Iridaea cordata, including varieties cordata (Turner) Bory and splendens (Setchell and Gardner) Abbott, has a geographic distribution that rims the north Pacific basin from Honshu, Japan to northern Mexico with its major populations from central California to southern Oregon (Abbott, 1972). Morphological and cytological descriptions of the life history stages have been reported (Setchell and Gardner, 1903; Kylin, 1928; Smith, 1938; Norris and Kim, 1972; Fralick and Cole, 1973; Kim, 1976) and the taxonomy of the genus has been reviewed (Abbott, 1971; Kim, 1976). The life history described (Kylin, 1928), involves the alternation of morphologically similar haploid and diploid generations. I. cordata is a source of the polysaccharide carrageenan and sporadic commercial harvesting of natural populations of this plant has occurred in northern California (Tseng, 1947) and Washington (Silverthorne and Sorensen, 1971). Some quantitative work on the population biology of Iridaea spp. (Hasegawa and Fukuhara, 1952; 1955; Fralick, 1971; Austin and Adams, 1974; Waaland, 1973; 1976; Hansen, in press) and other closely related genera, Gigartina spp. (Marshall et al., 1949; Burns and Mathieson, 1972) and Chondrus (Marshall et al., 1949; Taylor, 1970; Prince and Kingsbury, 1973; Mathieson and Prince, 1973; Mathieson and Burns, 1975) has been done.
This is the first detailed study designed to explore the relationships between the population biology and physiological ecology of a red alga: Iridaea cordata.
