Joe wrote:
The water is warm, and crystal clear off the shelf. Great currents,
and the bottom is covered with shrimp, treasure ships, pipelines, salt
domes.

Your little lake is just a dead pond compared to the Gulf of Mexico.

Odd choice of words, Joe.
http://www.tulane.edu/~bfleury/envir...b/DeadZone.htm

"The Dead Zone"

"The Gulf of Mexico hypoxic zone is a seasonal phenomena occurring in
the northern Gulf of Mexico, from the mouth of the Mississippi River to
beyond the Texas border. It is more commonly referred to as the Gulf of
Mexico Dead Zone, because oxygen levels within the zone are too low to
support marine life. The Dead Zone was first recorded in the early
1970's. It originally occurred every two to three years, but now occurs
annually."

The Dead Zone reaches a size every summer of about 8,000 square miles.
Fortunately it retreats in winter, but the likelihood is that it will
become permanent in the coming years. The Gulf Dead Zone is 100%
attributable to our "civilization's" effluent. There are other similar
dead zones in other large bodies of water about the Earth.

DSK