[BCNnet] [Fwd: [Aliens-L] prolific invader species -- the round goby and the quagga mussel]

[Terry Schilling]

Here's an interesting message from the ALIENS-L List. I wonder, if Lake Ontario
IS next, if those cormorants that breed there eat gobies too...

-------- Original Message --------
Subject: [Aliens-L] prolific invader species -- the round goby and  the quagga
mussel
Date: Mon, 4 Mar 2002 22:28:58 EST
From: Mjrauz@aol.com
Reply-To: <aliens-l@indaba.iucn.org>
To: aliens-l@indaba.iucn.org

This item from another listserve illustrates an ecological relationship 
developing among native and invasive species that might be of interest.



BOTULISM, AVIAN, TYPE E - USA, CANADA
******************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail, a program of the
International Society for Infectious Diseases
<http://www.isid.org>

Date: 03 Mar 2002
From: ProMED-mail <promed@promedmail.org>
Source:  The Buffalo News, 1Mar 2002 [edited]
<http://www.buffalonews.com/editorial/20020301/1033487.asp>


When the first massive outbreak of Type E botulism (_Clostridium 
botulinum_) on the Great Lakes since the 1960s killed thousands of 
fish and birds along Lake Erie (2 years ago), there were many more 
questions than answers. But after another extensive die-off in the 
summer, some of the pieces of the puzzle are beginning to come 
together, 100 scientists and environmental advocates were told at a 
seminar Thursday sponsored by the New York Sea Grant and Assemblyman 
Richard Smith, D-Hamburg.

Scientists are coming to believe there is a relationship between 2 
prolific invader species -- a small fish called the round goby and a 
mollusk called the quagga mussel -- and the washing up of thousands 
of bird and fish carcasses on the lake shoreline.

Both Canadian and US pathologists have determined the majority of the 
loons, gulls, mergansers, and other birds found along the lake shore 
were killed by Type E botulism, which is produced by a toxic 
bacterium and leads to paralysis and death.

An examination of stomach contents of those birds revealed their last 
meals were often gobies. Of 192 dead loons found on New York's Lake 
Erie shoreline, 59 percent were found to have eaten gobies.

"The goby is the key," said Ward Stone, the state Department of 
Environmental Conservation's senior wildlife pathologist. The goby is 
one of the few fish feeding on the hard-shelled mussels. In turn, the 
goby is a preferred food for a number of birds.

Stone said his department normally doesn't do pathological 
examinations of fish, but he had done some anyway "and found Type E 
toxin in them" and  "we found no other reason for the fish to be 
dying except Type E botulism."

While gulls and loons were the main birds impacted, other species 
were also involved. Stone did a necropsy of a bald eagle found in 
Chautauqua County last summer and found botulism- contaminated fish 
led to the eagle's death.

In examinations of loons, ducks, cormorants, and gulls, Stone said he 
found "lots and lots of ground quagga mussels, and Type E was 
isolated from them."

The botulism bacterium is believed to grow in sediment and in the 
carcasses of dead birds and fish. Maggots feeding on the dead animals 
concentrate the toxin and are often eaten by birds.

"Ultimately, we are going to have to come up with ways of breaking up 
the cycle," Stone said. "How to do that on something like Lake Erie 
is a massive task."

Although there has been no report of Type E botulism on any of the 
other Great Lakes, Stone said it is "likely Lake Ontario" is next. 
Indeed, he was planning to pick up a dead lake sturgeon found on Lake 
Ontario to bring back to Albany for testing.

If it does show up in Lake Ontario, Stone said the potential for an 
even greater bird and fish die-off is possible because more birds 
spent winter on the lake, which is too deep to freeze over.

- --
ProMED-mail
<promed@promedmail.org>

[The sporulating anaerobic gram-positive bacillus _C. botulinum_ 
elaborates 7 types of  antigenically distinct neurotoxins, 4 of which 
affect humans--type A, B, or E, or rarely  type F toxin. Types A and 
B toxins are highly poisonous proteins resistant to digestion by GI 
enzymes. Approximately 50 percent of foodborne outbreaks in the USA 
are caused by type A toxin, followed by types B and E.

Type C botulism occurs principally in waterfowl and other birds 
living in an aquatic environment and causes tremendous losses, most 
notably in waterfowl in the western US. In addition to North America, 
it has been reported in birds in Europe, South Africa, Uruguay, and 
Australia. In the Great Lakes region, it was first identified in 1936 
in ducks on Green Bay of Lake Michigan and, in 1941, in Monroe County 
marshes along Lake Erie. Type C is most often associated with 
limberneck paralysis in birds.

Type E botulism is connected with consumption of fish and occurs 
mainly in gulls and loons, to a lesser extent in mergansers, mute 
swans, grebes, and shorebirds. It now appears any birds or mammals 
susceptible to botulinal toxin run a risk of becoming poisoned if 
they scavenge dead fish. Evidence for this includes the 
identification of type E toxin in a bald eagle, wood ducks, and 
muskrats with fish remaining in their digestive tracts.

_C. botulinum_ spores are highly heat-resistant and may survive 
boiling for several hours at 100 degrees C  (212 degrees F); however, 
exposure to moist heat at 120 degrees C (248 degrees F) for 30 
minutes will kill the spores.

Toxins, on the other hand, are readily destroyed by heat, and cooking 
food at 80 degrees C (176 degrees F) for 30 min safeguards against 
botulism. Toxin production (especially type E) can occur at 
temperatures as low as 3 degrees C (37.4 degrees F), i.e., inside a 
refrigerator, and does not require strict anaerobic conditions.

Human illness from Type E is most often associated with improperly 
smoked fish. Since the toxin is destroyed by heat, it appears that no 
problem with botulism will result from eating cooked waterfowl. - 
Mod.TG]

..........


Mark Rauzon
Marine Endeavours
4701 Edgewood Ave. 
Oakland, CA 94602
510-531-3887


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