Zebra Mussels - good or bad?

[DawgDiver]

I've heard alot of talk lately about Zebra mussels. It seems mostly the talk I've heard is people talking about how they clear up visibility, and make for better diving. I've even heard some folks suggest introducing them into local quarries to clear up the viz. But I was watching that Jean-Michel Cousteau show this evening and they were diving in the great lakes and commented very negatively on the zebra mussels. I suppose because they cover the wrecks?

So what's the deal? are they a good or a bad thing?

 

[gomi_otaku]

Simply because they are an invasive, non-native species that multiplies out of control. In the Great Lakes they were introduced, like many of the other invasive species there and in other areas with problems, in the ballast water of international freighters. Any species that multiplies out of control displaces the native flora and fauna- in a quarry that may not be a problem, since there is really no native life before it fills with water. But in an interconnected system of waterways, there is no disrupting the flow of species. Look at Eurasian Water Milfoil- there are native species of Milfoil in most fresh water, but you will likely not find it due to the choking out of the Eurasian species, introduced from aquarium dumping. Look at the introduction of Asian carp in the Mississippi river, the ones that leap out of water when they hear a boat motor, and result in people being whacked in the head and injured. Look at the sea Lamprey in the St. Lawrence seaway, which was kept out as long as there was no exit to salt water, but now can move freely into the Great Lakes and attach itself to fish and suck their guts out.
The first time I took a trip to the Upper Peninsula of Michigan, I was amazed at how clear the water was (from the surface). I lay down on the end of the dock, and could see 20' to the bottom. And there I saw a freshwater Goby. They are not native. I also saw them on my OW checkout dives. I didn't see any other fish.
Zebra Mussels, like milfoil, are easily carried on the hulls or bilge water of boats. Even if you don't have adult mussels, you can carry immature mussels.
gomi_

 

[SoggyShoes]

DawgDiver,

Here are a couple of recent threads about Zebra Mussels, including one that I believe has the same title as yours:

http://www.scubaboard.com/showthread.php?t=157989&highlight=zebra

http://www.scubaboard.com/showthread.php?t=152604&page=2&highlight=zebra+muscles

Hope you find these informative.

Soggy

 

[DawgDiver]

thanks for the info guys.

 

[MarkH]

It's good for visibility, but bad for marine traffic (the mussels clog cooling pipes and heat exchangers). I think the major concern is economic because of this clogging thing. I also heard that they are damaging the pristine old wrecks because the weight of the growth is starting to make pieces of the wrecks fall off). I wouldn't be suprised if much of this damage is caused by divers. Technical diving is becoming hugely popular and many of the deeper, once inaccessible wrecks are now commonly visited by charters boats. I admit I've never even been to the great lakes, so my opinion could be the result of misinformation. I should work for the media.

 

[rcolsen]

No natural preditors to keep the population in check and easly chock out native speries. Minnesota is having a big problem with them.

 

[Traijin]

The Zebras are filter feeders, the vis does clear up, but that stuff in the water is food for other organisms native to the Great Lakes. I have been observing the coming and overtaking of Lake Huron since the Zebras became an issue. The absence of basic sustenance leads to lack of food further up the chain. Not to mention those little buggers are razor sharp and slash flesh in an instant. Is clear vis worth not seeing Northern Pike, Perch, or Small Mouth?

 

[muddiver]

They are good for the commercial diving business.

Somebodys got to clean the water intakes of the power plants or they become clogged with those little buggers.

 

[drbill]

The Zebras are filter feeders, the vis does clear up, but that stuff in the water is food for other organisms native to the Great Lakes. I have been observing the coming and overtaking of Lake Huron since the Zebras became an issue. The absence of basic sustenance leads to lack of food further up the chain. Not to mention those little buggers are razor sharp and slash flesh in an instant. Is clear vis worth not seeing Northern Pike, Perch, or Small Mouth?

Precisely. When one species, especially a non-native one, dominates to the extent the Zebra mussels have there (or the invasive Japanese Sargassum filicinum has here) the consequences for native species are often very serious. The improved visibility is at the cost of food for the native species of invertebrates and plankton feeding fish.

 

[theduckguru]

When zebra muscles invaded Europe, they actually changed bird migration routes.

Scaup, a migratory diving duck, have declined drastically over the last decade. Possibly due to the selenium ingested when the birds eat zebra muscles in the Great Lakes.