The Walvis Bay Lagoon is considered one of the richest and most important wetlands in southern Africa. The Lagoon lies in the south-east corner of the bay area of the city and is formed by the prominent 7km long barrier-arm named Pelican Point. The lagoon is approximately seven km long and up to 2,5m deep at high tide. Radiocarbon-dating of the white mussel found in the lagoon indicates an age of at least 3,000 years. Because of its richness in bird life and species it was designated as a Ramsar site in 1995. People have frequented the edge of the lagoon for centuries as evidenced by the abundance of kitchen middens and other archaeological sites in the area. Today urban dwellers, tourists and recreation seekers use the lagoon for a variety of way leisure activities, including, kite-boarding, jogging, kayaking, bird-watching and photography.
The nutrient-rich deep-water fertilizes a very high primary production of phytoplankton, which then fuels the very productive food chain of zooplankton, marine invertebrates, fish and marine mammals. The Walvis Bay Lagoon together with the tidal areas is a key wetland in ecological terms because of its immense importance for coastal biodiversity, in particular birds and cetaceans. Coastal fish species are said to have been caught in great numbers in the lagoon in the past.
Presently large schools of small mullet and springer and some skates and rays are found. Bottle-nosed Dolphins and whales frequently enter the lagoon but can be stranded by the outgoing tide. The Walvis Bay Ramsar Site supports up to 250,000 birds at peak times during the summer season. Intra-African migrants, including Greater and Lesser Flamingos, breed elsewhere in Africa but feed in the Walvis Bay wetlands, and may be seen throughout the year and particularly during the winter months. The Lagoon is one of the best flamingo viewing localities in the world, and attracts bird-watchers and visitors from around the world. More than 50 species of birds, including the Greater and Lessor Flamingo, sea gulls, the Chestnut-banded Plover, Damara terns, pelicans and cormorants depend on the Walvis Bay Lagoon as feeding grounds. A promenade along the lagoon and information boards are widely used by residents and tourists alike. The lagoon is also popular for kayaking, kite-boarding, and wind surfing.
At the south end of the Lagoon lay the salt pans. Established in 1964 the salt pans are one of the largest solar evaporation facilities in Africa and operate in an area of 4,500 hectares. Thirty million tonnes of seawater is processed per year to produce about 750,000 metric tonnes of high quality salt p/a. The pans also support 40% of the African sub-species of Black-necked Grebe and provide a good habitat for rarer waterbirds such as the Rednecked Phalarope, Common Redshark, Eurasian Curlew, Bairds Sandpiper and many others.
Plankton species include several species of the salt-tolerant unicellular green algae such as Dunaliella species. The most numerous species are lesser and greater flamingos, with sometimes more than 40,000 individuals. The largest number of rare Chestnut-banded Sandplovers is also found within the salt pans and ponds. The red colour from the Halobacteria is important in the operation of the ponds as more colour in the water increases the heat absorption of sunlight, increasing the temperature of the water and also the evaporation rate. In addition the red colour from the Halobacteria is found in the blue green algae on which both the Lesser and Greater Flamingos feed and this is what gives the pink-redish colour to the flamingos.
Concessions for aquaculture in the form of oyster rafts have been granted within the salt works area during the past decade. Oyster production in Walvis Bay has been a financial success, and extensions of this activity are expected. However, sedimentation of the lagoon became a cause for concern in the 1970’s as there were indications that the lagoon could be silting up. The main source is wind blown sand and dust, with very small and infrequent contributions from the bay and floods in the Kuiseb River. Following sedimentation, pollution from activities in the Walvis Bay harbour has the largest impact on the functioning of the Walvis Bay Lagoon.
Pollutants affecting the water column have been identified as petroleum products, fish processing waste, ore dust, cargo packaging waste, heavy metal waste, toxic waste, galley waste and dredged material. In contrast to the severe effects of water-borne pollutants, air and ground pollutants originating in the harbour have a relatively small impact on the lagoon.
Similarly the organic load produced from the fish factory outfalls in the harbour leads to accumulation and decomposition of organic matter on the bottom, which, in turn, causes sulphur eruptions. These eruptions are more common in summer than in winter and may kill fish in the harbour and lagoon, turning the water a variety of colours and producing an unpleasant sulphurous smell. In addition to the reduction in total area of the lagoon caused by surrounding development, the Walvis Bay Lagoon is directly and indirectly affected by a variety of influences originating in the surrounding area. Currents entering and flowing from the lagoon carry sediments that are deposited, mainly at the mouth of the lagoon. The water-borne sediment load has apparently been augmented by dredging in the harbour. Windblown sand is the other major source of sedimentary input into the lagoon.