Hypereutrophication of an Hawaiian Alpine Lake

A drought during the period 1977-1978 resulted in a roughly fourfold reduction in the volume of Lake Waiau, a small perched body of water near the summit of a volcano in Hawaii, and an over 200-fold increase in the late-summer chlorophyll a concentration. The normal planktonic flora of the lake was replaced during this time by an almost complete monoculture of the chlorophyte Nannochloris bacillaris. Nutrients required to support this bloom appear to have been supplied by an influx of interstitial water as a result of the development of an unusual hydrostatic head between the perched groundwater around the lake and lake surface water. The lake had not fully recovered from this episode 2 yr after termination of the drought