High biodiversity of leptocephali in Tomini Bay Indonesia in the center of the Coral Triangle

- About 126 species of leptocephali were collected in Tomini Bay and the Celebes Sea.
- 105 species were collected in Tomini Bay compared to 78 in the Celebes Sea.
- Chlopsidae and Serrivoeridae leptocephali were especially abundant in Tomini Bay.
- A wide size range of most taxa was collected in both areas.
- The semi-enclosed Tomini-Bay may facilitate self-recruitment of marine eels.

The Indonesian Seas in the center of the Coral Triangle have high marine biodiversity, and a unique area is Sulawesi Island that has the large semi-enclosed Tomini Bay, including the Togian Islands, formed within the island. A sampling survey for leptocephali was conducted in March 2010 at 48 stations in the southern Celebes Sea and in Tomini Bay that collected 2056 leptocephali (6.0-319 mm) of at least 11 anguilliform and 3 elopomorph families and ∼126 species. About 44 Muraenidae, 26 Ophichthidae, 25 Congridae, and 11 Chlopsidae species and < 5 species of each of the other families were collected. The congrid, Ariosoma scheelei, the chlopsid, Kaupichthys, serrivomerids, Nemichthys and an ophichthid species of Neenchelys were the most abundant species/taxa. Comparisons of the two sampling areas found that ∼105 species were among the 1090 leptocephali from 21 tows in Tomini Bay and ∼78 species were among the 966 leptocephali from 30 Celebes Sea tows. Species such as chlopsids (25% of leptocephali in Tomini Bay), some muraenids, congrids, moringuids, and serrivomerids were more abundant in Tomini Bay than in the Celebes Sea, and some rare species were only collected there. The wide size range of most taxa indicated that many species spawn in the bay and their larvae are likely retained there. Large eddies in the Celebes Sea appeared to have transported leptocephali offshore. The high biodiversity of marine eel larvae suggest the unique semi-enclosed Tomini Bay may offer a good environment for spawning and self-recruitment, which may partly explain the high number of species of some families. More research is needed to evaluate the species composition of eels in Tomini bay and the wider region and to facilitate understanding and conservation of the diverse marine habitats of the Indonesian Seas.