SURVIVAL OF FUCOID EMBRYOS IN THE INTERTIDAL ZONE DEPENDS UPON DEVELOPMENTAL STAGE AND MICROHABITAT

Embryos of the fucoid alga Pelvetia fastigiata (J. Ag.) DeToni were outplanted into the intertidal zone to assess survival during the physical stress brought about by emersion during a single low tide. Survival varied among microhabitats. Under the adult Pelvetia canopy, survival of 6-h-, 24-h-, 48-h, and 1-wk-old embryos was nearly 100%. Almost all embryos of all ages died in exposed habitats on bare rock or within habitats where the Pelvetia canopy was removed experimentally. However, within red algal turfs, where most juvenile Pelvetia occur, survival was unusually age specific: 24- to 48-h-old embryos survived poorly compared to younger (6 h old) or older embryos (1 wk old). Survival patterns reflected microhabitat temperatures during the experiments. The fate of young post-settlement stages must be studied at these fine temporal and spatial scales to understand the organization of intertidal communities.