XVI International Botanical Congess

Reproduction and recruitment varied seasonally and spatially in a southern California population of Pelvetia compressa (J. Ag.) DeToni. The number of fertile receptacles peaked during fall while zygote recruitment on disks was greatest from fall through late winter. Receptacle production and recruitment varied strongly over horizontal scales of centimeters to tens of meters. Recruitment of zygotes was greatest beneath the rockweed canopy and fell off sharply at short distances (< 50 cm) from P. compressa fronds. Successful recruitment of juvenile plants (< 2 cm) in fixed field plots was very low compared to egg and zygote production indicating high mortality rates of these very early stages. (Supported by NOAA Grant NA46RG0472 to USC Sea Grant and the California Resources Agency).