Friday, November 16, 2007

Zebra and Quagga Mussels

Several months ago, I went out to our Gondola Adventures™, Inc. location on Lake Las Vegas, in Henderson, Nevada. It’s about 15 miles off the Las Vegas strip and a few miles upstream from Lake Mead. I enjoyed no shortage of heat and had no problems getting paint to dry in little time. The only hassles were the second-degree burns experienced when touching any metal surface that was in direct view of the sun – and then there’s that whole “heat exhaustion” thing – gotta watch out for that.

At the end of my week in Nevada, I hooked my truck up to one of our gondolas, recently trailered, and made my way across the desert towards home in Newport Beach. The date was July 4th, and my wife and I were looking forward to arriving home in time to see some fireworks. It’s not unusual to move boats around between our three locations (the third being Irving, Texas). The gondola at the center of our story is the Isabella Celeste (named for our second daughter), a 25 foot-long, US-built replica. This gondola had operated in all three locations by the time I started across the desert with her. All went well from the driving and trailering perspective; I’ve dragged boats across that stretch of road a dozen times or more, and many of them much bigger than this one. The story got interesting when we pulled into the Agricultural Inspection Station in Yermo, California. Usually they wave you through with an “I hate this job, it’s so unnecessary” kind of look. Not today. Today they were quite interested in my little black boat and had all kinds of questions about her. At first I thought it was the typical curiosity I encounter whenever I’m operating or trailering a gondola, but then their questions zeroed-in on where the boat had been. Which waterways? Which marinas? What are all those little tan specks on the side of the hull? This was all quite unexpected. The folks there were all nice and understanding, knowing full well that most boaters in the US are not aware that we have some “new species” in our midst. I was surprised to learn about both Zebra and Quagga Muscle infestations taking place in US waterways. They were quick to assure me that there would be no fines or charges but I would need to repaint my boat (something I’d planned to do anyway) and I would receive a “free powerwash” (whether I liked it or not) compliments of the US Department of Agriculture.

In the office there, I was given instructions on who to contact after the repainting was complete, as an inspection of the hull would be required before I’d be allowed to launch the gondola. My experience at the Yermo inspection station made me realize two things: first, that the folks there have an mportant job to do, and while I may have complained about having to slow down from time to time, their presence there is vital. While in the station, I witnessed dozens of truckers being questioned about what they were hauling, where they’d come from, where they were going. They were vigilant. The second thing I realized is that all boat owners, including us gondoliers, need to be informed so that we don’t contribute to the problem.

Now for a brief history lesson: if you’re like I was back in July, you’ve heard little or nothing about these shellfish, known as “invasive species” by the authorities. It all started in the 1800’s when these freshwater mussels were inadvertently imported from rivers and lakes in Russia and the Ukraine, to other parts of Europe. They didn’t pose as much of a threat to society until we started using things like “intake pipes” for cooling systems on ships and shore. The little plankton-feeding bivalves are fast reproducers and can clog a system in a short time.

The first appearance of Zebra Mussels was in 1988 in the Great Lakes; Quaggas followed in ’89. The most commonly held belief is that they were sucked into ballast tanks of cargo ships in places like the Caspian and Black Sea; ships which crossed the Atlantic and made their way into the Great Lakes chain before purging their ballast tanks to accommodate the changing balance of the vessel due to cargo loading and unloading. Once these little striped mussels (often as small as a fingernail but sometimes as big as two inches in length) were in our waters, they thrived with few natural enemies to control their numbers.

They don’t just clog systems however, they are filter feeders that live on plankton (the base of most marine food chains). By reproducing quickly, these mussels not only crowd out other species, they starve them by taking the lion’s share of the food. They do such an effective job of filter feeding that they leave the water cleaner than it was. Arguments abound on both sides as to whether these aggressive filter-feeders are beneficial or detrimental to our American aquatic ecosystems. They are becoming famous for cleaning up the water because they remove pollution along with everything else they take in. Their filter feeding prowess is so effective that Chicago residents have been known to compare some shallow water areas of Lake Michigan to those of the Caribbean. Areas which were dark and where one could not see the bottom are now depth-discernable due to the remarkable clarity of the water. This water clarity has allowed bottom-feeding fish to thrive, and the new mussels have been credited with increasing Lake Erie’s Small Mouth Bass population.

Negative effects are easy to find. As mentioned earlier, Zebra and Quagga Mussels crowd out, and in many cases irradicate, other competing species, often attaching themselves directly to the shells of other mussels in the process. They can cover anchors, pier pilings, the undersides of boats and float-docks, and are even capable of covering the entire floor, or “substrate”, of a waterway. There are many shellfish with sharp edges out there, but the dorsal edge of the Zebra can slice as deep as an inch into human flesh. The razor sharp edges have been known to cut hands and feet of swimmers and waders who often don’t initially realize they’ve been cut. And then there’s the problem of clogging intake pipes. This becomes a giant-sized problem when it happens at a power plant which relies on water to cool its systems.

This “invasive species” situation is nothing new; many continents have experienced much more extreme invasions throughout history.

The deliberate release of European Rabbits in Australia had a devastating effect on the continent. It started with 24 rabbits in 1859, and ten years later the population was so strong that an annual count of two million hunted or trapped made no impact on the strength of the species.

In Plague situations, literally millions of people throughout the world died due to illnesses spread in part by rats that travelled on ships to many parts of Europe and Asia.

In North America: European Honeybees were introduced to the American colonies in the 1600’s, making no apparent negative impact. In the 1970’s however, Africanized Honeybees were one of the most worried about species of the decade.

From the Asian Tiger Mosquito, to Fire Ants, to the recently infamous Snake Head fish, we’ve seen our share of introduced species. Mention the West Nile Virus anywhere in America and you’re likely to get people’s attention.

Not all introduced species have been viewed as bad. The House Sparrow, Rock Pigeon and Wild Boar have become so commonplace in North America that most folks probably don’t even know they aren’t indigenous.

Some obvious questions about Zebra and Quagga Mussels arise:

1. Where can they survive? These two bivalve species are freshwater only. If they are attached to your boat and you park it in salt water, they will die. The only reason they were able to make it across the Atlantic is that they made the trip in sealed ballast tanks. They seem to be capable of living and multiplying in several climates. They have been discovered as far north as Sweden and all the way to the equator.

2. Are they in my waterway? If your waterway is fresh water, quite possibly. They don’t need to travel in ballast tanks or attached to the bottom of your boat. A rubber boot or bait bucket with a few inches of water can be sufficient to transport them.

3. How can they be eliminated/irradicated? Some aggressive chemical programs have worked in isolated bodies of water but there are obvious negative effects on other organisms in the water. Some applications of electrical or sonic fields have yielded some results but the “cure” hasn’t really been found yet. The biggest struggle right now is simply to prevent the spread of Zebras and Quaggas.

4. How can I help prevent the spread of these mussels? The biggest problem area is transporting boats between fresh water locations. If you are doing so, make sure your boat is clean, not only under the water but alongside the hull too. Watch for standing water in the boat, on the deck, and even on your trailer. These shellfish can be tiny at first so if you see something but think it’s too small – think again. Most of all, report anything you see that could relate to the problem.

So, back in Yermo, after having been stopped, questioned, educated, and after having my gondola washed by a kerosene-heated power washer that was about the size of a compact car, I was finally dismissed…with instructions, of course. It turns out that we now have Zebra and Quagga Mussels in almost every major river in North America, all the Great Lakes, and in January of this year they were discovered in Lake Mojave, Lake Havasu, and Lake Mead.

No wonder they stopped me in Yermo.

The verdict isn’t in yet as to whether these “invasive species” are a blessing or a curse. One thing is certain: once they take hold of an area, things are not the same again.

Here are a few interesting links: scroll down to “exotic species” for a great shot of a shopping cart covered with Zebra Mussels. great photo of Zebra and Quagga side by side, as well as more information on both species. A Lake Powell Quagga Mussel alert.

“spread the message, not the mussels”

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