Chan Yee Qi

Main supervisor: A/P Darren Yeo Chong Jinn
Co-supervisor: Dr Ang Yuchen
Project Title: Diversity and Distribution of Caddisflies (INSECTA: TRICHOPTERA) in Singapore’s Freshwater Streams 

Trichoptera, also known as caddisflies, is one of the world’s most diverse insect orders, boasting 16,266 species across 28 families that are distributed globally. As a holometabolous insect, Trichoptera larvae hatch from gelatinous-enclosed egg masses known as spumalin, and often feature five instar stages that lead to a cocoon phase, through which the adult emerges. Trichopterans can be found in the riparian zone, with both lotic and lentic freshwater systems providing important larval habitats. In these highly heterogeneous habitats, diverse trichopteran larval assemblages occur and fulfil multiple niches — this diversity is driven by the high functional diversity of Trichoptera larvae. Having low pollution tolerance, Trichoptera larvae also act as important bioindicators for water quality in freshwater habitats.   

Despite trichopteran diversity and importance, there has yet to be any comprehensive study done on Trichoptera distribution in Singapore. In addition, there are also no species recorded from Singapore to date, in which adult male caddisflies are required for species identification. Although larval DNA could alternatively allow for the identification of species as well, such adult-larval associations are currently not well-established in Singapore. Therefore, this study seeks to address these research gaps by addressing the following research questions:  

(1) What is the diversity and distribution of Trichoptera in Singapore’s freshwater streams across nature reserves, buffer parks and urban areas? 

(2) How does trichopteran distribution relate to environmental conditions and macroinvertebrate communities across sites?  

(3) Based on adult-larval associations, what species of trichopterans occur in Singapore’s freshwater streams? 

Hou Yunhan

Main supervisor: Dr. Hwang Wei Song
Co-supervisor: A/P Darren Yeo Chong Jinn
Project Title: Distribution and ecology of the introduced assassin bug Zelus renardii (Hemiptera: Reduviidae: Harpactorinae: Harpactorini) in Singapore

Singapore hosts a diverse range of introduced fauna species, from the common changeable lizards in urban greenery, to the Motoro stingrays in her reservoirs. In recent years, a new Reduviid (Assassin bug) Zelus renardii has joined their ranks. Originally from North America, it has now been recorded in various European, South American and Asian countries, likely introduced via the exotic plant trade. Its proliferation in foreign environments was aided by adaptations such as a generalist diet, intraguild predation, and a wide temperature tolerance range. Though prevalent in Singapore’s urban and park areas, it has yet to be recorded in naturalised areas like the Central Catchment Nature Reserve (CCNR). Additionally, limited knowledge of its local distribution and ecology warrants further research to truly determine its invasive potential. This project aims to offer the first insights into Z. renardii’s local distribution and ecology, setting the stage for future studies into its ecological impact and invasiveness.

Yeo Lifang

Main supervisor: A/P Darren Yeo Chong Jinn
Project Title: A survey of freshwater snails in the Central Catchment Nature Reserve and Buffer streams with a focus on Melanoides tuberculata diet and distribution

Forest streams are a critical part of freshwater habitats around the world. However, urbanisation and canalisation of waterways have led to few natural forest streams remaining in Singapore, confined to nature reserves. The Central Catchment Nature Reserve (CCNR) is one such nature reserve that also serves as a stronghold for native freshwater biodiversity in Singapore. On top of the removal and alteration of freshwater stream habitats, the added pressure of the introduction of alien freshwater species poses a huge threat to these ecosystems. Melanoides tuberculata, or the Malayan trumpet snail, is an example of a freshwater species that has been affected by invasion in its native range. Despite the species’ ubiquity in Singapore’s waterways, there is no comprehensive study investigating the diet and trophic niche of the native M. tuberculata in the streams of Singapore and if their diet and distribution has been affected by dual pressures of habitat loss and the introduction of non-native freshwater snails. This study therefore aims to investigate the abiotic and biotic factors that influence the differences in trophic niches, diets and distribution of M. tuberculata found in forest, buffer park and urban streams in Singapore. The study will address the following research questions: (1) Are there overlaps in diet and trophic niche between M. tuberculata and other freshwater snails occurring in the same habitat? (2) Are there differences between the distribution and diets of M. tuberculata across an urbanisation gradient?

Lim Yang Jin, Stanley

Main supervisor: Dr. Maxine Allayne Darlene Mowe
Co-supervisor: A/P Darren Yeo Chong Jinn
Project Title: Examining phytoplankton community responses to nutrient limitation with a focus on the effects of trace metals on Microcystis ichthyoblabe and Microcystis viridis growth and toxin production

Phytoplankton are microscopic organisms that can photosynthesise and constitute the base of food webs in Singapore’s reservoirs. However, some groups can produce toxins that negatively affect water quality. Many are also capable of blooming which could damage ecosystems. Macro-nutrients such as phosphorous and nitrogen are some nutrients that allow for such blooms to occur. Trace metals such as Iron, Manganese, Cobalt and Zinc are also important for many cellular functions. However, the effects of macronutrients on phytoplankton communities are understudied in the tropics. In addition, the effects of trace metals on growth and toxin production are less understood. This project aims to investigate differences in the phytoplankton community responses between protected and unprotected reservoirs through ex-situ nutrient-addition bioassay experiments and the observation of cell counts and biovolume data. More specifically, this study will also experimentally investigate the effects of trace metals on the growth and toxin production of cyanobacteria strains isolated from local reservoirs.