THE EFFECT OF TEMPERATURE ON THE DEVELOPMENT OF RESTING EGGS OF DIAPTOMUS OREGONENSIS LILLJ (COPEPODA: CALANOIDA)

Abstract

Diaptomus oregonensis in Teapot Lake produces diapausing eggs between October and the time in November when a fall overturn deoxygenates the water and kills all zooplankton. The only visible difference between resting and subitaneous eggs was that the former were reddish‐brown and the latter green. Resting eggs incubated in the laboratory at about 4C in October and November will hatch at about the same time the following spring in the laboratory as they do in Teapot Lake, but they can be induced to hatch sooner at higher temperatures if they have experienced about 3–4 weeks at 4C. Diapausing eggs that have not initially experienced the low temperature are capable of surviving at warmer temperatures (14C) for extended periods and can subsequently be induced to hatch by exposure to cold.