Primary signal: Ecological and environmental factors—Report from Working Group 2

Alkenone-based proxies are routinely used for paleoceanographic and climatologic reconstructions despite the fact that their calibration to environmental parameters is still a matter of debate. Significant differences are observed among culture calibrations using different strains of alkenone producers, between regional field calibrations within the euphotic zone, and between water column- and core top-based calibrations. The reasons for these discrepancies are not well understood and call for further evaluation. The possibility is raised that several aspects of genetics, physiology, and ecology of alkenone-producing haptophytes may be responsible, and suggestions of future research are proposed.