Mesoherbivore-macroalgal interactions: Feeding ecology of sacoglossan sea slugs (Mollusca, Opisthobranchia) and their effects on their food algae

The feeding interactions between sacoglossan (= ascoglossan) sea slugs and their algal prey are discussed. Many of these gastropod molluscs are capabl e of kleptoplasty - a process whereby the slugs photosynthesize using chlor oplasts ingested from their algal diet. Despite extensive study, the import ance of kleptoplasty in sacoglossan (slug) feeding ecology remains poorly d efined. The effects of slug grazing on marine algae, particularly in tropic al - subtropical regions are also unclear. We extend the scope of previous reviews and synthesize the disparate areas of sacoglossan feeding ecology. The review is in three parts: first, the diet of sacoglossans is discussed; secondly, the role of kleptoplasty in slug feeding ecology is examined and thirdly, the effects of grazing by the slugs on their food algae are consi dered. Further research is required to clarify sacoglossan feeding ecology, in particular slug food choice in the field, the importance of kleptoplast y to the range of slug diets and the effects of slug grazing on tropical ma rine algae.