Variations in standing stocks of central California macrophytes from a rocky intertidal habitat before and during the 1982-1983 El Nino

Abstract

Intertidal macrophytes inhabiting a central California site near Point Piedras Blancas were investigated before and during the extreme 1982-1983 El Nitio/Southern Oscillation (ENSO). In contrast to its effects on South American intertidal systems, the 1982-1983 ENSO did not dramatically or immediately affect these central California macrophyte populations. Observed variations from pre-ENSO patterns in total macrophyte abundance and diversity were few and mostly limited to the late-ENSO winter (December 1983); values for the ENSO summer (August 1983) were not significantly different from those obtained for 2 previous non-ENS0 summers at high-, mid-and low-intertidal levels. At the population level, increases in cover of crustose coralhne algae and decreases in fleshy red algae, such as the erect phase of Mastocarpus papillatus, were more extreme during the late ENSO winter. Multlvariate analyses distinguished December 1983 from the other winter periods at all 3 intertidal levels, but August 1983 could not be discriminated from pre-ENS0 summers.