Wednesday September 17, 2003



Fighing conch talk, hurricane discussions discussed
Debi Ingrao is a senior biologist at Mote Marine Laboratory specializing in benthic research - the stuff on and under the bottom of the water. We asked her about the Florida fighting conch invasion on the beach at Bean Point in Anna Maria last week.

As you may remember from the front-page picture in The Islander Sept. 10, thousands of the 4-inch-long shells appeared on the beach. Suzi Fox from Turtle Watch said they acted like lemmings, only instead of leaping off a cliff into the water, they were hurling themselves out of the water and up on the beach.

"I find it hard to believe that the fighting conchs would intentionally crawl out of the water for any reason, Ingrao said, "although they are sometimes stranded as the tide goes out.

"Most likely it is storm related. However, there is a remote chance it may be related to secondary effects of red tide events in our area. Or it could be a combination of the two."

Ingrao said the fighting conchs are very common in our area. She said they probably "got washed ashore when strong winds created a big surf. These snails prefer to be in the water and not exposed to air, heat, sunshine or freshwater. Since they cannot always control where they are they have developed some protective maneuvers.

"When they get stranded on the beach, their strongest desire is to get back to the water. Some may not be very patient and try to crawl back to water's edge. Some may be a bit lazy and stay put on the surface of the sand hoping the tide or a big wave will wash them back into the sea. If they are not close to the edge of the water, neither of these choices is a very wise one - a land predator could eat them, humans could pick them up for a treasure, but, worst of all, they could slowly bake inside their shells as the sun beats down on them.

"Other fighting conchs have a strong will to survive and will bury in the sand to protect themselves from the predators, heat, etc. Then, when they sense the incoming tide, the conchs will pop out of the sand and start leaping, hopefully toward the water and safety. I suspect it might take them a bit to figure out the right direction to go so it might appear that they are 'leaping' away from the water for a while. Many eventually figure it out."

Ingrao offered a little historical background on the occasional conch invasion on our shores.

"After Tropical Storm Gabrielle a couple of years ago, I received many phone calls about thousands of conchs washed up on Longboat Key and Siesta Key beaches. I visited several sites and there were thousands washed up on the beaches and observed them for a while. In your picture, it looks like quite a few have just popped out of the sand as I watched them do after Tropical Storm Gabrielle."

And what about that leaping, hurling motion many of the snail were engaged in?

"The 'hurling' you observed is one of their means of transportation - normally they crawl on their foot, but when they are trying to escape a predator - move a 'long' distance quickly - they will use their operculum (the 'trap' door they close when picked up, threatened by predators or stranded above the water line) to 'pole vault' across the beach. They stretch the operculum out as far as they can then flip it really quickly giving the impression they are 'hurling' themselves - it basically throws the whole animal into the air and forward."

And what about getting the heck out of the water due to a red tide bloom? Ingrao said it was unlikely.

"During red tide blooms (or any large algae bloom), one of the secondary effects is a decrease in dissolved oxygen in the water, which negatively affects all animals living in the water to varying degrees. Few scientific studies have been completed to determine how these red tide events affect bottom-dwelling invertebrates like the fighting conch. Based on limited diver observations of bottom habitats in red tide affected areas - and the dissolved oxygen decreases near the bottom and in the sediment - many of the animals living in the sediment will come to the surface of the sediment and try to leave the area if they are able. (Fish, crabs etc., might be able to leave the area.) "Others animals, like clams, basically can only come to the sediment surface and hope for better dissolved oxygen levels than what they have experienced in the sediment. If the dissolved oxygen levels are not high enough, the clams will gape trying to get as much of the limited oxygen out of the water as possible and eventually die.

"Fighting conchs have some mobility and it may be possible that they might be able to move away from an area into shallower water where there is more wave action increasing the dissolved oxygen. This could put them at the mercy of the beach surf and result in them being tossed ashore. At this point, this is speculation."

Another odd time on the beach, eh?

Fish farm flounders in Gulf
It looks like local, Gulf farm-raised snapper, cobia and amberjack won't be coming to a fish market near you anytime soon.

Members of the Gulf of Mexico Fisheries Management Council have recommended to deny any permits to allow a fish farm in about 100 feet of water in the Gulf about 30 miles from Anna Maria Island.

The National Oceanographic and Atmospheric Administration's fisheries officials will have the final say on whether or not Florida Offshore Aquaculture will begin the pilot program, the first open-water fish farm off Florida. That decision is expected after myriad other federal agencies review the proposal and make recommendations, but Gulf council's decision will have a big say, and should cause some big sway, in the final fed decision.

FOA is a Pinellas County-based company comprised of Capt. Tommy Butler, known for his super-fast boat, Reality Check; Thomas D. Powell, who launched the Sound Advice stores in the mid-1970s; and Jody Symons, who retired as a Motorola salesman several years ago.

The trio's proposal was to secure fish cages on the bottom, then raise snapper, mahi-mahi, pompano, cobia and amberjack until they reach legal size and sell them.

The aquaculture project would be the deepest such fish farm in the United States. The farming promoters argued the need for the deep system to avoid any red tide outbreaks.

Gulf council members questioned FOA's principals on their experience - almost nil - and the threat of pollution from all the by-product fish food and fish waste products the farm would produce.

Sandscript factoid
Hurricane Isabel has kept many of us glued to our television sets watching weather forecasts in the past week as it churned across the Atlantic Ocean, at times reaching maximum sustained winds of better than 160 mph. That wind speed made it more powerful than Hurricane Andrew, and we all know what happened 11 years ago to Homestead and Cutler Ridge.

Here's a place to go for some trivia for those of you who want more data than provided by the talking heads on TV:

The National Hurricane Center, National Oceanographic and Atmospheric Administration Website offers lots of information. The above address is for an esoteric element of the information, called "Discussions."

The discussion section is basically just that - a discussion of the various computer models, data from ocean buoys, satellite imagery and all the other stuff that goes into a forecast.

I guess you could call it the behind-the-scenes look at a tropical disturbance.

For example, with Hurricane Isabel, several of the computer models were arguing for a more northerly track days and days before the turn actually became a reality. The official forecast did not bring up that northward turn, since only two or three of the models were predicting it at the time, but the forecasters in their discussions were saying it had a good chance of veering right.

And so it eventually did, sparing Florida again from a Category 5 storm.

Factoid's factoid
Back a few years ago, Tropical Storm Harvey was churning around in the Gulf, with an expected landfall near Cedar Key. The computer models at the time were pretty much in agreement on where the storm would hit with one exception: a "rogue" model that suggested that the unthinkable would happen and Harvey would do a 180-degree turn and head to the Florida Keys.

That model, known as NOGAPS, was right, and the storm hit near Flamingo with very little damage. I always pay attention to whatever NOGAPS has to say as a result of that brilliant prediction. Some of us weather watchers even talked for a while about coming up with some T-shirts: NOGAPS RULES!

To find out about the various models, by the way, go to the link at the left of the NWS-NOAA site called "Forecast Models," and you can learn more than you would ever want to know about hurricane modeling.



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