Diversity and distribution of caddisflies (Insecta, Trichoptera) in Singapore’s freshwater streams

In land-scarce Singapore where fresh water is a critical resource, Trichoptera communities can serve as a biomonitoring tool yet are poorly known. This study seeks to address this gap by establishing a preliminary understanding of trichopteran diversity and distribution in Singapore’s freshwater streams. From October 2023–January 2024, 11 stream sites across forested nature reserves (n = 5), buffer parks (n = 4), and urban areas (n = 2) were surveyed for trichopteran larvae. Only eight sites (four in forest streams, four in buffer streams) yielded Trichoptera, totalling 107 larval specimens comprising six families (Calamoceratidae, Ecnomidae, Hydropsychidae, Leptoceridae, Odontoceridae, and Polycentropodidae). Leptoceridae were most abundant, while Ecnomidae was the rarest, and Hydropsychidae were the most widely distributed. In this study, Trichoptera were absent from the urban streams, which had greater depth and total dissolved solids, but similar Trichoptera assemblages and environmental parameters were recorded in both forest and buffer streams. Although differences between the latter two stream types were not statistically significant, buffer streams had the highest abundance and taxonomic richness. Comparison with past literature also reveals differences in recorded Trichoptera diversity, thus this study presents an updated record for Trichoptera in Singapore’s streams. These findings further add to a baseline for future biomonitoring, research, and informing long-term freshwater conservation efforts in Singapore.