More on black water (Miami herald)

Precht, Bill Bprecht at
Wed Mar 27 09:33:01 EST 2002


This is the most recent news regarding the "Black Water" event?
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Miami Herald,

Posted on Wed, Mar. 27, 2002
Dying sponges offer clues about the `blob'
cmorgan at
A zone of dying sponges and coral off Key West has suddenly elevated the
formation dubbed ''black water'' from scientific mystery to major
environmental concern.
In the first reliable underwater assessment of impact on marine life, a
commercial diver documented enough damage to raise alarms that the baffling
blob may have left a swath of unseen destruction in its wake as it slowly
drifted from the Gulf of Mexico across Florida Bay over the last few months.
''This certainly sounds like it's the effects of something very nasty going
on,'' Billy Causey, superintendent of the Florida Keys National Marine
Sanctuary, said Tuesday.
The devastated sponges were observed over the weekend in the northwest
channel off Key West by Ken Nedimyer, a member of the sanctuary's advisory
council who collects specimens for the aquarium trade.
''The water was a creepy green at the surface and by the time I got to the
bottom, it was really creepy and dark,'' wrote Nedimyer in an e-mail sent to
the sanctuary and several of scientists studying the curious discoloration.
He noted six species of rope sponge as the hardest hit, with 50 to 75
wiped out, as well as a number of other sponges dead or dying. Brain coral
and starfish also seemed to be suffering. Fish in the area seemed healthy,
though curiously unhungry.
''There's a real meltdown occuring down there right now,'' Nedimyer wrote.
Before Nedimyer's report, scientists had not confirmed any toxic effects
the black water but Nedimyer's observations were serious enough that the
sanctuary planned to dispatch its own divers to survey for more widespread
damage. While the mass described as the color of sewer water is breaking up
and shrinking, at one point it spanned several hundred miles.
While scientists were still sorting through water samples, satellite images,
weather reports and historical studies and observations, the sponge dieoff
another strong indicator that the culprit is an explosion of some sort of
microscopic plankton, said Brian Keller, the sanctuary's science
During a series of algae blooms that plagued Florida Bay in the mid-1990s,
sponges, which feed by filtering water, were among the first organisms to
in vast acres, followed by seagrass beds. Those blooms did not kill fish,
like red tide does, but fish do avoid the areas during outbreaks and lose
forage and shelter until the areas recover, which can take years.
''The fact that it appears to be a fairly selective mortality indicates to
that it's not like some general toxin in the water column that would kill
everything,'' Keller said.
But Keller agreed it would take more study to issue a definitive word. A
loose-knit team of state, federal and private scientists studying the patch
plans to discuss the data and issue a list of probable causes, perhaps by
week's end.
As of now, ''it's a phenomenon about which we are uncertain,'' said Beverly
Roberts, research administrator at the Florida Marine Research Institute in
St. Petersburg. It could be caused by anything from pollution to some sort
decaying plant material, perhaps flushed to sea from land.
Scientists at the institute, the Mote Marine Laboratory in the Keys and
Sarasota, and the University of South Florida were all analyzing data. Water
samples have shown medium to high levels of two types of phytoplanktons,
plants so essential to the marine food chain that they're called ''the grass
of the sea,'' Roberts said.
''It's eaten by a lot of smaller stages of the fishes,'' she said. They're
normal in sea water but plankton or a variety of them can cause problems in
high concentrations.
The samples also detected low concentrations of another bottom plankton that
produces ciguatera, a toxic that can sicken people who eat fish with high
levels. But Roberts said it unlikely it played a major part.

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