Abstract

An intertidal fish assemblage was studied in central Chile for 15 years in three localities: Isla Negra, El Tabo, and Las Cruces. Analyses of their multivariate dissimilarities were carried out considering temporal and spatial factors. Temporal factors included intra-annual and year-to-year variability. Spatial factors included locality, intertidal tidepool height, and each tidepool considered as a unique unit. Complementary to this, we tested the hypothesis that the El Nino Southern Oscillation (ENSO) would help explain year-to-year dissimilarities in the multivariate structure of this fish assemblage for the 15 years of data. To this end, the ENSO was regarded as a continuous inter-annual process as well as a set of discrete events. Additionally, dissimilarities in the temporal dynamics of the fish assemblage were evaluated considering each locality and tidepool unique units. Results indicated the following: (i) The most representative species for the whole area and period of the study were Scartichthys viridis (44 %), Helcogrammoides chilensis (17 %), Girella laevifrons (10 %), Graus nigra (7 %), Auchenionchus microcirrhis (5 %), and Helcogrammoides cunninghami (4 %); (ii) there is intra-annual (i.e., seasonality) and year-to-year multivariate variability in fish assemblage dissimilarities throughout the entire area of study, including all the tidepools and localities; (iii) when considering the spatial factor specifically, each tidepool unit, as well as their heights and localities, presented their own unique temporal yearto-year dynamics. The latter can be explained by the ENSO factor, also considering the intensity of the El Nino and La Nina events. In summary, the multivariate structure of the intertidal fish assemblage was statistically dissimilar when