- HOUSTON (Reuters) -- A huge
"dead zone" of water so devoid of oxygen that sea life cannot
live in it has spread across 5,800 square miles of the Gulf of Mexico this
summer in what has become an annual occurrence caused by pollution.
- The extensive area of uninhabitable water may be contributing
indirectly to an unusual spate of shark bites along the Texas coast, experts
- A scientist at the Louisiana Universities Marine Consortium
said on Tuesday measurements showed the dead zone extended from the mouth
of the Mississippi River in southeastern Louisiana 250 miles west to near
the Texas border and was closer to shore than usual because winds and currents.
- "Fish and swimming crabs escape (from the dead zone),"
said Nancy Rabalais, the consortium's chief scientist for hypoxia, or low
oxygen, research. "Anything else dies."
- In the last 30 years, the dead zone has become an annual
summer phenomenon, fed by rising use of nitrate-based fertilizers by farmers
in the Mississippi watershed, Rabalais told Reuters.
- The nitrates, carried into the gulf's warm summer waters
by the river, feed algae blooms that use up oxygen and make the water uninhabitable.
- The dead zone's size has varied each year depending on
weather conditions, but averages about 5,000 square miles and remains in
place until late September or early October.
- Virtually nothing is being done to stop the flow of nitrates
into the river, meaning the dead zone will reappear every year, Rabalais
- The dead zone forces fish to seek better water, which
may be a reason for the recent shark bites on Texas beaches.
- Three people have been bitten by sharks along the upper
Texas coast this year -- a high number for a state that has recorded only
18 shark attacks since 1980.
- Terry Stelly, an ecosystem biologist with the Texas Parks
and Wildlife Department, said increasing numbers of sharks have been found
in recent years in the waters along the Texas-Louisiana border, near the
edge of the dead zone.
- Along with other factors, "chances are good they
(sharks) were looking for higher dissolved oxygen in the water," he
- Rabalais agreed, saying "The higher number of sharks
in shallow waters may very likely be due to the low oxygen being close
to the shore at the time of the attacks."
- "The available habitat for the sharks is definitely
less when the low oxygen is so widespread," she said.
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