Natural resources in the Mauritian waters

Underwater image showing 2 fishes, grey, black, white and yellowish in color amongst a variety of natural resources like white and brown coral species.

According to the Maritime Zones Act 2005, natural resources refer to minerals and other non-living materials found in the subsoil and seabed and the marine organisms in a sedentary state, that is, they are unfit for movement when they are harvested or depend on water or soil movement for displacement [1].

Minerals present in the continental shelf

The island of Mauritius emerged from the sea about 7-10 million years ago; four volcanic episodes created the land mass that we can now see. Each phase created a different layer of minerals, starting from the oldest to the most recent: [2]

  • the Breccia series – basalt oceanites (mineral olivine)
  • the Old lava series – picrite basalt (rich in the mineral olivine), olivine basalt, hawaites (rich in andesite pyroxene), basalt rich in feldspars, andesites, hawaites, mugearites (oligoclase)
  • the Early lava series – olivine basalt
  • the Recent lava series – olivine basalt

Resources found on the ocean floor

Deep-sea drilling of the ocean floor reveals the presence of polymetallic nodules in the Indian Ocean. It is estimated that these nodules have a coverage of about 10-15 million km2, weighing about 1.5×1011 tonnes, across the whole of the Indian Ocean [3].

Mauritius is located in the West Indian Ocean Basin; geomorphological analyses of the seabed near Mauritius report numerous seamounts and guyots (flat based mountains), trenches and fractures [2]. All these different structures influence the type of minerals that can possibly be found in the areas close to Mauritius.

  1. Polymetallic nodules – they are rich in manganese and are located in the sediment of the deep sea; important metals include copper, nickel, cobalt.
  2. Ferromanganese crust – 11% of the total ferromanganese crust minerals is evaluated to be in the Indian Ocean. They usually form on the surface and flanks of seamounts. The crust is a source of cobalt, nickel, manganese, titanium, copper, cerium and trace metals tungsten, molybdenum, platinum and tellurium.
  3. Polymetallic sulphides – hydrothermal polymetallic sulphides are usually located around volcanic structures in mid-ocean ridges, island arcs or back-arc spreading zones. These are the black smoker zones pilling up important metal ores of copper, lead, zinc, gold, silver, germanium, bismuth, indium and selenium [4].

Recently, new discoveries suggest that Mauritius may be lying on a part of an oceanic crust or microcontinent called ‘Mauritia’. The land mass broke off Madagascar during plate separation 65 million years ago but finally sunk to the bottom [5]. Being made of continental granite, mineral content in this layer could be fascinating. Detrital zircons have already been found in the granitic rock as lava-plumes have brought minerals to the surface [6].

Sedentary marine organisms in the Mauritian waters

Shallow water species that have been identified include the:

  • annelida (worms; ⁓42 species),
  • arthropoda (crustaceans, organisms with exoskeleton; about ⁓660 species),
  • ascomyta (fungi; ⁓74 species),
  • bacillariophyta (microalgae; 1 species),
  • basidiomycota (fungi; 2 species),
  • brachiopod (organisms with upper and lower valves; 3 species),
  • chaetognatha (arrow worms; 18 species),
  • chlorophyta (green algae; about ⁓180 species),
  • cnidaria (jellyfish, coral polyps; ⁓450 species),
  • cyanophycota (blue green algae; ⁓76 species),
  • deuteromycotina (imperfect fungi; 14 species),
  • echinodermata (organisms with radial symmetry like starfish; ⁓170 species),
  • echuira (spoon worms; 2 species),
  • ectoprocta (filter feeders; ⁓40 species),
  • hemichordate (worms; 2 species),
  • heterokontophyta (algae; 1 species),
  • magnoliophyta (flowering plants; 10 species),
  • mollusca (molluscs; ⁓2050 species),
  • nemertea (ribbon worms; 5 species),
  • phaetophyta (brown algae; ⁓85 species),
  • phyllophoridae (sea cucumber; 1 species),
  • porifera (sponge; ⁓80 species),
  • rhodophyta (red algae; ⁓species) and
  • sipuncula (worms; 17 species) [7].

To date, 8,000 sedimentary marine organisms have been documented in the Western Indian Ocean shallow waters [8]. A comprehensive study of the marine creatures on the ocean floor is still to be made as deep sea exploration is quite difficult to undertake.

In 2011, 6 new sea creatures were discovered in vents in the South West Indian Ocean floor [9]. More recently, oil and gas reserves have been detected near Seychelles [10]. All these discoveries suggest that the deep ocean floor around Mauritius may be hiding a lot of amazing treasures.


  1. United Nations. United Nations Convention on the Law of the Sea. [pdf]. Available at [Accessed 08.03. 2018]
  2. Saddul, P. (2002). Mauritius, A Geomorphological Analysis. Moka, Mauritius: MGI, pp 32,33; pp8
  3. Siddiquie, A.R., et al. (1984). Superficial mineral resources of the Indian Ocean. Deep Sea Research Part A. Oceanographic Research Papers. Vol 31 (6-8), pp763-812. Available at [Accessed 08.03.2018]
  4. Investigation of marine mineral resources. [online] Available at [Accessed 08.03.2018]
  5. Geological Report. (2015). Opportunity assessment for the development of geothermal energy in Mauritius. [pdf]. Milano, Italy: ELC-Electroconsult. Available at [Accessed 08.03.2018]
  6. Torsvik, T.H., et al. (2013). A precambrian microcontinent in the Indian Ocean. Nature Geoscience, [online] Vol 6, p 223–227. Available at [Accessed 10.03.2018]
  7. Database of Marine Organisms of Mauritius. (2007). Mauritius Oceanography Institute. [online]. Available at[Accessed 23.03.2018]
  8. Richmond, M.D. The marine biodiversity of the western Indian Ocean and its biogeography: How much do we know? VLIZ, Platform for marine research. [pdf] Available at [Accessed 08.03.2018]
  9. Lewis, D. (2016). Six new deep sea creatures just discovered at site slated for underwater mining. [online]. com. Available at [Accessed 08.03.2018]
  10. Kabukuru, W. (2014). Oil and gas finds lift western Indian Ocean prospects. [online] Available at [Accessed 08.03.2018]

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