W. T. Edmondson

Conochilus in Lake Washington

The rotifer Conochilus unicornis appeared in Lake Washington sporadically and usually in small numbers during a total of 28 years of observation since 1933. Conochilus hippocrepis was present even less frequently until the 3 year period 1977–1979, when it became extraordinarily abundant. The abundances of food organisms and known predators have been examined.

Rotifer study as a way of life

When Claudia Ricci asked me to present a review of my research program on rotifers at the Fifth International Rotifer Symposium I was puzzled about what to do because I did not think I had a program. All my life various opportunities have come up and I have gone along step-by-step, doing whatever seemed most interesting at the time, within the normal constraints of existence. In fact, when I look back now I can see a sort of pattern, but it was not the result of planning. Apparently there was some selection on my part from a random assortment of opportunities.

Morphological variation in Kellicottia longispina

The lengths of the body, the posterior spine and the three longest anterior spines were measured for 25 specimens of Kellicottia longispina from each of the eight lakes distributed from Imikpuk at Point Barrow, Alaska (latitude 71° 15′) to Lake Washington (latitude 47° 38′). Collections were available for more than two dates from six of the lakes. Temperature ranged from 1.2° to 18 °C. Mean lengths and ratios were examined in relation to latitude and temperature. Each population differed from the others in some aspect of absolute size, variability, or shape as expressed by the ratios of the dimensions. The population from Point Barrow is similar but not identical to Olofssons var. heterospina.

Mt. St. Helens ash in lakes in the lower Grand Coulee, Washington State: With 1 figure in the text

In 1979, an experiment to assess the effects of an introduced predator, cutthroat trout (Salmo clarki henshawi), on the biota of two alkaline lakes, Soap Lake and Lake Lenore, in Washington was initiated. This report discusses the effects of the Mt. St. Helens eruption and associated ash fall on the experiment. (ACR)