Qualifying Examination
“Investigating the introduction and impacts of gastropods in Singapore’s fresh waters”
Ng Ting Hui
Graduate Student
Dept. of Biological Sciences, NUS
Friday, 19 April 2013: 10.30am
@ DBS Conference Room (S3 L5)
Supervisor: Asst. Prof. Darren Yeo, Dr. Tan Heok Hui
All are welcome
Abstract:
“Introduction of freshwater gastropods are a concern globally owing to negative impacts like habitat-modification, competition with native species, and the spread of zoonotic parasites. In contrast to other native aquatic fauna in Singapore, which are usually found in unmodified habitats, freshwater molluscs here are almost exclusively found in human-impacted habitats, e.g., reservoirs and canals. Hence, it is suspected that many species may have been introduced. The lack of comprehensive information regarding native freshwater molluscs has made it difficult to determine the true status of many species found here. My inspection of museum collections and unpublished data found that only six species of gastropods were found here half a century ago, while the current malacofauna consists of 33 species, including freshwater bivalves. Preliminary data from a review of freshwater mollusc introductions to Southeast Asia shows that the aquarium trade has been most often proposed as a source for introductions, including in Singapore. A survey of the aquarium trade here revealed 58 species. While the results indicate that the trade is a likely introduction pathway, it is also implied that there are other potential pathways.
I also aim to investigate if the genetic diversity of local freshwater molluscs can resolve the status of cryptogenic species, and to examine the factors facilitating the spread of freshwater molluscs by investigating physico-chemical parameters and life history traits that may influence their distribution in canals. Finally, preliminary data indicates that the decline in distributions of native apple snail Pila scutata coincides with the introduction and spread of the confamilial golden apple snail Pomacea canaliculata. Potential ecological overlap between these two species will thus be investigated. The results of the genetic and ecological studies will be used to determine the management measures necessary to control introduced freshwater gastropods in Singapore.”
The Biodiversity Crew @ NUS 