Ganl. Bull. Singapore 70 (Suppl. 1) 2018 
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Lower 1 Lower Z Lower 3 Mid 1 Mid 2 Mid 3 Upper 1 Upper 2 LPR 
Subcatchment 
■■Total species —-Total Individuals 
Fig. 2. Species richness and abundance graph of odonates at various sub-catchments. 
sub-catchments had high abundance and species richness. The comparative site in 
Lower Peirce sub-catchment had the highest abundance and relatively high species 
richness. Mean species richness ranged from 3.5 to 9.25 species/site with the highest 
mean species richness at Lower 3 and the lowest at Mid 1. 
The mean species diversity at each sub-catchment was plotted using Shannon- 
Wiener Index (H’) (Fig. 4). Lower 3, with H’ value of 0.88, had the greatest species 
diversity among the sub-catchments, while Mid 1, with H’ value of 0.46, had the 
lowest species diversity. 
Odonate larvae 
Larvae were collected together with aquatic fauna surveys. The specimens were 
identified to family level. Table 2 shows the mean abundance of larvae collected from 
each survey site. The most abundant family was that of Libellulidae, with a total of 33 
identified at six of the eight sites surveyed. 
Distribution pattern and habitat characteristics 
Hierarchical clustering (Fig. 5) and DC A (Fig. 6) indicated that three main groupings 
of sites existed, each with a distinct community of associated species. Based on one¬ 
way PERMANOVAtest, all groups different significantly from each other (p=0.0001). 
Further analysis by CCA (Fig. 7, Table 4) with 12 significant environmental variables 
which were selected based on a multivariate liner regression model test (Table 
3). Results showed that these groups were significantly associated with several 
environmental variables. The first group of sites are mostly located at the outskirts 
of the Nee Soon freshwater swamp forest, including Lower 1 A, B, C; Lower 2 A, B; 
Lower 3 D and LPS. Species representative to this group were mainly Neurothemis 
fluctuans, Acisoma parnorpoides, Trithemis festiva, Cratilla metallica, Pseudagrion 
