Jacqueline Choo

Wun Pin

Supervisor: Assoc. Professor Darren Yeo Chong Jinn

Project: Trophic interactions in tropical lentic systems: evaluating the relative importance of nutrient enrichment versus trophic cascade and the effect of intraguild predation.

Nutrient enrichment is known to be detrimental to water bodies as it promotes algae blooms which might produce toxins and lower the water quality. Based on the trophic cascade theory, biomanipulation mainly involves the addition or removal of predators which subsequently have effects down the food chain. For instance, the removal of planktivorous fish can result in the increase in zooplankton population which subsequently lead to a reduction in phytoplankton and algae population. Hence, this study aims to determine which effect (nutrient enrichment or trophic cascade) is stronger in tropical lakes. Furthermore, the effect of intraguild predation will be studied as it is hypothesized that the presence of an intraguild predation structure can lead to a weaken trophic cascade effect. The results can be used as a management tool for managing tropical lakes as there will be better understanding of which approach is more effective in reducing algae blooms.

Tan Zhi Wan

Supervisors: Assoc. Professor Darren Yeo Chong Jinn

Project: Habitat characterisation of freshwater Macrobrachium shrimps in Singapore

Benthic invertebrates such as freshwater shrimps play important ecological roles in food web ecology and nutrient cycling of  tropical streams. However, Singapore has experienced large scale urbanization which has resulted in a huge reduction in shrimp habitats. Remaining natural streams situated in protected areas are often impacted by anthropogenic modifications, including concretisation, forced step pools and trail modifications which alters natural rates of sedimentation and erosion of substrate and organic matter. Yet, little is known about habitat associations of freshwater Macrobrachium shrimps in Singapore. Hence this project aims to establish a baseline for habitat characterisation of freshwater Macrobrachium shrimps in Singapore. Additionally, functional response can explain processes that affects the distribution and assemblage of shrimps. Given shrimp species also exhibit associations with different substrates and physiological stresses including changes to their habitat can affect resource consumption, this project also aims to look into a local research gap, to understand the effect of substrate type on resource consumption of native Macrobrachium species which can help inform the species’ resilience to anthropogenic disturbance.

Darren Lee Kay Oon

Supervisors: Assoc. Professor Darren Yeo Chong Jinn & Dr. Maxine Mowe

Project Title: Microplastic abundance and distribution in local water bodies and ingestion by freshwater macroinvertebrates in Singapore

Microplastics are found in many freshwater bodies worldwide, however the impact that these microplastics (smaller than 5 mm) have on freshwater macroinvertebrates communities is not well known. Previous studies have found that microplastics can be ingested by the macroinvertebrate taxa, but there is no clear evidence of microplastic ingestion in Singapore’s freshwater invertebrate fauna. Thus, this project is aimed at 1) comparing the abundance of microplastic and their ingestion by macroinvertebrates among a few local freshwater environments, 2) drawing up a possible correlation between the abundance of microplastic in the selected freshwater environment and that ingested by the macroinvertebrates living in them and 3) investigating the possibility of significant differences in microplastic ingestion by macroinvertebrates with different feeding types. To do so, field sampling of various local water bodies (Jurong River, Sungei Ulu Pandan, Windsor Nature Park and Bishan Ang Mo Kio Park) for microplastics and freshwater macroinvertebrates and chemical gut digestion of said macroinvertebrates will be carried out.

Shermaine Teo Huimin

Supervisor: A/P Darren Yeo Chong Jinn

Project: Investigating the population structure and condition factor of the Singapore Freshwater Crab, Johora singaporensis.

Johora singaporensis is an endemic potamid of freshwater crab in Singapore which has been classified as “critically endangered” by the International Union for Conservation of Nature (IUCN). The species is restricted to only a few streams in Singapore due to relatively specialized habitat preferences coupled with rarity and disruptions of its preferred unique habitat. Hence, understanding the demographics of Johora singaporensis across space and time, as well as the potential effects of endogenous and exogenous variables on their condition factor can aid in informing conservation management of the species. This project aims to: 1) monitor spatial and temporal trends in the population size and structure of the crabs, 2) explore and compare the condition factors of the crab across streams and seasons and 3) investigating how the aforementioned differences in condition factor might be affected by abiotic habitat factors.