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Study by PUB, NUS identifies 55 fish species in Singapore's 17 reservoirs

2021-08-09 00:00:00.0 海峡时报-新加坡原网页

SINGAPORE - A recently-concluded biodiversity study of Singapore's reservoirs has revealed much about the distinct aquatic communities living in them, along with their respective food webs.

The seven-year-long study was carried out by the national water agency PUB in collaboration with researchers from the National University of Singapore's Freshwater and Invasion Biology Laboratory at the Department of Biological Sciences.

It also looked at how the water quality and ecological state of the country's reservoirs could be improved.

A total of 55 fish species were identified across the 17 reservoirs, each one recording a range of between nine to 21 species, said Ms Tricia Poh, a biologist at PUB's water quality department.

"The reservoirs were dominated by non-native species - where a significant number had originated from the aquarium trade, and likely stemmed from the release of unwanted animals into the reservoirs," said Ms Poh.

The largest family found in the reservoirs are the cichlids with 14 species - the most common being the eartheater cichlid and the green chromide, she noted.

Cichlids are typically omnivores, which feed on both aquatic plants and invertebrates, such as prawns and snails.

She noted that the only two native species found in all 17 reservoirs were the marbled gudgeon, an invertivorous fish that inhabits rocky areas at the bottom of the reservoir bed, and the common snakehead, an apex predator which feeds on other fish.

"Overall, the findings indicated that each reservoir houses distinct aquatic communities with unique combinations of food web interactions among the fish, macroinvertebrates and plankton there," said Dr Jeffrey Kwik, senior research fellow at the NUS' Department of Biological Science.

For instance, the food web at Upper Peirce reservoir was simpler and more robust compared to Serangoon reservoir, making it more resilient to changes and disturbances, said Dr Kwik, who is also the co-principal investigator of the study .

"This may be attributed to the fact that Upper Peirce is an older and protected inland catchment reservoir with fewer anthropogenic disturbances, whereas Serangoon reservoir is a younger, unprotected coastal reservoir that is easily accessible to the public."

To improve the water quality of the reservoirs, the research team also conducted small-scale and short-term biomanipulation experiments that significantly impacted the population of macroinvertebrates, such as midges in certain reservoirs, said Dr Kwik.

Dr Jeffrey Kwik holds a fish caught via electro fishing at Serangoon Reservoir on Aug 5, 2021. ST PHOTO: JASON QUAH

Biomanipulation is a way of altering the ecosystem by adding or removing certain species.

"However, as each reservoir's ecosystem is unique, our studies suggest a need for biomanipulation strategies to be catered specifically to each individual reservoir," he added.