Shoal Grass Halodule wrightii

  • Seagrass
  • seagrass
  • Plant
  • Pioneer species


Halodule is a genus of seagrass. In Mauritius, it is represented by two species: Halodule wrightii and Halodule uninervis. These are the dioecious species: the male and female plants are different. Their flowers are solitary.

The leaves of Halodule wrightii are flat, ligulate and consist of three nerves. Leaves are of a dark reddish-brown colour. Fruits are globose or egg shaped. Halodule wrightii can tolerate a wide range of environmental conditions.

The leaves of Halodule uninervis are green, rectangular, thin and elongated. It can reach 15 cm in length and 5 mm in width. Three parallel ribs run across the sheet. The one in the middle is particularly visible. These ribs end at the upper end of the limb with small points, thus appearing trident-like.

Habitat and ecology

Halodule wrightii is mostly present in the Atlantic Ocean but can also be found in the Eastern Tropical Pacific Ocean and in the Indian Ocean.

Halodule uninervis is present in the Indopacific.

These species generally grow in sandy and muddy bottoms and can be found in multispecies assemblages. Highly adapted to disturbances, it is a pioneer species and in certain regions, it dominates the meadows. The species is known to recover rapidly in the face of destruction.


Conservation and management

Halodule wrightii is widespread and locally abundant; its population trend has been deemed stable and increasing in certain areas. This species can tolerate disturbances and replaces other species under certain conditions of eutrophication, habitat destruction or increased turbidity. Besides anthropogenic activities, there are no other major threats. It is listed under the ‘Least Concern’ category of the IUCN Red List. It can be found in many MPAs throughout its range.

Halodule uninervis is a very common species and has a wide distribution. It is also considered a "least concern" on the IUCN Red List. Overall, the overall population trend is stable.

Did you know?

The optimum temperature for Halodule to thrive is between 20 to 30 degrees Celsius.