Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

A comparison of epifauna and epiphytes on native kelps (Laminaria species) and an invasive alga (Codium fragile ssp. tomentosoides) in Nova Scotia, Canada.

Abstract

The epifaunal and epiphytic assemblages were compared on the invasive alga, Codium fragile ssp. tomentosoides, with those on native kelps, Laminaria longicruris and L. digitata, at a moderately exposed site on the Atlantic coast of Nova Scotia, Canada. Thalli of each algal host (Laminaria and/or Codium) were sampled in 2 stands with monospecific canopy cover and one mixed canopy stand (Laminaria and Codium) in June and November 2004 and February 2005. Epifaunal assemblages on both fronds and holdfasts differed between algal species and among months, but no differences were detected between mixed and monospecific stands for each host type. Fronds of Laminaria supported greater densities of gastropods and asteroids, while amphipods, harpacticoid copepods, and a specialist herbivore (Placida dendritica) were more abundant on fronds of Codium. Holdfasts of Codium supported greater densities of nematodes and bivalves. Diversity of epifauna was greater on fronds of Codium than Laminaria and similar on holdfasts of both species. Codium supported a greater density of epiphytes than Laminaria. Total frond area of Laminaria and/or Codium and density of epifauna per m2 of substratum did not differ between stands. The results suggest that habitat selection by epibionts is likely determined by specific chemical, structural and morphological characteristics of the algal species, rather than the amount of habitable area available for colonization.