curve for autotrophic growth following a period of heterotrophic growth, however, is not so easily explained. Growth was definitely inhibited in relation to the level of the control, but toxicity was greatly reduced in comparison to autotrophic cultures. This reduced toxicity was too great to be attributed to the acetate medium. These observations suggest that Chlamydomonas reinhardi might be capable of degrading atrazine under conditions of heterotrophic growth.

Contributed by P. V. Kirch, May 15, 2004 Beginning ca. A.D. 1400, Polynesian farmers established permanent settlements along the arid southern flank of Haleakala Volcano, Maui, Hawaiian Islands; peak population density (43-57 persons per km 2 ) was achieved by A.D. 1700 -1800, and it was followed by the devastating effects of European contact. This settlement, based on dryland agriculture with sweet potato as a main crop, is represented by >3,000 archaeological features investigated to date. Geological and environmental factors are the most important influence on Polynesian farming and settlement practices in an agriculturally marginal landscape. Interactions between lava flows, whose ages range from 3,000 to 226,000 years, and differences in rainfall create an environmental mosaic that constrained precontact Polynesian farming practices to a zone defined by aridity at low elevation and depleted soil nutrients at high elevation. Within this productive zone, however, large-scale agriculture was concentrated on older, tephra-blanketed lava flows; younger flows were reserved for residential sites, small ritual gardens, and agricultural temples.