Water sprays up in the air as the explosion goes off to fracture a concrete structure under the old John's Pass Causeway on Aug. 24.
No one would experiment to see how wild dolphins react to underwater explosions, however crucial that information is to coastal demolition planning.
Yet such an experiment occurred on Aug. 24 when John’s Pass Causeway was closed for demolition duty to remove part of the old bridge.
The explosion was a confined blast that would fracture a concrete structure under the old bridge for easy removal.
The problem is that underwater explosions radiate great thumping waves of percussion through the water. As the explosion demolishes concrete, its radiating sound waves can damage or demolish the hearing system of marine animals. They can even kill marine mammals. The repercussions of a blast depend on how it is handled.
The day before the blast was rich with dolphins. A riotous group cavorted east of Eleanor Island. Grin and Riptab, with help, were working on next year’s crop of newborns. The activity attracted many other dolphins, drawn like innocent voyeurs. Widely scattered, it was impossible to count them accurately.
A delicate nursery group meandered by. They gradually wound around the islands, heading nowhere in particular. Mothers carefully tended two tiny clumsy calves.
LA Stick and calf Cactus fished off Little Bird Key. Cactus’ shark bite is healing nicely. To the north, we were particularly relieved to find Michigan, who’s surviving a wretched summer. Stick roved alone in the waters of its infancy. X and Little X swam past with Face, Slight and Slight Twin. Shave, Huckster and compatriots hunted the waters of the big morning gathering, including Biscayne, away since 26 March 06, and White Point’s fragile calf.
Basically, most of the dolphins were exactly where they shouldn’t be: in direct line with the battering sound waves from the blast. However, like people, dolphins aren’t necessarily in the same place two days in a row. We fervently hoped they would be elsewhere on the morrow.
At dawn the day of the blast, the water around John’s Pass appeared empty when a dolphin suddenly cut across my bow like a cat flinging itself across your path when it wants to play. There were five altogether, foraging where waters could reverberate with shattering sound waves. I wanted to say, “Leave! Quick! Go!”.
The blast was scheduled for 8:30 a.m. Law enforcement boats kept private boats out of the area. One by one, helicopters appeared and hovered. Aerial observers, they work with state and federal observers on land to watch for animals in the water.
I watched from John’s Pass Marina Charter and Bait. Manatee biologist Ken Arrison of the Florida Wildlife Commission, a land observer, was stationed nearby.
Everything was ready. Then a manatee surfaced. It was like watching a slow motion ambassador from a lost civilization.
One dramatic minute from blast time, five dolphins swam into the keep-clear zone, the five I’d seen earlier. It’s hard to predict what they’ll do next in the Pass. Sometimes they linger inside, exploring for food. Sometimes they head directly for the Gulf.
I sprinted to Arrison. Instantly, he radioed Bruce Hasbrouck, Environmental Services director for Faller, Davis and Associates Inc., the engineering firm overseeing the demolition. Hasbrouck immediately gave the order to delay the explosion.
Observers in helicopters tracked the manatee and dolphins from above. The manatee flowed slowly out of the danger zone. Everyone was riveted on the dolphins. Luckily, they swam into the Gulf rather than stopping to feed.
It took nine long minutes. Helicopter observers reported when the dolphins swam past the carefully calculated danger zone and Hasbrouck’s added safety factor of an extra 300 feet.
“Ka-Boom!”
All the men cheered. If women ran the world, I thought, we’d never blow anything up.
Conscience-free, pelicans immediately dove on fish that floated to the surface. Just as quickly, FWC biologists began collecting the dead to track the immediate impact of the blast.
Friday morning back at sea. And what of the dolphins? There wasn’t a fin to be found near John’s Pass. But the dolphins were out in numbers over the weekend. I watch for Scrapefin and Face, among the fated five that headed out to sea that blasted day.
Our lives are so much richer when we show respect and kindness for animals. This spirit should be recognized and rewarded. Ken and Bruce and so many others ensured the safety of the animals during demolition, including the Coast Guard, Department of Transportation, Faller, Davis and Assoc., Flatiron Construction, Treasure Island Police, U.S. Fish and Wildlife Service and the Florida Wildlife Commission. How proud we should be of them all.
Dr. Weaver studies wild dolphins under federal permit GA1088-1815, National Oceanic and Atmospheric Administration. Contact her at www.dazzlingdolphins.com.
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