Lake Matano is listed among ancient lakes of the world, with a depth of nearly 600 m. It is inhabited by numerous endemic biota that are evolutionary distinct but globally endangered. Among these endemics, mostly listed as critically endangered, is Tylomelania zeamais which has been reported to be potentially extinct in its range under IUCN Red List, following survey in 2017 and 2018 that failed to observe this species at sites where it was abundantly found two decades ago (IUCN, 2018; von Rintelen et al., 2007). Therefore, the project’s goal was to conduct a survey to rediscover the existence of the species and map its distribution as well as to assess the habitat condition.

Through this project, my team and I have successfully surveyed all shallow parts of the lake with total surface of 164 km2, which allowed us to rediscover the snail existence and map the population distribution in the lake. Out of 32 stations suggested by the project advisor, Dr. Thomas von Rintelen, to survey, only in 20 stations T. zeamais can be observed. Major threats including thick algal bloom covering the rocks’ surface and invasive alien species have been documented and been linked closely to the decline of Tylomelania. Educational campaign were also carried at two elementary schools in two villages around the lake, engaging 103 students in conservation campaign through storytelling and educational comic. Additionally, the team attempted to breed the snails and eventually succeeded in breeding them ex situ before releasing them back into the lake.

To sum up, apart from successfully confirming the existence of T. zeamais, major actions are undoubtedly required to solve the issue of habitat deterioration and invasive alien species in Lake Matano, which will ensure the survival of endemics for years to come.

Looking Ahead

The project has not only supported the implementation of planned activities but has also facilitated the establishment of a youth-led organisation called Tapak Diversitas Hayati Nusantara (TARSIUS). With this team, we have committed to take actions beyond this project to collaboratively save endemics of Sulawesi, particularly in Malili Lake System, through biodiversity conservation. Hence, there are some follow up activities that we expect to see in the near future.

• Continuous population monitoring, following a baseline data, series of monitoring are essential to see the change of population and habitat condition over time.
• Eradication of invasive alien species (on-going) has been one of concrete actions to reduce the intensity of threats faced by endemic biota in Lake Matano. Funded by another donor, TARSIUS is now leading an eradication program in the lake by combining science and community based action to give pressure on invasive species population while hoping that the endemics will recover.