Salt Ponds

Produced by the V.I. Department of Planning and Natural Resources Division of Fish and Wildlife
Distributed as a public service by Maho Bay Camps.

Most of the salt ponds ("ponds") in the Virgin Islands were bays that, over time, have been closed in by reef or mangrove growth across the bay's mouth. Sand, sediment, and rubble also accumulate on the developing berm area during storms and aid in separating the pond from the bay.

The water in the pond is seawater that remained inside the newly made berm. Once the pond is separated from the bay, salt water can still seep into the pond at high tides or it can wash over the berm during storms.

Fresh water from rain and storm water runoff also enters salt ponds. These fresh water inputs lower the pond's salinity. These changes in salinity can be very large and can occur very rapidly.

During dry periods, the pond's water evaporates quickly, increasing the salinity. Sometimes, salt ponds can dry up completely, leaving crystallized salt behind.

Salt ponds are usually exposed to the sun. This, combined with the frequent changes in water level caused by sudden storm water inputs or evaporation can lead to drastic changes in water temperature in salt ponds.

Life in a Salt Pond

Very few organisms are able to withstand the drastic fluctuations in temperature and salinity that salt ponds experience. These unstable conditions make salt ponds "unfriendly" environments to live in. Yet, many crabs, insect larvae, brine shrimp, and some halophilic (salt- loving) plants can be found living in salt ponds. Brine shrimp and algae give ponds a variety of different colors, including brownish-pink, orange, green, or red.

Many wading birds (herons, stilts, sandpipers, and sometimes, flamingos) and waterfowl (ducks, teal, coots) feed on organisms in the ponds. Other birds (kingbirds, martins, and swallows) feed on insects that fly over the ponds, and many nest or roost in the surrounding vegetation. Insect and fish-eating bats also frequent ponds in the evening.

A pond that has been recently opened to the sea by a storm may contain fish sennet barracuda, tarpon, mullet, snook, etc.). These are often fed upon by birds such as kingfishers, herons, and ospreys.

Animal and plant life associated with ponds are not well studied. The complex ecology of a pond is only partly understood. We do know that a pond is a very dynamic system with constant modifications in the natural community in response to continuous changes in salinity, temperature, turbidity, and levels of oxygen and hydrogen sulfide (from decaying organic matter) in the pond.

Are Salt Ponds Important?

YES! Salt ponds serve a number of very useful purposes that benefit us and the marine environment! Ponds

• are natural settling basins, trapping upland storm water runoff end the sediments and pollutants it carries. This protects marine habitats (sea grass beds and coral reefs) and keeps the water in adjacent bays clean.
• provide feeding places for wading birds, fish- eating bats and insects. The vegetation around the pond also provides nesting and roosting places for many birds and other wildlife.
• are excellent areas for bird watching, environmental research and education.
• have many traditional uses, including: gathering salt for cooking; "soaking" for medicinal purposes; and, gathering brine shrimp as tropical fish food.

Threats to Salt Ponds

Salt ponds in the Virgin Islands are an endangered habitat. Numerous activities have eliminated them or reduced their value as sediment traps or wildlife habitat. Threats include

• Development of upland areas without proper use of sediment control measures. This leads to rapid "filling in" and loss of a pond.
• Filling of salt ponds by developers to create land to build on.
• Opening of salt ponds for marina basins. When this is done all runoff into the pond goes directly into the sea.
• Pollutants such as waste oil, septic discharge, and household and commercial chemicals entering the pond in storm water runoff from upland sources. This results in the death of pond animals and plants and a disruption of the ecology of the pond.

If we overload our salt ponds with too much sediment or pollution, they will eventually stop working for us. Without functioning salt ponds, many of our marine resources -- reefs, sea grasses, fish, and birds -- will be in danger.

This brochure was funded by the U.S. Fish and Wildlife Service, Sport Fish and Wildlife Restoration Acts.