Damsels in distress – seasons, habitat structure and water pollution changes damselfly diversity and assemblage in urban wetlands

Abstract

Odonates are considered to be good ecological indicators, hence, they are used in biological assessment of habitat quality. However, species responses may vary spatiotemporally and therefore, it is useful to establish species-habitat relationships at a regional level. To test if tropical urban odonates respond to seasons, and to explore species-habitat relationships with an emphasis on water pollution, I studied six wetlands in the city of Pune for a year. I also investigated whether combining data on dragonflies and damselflies, as is often done in many studies, skews the results. I recorded seasons, water pollution and habitat attributes as predictors of the odonate diversity and assemblage. I analyzed the data on dragonflies, damselflies and odonates (dragonfly-damselfly combined) separately for seasonal variation, and species-habitat relationships. I used multiple regression and canonical correspondence analyses. Forty-four species were recorded during the study. No seasonal variation was detected, except for damselflies, which showed an increase in the diversity and species number post-monsoon. Multiple regression analysis showed that damselfly and dragonfly diversity varied as a function of season and water pollution, and monsoon respectively. In pre-monsoon, damselfly diversity marginally increased with pollution. Both the analyses suggest that combining data on dragonflies and damselflies may skew the end results. Therefore, I recommend further intensive and long-term research using accurately sampled habitat and pollution attributes, as well as habitat restoration through conserving urban green spaces and promoting gardens with streams and ponds