Introduction: What conservation problem or question does your study address?Talangama tank is an artificial tank located in a densely populated area and is a highly important urban biodiversity refuge. Odonates play an important role in a wetland as predators and bioindicators. The diversity and phenology of odonata in Talangama wetland is hitherto unstudied and the contribution of different habitats to the odonata diversity in wetlands is also largely unknown in Sri Lanka. Thus this study is aiming at minimizing these knowledge gaps.
Methods: What were the main research methods you used?100*4 m transects were laid representing the four major habitat types found in the Talangama wetland namely, the tank, canals, paddy fields and marshland. Each habitat type is represented by 3 transects based on accessibility and availability of habitats. Transects are sampled once every month for a duration of one year between 0800-1100 h using 30 minutes for each transect. Sampling order of transects are varied during visits and all the sampling will be done by same observer. Every odonate observed is visually identified in the field and recorded with species and sex. Breeding activities of the odonates such as mating, oviposition and emergence of adults are also recorded. Habitat preference of each species will be analysed by the % occurrence of a species in different habitats. Distribution of breeding activities along the year will allow identifying peak breeding seasons. Suitable statistical software will be used in analysis.
Results: What are your most important results?The initial sampling recorded 15, 11, 15 and 8 odonata species from the tank, marsh, canal and paddy field habitats respectively. Altogether 30 odonata species has been recorded thus far including 2 nationally VU species (Onychargia atrocyana and Ceriagrion cerinorubellum) and 9 nationally NT species. Further sampling will provide data to investigate the habitat preference of odonata in a wetland and seasonal variation of their populations and breeding activities.
Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?The end results of the study will highlight the importance of different habitats including the invasive Annona glabra dominated marshlands, for the diversity of odonata in an urban wetland. It will also provide some knowledge on the ecology of odonates present in the area. These results will be useful in management of similar wetlands with a better odonata diversity and ecological stability. The species presence data can be used for the next national red list assessment.