Megafaunal distribution and biodiversity in a heterogeneous landscape: the iceberg-scoured Rockall Bank, NE Atlantic

Abstract

Species distributions are influenced by spatial structure in environmental factors, but the scales at which these dependencies occur and the effect of habitat patch diversity, connectivity and spatial arrangement have rarely been investigated in deep-sea settings. In this study, spatially limited photographic transects collected from Rockall Bank, NE Atlantic, were combined with sidescan and multibeam sonar maps to model spatial patterns in species distribution and biodiver- sity. Sediment interpretation maps were created and canonical ordination techniques were used to examine relationships between fine-scale sediment characteristics extracted from the digital stills as well as landscape metrics describing the patch mosaic structure of the surrounding areas. Fine-scale sediment characteristics explained 45.1 and 63.8% of the variation in species composi- tion and biodiversity, respectively. This survey effectively captured variation in species distribu- tion resulting from iceberg ploughmarks, occurring at a scale of <50 m — which would normally go undetected by traditional ship-based studies. Our study suggests that fine-scale environmental information is required to capture the spatial heterogeneity of complex seafloor areas in sufficient detail to model species distributions and biodiversity.