Who's on fish: comparing macro-scavenger communities on fish and kelp bait across an intertidal-subtidal depth gradient.

Abstract

The importance of scavenging communities, and the detritus and carrion on which they feed, has been well studied from the perspectives of spatial food subsidies (marine to terrestrial, terrestrial to marine, and marine to marine) and community structure (e.g. whale and wood falls in the deep sea). Most of these studies focus on comparing scavenging rates or scavenger diversity within a single habitat, usually deep-sea or intertidal, and seldom make comparisons between these regions. A baited trap experiment was conducted to quantify the macro-scavenger community and scavenging rates on aged fish and kelp at intertidal, shallow subtidal, and deep subtidal sites around San Juan Island, WA, USA. Bray Curtis cluster analysis showed a distinction between macrofaunal communities in the intertidal and both subtidal sites, with higher scavenging rates on fish than kelp at all sites. Differences in the Shannon-Weiner diversity index were found in trap macrofaunal communities between sites, although further study is needed to show if these differences are really the result of different communities of scavengers or merely the influx of ambient macrofauna into the traps at different sites.