PATTERNS OF ALGAL SUCCESSION IN A PERTURBATED MARINE INTERTIDAL COMMUNITY1

Abstract

ABSTRACTPatterns of algal succession for a sewage‐polluted and an unpolluted habitat near Wilson Cove, San Clemente Island, California, were studied from December 1974 to June 1977. Resident populations were analyzed for 56 fully denuded and 34 undisturbed control quadrats during 11 assessment periods. The denuded quadrats in the perturbated (polluted) habitat showed recovery within 1.0 mo as determined by cover, percent similarity and species diversity comparisons with control plots. The short recovery times of the algal populations dominating the perturbated habitat indicate that these species maintain relatively constant overall abundances due to their potential for rapid recruitment and growth. Denuded quadrats in the unpolluted habitat did not show recovery even after 30.0 mo. These quadrats were dominated during the first 1.3 mo by algae characteristic of the perturbated area, including filamentous Ectocarpaceae, colonial diatoms and bluegreen algae. Petalonia fascia (Müll.) Kuntze (1.3–3.0 mo), and Scytosiphon lomentaria (Lyngb.)J. Ag. and Colpomenia sinuosa (Roth) Derb. & Sol. (1.3–5.0 mo) were abundant shortly following plot denudation and provided thick growths that may have excluded other algae. The similarity between the species occupying the sterilized plots during the first few months and those that provide the majority of cover in the perturbated area supports the hypothesis that the dominant algae of the upper and midintertidal regions of this habitat consist largely of early successional or opportunistic species with high capacities for growth and reproduction. Additionally, these experiments suggest that algal populations described for other perturbated epilithic systems also represent resilient subclimax associations.