and clogging water-cooling systems, annoy boat-dock owners by completely covering anything left under water and can make water recreation hazardous because of their razor-sharp edges.

With Lewisville Lake being such a popular boating destination there is a heightened risk of zebra mussels being transported to non-infested lakes by boaters. However, the spread can be slowed by making sure boats that operate in zebra mussel-infested waters are not used in any other body of water until they have been cleaned, drained and dried. In addition, TPWD adopted rules regarding the transfer of zebra mussel larvae in water from lakes Texoma, Lavon, Ray Roberts and Lewisville. To comply with these rules, boaters and anglers need to drain all water from their boats (including live wells) before leaving those lakes.

From the environmental perspective, zebra mussels are filter feeders, which mean they compete with baitfish such as shad for available forage. Any impact on baitfish in turn can affect their predators � game fish such as bass, striped bass and catfish. Zebra mussels are also very harmful to native mussel populations because they will colonize on their shells and essentially suffocate them.

TPWD Executive Director Carter Smith emphasized that the discovery underscores the importance of boaters helping to prevent the spread of zebra mussels, which can be unknowingly spread when boats and trailers are moved from lake to lake.

TPWD and a coalition of partners have been reaching out to boaters in Texas with an advertising campaign to educate them not to transport the tiny mussels or their microscopic larvae, which are invisible to the naked eye and can stay alive inside livewells, bait buckets and other parts of the boat for up to a week. These partners include: North Texas Municipal Water District, Tarrant Regional Water District, Trinity River Authority, City of Dallas Water Utilities Department, Upper Trinity Regional Water District, Sabine River Authority, Canadian River Municipal Water Authority, San Jacinto River Authority, Brazos River Authority, City of Grapevine, City of Houston, City of Waco and Lady Bird Johnson Wildflower Center.

�With this somber news, I hope Texas boaters will always remember to �Clean, Drain, Dry� their boats, trailers and gear because all it takes is one instance of not properly cleaning to introduce this highly invasive and unwelcome species to a water body in Texas; and once they are established there is no known way to get rid of them,� Smith said.

Originally from the Balkans, Poland and the former Soviet Union, zebra mussels found their way to the Americas in the 1980s via ballast water of a ship. The small invaders were first found in 1988 in Lake St. Clair, Mich., and are currently known to have infested 29 states and more than 600 lakes or reservoirs in the United States.

Anyone wishing to receive a supply of informational brochures, wallet cards or posters about zebra mussels to distribute to boaters around lakes Lewisville, Ray Roberts or Texoma, please contact marketing@tpwd.state.tx.us. For more information regarding zebra mussels visit www.texasinvasives.org.

Well that will clear up the water.

they are in several of the north texas lakes, TP$W will not admit it yet. part of the problem is the fishermans boats, the rest is natural wildlife transporting them, which we have no control over.

I think the wildlife is probably the largest transporter of these little rascals. Plus, it would seem the municipal water districts are the one's who really hate them, because they have to clean their water pipe inlets/outlets more often....other than that, they really do improve water clarity.

I have often wondered if they can improve our water quality, as well. Sort of a natural way to filter man induced pollution. Seems every one is so negative about them, the environmental benefits from having them around are being overlooked. Just saying...maybe we SHOULD be studying their BENEFITS to mankind....

Zebra mussels do clarify the water, which seems like a good thing, but there are consequences of that, as discussed below. Of concern to boat and lakeside property owners is the fact that they settle in large numbers on anything left in the water and can do considerable damage. Evidence in the Great Lakes shows that zebra mussels can decrease the amount of food available for fish, which could translate into poorer fishing in the future. Texas has not had zebra mussels long enough for all the impacts to become known, but eventually we will find out.

ZEBRA MUSSELS CHANGING GREAT LAKES ECOSYSTEM

In a just-published series of scientific papers, university researchers and scientists from the Great Lakes Environmental Research Laboratory in Ann Arbor, Mich., have documented basic changes in the food chain in zebra mussel-infested waters of Lake Huron's Saginaw Bay that threaten water quality and healthy fisheries across the Great Lakes ecosystem. The lab is run by the Commerce Department's National Oceanic and Atmospheric Administration.

In general, the research shows an alarming shift in how energy and nutrients are routed through the food chain. Results show that Saginaw Bay's energy base is no longer dominated by phytoplankton because these microscopic, free-floating plant cells are choice food for zebra mussels, which are able to selectively filter the cells out of the water.

The spread and growth of zebra mussels have decimated this important free-floating part of the food chain, raising concerns that all of the bay's fish stocks may suffer.

Zebra mussels are also encouraging growth of harmful blue-green algae by rejecting them as food, thus giving them a competitive advantage over less abundant algae that are eaten by the mussels. The mussels may also release nutrients that encourage algae growth, especially blue-green algae.

This in addition to a sudden change from a free-floating to a bottom-dominated food base may force scientists and decision- makers to reassess current models used to guide the management of water quality, fisheries and toxic contaminants throughout the Great Lakes region.

###
BACKGROUND INFORMATION

Zebra Mussels in Saginaw Bay
Saginaw Bay was studied because it serves as a ready-made laboratory large enough to reflect changes expected for a whole lake, but small enough to allow scientists to sample everything up and down the ecosystem food chain. Also, there was already much information available on the bay--a water body with a rich fishery made possible by the high biological production of its microscopic phytoplankton and zooplankton.

Zebra mussels were found capable of filtering Saginaw Bay's entire water volume in one to four days. While this high filtering rate fuels explosive zebra mussel growth, it also means that other parts of the food chain are deprived of needed energy and nutrients. Prior to the zebra mussel's arrival, much of this energy and nutrients supported microscopic animals (zooplankton) that in turn served as a food base for young (larval) fish. The spread and growth of zebra mussels have decimated this important free-floating part of the food chain, raising concerns that all of the bay's fish stocks may suffer.

Mussels may also release nutrients that encourage algae growth, especially blue-green algae. Certain forms of a blue-green algae named Microcystis are toxic to fish and cause gastro-intestinal distress in humans. Blooms of Microcystis have recently been noted in Saginaw Bay and in western Lake Erie, where studies are underway. With increased water clarity due to the mussel's continued filtering of the bay's water, thick mats of thread-like algae now are abundant near and on some water intakes. These algae have the capability of producing off-flavor compounds that can affect taste and odor of municipal water supplies.

The zebra mussel has transformed the Saginaw Bay ecosystem from one that scientists understood fairly well, to a new system with a large number of unknowns. Additional work will be needed to document and fully understand how this new system behaves.

Although a certain amount of change has and will continue to occur in the structure and function of Great Lakes ecological systems, NOAA and university scientists emphasized that the zebra-mussel-induced changes they have seen in Saginaw Bay's ecology are more extreme because it is shallow and has suitable substrate for the mussels. In the long run, more ecological instability can be expected wherever zebra mussels spread, making the ecosystem more difficult to predict and, therefore, more difficult to manage and protect vital resources.

In addition to the yet-unknown economic impacts on Great Lakes fisheries, costs to reverse or prevent zebra mussel fouling in water plants and other industrial water works alone are estimated to total $5 billion by the year 2000."

I guess to accurately discuss this subject you would need to find out the variables of that ecosystem and how it is similiar/dis-similiar to Texas lakes. I DIDN'T see any mention of the CONTROL synopsis only the conclusions section. Plus issues such as water depth of the bay, the type of substrate preferred by the zebra mussels, how much money is currently spent on cleaning the industrial water supply lakes for other problems that might be cured with the zebra mussels, the changes necessary for TP&W to handle zebra mussel issues.

It is entirely conceivable that the zebra mussels can't establish effective colonies in the majority of our lakes (I don't know and don't imagine anyone else does either). Quite frankly, the information cited above doesn't give me a COMPLETE OR ACCURATE picture of the research sufficient to cause ME any real concern. Indeed, it really seems to just pander to the industrial water supply folks, with an alarmist liberal slant. Sorry, but I remain unconvinced of the threat with the information as provided. Is is a good idea to wash/dry your boat after a tourney in a zebra mussel lake...sure.

It may be that we HAVE to eliminate all the migratory birds to PROTECT our waters from the zebra mussels (not)...More laws are NOT going to do anything to stop this infestation, but it always seems to be a preferred (laughable) method...public awareness is an EXPENSIVE option as well. May be easier to live with the problem than try eliminate it...just saying...take a real hard look at BOTH SIDES OF THE ISSUE...not just one...the answer may be right in front of your nose.

Kind of reminds me of the KILLER BEE issue...not really a threat, easy to deal with, but lauded as a PUBLIC SAFETY HAZARD.

As reported in The Wise County Messenger, Zebra Mussel Larvea has been found in Lake Bridgeport.

So zebra mussels are major contributors to global warming. There must be a way to control them with some sort of ill contrived phytoplankton consumption tax.

The background information mentioned above was from 2000? What, if anything in the last 13 years has been discovered about these muscular zebras?

How do the saltwater communities deal with oysters, barnacles and other clinging critters?

I HAVE discovered a BENEFIT of the ZEBRA MUSSEL....Catfish bait...apparently catfish love them....so we can get paid to clean the municipal water supply lines, then sell them to Danny or Lew King to make catfish bait...so maybe we take them from problem to profits....just like Waste Management...profiting from trash....Hmmm, maybe I need to explore and/or research this subject some more.

They take shrimp boats and muddy up the water to give them something to do?

Zebra mussels will have a different affect on different body of waters. They will cause a shift in the ecosystem. Some organisms may benefit, others will not.

Baitfish will suffer as the zebra mussels will outcompete them for the phytoplankton, and native fish will have to find new sources of food, which many of them will do, and many of them will resort to feeding on the zebra mussels themselves. Whitefish, and important commercial fish in the Great Lakes, have done this, and although they are still present, the shift in nutrition has affected their average size and hurt the commercial fishery.

Because they prefer shallow water (less than 50 feet), their effect may be different on small lakes vs large lakes, or even shallow lakes vs deep lakes.

As mentioned in this thread, expect them to clean up the water. Largemouth bass fisherman will see an increase in habitat for this species as the clearer water will encourage weed growth in deeper waters. Increased habitat means a better fish population as long as a food source is available. A lack of food source an a lot of fish means a stunted fish population, so bass fisherman could see something good or bad depending on the effect of weed growth and the bait situation.

A bad thing about these guys is they prefer the larger members of the phytoplankton, so they ignore bluegreen algae. This gives these little guys a competitive advantage resulting in an increased chance of blue green algal blooms. Algal blooms are associated with oxygen depletion and fish kills.

Predation on these things will happen but will likely not curve their population growth as it will occur exponentially. The population growth will curve when the food situation becomes poor for the zebra mussels, which also means the food situation will be poor for bait fish.

LIke I said,fish will have to adjust to the new food situation. Food sources at the top of the water column will decrease. Food in the bottom part of the lake will increase (small worms, zebra mussels, etc.)

If pollution is in the soil, count on it concentrating in the tissues of the mussels, and if the mussels become a main food source, it could really affect the safety of the fish flesh for eating. PCB's and other pollutants that may be covered up by sedimentation at present, will come back.

So here is my take. Possible positive affect on the bass population. A disaster for intake pipes, marinas and the boats that are permanently wet stored, a disaster for beaches and swimming areas, a disaster for forage in the upper part of the water column.

The bad things will definitely outweigh the good things in most lakes. Bottom line, we don't want them, but reality is we will probably have to deal with them because it only takes one mistake to spread these little guys, and to get 100% compliance will be pretty impossible.

In a cost/benefit analysis, Lake Erie might be an example where you could say zebra mussels helped because the lake was considered dead in the middle 1970's. The mussels helped bring that lake from a polluted mess to a much nicer body of water today, but if you have a lake that is not "dead", the costs will most likely outweigh the benefits.

Sounds like we have finally got a little knowledge on the subject. From what I read of your post wrestlefish, it seems the TPW will have to learn how to manage the mussels on the lakes they inhabit.

You say they are a disaster on the beaches...I suppose I don't understand that comment.

Let me see if I got this figured out. So zebra mussels will clear the water up, then become an important source of food for other fish, as they out compete the baitfish. At first they will grow exponentially then as they clear/clean the water their growth will slow down and/or decline.

Water clarity to 50 ft may become a reality on the shallower lakes, potentially hurting the fishery but helping the recreational aspects of a lake (boating, snorkeling, diving, skiing, etc.,) Possibly it could increase the recreational diving and snorkeling industry with the increased water clarity. Also, it appears the mussels will require the launching of a new industry in cleaning the municipal water supply pipes, and re-launching of an old "dead" industry such as dry docking and periodic cleaning of wet stored boats.

Fortunately, our Southern waters are not as polluted as many other places with the harmful PCB's, so this issue, for the most part is a non-issue. But apparently they will improve water quality, which could decrease and/or change the amount or type of chemicals that the municipal water supply have to use to treat the water we drink.

Currently, we use triploid grass carp to eat the high concentrations of algae (and dirty up the water) of which Cypress Springs is an example. Seems that these carp can be an effective tool to can handle the remaining blue green (problem, less desirable) algae?

As I recall, what our northern friends call whitefish we call carp, so we now can count on catfish and carp to eat the mussels.

Basically, as I have already stated, we really don't know what impact the zebra mussels will have on our lakes. It does appear there are trade-offs and it does appear we will get an opportunity to deal with it, like it or not. So while common sense and good judgement is seldom involved in any campaign to "Stop Something" that can not be stopped despite our best efforts (ie., via Migratory birds), sensationally beating the drums about these creatures being the demise of western civilization is NOT the answer either. In fact, these mussels will have both positive and negative impacts on our waters, our fishing, our lake use opportunities, and our lake management plans. Of course, the municipal water supply folks won't like it, but they generally don't like anything...that fishermen do.

As for beaches, the mussels will cover the lake floor, and the broken shells are sharp. Large weeds like Hydrilla often infest zebra mussel waters. Bad for swimming and boating.

Don't confuse clear water for good drinking water. Remember, they only eat phytoplankton, and the clearing water will make room for larger weed plants like Hydrilla. Lakes full of hydrilla have "slimy" water, and that will be a cost.

Hydrilla can create some good bass habitat, so bass can be winners sometimes with zebra mussels, especially if the oxygen content and food sources stay viable.

Things that rely on shad as their food base and don't adapt to new food sources will be losers. Bluegill populations should theoretically increase as weed growth increases, so striped bass and white bass will need to adapt. I would think that zebras will affect whites, hybrids, and striped bass more so than say largemouth and smallmouth bass.

Lake Worth is just starting to get some favorable reports on the tissue of fish as the PCB's are getting trapped under sedimentation and thus away from the food chain. This is a good thing. A zebra mussel infestation in this lake would likely bring those nasty chemicals back into the food chain and make those fish dangerous for the table. It has been reported that a zebra mussel can take contaminates in the water and concentrate them by 300,000 times in their tissue, and that is not a typo. Anything that eats them becomes vulnerable. That includes fish and waterfowl that enjoy eating these things.

Bottom line. They are not suppose to be here. Anytime you put something someplace that is not suppose to be there, it is bad, but we will most likely have to deal with it as bad as it is.