ECOLOGICAL CONSEQUENCES OF COSEISMIC UPLIFT ON THE INTERTIDAL KELP BELTS OF LESSONIA-NIGRESCENS IN CENTRAL CHILE

Coseismic uplift from the Chilean earthquake of 3 March 1985 caused changes in the biomass and vertical zonation of rocky intertidal organisms at four sites along 150 km of the central Chilean coast. The 11-60 cm uplift caused widespread mortality mainly of the dominant intertidal kelp Lessonia nigrescens, reducing its biomass in the upper part of its pre-earthquake range and altering the vertical zonation. The L. nigrescens belt shrank from the top by about 0·5-1 m within 1 year of the shock, then expanded downward by about 1 m. An important part of the primary space liberated at the pre-earthquake upper border of Lessonia was invaded by the barnacles Chthamalus scabrosus and Jehlius cirratus. None of the foregoing changes occurred at two control sites located outside the shock area. The ecological effects of these recurrent sudden and drastic environmental processes on rocky intertidal communities include the liberation of primary space, enhancement of mosaic areas and modification of the vertical zonation of competitively dominant organisms. © 1990.