Temporal and spatial variation in the morphology of the brown macroalga Hormosira banksii (Fucales, Phaeophyta)

Abstract

Hormosira banksii is a morphologically variable macroalgal species from southeastern and southern Australia, which has been previously categorised into ecoforms according to habitat. This study is by far the largest quantitative evaluation of morphological variation in H. banksii. covering 74 sites from South Australia, Victoria, New South Wales and Tasmania. Morphological features from 505 samples were analysed using principal components analysis, with the patterns identified being statistically assessed with a Monte Carlo permutation test. There was considerable morphological variation between samples taken at several marine (but not estuarine) sites in both 1994 and 1999. However, this variation was not consistent across either morphological features or populations, and presumably represents random fluctuations. Analysis of the entire dataset demonstrated a significant difference between samples growing in marine and estuarine habitats. Further assessment of variation within these two groups revealed some significantly different populations based on geographical locations but not habitat variation. While this study presents strong evidence for two distinct taxa within H. banksii (marine versus estuarine populations), the taxonomic status of this species should not be altered until genetic studies have been conducted.