Conserving a natural heritage icon

27 Jun 2015 NUS researchers highlighted conservation challenges facing the Singapore freshwater crab, and the measures being taken.

Discovered in 1986, the critically endangered Singapore freshwater crab, Johora singaporensis, (see Figure) known only from a few hill streams in Singapore and nowhere else in the world, is among the top 100 most threatened species globally. Surveys conducted by NUS researchers led by Dr Daniel NG Jia Jun and Prof Darren YEO Chong Jinn from the Department of Biological Sciences in NUS revealed that the species had declined in its original locality within a nature reserve, but continued to thrive in a few unprotected sites outside it.

The decline was believed to be associated with stream acidification, which may be the first documented example of such an effect on a tropical freshwater species. As its occurrence in a protected area does not necessarily guarantee its survival (i.e. it is insufficient to simply leave “good enough” alone), long-term monitoring together with other conservation measures are also needed to ensure that this unique species does not become globally extinct. Of particular importance are onging collaborative conservation efforts between NUS and the National Parks Board, Singapore (NParks) and Wildlife Reserves, Singapore (WRS), which ensure an effective, comprehensive, multi-pronged approach to safeguarding the species. One recent product of their combined efforts (working with the International Union for Conservation of Nature, IUCN), is the publication of a detailed conservation strategy for the Singapore freshwater crab—the first time this has been done for a single invertebrate species—that provides a structured framework and roadmap for the conservation of the species.


The critically endangered Singapore freshwater crab (Johora singaporensis) hiding among leaf litter in a hill stream. [Image credit: Daniel Ng]



1. Ng DJJ, McGowan PJK, Raghavan R, Cai Y, Cumberlidge N, Davison G, Luz S, Yeo DCJ. “Conservation Strategy for the Singapore freshwater crab Johora singaporensis”, Singapore. (2015). 19 pp.

2. Ng DJJ, Yeo DCJ, Sivasothi N, Ng PKL. “Conservation challenges and action for the Critically Endangered Singapore freshwater crab Johora singaporensis". Oryx 49 (2015) 345-351.