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| Aquatic Life |
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  Oceans,
tidal pools, lakes, rivers, and ponds - all bodies of water that sustain
life - and all contain copper as a vital, naturally occurring element.
Copper's presence in basic life processes spawns species that swim,
scurry, wiggle and wallow in the waters of the world.
Simply stated, copper is indispensable because it is necessary for
normal growth in all living things.
Copper is a key component of enzymes - compounds that act as catalysts
in the metabolism of organisms. It's main role is through metalloenzymes
that catalyze many different chemical reactions.
Copper in Fresh & Marine Waters. Levels of copper in fresh
and salt water have been found to be generally low. Studies of raw,
untreated fresh water in the US have shown copper contents ranging
from 0.001 milligrams per liter to 0.28 milligrams per liter.
The mean was 0.015 milligrams per liter. In open oceans, copper levels
ranged from 0.1 milligrams per liter to 0.39 milligrams per liter,
with an average of 0.8 milligrams per liter. These figures show how
copper is effective in small quantities.
Copper in Aquatic Plants. Aquatic plants are reliant on copper,
which plays an important role in photosynthesis and respiration. Plants
get copper that is dissolved in the water, as well as copper that
is present in particles, sediment, and in food.
Copper in Fish and Aquatic Life. The normal level of copper
in whole fish tissue is on the order of one to two parts per million.
The amount of copper and other trace minerals in the growth and development
of fish, crustaceans (shellfish) and mollusks such as oysters and
clams may be minute in quantity but enormous in economic terms. Many
of these species are part of the renewable foundation of fishing,
a vast worldwide activity that helps meet a growing demand for protein.
Commercial and recreational fishing is practiced just about everywhere
in the world, including such land-locked countries as Bolivia, in
South America, and Azerbaijan, in Asia. Bolivians have been fishing
the waters of Lake Titicaca for centuries, and the valuable caviar
industry of the world is centered in Azerbaijan, on the Caspian Sea.
The Food and Agriculture Organization (FAO) of the United Nations
estimated that in 1997 the world's food fish production reached 90
million tons, an almost threefold increase since 1960. Almost a third
of that catch was raised on fish farms in a fast-growing commercial
process known as aquaculture. Fish grow under controlled conditions
within enclosures and are fed a carefully balanced diet that invariably
includes copper.
At Bio-Oregon, in Warrenton, Oregon, a producer of formulated food
for fish farms, copper has always been a supplemental trace element.
Because copper can be virtually recycled from healthy animal tissue,
fish food industries find copper in inorganic forms (such as copper
sulfate) in the offal of salmon and other edible fish that has already
been processed.
By including copper in fish food, fish farmers are replicating what
nature does so well in the wild: providing an environment that nurtures
life and growth. In this respect aquatic life is similar to other
species.
The requirements for copper is fairly steady among vertebrate animals.
Crustaceans, such as shrimp, lobster and crab, are in particular need
of copper because its serves as an oxygen carrier in their blood.
Some scientists believe that copper concentrations in crustaceans
may be elevated compared with other groups since many crustaceans
use copper in their blood pigment. That is why, if you look closely,
an uncooked shrimp looks bluish, a typical color of certain forms
of oxidized copper.
It doesn't take much copper to perform its critical role in marine
species. Atlantic salmon, Channel catfish, rainbow trout, and carp
require only 3 milligrams of copper per kilogram of feed.
Although requirements have not been determined for all marine species,
scientists do know that copper deficiencies in certain species can
result in reduced growth and cataracts, among other symptoms. Scientists
have also observed that overly high presence of copper in natural
waters may damage the gills, liver, and kidneys of fish or cause neurological
damage.
Copper plays an important role in other aquatic environments, too.
It is a key component of marine plant life. It is commonly used to
purify and distribute drinking water. And it combats the growth of
unwanted organisms that foul water intake lines, aquaculture facilities
and the hulls of vessels.
Copper's Role in Aquaculture. Copper is essential to the growth
and development of aquaculture species. It also plays a frequent role
in the supply of water that makes fish farming possible.
To ensure healthy development of fish, water has to flow easily in
and out of the enclosures were they are raised. Undesirable growths
can impair the flow of water by blocking ducts, pipes, grates and
other conduits. The reduced flow will result in less life-sustaining
oxygen being circulated in the waters.
To keep fish farms operating at an optimal level, operators resort
to copper-containing compounds, known as antifouling agents, as a
weapon against the growth of organisms that impair the flow of water.
When properly used, these agents - copper alloys, metal-containing
plastic and copper-containing paints and coatings - create a durable
antifouling surface that reduces maintenance and eliminates the need
for more hazardous types of coatings. |
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