Ecological role of offshore artificial structures

Energy production in the global oceans through renewables and hydrocarbons is critical for human society and continues to expand. Complex structures are routinely installed in the marine environment including pipelines, cables and other infrastructure. These structures are eventually removed (decommissioning), something that is particularly prevalent at present for offshore oil and gas industry infrastructure.

Offshore infrastructure alters ecological structure and functioning through habitat provision, increased biomass and enhanced connectivity, and supports species of conservation importance. Assemblages supported by artificial structures vary over a range of spatial scales from regional (e.g. between ocean basins) to fine scales (e.g. location on the structure) and on temporal scales related to the age of the structure and stage of succession.

There is increasing policy debate about best practice for permitting structure installation and removal, with major differences in approach across the world. There is urgent need for scientific evidence on the role of artificial structures to support this. This project will advance our understanding of how fauna associated with offshore structures changes over different spatial scales (e.g. ocean basins or depth gradients) and over time, through repeat observations.

It will focus on subsea pipelines, which are common structures that cover broad spatial scales in open ocean.

Offshore industries collect vast quantities of marine images for a range of purposes, some of which have high potential to generate ecological data, including the emerging Global Ocean Observing System (GOOS) Essential Ocean Variable (EOV) 'invertebrate abundance and distribution'. This project has access to an archive of high-quality seafloor imaging surveys of offshore pipelines, collected by remotely operated vehicles operated by a major offshore industry service provider and CASE project partner (Subsea7).

Biological and other environmental information will be annotated in images using standard software. The resulting data will allow for the assessment of spatial and temporal patterns in benthic megafaunal assemblages in areas with and without a range of anthropogenic structures. Biological change will be interpreted from time-series investigations.

Changes will be assessed using a variety of statistical approaches and interpreted using ecological theory. Patterns in standing stock, size, biomass, biodiversity, and community structure will be the primary focus of the project.