Underwater microscopic sampling of a sublittoral kelp community

An encased incident-light microscope was constructed for use underwater to determine the relative abundances of micro-organisms living on natural sublittoral substrata in an Ecklonia radiata (C. Agardh) J. Agardh forest. By comparisons of data gathered using the microscope with data obtained from microscopic sampling of chips of natural substratum in the laboratory, the practicality and accuracy of the underwater microscope could be assessed. The repeatability of microscopic sampling in the field was determined by sampling certain areas of natural forest twice on the same day.A pilot survey of natural substrata in the kelp forest was done to determine patterns of spatial variability in the distribution of organisms sampled with the microscope. Analyses of variance and cost-benefit analyses of these data allowed calculation of optimal patch sizes and numbers of replicates to be used in future experiments. The importance of testing field methodologies and pilot studies was noted.