Water quality changes Odonata assemblages: Habitat associations and Seasonal changes in Odonata assemblages across land-use types
Department Of Biodiversity, Abasaheb Garware College, Pune
Purushottam Patil, Pankaj Koparde
Introduction: What conservation problem or question does your study address?
Odonata, a group of freshwater insects, rely on water during their entire life-cycle. Micro-habitat variables generally shape assemblages in such groups; however studies on this are few, globally. Our work tries to find out whether micro-habitat structure or water quality and/or seasons influence Odonata assemblages and diversity across land-use types. Another objective of the project was to document Odonata fauna from Pune and update recent lists.
Methods: What were the main research methods you used?
We studied adult Odonata fauna from six localities in and around Pune city during June 2012-August 2013. Odonates were recorded on belt transects of 120m X 10m (length X width) dimensions. Sampling was done in duplicates across three seasons – Pre-monsoon, Monsoon and Post-monsoon. Species sample curve was plotted. Chao1, Chao2 and Michaelis-Menten estimate of species number were calculated. Habitat variables, which were measured semi-quantitatively, were noted during each visit. Species richness across seasons was compared and a multiple regression analysis was carried on diversity index and across seasons and sites and habitat variables. A Canonical correspondence analysis (10,000 bootstraps) was carried out to find out variables driving assemblages.
Results: What are your most important results?
Multiple regression analysis did not show relation between habitat variables and diversity index (R^2 = 0.2277, p = 0.86819). Most of the species aggregated in high water quality areas with good amount of water, surrounded by grass; however few species were found to be relatively tolerant to low water quality. We recorded 60 species during the study, of which 39 were observed on transects. As per species number estimates, our study captured a near complete list of species.
Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?
Although we did not find effect of habitat variables on diversity, assemblages were prone to changes in water quality and micro-habitat structure. Our study recorded ~80% known Odonata fauna of Pune. Many species were found to be highly localized, perhaps due to recent habitat loss. The habitat degradation was mainly due to anthropogenic disturbances. Conservation awareness and solid waste removal drives might maintain suitable habitat for odonates of Pune.