Wetlands of Vanuatu

-

Wetlands - Republic of Vanuatu

Dahl (1980 & 1986) lists the following wetland habitats as occurring in Vanuatu:
• permanent lake (Ambae, Ambrym, Efate, Epi, Espiritu Santo, Gaua, Maewo, Malekula, Tanna and
Thion);
• hot springs with algae (Efate);
• freshwater swamp and marsh (Anatom, Efate, Epi, Erromango, Espiritu Santo, Gaua, Maewo, Tanna
and Thion);
• mountain streams (common);
• lowland rivers (common);
• riverine forest on alluvial soils;
• swamp forest (Efate, Malekula and Espiritu Santo);
• non-tidal salt marsh (Loh);
• closed lagoon (Efate);
• mangrove forest (mostly on Malekula);
• sea-grass beds (common in coastal areas).
There are about 25-30 natural freshwater lakes in Vanuatu. Several of these are crater lakes, some
within active volcanoes. Much the largest is Lake Letas (1,900 ha), the largest freshwater lake in the island
Pacific outside of New Guinea. This lake lies within the occasionally active Mount Garet on Gaua
Island. The caldera lakes of Ambae's active volcano Waivundolue, at over 1,300 m elevation, are
the highest lakes in the South Pacific. Many of the other freshwater lakes occur in lowland areas
and usually support marsh vegetation. Most are very small, and some are seasonal. There are also
a few brackish and saline lagoons in the coastal zone of some islands, e.g. on north Efate and south
Espiritu Santo. The largest of the brackish lagoons is Lake Nalema on east Epi. Vanuatu's largest
closed saline lagoon, Ekasuvat Lagoon near Port Vila on Efate, is now much disturbed by urban
development.
Rivers and streams are abundant in the islands, the largest occurring on Espiritu Santo and Malekula. Although of
no great length, these rivers may carry large amounts of water during rainy periods. Most of the rivers are
characterized by their large and rapid fluctuations in flow regime coupled with generally steep gradients.
Many, such as the Teouma River on Efate and the Matenoi River on south Malakula, flow through
spectacular and almost inaccessible gorges for much of their length. The only extensive floodplain area in the
country is formed by the rivers which drain the Tabwemasana Range of central Espiritu Santo and flow
north into Big Bay. Some rivers, particularly in areas made up largely of raised reefs, e.g. eastern Espiritu
Santo, coastal Efate and the Torres Islands, flow only at times of heavy rainfall. On some islands, there is little
or no surface water for all or much of the year because of the porous nature of the uplifted coral substrates.