Subject: Estuary = Dynamic System
Phillip Colla (oceanlight@oceanlight.com)
Wed, 09 Jun 1999 10:04:22 -0700
Why is an estuary called a 'dynamic
system' ?
Although this is not directly related to cetaceans or marine
mammals,
I'll take a stab at it. I believe "dynamic" is used to
describe
estuaries because estuaries are ever-changing, principally due to
tidal effects. Consider:
Sometimes shallow water or mud flats, sometimes deeper
water.
Water flowing in from the ocean, water stationary at high or
low tide, water flowing out to the ocean.
Water flowing in from contributing fresh water sources, such
as streams or rivers.
Changing salinity, water clarity, water temperature.
Sometimes an estuary may be cut off from its water sources,
so
that is become a "standing" body of
water. This in itself
causes changes that estuary inhabitants must
deal with, such
as diminishing oxygen levels in the water,
changes in water
temperature, inability to flush out pollutants,
etc.
The animals that inhabit an estuary must deal with all of these
stresses, and probably many more that I did not mention. The
changing
nature of the estuary environment is dynamic.
Best regards,
Phillip Colla