Effect of salinity gradients on species composition of Odonata naiads

Abstract

In present study the relationship between salinity gradients of various water bodies and inhabiting Odonata naiads was studied. Naiads, being a popular group of water pollution indicators, were studied. Totally 35 sites were surveyed for collection of naiads and water samples were taken from each positive site. Eight factors viz. Electrical Conductivity (Ec), Calcium +Magnesium (Ca+Mg), Sodium (Na+), Carbonates (Carb), Bicarbonates (Bc), Sodium Absorption Ratio (SAR) and Residual Sodium Carbonate (RSC) were studied for each water sample. Interesting results were obtained both for Anisoptera and Zygoptera species. Among dragonflies, genus Crocothemis of family Libellulidae appeared to be resistant while Genus Gomphidia and Sympetrum of families Gomphidae and Libellulidae were observed to be affected by variations in salinity gradients of waters of different sites. However in case of damselflies Genus Ischnura of family Ceonagrionidae and genus Pseudagrion of family Ceonagrionidae were observed to be adaptive followed by genus Ceriagrion of same family. As an overall conclusion, Anisopterous naiads were found more susceptible to salinity gradients than Zygoptera and thus can be better used in water salinity diagnoses studies.

Keywords

• salinity
• chemical composition
• Odonata
• naiads