Mayfly Nymphs as Water Pollution Bioindicator

Abstract

Ephemeroptera is an order of insects, comprising of over 3000 species (Barber-James et al., 2008). Ephemeroptera means Short lived, winged adults having lifespan about 1–2 hours to few days and maximum of 14 days. They are terrestrial in adult life and aquatic in the immature called naiads (nymphs). The sub-imago is the early, reproductively immature adult and the mature ones are imago. The nymphal stage of mayflies is always aquatic and they are dominant in life history stage. Depends upon external factors such as temperature, food availability and current velocity the nymphs undergo a series of molts as they grow (Brittain and Sartori, 2003). Water temperature is higher at summer season and lower at winter season. The maximum pH value recorded in the month of August (monsoon) and minimum in the April (summer). The pH was alkaline throughout study period. The maximum values recorded in the month of summer and winter. The high Do in summer attributed to increase in temperature and duration of bright sunlight. The maximum value recorded in the month of December (winter) and absent in the month of March (monsoon). The results showed that nymphs of mayfly are abundant in the month of March, April and May because of suitable water conditions like temperature, pH and DO. The lower number of nymphs observed in month of July, August and September in rainy season.