Monday, January 21, 2008

Zebra vs. Quagga elucidation

Well, the highly invasive zebra mussels have finally made it to California. It was only a matter of time as Quagga mussels were found here back in February. The economic impacts of this will far outweigh the dreaded Mediterranean fruit fly (Ceratitis capitata). For one thing, Medflys only attack fruit crops. Zebra and quagga mussels attack water and eco-systems. Medflys are eradicable. Zebra and quagga mussels aren't.

California is a state whose economy is highly dependent on the extensive water system. Snowmelt is captured in giant reservoirs and distributed via rivers and giant aqueducts throughout the state. These mussels will clog the distribution plants and pumps and cause millions of dollars in damages, as they already have done in the Great Lakes and Mississippi River drainage. Here is a photo of a boat prop taken by David Britton of the U.S. Fish and Wildlife Service.
And a Budweiser can.

I don't even want to think about what they will do to the ecosystem. Zebra mussels are notorious for filtering out all the plankton (food for other species), as well as attaching to and potentially suffocating any aquatic creature with a hard surface. They have caused severe declines in native Unionid mussel populations, many of which are already on the brink. This is why: (UPDATE--No, this is NOT a shoe, as someone who shall remain nameless, but happens to be married to me thought. It is a larger native Unionid mussel covered in zebra mussels. Can you tell what species, Kia?)I found this photo on the U.S. Army Corps of Engineers website regarding the zebra mussel caused devastation to the native Unionid mussel species in Lake St. Claire.

The giant reservoirs have already caused declines in most of the anadromous fish species, and many are threatened with extinction, including Chinook salmon (Oncorhynchus tschawytscha), steelhead (O. mykiss), green sturgeon (Aciperser medirostris), and very likely river lamprey (Lampetra ayresii) by among other things blocking them from their historic breeding grounds. The Sacramento-San Joaquin River Delta ecology is collapsing due to intensive modification over the last 150 years, other invasive species including two other bivalve species (Corbula amurensis and Corbicula fluminea), pollution, and heavy water diversion. All the Delta pelagic fish species have recently suffered a precipitous step-decline - introduced species as well as native. Zebra mussels have the potential to finish off species like the Delta smelt (Hypomesus transpacificus) that are just barely holding on as it is.

When the quagga mussels were first discovered, I happened to be the only Environmental Scientist working with a group of engineers. I put together an e-mail for them, because I feel that enginerds need this occasionally (I know Kia has already seen it):

Your Biology lesson for the day


Equus sp.

Zebra mussel:

Dreissena polymorpha


Equus burchelli quagga - a sub-species of Burchell’s Zebra hunted to extinction in the late 1800’s. The last Quagga died in the Amsterdam Zoo in 1883.

Quagga mussel:

Dreissena bugensis
- a NON-extinct close relative of the zebra mussel


Kia said...

That poor, unfortunate unionid might be a Lampsilis siliquoidea, based on the color and shape of the bit of shell I can see. It's so covered up with D. polymorpha, it's hard to say for sure. There's never any shortage of disturbing news about the environment, is there?

Laurie said...

I was afraid that there wasn't enough visible for even you to ID.

Actually, I said to Bill that I thought it was some kind of mucket - NOT a shoe. You taught me well!

To my other readers (insert cynical snort here). In the post it almost sounds as though Kia is an enginerd. I wanted to set it straight that Kia is NOT an enginerd and IS in fact a malacologist.

artificialhabitat said...

Invasions of non-indigenous species (NIS) are pretty worrying, and certainly one of the biggest threats to marine (and freshwater!)ecosystems.

I'm planning a post on it at some point as I've been doing some reading around the subject.

I sometimes wonder if all the clamour about climate change means that less attention is given to other environmental issues. Not that climate change isn't a serious problem. For one thing, a lot that I've read seems to suggest that many native assemblages are generally resistant to invasion unless they are first hit by some kind of disturbance - which gives the NIS the opportunity they need. Climate change is one such disturbance.

I have found a couple of examples of positive effects of NIS (superabundance of invasive amphipods on a Californian oil platform provided a ffod subsidy for resident fish, and an invasive alga in the Adriatic actually enhanced recruitment and survival of native mussel species), but these are very much the exceptions