iSimangaliso wetlands (St. Lucia Estuary)

• Category: Marine and Oceanic Biomes.
• Geographic Location: Africa.
• Summary: The iSimangaliso Wetlands is a tidal estuary of unparalleled beauty and diversity, whose Zulu name aptly means “miracle and wonder.”

The iSimangaliso Wetlands biome in South Africa is a tidal estuary ecosystem on the Indian Ocean, situated along the northeast coast of the KwaZulu-Natal province. It stretches from Kozi Bay in the north to St. Lucia in the south. Virtually the whole of the iSimangaliso Wetlands biome has been incorporated into iSimangaliso Wetland Park, and has been recognized as a World Heritage site by the United Nations Educational, Scientific and Cultural Organization (UNESCO).

iSimangaliso is a Zulu word meaning “miracle and wonder,” which appropriately describes this beautiful and diverse tidal estuary. One of South Africa’s largest protected areas, it encompasses 1,266 square miles (3,280 square kilometers), and extends 174 miles (280 kilometers) along the coast. The estuary area includes some of the world’s largest forested coastal dunes; they reach up to 656 feet (200 meters) high. The park also includes all of Lake St. Lucia, the St. Lucia and Maputaland Marine Reserves, the Coastal Forest Reserve, and the Kosi Bay Natural Reserve.

As a tidal estuary, iSimangaliso has interconnected habitats and wetlands that vary seasonally, with fresh- and marine-water inputs and varied salinity levels. There are swamps along Lake St. Lucia; these and other areas are fed by water seeping through the coastal dunes, that provide freshwater habitats year-round, irrespective of the changing salinity of the lake and estuary. There are also swaths of grassland habitat here.

Biodiversity

The iSimangaliso Wetlands biome is important as a breeding ground for giant leatherback and loggerhead sea turtles. Other species include 100 corals, 1,200 fish, 36 snakes, 80 dragonflies, 110 butterflies, and approximately 520 bird types. Important birds include the sea-eagle, pink-backed and white-backed pelican, greater and lesser flamingo, and the fish-eagle. There are 11 animal species endemic (found nowhere else) to the biome and at least 100 species that are near-endemic; these are also found in other places around South Africa.

The large submarine reefs harbor many fish and corals, with particularly strong coral diversity in Sodwana Bay. Whales and dolphins migrate through off-shore waters. Lake St. Lucia, 50 miles (80 kilometers) long and up to 14 miles (23 kilometers) wide, is home to hundreds of hippopotamuses and crocodiles, as well as pelicans, flamingos, ducks, waders, and fish.

In addition to modern species, the iSimangaliso Wetlands biome contains a living fossil: the coelacanth. This is a fish species virtually unchanged from millions of years ago; it was known only from the fossil record and presumed to be extinct—until a live specimen was found off the southeast African coast in 1938. It is still a rare protected fish, but several living specimens have been found and photographed in a submarine canyon off the coast near Sodwana Bay.

Threats and Conservation

The iSimangaliso Wetlands biome is vulnerable to anthropogenic changes. Extensive use and alteration of the rivers flowing into Lake St. Lucia for agriculture and other purposes have reduced freshwater flows. At the same time, the wetlands and particularly the lake were subject to drought for more than 10 years, ending in 2011. For much of this time, the estuary was closed off from the Indian Ocean, but due to low freshwater inflow and high evaporation, salinity levels rose throughout the ecosystem here. This led, in June 2009, to a red-and-orange algal bloom in parts of Lake St. Lucia that lasted for at least 18 months, ending only with heavy summer rains in 2011. The extent and persistence of the algal bloom illustrates a likely effect of global warming, and the fragile balance of the wetlands ecosystems. Recent studies on the wetlands have revealed the shrinking size of the biome. Using satellite images, researchers found that the wetlands shrank 5 percent between 1987 and 2017. Water depletion combined with weather patterns in this area could result in even further shrinkage. In addition to water changes, temperatures during the next 80 years are expected to increase from 20 to 80 percent. In 2020, researchers conducted laboratory experiments to see the effect of such temperatures on the region's coral reefs and found that hard corals bleached and died after only a month of exposure to such temperatures.

Other threats include damage by excessive tourism and overfishing. As a result of heavy traffic, the wetlands have been zoned into three ecotourism use zones: a zone of low-intensity use in the wilderness, where all visitor access is by foot; a moderate-use zone, where visitors can view wildlife from vehicles, camps, and shelters; and a high-intensity use zone, where (in seven clusters) there are roads, interpretative and educational displays, guided walks, accommodations, and other tourist facilities. Overall human activity is confined to one-third of the wetlands here.

The iSimangaliso Wetlands biome is relatively well managed under national and provincial regulations. South Africa protects wetlands under the World Heritage Convention Act of 1999. The wetlands also contain four Ramsar sites that recognize the ecological functions of wetlands and their importance as economic, cultural, scientific, and recreational resources. There is intensive management, research, and monitoring of human activity in the wetlands. Sufficient funds are in place nationally and through internationally-funded projects for the ongoing operation of the wetlands park.

Bibliography

Carnie, Tony. "KZN's iSimangaliso Wetland Park Threatened by 'Land Invasion.'" Daily Maverick, 24 Mar. 2022, www.dailymaverick.co.za/article/2022-03-24-kzns-isimangaliso-wetland-park-threatened-by-land-invasion/. Accessed 19 Dec. 2024.

Linden, Aretha. “New Study Highlights Urgent Conservation Efforts Needed to Preserve World Heritage Status of Isimangaliso Wetland.” University of Fort Hare, 26 Jan. 2024, www.ufh.ac.za/news/News39. Accessed 19 Dec. 2024.

Porter, Dr. Sean, and Tanja Hanekom. "Predicting Local Coral Reef Responses to Global Warming in the Anthropocene." South African Association for Marine Biological Research (SAAMBR), 16 July 2020, saambr.org.za/wp-content/uploads/2023/03/Coral-News-sml.pdf. Accessed 19 Dec. 2024.

Saarinen, Jarkko, Fritz Becker, and Haretsebe Manwa, eds. Sustainable Tourism in Southern Africa: Local Communities and Natural Resources in Transition. Bristol, UK: Channel View Publications, 2009.

Somers, Michael J. and Matthew Hayward, eds. Fencing for Conservation: Restriction of Evolutionary Potential or a Riposte to Threatening Processes? New York: Springer, 2011.

Surhone, Lambert M., Mariam T. Tennoe, and Susan F. Henssonow, eds. iSimangaliso Wetland Park. Beau Bassin, Mauritius: Betascript Publishing, 2001.

World Heritage Centre. “iSimangaliso Wetland Park.” . Accessed 19 Dec. 2024.