The functional diversity of fish assemblages in the vicinity of oil and gas pipelines compared to nearby natural reef and soft sediment habitats.

As the offshore hydrocarbon industry matures and decommissioning activities are expected to increase, there is a requirement to assess the environmental consequences of different pipeline decommissioning options. Previous research on fish and other ecological components associated with pipelines has focused on examining species richness, abundance and biomass surrounding structures. The extent to which subsea pipelines mimic or alter ecosystem function compared with nearby natural habitats is unknown. We analyse differences in fish assemblage biological trait composition and the functional diversity at exposed shallow-water subsea pipelines, nearby natural reef and soft sediment habitats, using mini stereo-video remotely operated vehicles (ROV). Habitats significantly differed in assemblage trait composition. The pipeline and reef habitats shared a more similar functional composition and had the presence of key functional groups required for the development and maintenance of healthy coral reef systems. The reef habitat had the greatest functional diversity, followed by the pipeline habitat and soft sediment habitat respectively.