Experimental evidence for aging food patches as a factor contributing to high deep‐sea macrofaunal diversity

Abstract

To determine whether deep‐sea macrofaunal succession is observed in response to small‐scale patches, we deployed colonization trays at 900‐m depth for 23 d and 28 months. Treatments included sediment that was unenriched or enriched with Sargassum natans. Short‐term Sargassum trays contained significantly higher and short‐term unenriched trays significantly lower total densities than the ambient sediment. Both Sargassum treatments attracted high densities of a low‐diversity fauna, but they differed in species composition. Short‐term, unenriched trays attracted low densities of a high‐diversity fauna, and long‐term unenriched trays attracted high densities of a moderately diverse fauna. All treatments showed low faunal affinity with the ambient community. In a 19‐d experiment with S. natans incubated in situ or in sterilized seawater, different species dominated. Thus, differences between 23‐d and 28‐month Sargassum trays may have been related to changes in the food source; a succession of different species colonize aging patches, indicating that patch age may be an important source of microheterogeneity for deep‐sea macrofauna.