Morphological Survey

To compare the morphology of individuals of D. antarctica and D. willana with different degrees of wave exposure, we conducted a field survey at St. Kilda Beach, a suburban beach near Dunedin, in February 1999. Quadrats (1 x 1 m) were randomly placed within stands of kelp of both D. antarctica and D. willana. The wave exposure typical of any particular quadrat was qualitatively determined by the predominant blade morphology of the kelp growing within the quadrat. Thus, individuals of both species were categorized as either "wave exposed" or "wave sheltered." Factored by species and wave exposure, four random quadrats were used to sample each of the four groups, giving a total of 16 quadrats (D. antarctica: sheltered/exposed; D. willana: sheltered/exposed). All individuals of either Durvillaea species growing within a quadrat were harvested and four morphological parameters were recorded. Measurements of the blade length, stipe length, and maximum stipe diameter were used to examine possible correlations between these three morphological parameters and the species or wave exposure as indicated by the forth parameter, blade morphology.

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