ABSTRACT: Marine amphipods commonly use other organisms as both habitat and/or food, offering an opportunity to contrast host associations in marine environments with that of terrestrial invertebrates. A few species of amphipods have been found to specialise on their hosts for habitat or food; however, their host associations remain poorly described and previous studies have confounded habitat and feeding specificity. We examined the patterns of host use for amphipods associated with macroalgae and sponges. For macroalgae, the analysis was limited to strictly herbivorous species in order to address feeding specificity only. On both hosts, amphipods displayed a range of host specificity, from more generalised to more specialised species. Even when not specialised, amphipod species had disjunct distributions, resulting in a distinct assemblage of amphipods associated with each host species. This was true for both herbivorous amphipods inhabiting algae, where host specificity relates to feeding specificity, and for amphipods on sponges, where host specificity is likely to relate to habitat specificity only. For most species of herbivorous amphipods, patterns of host use were largely unrelated to sampling time (day vs night), remained distinct across seasons, and were unaffected by the presence of alternative food sources (epiphytes).

KEY WORDS: Amphipods · Host specificity · Algae · Sponges · Herbivory · Epiphytes

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Published in MEPS Vol. 208 (2000) on December 8
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 2000