Benthic communities in Atlantic Canada continental shelf basins: patterns and their influence on ecosystem functions

Abstract

Macrofauna, an abundant and often patchy constituent of benthic soft sediments, alter important processes such as sediment oxygenation and nutrient fluxes. This study links spatial patterns in faunal biodiversity and ecosystem functions. I collected 39 sediment cores from 4 basins within the Gulf of Maine to characterize fauna and sedimentary characteristics. At coarse taxonomic levels (phyla and feeding guild), faunal composition was homogenous across the Gulf of Maine, whereas species-level taxonomy revealed heterogeneous composition and limited species turnover. Of the abiotic variables, all factors varied locally (across sites within basins) but only bottom depth differed significantly regionally. Ecosystem function varied significantly across and within basin, and additional analyses confirmed polychaete biodiversity, as well as abundance, were significant, positive predictors of secondary (microbial) production. Feeding guild biodiversity predicted more ecosystem functions than species or family level groupings, demonstrating that activity and behaviour better predict ecosystem functions in sediments than species diversity.