MOBILE EPIFAUNA ON SUBTIDAL BROWN SEAWEEDS IN NORTHEASTERN NEW-ZEALAND

This paper examines the distribution and abundance of mobile epifauna > 1 mm inhabiting 10 species of subtidal brown seaweeds (Phaeophyceae) in northeastern New Zealand. Gammarid amphipods and isopods were the most abundant animals captured, while a diverse group of gastropods wa s also present at lower densities. Finely structured seaweeds such as Carpophyllum plumosum var. capillifolium and Cystophora retroflexa ten ded to support far more animals (up to 2000 ind, per 100 g algal wet w t) than did coarsely structured seaweeds. Comparison of epifaunas amon g C, plumosum growth forms of varying thallus width indicated that thi s pattern was due to the morphology of the plants rather than differen ces in their internal composition. There was a trend for isopods with tubular body shapes to live on algal species with narrow fronds, and f or dorso-ventrally flattened isopods to Live on algae with wide fronds . Most of the seaweed species held epifaunal assemblages that were dis tinct from one another in multivariate space, but the individual epifa unal taxa were generally not strongly host-plant specific, with most o ccurring on more than 1 algal species. It is suggested that most of th e epifauna have a weak relationship with their host plant. Epifaunal d ensities on Ecklonia radiata peaked at 6 m depth, and declined with in creasing depth.