Recruitment and Standing Stocks in Populations of One Green Alga and Five Brown Algae in the Intertidal Zone Near La Jolla, California, During 1973-1977

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Abstract
For 4 yr, populations of Codium fragile, Eisenia arborea, Egregia laevigata, Sargassum muticum, Halidrys dioica and Cystoseira osmundacea were surveyed in 25 m2 permanent quadrats at La Jolla, California, USA. The algae had annual periods of reproduction and recruitment and thus annual standing stock variations. Most species reproduced in winter-spring and/or recruited in spring-summer. S. muticum, reproduced in late spring and recruited at the end of summer. For most species, seasonality was adaptive for regional tidal exposure and storm patterns, desiccation, water motion and availability of free space. Populations of several species varied substantially between years: between 1973 and 1977 standing stocks generally increased for S. muticum and C. osmundacea, and declined for C. fragile, E. laevigata and E. arborea. Within years the recruitment and standing stocks of each species were generally similar at comparable quadrats. Population fluctuations were caused by regional environmental factors such as cloud cover, air or water temperature, and wave action varying during the reproductive and recruitment periods of each species; no single factor, however, could be identified as predominantly important.