Oxygen and temperature tolerance in Cloeon perkensi larvae (Ephemeroptera: Baetidae)


Laboratory experiments were carried out to determine the water, temperature and oxygen concentration ranges in which the larvae of the
Mayfly, Cloeon perkinsi Barnard (Ephemeroptera; Baetidae) can survive. The observed mean 24 hours LC50 ranged from 4.2 to 4. 6mg (mean =4.35 ± 0.141 mg ° while calculated mean was 4.4 mg.

Survival was maximal (100%) at 200 and 25°C. The calculated lower LC50 was 7.5°C and the upper, 35°C which implied that C. perkinsi larvae can withstand wide temperature fluctuations. These
results are in keeping with the findings for this and related species in many tropical lakes. This is because C. perkinsi larvae are mobile and can move from areas of high temperatures and low oxygen
concentrations to the shallows where submerged aquatic weeds provide shelter and abundant oxygen supply. This behaviour is very significant to their microdistribution.

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