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Offshore Oil and Gas (O&G) infrastructure affords structurally complex hard substrata in otherwise featurless areas of the seafloor. Opportunistically collected industrial ROV imagery was used to investigate the colonization of a petroleum platform in the North Sea 1–2 years following installation. Compared to pre-construction communities and pioneering colonizers, we documented 48 additional taxa, including a rare sighting of a pompano (Trachinotus ovatus). The second wave of motile colonizers presented greater diversity than the pioneering community. Occurrence of species became more even over the 2 years following installation, with species occurring in more comparable abundances. No on-jacket sessile taxa were recorded during first-wave investigations; however, 17 sessile species were detected after 1 year (decreasing to 16 after 2). Motile species were found to favour structurally complex sections of the jacket (e.g. mudmat), while sessile organisms favoured exposed elements. Evidence of on-jacket reproduction was found for two commercially important invertebrate species - common whelk (Buccinum undatum) and European squid (Loligo vulgaris). Moreover, abundance of larvae-producing species experience an 8.5-fold increase over a 2-year period compared to baseline communities. These findings may have implications for decommissioning and resource-management strategies, suggesting that a case-by-case reviewing approach should be favoured over the most common “one size fits all”.

Offshore Oil & Gas (O&G) infrastructure creates artificial reef complexes that support marine communities in oceans. No studies have characterized the first wave of colonization, which can reveal information about habitat attraction and ecological connectivity. Here we used opportunistically-collected industrial Remotely Operated Vehicles (ROVs) to investigate fish and invertebrate colonization on a new North Sea O&G platform and trenching of an associated pipeline. We observed rapid colonization of fish communities, with increases in species richness (S), abundance (N), and diversity (H′) over the first four days (the entire study period). By contrast, there was minimal change in motile invertebrate communities over the survey period. After trenching, invertebrate S, N and H′ decreased significantly, whilst fish S, N and H′ increased. This study is the first to report on the pioneer wave of fish and invertebrate colonization on O&G infrastructure, thereby providing rare insight into formation of new reef communities in the sea. These short and opportunistic data are valuable in terms of showing what can be discovered from analysis of ‘pre-installation’ ROV footage of O&G structures, of which there are terabytes of data held by O&G companies waiting to be analyzed by environmental scientists.

Distributions of Daubenton's bat (Myotis daubentonii), common pipistrelle, (Pipistrellus pipistrellus), and soprano pipistrelle (Pipistrellus pygmaeus) were investigated along and altitudinal gradient of the Lledr River, Conwy, North Wales, and presence assessed in relation to the water surface condition, presence/absence of bank-side trees, and elevation. Ultrasound recordings of bats made on timed transects in summer 1999 were used to quantify habitat usage. All species significantly preferred smooth water sections of the river with trees on either one or both banks; P. pygmaeus also preferred smooth water with no trees. Bats avoided rough and cluttered water areas, as rapids may generate high-frequency echolocation-interfering noise and cluttered areas present obstacles to flight. In lower river regions, detections of bats reflected the proportion of suitable habitat available. At higher elevations, sufficient habitat was available; however, bats were likely restricted due to other factors such as a less predictable food source. This study emphasizes the importance of riparian habitat, bank-side trees, and smooth water as foraging habitat for bats in marginal upland areas until a certain elevation, beyond which bats in these areas likely cease to forage. These small-scale altitudinal differences in habitat selection should be factored in when designing future bat distribution studies and taken into consideration by conservation planners when reviewing habitat requirements of these species in Welsh river valleys, and elsewhere within the United Kingdom.

In oceans and seas worldwide, an increasing number of end-of-life anthropogenic offshore structures (e.g. platforms, pipelines, manifolds, windfarms, etc.) are facing full or partial removal. As part of the decommissioning process, studies on potential importance of subsea infrastructure to marine megafauna (defined as: cetaceans, pinnipeds, sirenians, large fish – such as sharks, rays, billfishes, and tuna, as well as marine reptiles, and seabirds) are lacking. Dedicated scientific Remotely Operated Vehicle (ROV) surveys around offshore installations are rare, but there is a wealth of archived industrial data and noteworthy species sightings posted publicly on various social media platforms. This study used routine, incidentally-collected ROV (n = 73) and commercial diver (n = 9) video recordings spanning 1998–2019 globally. Data were gathered directly from industrial partners (n = 36) and the public domain (YouTube; n = 46) to provide an account of marine megafauna presence and potential feeding behaviour in the near visible vicinity of subsea anthropogenic structures. A total of 79 video clips and 3 still images of marine megafauna near offshore structures were examined, resulting in 67 individual sightings and 16 sub-sightings (in which an individual was recorded within the same day). At least 178 individuals were identified to a minimum of 17 species of marine megafauna, amounting to a total (combined) sighting duration of 01:09:35 (hh:mm:ss). Results demonstrated proximate presence of marine megafauna (many of which are threatened species) to anthropogenic structures, with most animals displaying foraging or interaction behaviours with the structures. Observations included the deepest (2,779 m) confirmed record of a sleeper shark (Somniosus spp.) and the first confirmed visual evidence of seals following pipelines. These ROV observations demonstrate a latent source of easily-accessible information that can expand understanding of marine megafauna interactions with offshore anthropogenic infrastructure. Consequently, other workers in this field should be encouraged to re-analyse archived datasets, commence further collaborative research projects with industrial partners, and/or expand Internet search terms to additional species assemblages, in a bid to quantitatively elucidate relationships between offshore infrastructure and marine species.

Remotely-operated vehicles (ROVs) are used extensively by the offshore oil and gas and renewables industries for inspection, maintenance, and repair of their infrastructure. With thousands of subsea structures monitored across the world’s oceans from the shallows to depths greater than 1000 m, there is a great and underutilised opportunity for their scientific use. Through slight modifications of ROV operations, and by augmenting industry workclass ROVs with a range of scientific equipment, industry can fuel scientific discoveries, contribute to an understanding of the impact of artificial structures in our oceans, and collect biotic and abiotic data to support our understanding of how oceans and marine life are changing. Here, we identify and describe operationally-feasible methods to alter adjust the way in which industry ROVs are operated to enhance the scientific value of data that they collect, without significantly impacting scheduling or adding to deployment costs. These include: rapid marine life survey protocols, imaging improvements, the addition of a range of scientific sensors, and collection of biological samples. By partnering with qualified and experienced research scientists, industry can improve the quality of their ROV-derived data, allowing the data to be analysed robustly. Small changes by industry now could provide substantial benefits to scientific research in the long-term and improve the quality of scientific data in existence once the structures require decommissioning. Such changes also have the potential to enhance industry’s environmental stewardship by improving their environmental management and facilitating more informed engagement with a range of external stakeholders, including regulators and the public.

The ecosystem modelling complex ‘Ecopath with Ecosim’ has been implemented extensively in the field of marine science; however, despite its widespread application, descriptions of its functionality remain arcane in the literature. This study conducts an evaluation of the software's prediction capacity using eight published Ecopath models. Response of six ecosystem-status indicators to four basic input variables to which imprecision had been added was investigated. Kempton's Q Index and total system throughput emerged as the most consistently responsive parameters. Moreover, input biomass was identified as a ‘high-leverage’ parameter, its influence on outputs being greater than that exerted by any other input variable. This study constitutes one of the first comprehensive investigations of the response of selected outputs to imprecise input values, and provides sufficient basis to warrant a sensitivity assessment of the software, as well as introduction of a dedicated tool to perform such a task within Ecopath with Ecosim.

Distribution and abundance of two temperate-zone insectivorous bats, Daubenton's (Myotis daubentonii) and common pipistrelle (Pipistrellus pipistrellus), and their potential prey were studied along an altitudinal river gradient in relation to environmental variables including air temperature, wind speed, water surface state, and presence or absence of bank-side trees. Using a Latin square design at ten different habitat combination types, ultrasound recordings and insect sampling were carried out to quantify bat habitat preferences and potential prey abundance and classification. Myotis daubentonii and P. pipistrellus activity was significantly higher over smooth water river sections with trees on either or both banks while cluttered and rapid water sections were avoided. Conversely, insect abundance was not related to water surface condition or the presence or absence of bank-side trees. Nematoceran dipterans made up 98% of insect numbers, with small numbers of brachycerans and cyclorrhaphans. The most common insect families were Chironomidae and Ceratopogonidae. There was no correlation between bat activity and aerial insect activity, suggesting that aerial prey availability is not the sole driver of bat habitat choice. Bat and insect abundance were each correlated positively with night-time air temperature. No bat passes or flying insects were recorded at temperatures < 4°C. At 5°C, only M. daubentonii were observed foraging, and at 6°C there were more M. daubentonii present than any other bat species. No correlation was found between number of bat passes hr-1 and wind speed, moon visibility, moon phase, and percentage cloud cover. Rain did not affect M. daubentonii, but P. pipistrellus preferred to forage on dry nights. Bats were predicted to forage preferentially where aerial insect abundance was highest but this was found to not be case, and other aspects such as detection of prey against clutter may have an important role to play in habitat choice.

Decommissioning of offshore infrastructure has become a major issue facing the global offshore energy industry. In the North Sea alone, the decommissioning liability is estimated at £40 billion by 2040. Current international policy requires removal of offshore infrastructure when their production life ends; however, this policy is being questioned as emerging data reveal the importance of these structures to fish and invertebrate populations. Indeed, some governments are developing ‘rigs-to-reef’ (RTR) policies in situations where offshore infrastructure is demonstrated to have important environmental benefits. Using Remotely Operated Vehicles (ROVs), this study quantified and analysed fish and invertebrate assemblage dynamics associated with an oil and gas (O&G) complex in the Dogger Bank Special Area of Conservation (SAC), in the North Sea, Germany. We found clear depth zonation of organisms: infralittoral communities (0–15 m), circalittoral assemblages (15–45 m) and epi-benthic communities (45–50 m), which implies that ‘topping’ or ‘toppling’ decommissioning strategies could eliminate communities that are unique to the upper zones. Sessile invertebrate assemblages were significantly different between structures, which appeared to be driven by both biotic and abiotic mechanisms. The O&G complex accommodated diverse and abundant motile invertebrate and fish assemblages within which the whelk Buccinium undatum, cod fish Gadus morhua and lumpsucker fish Cyclopterus lumpus used the infrastructure for different stages of reproduction. This observation of breeding implies that the structures may be producing more fish and invertebrates, as opposed to simply acting as sites of attraction (sensu the ‘attraction vs production’ debate). At present, there are no records of C. lumpus spawning at such depth and distance from the coast, and this is the first published evidence of this species using an offshore structure as a spawning site. Overall, this study provides important new insight into the role of offshore O&G structures as habitat for fish and invertebrates in the North Sea, thereby helping to inform decommissioning decisions.

© The Ecological Society of America The removal of thousands of structures associated with oil and gas development from the world's oceans is well underway, yet the environmental impacts of this decommissioning practice remain unknown. Similar impacts will be associated with the eventual removal of offshore wind turbines. We conducted a global survey of environmental experts to guide best decommissioning practices in the North Sea, a region with a substantial removal burden. In contrast to current regulations, 94.7% of experts (36 out of 38) agreed that a more flexible case-by-case approach to decommissioning could benefit the North Sea environment. Partial removal options were considered to deliver better environmental outcomes than complete removal for platforms, but both approaches were equally supported for wind turbines. Key considerations identified for decommissioning were biodiversity enhancement, provision of reef habitat, and protection from bottom trawling, all of which are negatively affected by complete removal. We provide recommendations to guide the revision of offshore decommissioning policy, including a temporary suspension of obligatory removal.