The
complex balance of land and sea environments supports the incredible
natural beauty of St. John, the white soft sandy beaches, the
crystal-clear water, the colorful coral reef, the fish, the sea
creatures, the exotic tropical foliage, the birds, bats, butterflies
and every other living thing. One of these environments that
is often overlooked is the salt pond.
How Are Salt Ponds Formed?
Most of the salt ponds of St. John were once bays, open to the
sea. Coral reefs develop naturally around the rocky headlands
that jut out and define bays. In time the reef may extend out
from the headland toward the center of the bay. When this happens
simultaneously on both headlands, the bay begins to be closed
off. As the reef matures, the top of the reef rises toward the
surface of the water. Strong storms and hurricanes carry sand,
rocks and pieces of broken coral and pile them on top of the
reef creating a surface platform above sea level. Meanwhile heavy
rains and gut washes cause sediments and soil from the land to
collect on the protected side of the platform facing the land.
With the help of salt tolerant plants, such as mangroves,
to secure these sediments, the platform will gradually get larger
and denser. A salt pond is born when the spit of solid land builds
up enough to close off the bay from the sea.
How Do Salt Ponds Protect the Coral Reefs?
During heavy rains, water runs down valleys and hillsides into
guts leading to the low flat areas just inshore from the central
portions of the bay. Salt ponds are generally found in these
low-lying areas and serve as buffers between land and sea.
The salt pond acts much like the septic systems used by many
homes on St. John. Water flowing down the valley picks up soil,
organic debris and possibly dangerous pollutants. This mix
is deposited into the salt pond instead of washing directly
into the sea. The sediments settle to the bottom of the pond
and the now purified water can seep through the filter-like
sand and coral rubble wall of the pond into the bay without
causing turbidity or cloudiness.
The Salt Pond Environment
Salt ponds are extremely hostile environments for living things.
Depending on the salt pond's location and on conditions such
as temperature, rainfall and windiness, the water within the
pond can range from almost fresh to a super-saline solution
five times the saltiness of the sea. Add to this the high temperature
that the water can reach during sunny dry afternoons and you
would think that nothing could survive there. Nonetheless,
the salt pond is inhabited by such creatures as brine shrimp,
crabs, insects and insect larva, which provide the basis for
a food chain. Birds, waterfowl and bats that feed on these
organisms are attracted to the pond environment and several
species of birds tend to make their nests nearby.
Birds commonly found at or near St. John salt ponds include
herons, sandpipers, yellowlegs, and pin tail ducks. In addition,
certain fish, such as barracuda, tarpon, mullet and snook, attracted
by the brine shrimp, sometimes make their way into salt ponds
that have an opening to the sea. In some parts of the world the
brine shrimp from salt ponds are harvested commercially for tropical
fish food, and the larva produced by brine shrimp eggs has been
marketed (particularly in comic books) as “sea monkeys”.
Salt ponds can be smelly and murky and in the past they were
indiscriminately dredged, drained, filled or opened to the sea.
As a result they have been disappearing from the Virgin Islands
at an alarming rate. Fortunately, they are now protected under
the territorial Coastal Zone Management department and also under
federal legislation, which means no filling, opening or dredging.
If you would like to observe a St. John salt pond, the best
time to visit is in the early morning, while it is still cool.
The morning is also the best time to bird watch at the ponds.
Some easily accessible and healthy pond environments can be found
at Frank, Europa, Grootpan and Salt
Pond Bays. Salt ponds tend to be peaceful and quiet areas.
Take your time, stand still and look about carefully; you'll
be pleasantly surprised at all there is to see and contemplate.
