Wetlands of Mauritius

Grass blades reflecting in a small pool of water

A wetland is a place that is permanently or seasonally filled with freshwater, saltwater or a mixture of these two. As such, wetlands include areas such as marshes, ponds, borders of rivers and lakes and deltas. Though often neglected in environmental conservation programmes, wetlands are one of the most important ecological units of the environment. For instance, wetlands act as natural water filters, trapping metals and other toxic elements in the sediment [1].

Types of wetlands in Mauritius

Mauritius is entirely surrounded by seawater. Freshwater sources include reservoirs, rivers, lakes and ponds that cover an area of 435 ha [2]. The water basins, combined with the rugged topography of the island, have created different types of wetlands as follows:

Type of wetland Location Size (ha)
1.      Floodplain inland (such as the banks of rivers and lakes) 62
2.      Marshes coastal and inland (transition areas where the land meets the sea and ponds) 240
3.      Estuaries coastal 95
4.      Mangroves coastal 49
5.      Marine coasts coastal 118
6.      Lakes inland 25
7.      Depressions inland 50
8.      Reservoirs inland 1200

144 wetlands falling in the above-mentioned categories have been identified [3]. They cover an area of 1839 ha, concentrating mostly on the east and south-east coasts of the island. This is due to the amount of rainfall that these regions receive throughout the year. Water seeps into the ground and is retained in the soil causing the upper layers to remain moist and overflow. Natural wetlands cover only a surface area of 639 ha; they include marshes and mangrove swamps.

Importance of wetlands in Mauritius

1.      Environmental

It goes without saying that wetlands play a vital role in maintaining environmental balance. They act as sponges during heavy rainfall, absorbing excess water and also trap pollutants in their sediment. Moreover, this process protects ecosystems that are upstream such as coral reefs and allow them to grow properly. Mangrove forests protect the shore from violent waves, tsunamis, help to stabilize the shoreline sediment, act as carbon sinks and help mitigate the effects of climate change.

2.      Economic

Many plants of commercial value such as watercress and taro, brede songe, are grown in the muddy areas near river banks. Freshwater fish and crustacean farming are also practised at some sites. In addition to that, many marine species require the unperturbed sediment of mangroves to hatch and grow during their juvenile stages. Thus, wetlands are very important places for ecological food webs to develop from the early larvae stages to human consumption. Wetlands have important educational and recreational uses too. As it happens, many migratory birds can be observed at the Rivulet Terre Rouge Estuary Bird Sanctuary and kayaking is offered in the mangrove forest of Ile D’Ambre as an ecotourism activity.

Vibrant green large taro leaves that grow in the wetlands of Mauritius
Taro plants are commercially grown in the wetlands of Mauritius

Photo by SukantoBiswas on Pixabay

3.      Socio-cultural

Wetland sites such as marshes and river floodplains are peaceful places where people enjoy the calm atmosphere in families or with friends. This consequently has an impact on the health of individuals such as a decrease in stress level and creates a stronger bond with nature. The Grand Bassin basin also has religious importance for the Hindu community as it is considered to be a sacred lake connected to the Ganges River in India.

Wetland preservation in Mauritius (Ramsar Sites)

In September 2001, Mauritius adopted the Convention on Wetlands to protect and conserve the local marshes and to use them wisely is a sustainable way [4]. Also called the Ramsar Convention (after the city in Iran in which it was first adopted), three sites of international importance covering an area of 401 ha [5] were nominated in Mauritius namely the Rivulet Terre Rouge Estuary Bird Sanctuary, the Blue Bay Marine Park and the Pointe D’Esny Wetland.

1.      Rivulet Terre Rouge Estuary Bird Sanctuary (RTREBS)

The Rivulet Terre Rouge Estuary Bird Sanctuary is found in the north-west of Mauritius and covers an area of 26.4 ha. Declared as a wetland reserve in 1997 and listed as a Ramsar site in 2001, this humid coastal strip serves as a winter shelter for many birds from the northern hemisphere. Some 1200 migratory bird species have been recorded coming as far as Alaska (the Bar-Tailed Godwit) and including 6 rare migrants and 13 regular migrants. Common birds that can be seen at the sanctuary are the common Sandpiper, the Grey Plover, the Little Ringed Plover and the Green Shank. The estuary is usually open from 7 am to 3 pm from Monday to Friday and also on weekends during the migratory period from October to April.

Little ringed plover bird that migrates to the Rivulet Terre Rouge Bird Sanctuary wetland in Mauritius
A little ringed plover bird that migrates to the Rivulet Terre Rouge Estuary Bird Sanctuary during the harsh winter in Europe

Photo by Kathy2408 on Pixabay

2.      Blue Bay Marine Park

The Blue Bay Marine Park is located in the south-east of Mauritius, extends over an area of 353 ha and ranges in depth from 1-150 m. It was declared a National Park in 1997, a Marine Park in 2000 and a Ramsar site in 2008. While the Blue Bay beach is famous for its white sand and crystal clear blue water, the exquisite marine life that exists in the lagoon makes it even more marvellous. The patch reef in the park ranks amongst the best in the world and is also the only place in Mauritius where the stony coral Montipora aequituberculata has been found. The biodiversity of the Blue Bay Marine Park can be summarised to some 108 coral species, including a 1000-year-old coral brain that has a diameter of 6-7 m, 233 fish species, 201 mollusc species, 1 species of turtle, 31 species of algae plus the two species of mangroves that grow on the island. Registered glass bottom boats are available on a daily basis to visit the park.

School of damsel fish in the sea at the Blue Bay Marine Park Mauritius
School of damselfish at the Blue Bay Marine Park, Mauritius

Photo by Jeremy Wermeille on Unsplash

3.      Pointe D’Esny Wetland

Designated as a Ramsar Site in 2011, Pointe D’Esny Wetland is a 22 ha mangrove forest that is located in the south-east of Mauritius. It is the largest mangrove forest of the island where both species of mangrove trees grow as well as the endangered plant Zornia vaughaniana. The marsh provides shelter and food to a number of fishes, crustaceans and birds and a number of people depend on it directly and indirectly for their livelihoods. The wetland has become an important local and ecotourism site and can be visited at any time.

References:

  1. Defenders of wildlife. (2018). Basic facts about wetlands. [online] Available at https://defenders.org/wetlands/basic-facts [Accessed 12/04/2018]
  2. Paul, E.C. (1987). Fisheries Development and the Food Needs of Mauritius. Rotterdam, Netherlands: A.A Balkema Publishers, pp 39
  3. Mamoun, C.M., Nigel, R. and Rughooputh, S.D.D.V. (2013). Wetlands’ Inventory, Mapping and Land Cover Assessment on Mauritius. Journal of the Society of Wetland Scientists. Springer DOI 10.1007/s13157-013-0415-z [pdf] Available at https://www.researchgate.net/publication/236329515_Wetlands’_Inventory_Mapping_and_Land_Cover_Index_Assessment_on_Mauritius [Accessed 12/04/2018]
  4. Wetland Unit. [pdf] Available at http://npcs.govmu.org/English/Documents/Wetland.pdf [Accessed 12/04/2018]
  5. Ramsar Sites Information Service. [online] Available at https://rsis.ramsar.org/ris-search/?f[0]=regionCountry_en_ss%3AMauritius&pagetab=1 [Accessed 12/04/2018]

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