The epiphyte Microcladia coulteri (Rhodophyta): changes in population structure with spatial and temporal variation in availability of host species

Abstract

A comparison of the population structures of the epiphyte Microcladia coulteri and its 3 host species, Prionitis lanceolata, Iridea cordata and Odonthalia f1occosa. was made at Beaver Point, Saltspring Island, British Columbia. The 3 host species had distinct seasonal patterns in density and size class distribution. Principal components analysis (PCA) and analysis of variance (ANOVA) were utilized to partition the variation in epiphyte population structure into components due to differences in season, host species, size of host thalli, host reproductive status, and host spatial distribution. Small percentages of total determined variation were accounted for by seasonality in the abundance of size class and reproductive components of the epiphyte population, and by distribution of the epiphyte between host species. Larger percentages were due to fluctuations in size of host thalli and spatial variation in availability of host substrata. Persistence of temporally and spatially stable populations of M. coulteri was due to differential use of available host substrata combined with continuous recruitment of the epiphyte.