Enhanced ROV Survey of Tropical Fish and Benthic Communities Associated With Shallow Oil and Gas Platforms

Mapping Intimacies ◽

10.21203/rs.3.rs-746015/v1 ◽

2021 ◽

Author(s):

Dianne L. McLean ◽

Matthew Birt

Keyword(s):

Oil And Gas ◽

Fish Assemblages ◽

Tropical Fish ◽

Relative Mass ◽

High Definition ◽

Remotely Operated Vehicle ◽

Natural Habitats ◽

North West ◽

Stereo Video ◽

Encrusting Sponges

Abstract Understanding the ecology of oil and gas infrastructure in our oceans is required to inform decommissioning such that environmental impacts are minimised, and benefits maximised. This study equipped an industrial remotely operated vehicle (ROV) with a stereo-video system and collected seven hours of high-definition imagery of two platform jackets, for assessments of benthic (type, density, complexity) and fish assemblages (richness, abundance, length) present. Harriet Alpha (25 m depth) and Gibson/South Plato (8 m depth) are located ca. 120 km offshore of north-west Australia, adjacent to Varanus Island. Twenty-one ‘classes’ of benthic biota were observed in high density, with little bare structure on either platform. Encrusting sponges (average 19% cover per virtual quadrat), barnacles (17%) and sponges (16%) were common on Gibson/South Plato while encrusting sponges (16%) and macroalgae (18%) were ubiquitous on quadrats on Harriet Alpha. The sun coral Tubastraea faulkneri was common on Harriet Alpha (38% of quadrats), though coverage was low (<6%). A total of 102 fish species from 27 families were observed. This included 33 fishery target species with an estimated relative mass of 116 kg on Gibson/South Plato and 299 kg on Harriet Alpha, with these species typically concentrated near the seafloor-structure interface. Differences in benthic biota communities present on each platform likely reflect spatial variations in oceanographic processes, proximity to natural habitats and the age, configuration, cleaning regime and depth of the structures themselves. This study demonstrates the value of adding stereo-video systems to ROVs to undertake rapid scientific surveys of oil and gas infrastructure.

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Strategies for obtaining ecological data to enhance decommissioning assessments

The APPEA Journal ◽

10.1071/aj19235 ◽

2020 ◽

Vol 60 (2) ◽

pp. 559

Author(s):

Sean van Elden ◽

Thomas Tothill ◽

Jessica J. Meeuwig

Keyword(s):

Oil And Gas ◽

Offshore Platforms ◽

Ecological Value ◽

Ecological Data ◽

Remotely Operated Vehicle ◽

Natural Habitats ◽

Regional Context ◽

North West ◽

Faunal Communities ◽

Video Systems

Many offshore oil and gas platforms around the globe are reaching their end-of-life and will require decommissioning in the next few decades. Knowledge on the ecology of offshore platforms and their ecological role within a regional context in Australia is limited and the subsequent consequences of decommissioning remain poorly understood. Remotely operated vehicle (ROV) video is often collected during standard industry operations and may provide insight into the marine life associating with offshore platforms; however, the utility of this video for scientific purposes remains unclear. We propose a standardised method of analysing this large database of archival ROV footage with specific interest in analysing the vertical distribution of fish species. Baited remote underwater video systems (BRUVS) are a widely used tool for studying marine faunal communities, and we demonstrate the value of BRUVS for understanding the regional ecology around offshore platforms. A combination of BRUVS and ROV data can be used to determine the relative ecological value of offshore platforms within a regional context. The Wandoo oil platform on Australia’s North West Shelf was used as a case study to test these proposed methods by assessing demersal and pelagic fish populations both on and around the Wandoo platform and various natural habitats in the region.

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Fish associations with shallow water subsea pipelines compared to surrounding reef and soft sediment habitats

Scientific Reports ◽

10.1038/s41598-021-85396-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Karl D. Schramm ◽

Michael J. Marnane ◽

Travis S. Elsdon ◽

Christopher M. Jones ◽

Benjamin J. Saunders ◽

...

Keyword(s):

Oil And Gas ◽

Fish Assemblages ◽

Economic Value ◽

Trophic Levels ◽

Soft Sediment ◽

Feeding Guild ◽

Natural Habitats ◽

North West ◽

The North ◽

Subsea Pipelines

AbstractOffshore decommissioning activities are expected to increase as oil and gas subsea infrastructure becomes obsolete. Decisions on decommissioning alternatives will benefit from quantifying and understanding the marine communities associated with these structures. As a case study, fish assemblages associated with an inshore network of subsea pipelines located on the North West shelf of Western Australia were compared to those in surrounding natural reef and soft sediment habitats using remotely operated vehicles fitted with a stereo-video system (stereo-ROVs). The number of species, the abundance, biomass, feeding guild composition and the economic value of fishes were compared among habitats. The community composition of fish associated with pipelines was distinct from those associated with natural habitats, and was characterised by a greater abundance and/or biomass of fish from higher trophic levels (e.g. piscivores, generalist carnivores and invertivores), including many species considered to be of value to commercial and recreational fishers. Biomass of fish on pipelines was, on average, 20 times greater than soft sediments, and was similar to natural reefs. However, the biomass of species considered important to fisheries recorded on the pipelines was, on average 3.5 times greater than reef and 44.5 times greater than soft sediment habitats. This study demonstrates that fish assemblages on the pipeline infrastructure exhibit high ecological and socioeconomic values.

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Importance of Australia's offshore oil and gas infrastructure for fish

The APPEA Journal ◽

10.1071/aj20106 ◽

2021 ◽

Vol 61 (2) ◽

pp. 429

Author(s):

D. McLean ◽

T. Bond ◽

E. S. Harvey ◽

D. Ierodiaconou ◽

K. Cure ◽

...

Keyword(s):

Fish Species ◽

Oil And Gas ◽

Scientific Data ◽

Ecological Communities ◽

High Definition ◽

Remotely Operated Vehicle ◽

Data Set ◽

Marine Research ◽

North West ◽

The Impact

An assessment to remove, partially remove, leave in situ or repurpose oil and gas infrastructure at end of field life can be more robust if it uses rigorous, relevant and accurate data. We used industry remotely operated vehicle (ROV) video, specialised high-definition stereo-video systems and partnered with industry to enhance future ROV campaigns for the collection of scientific data from infrastructure. Data from 17 pipelines and 51 wells were analysed to report on patterns in fish species richness and abundance in Australia’s north, north-west and south-east regions. This represents the largest synthesised data set on marine communities for pipelines and wells, globally. We observed 401 fish species, 350 along pipelines and 113 on well infrastructure. Potential new fish species, critically endangered species, unique behaviours and diverse communities were discovered around pipeline and well infrastructure. Predicting the environmental consequences of different decommissioning options relies on a region-specific understanding of the ecological communities that are associated with these structures. We showcase marine research from around Australia that will inform local decommissioning and contribute to a more comprehensive global understanding of the impact of subsea infrastructure in our oceans.

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Comparing the Utility of Industry ROV and Hybrid-AUV Imagery for Surveys of Fish Along a Subsea Pipeline

Marine Technology Society Journal ◽

10.4031/mtsj.54.3.5 ◽

2020 ◽

Vol 54 (3) ◽

pp. 33-42

Author(s):

Todd Bond ◽

Jane Prince ◽

Dianne L. McLean ◽

Julian C. Partridge

Keyword(s):

Oil And Gas ◽

Fish Assemblages ◽

Survey Methods ◽

Autonomous Underwater Vehicles ◽

Time Of Day ◽

High Definition ◽

Subsea Pipeline ◽

Pipeline Inspection ◽

Video Footage ◽

Offshore Oil And Gas

AbstractIn recent years, video footage obtained from routine industry surveys using remotely operated vehicles (ROVs) has been used to assess fish assemblages associated with offshore oil and gas infrastructure. However, as industry moves towards using autonomous underwater vehicles (AUVs), it is important to understand how such a change may affect assessments of fish assemblages and whether these data collected from AUVs can be directly compared to those collected from historic and future ROV footage. In an extremely rare opportunity, we compare fish assemblages surveyed by an industrial ROV and an industrial hybrid-AUV (H-AUV) along the same 2,060-m section of subsea pipeline, at the same time of day, within 1 day of each other. A total of 206 transects, each 20 m in length, were analyzed, recording 406 fish from 10 species. The H-AUV recorded all 10 fish species, while the ROV recorded seven. Mean species richness was ~4% higher for H-AUV, and mean abundance was ~21% higher for ROV; these differences can be considered negligible. Multivariate analysis revealed nonsignificant differences in species composition between survey methods. This result suggests that future surveys of fish at this pipeline using a similar H-AUV can yield comparable results to ROV and, as such, facilitate comparison to historical ROV imagery. Future surveys of pipelines with AUV should consider adding extra lighting and high-definition cameras onto booms similar to those operating on ROVs, which will provide a useful field of view into pipeline spans and make it easier to identify fish. Our study provides insight into the utility and comparability of industry ROV and AUV pipeline inspection footage for the assessment of fish assemblages associated with subsea pipelines, which is used to inform policies and practices on the installation and decommissioning of subsea infrastructure.

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Decommissioning impacts on biotic assemblages associated with shell mounds beneath southern California offshore oil and gas platforms

Bulletin of Marine Science ◽

10.5343/bms.2018.0077 ◽

2019 ◽

Vol 95 (4) ◽

pp. 683-702 ◽

Cited By ~ 1

Author(s):

Erin L Meyer-Gutbrod ◽

Milton S Love ◽

Jeremy T Claisse ◽

Henry M Page ◽

Donna M Schroeder ◽

...

Keyword(s):

Species Composition ◽

Southern California ◽

Oil And Gas ◽

Fish Assemblages ◽

Ecological Value ◽

Remotely Operated Vehicle ◽

Wide Range ◽

Shell Mounds ◽

Offshore Oil And Gas ◽

Offshore Oil

The decommissioning of southern California offshore oil and gas platforms will create major economic, engineering, and environmental challenges in the next decade. Platform jackets, conductors, and shell mounds often host a diverse and productive marine community, and among the myriad considerations associated with decommissioning planning, platform operators and federal and state regulatory agencies will consider the ecological value of existing underwater structures as artificial reefs. In the event of partial removal of platform structure, fish assemblages on decommissioned platforms may remain unchanged in areas where structure is left intact. However, on the seafloor beneath the platforms, a mound of debris often called the shell mound will likely change over time if the supply of falling mussels and other organisms from the productive surface part of the structure is removed. In this study, we review shell mound research relevant to decommissioning, including mound formation, contaminant loads, associated biological communities, and transitions following the removal of platform structures at four sites. To address the gap in knowledge of shell mound fish community structure, we used manned submersible and remotely operated vehicle surveys from 1997 to 2013 to estimate the biomass, density, species composition and similarity between shell mounds at 22 southern California platforms. We found a wide range of variability in fish density and shell mound areal extent. Species composition also varied among sites, with three significant community clusters primarily distinguished by species depth preferences. These results will help inform a comprehensive net environmental benefit analysis of southern California offshore platform decommissioning alternatives.

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An analysis of the fish assemblages around 23 oil and gas platforms off California with comparisons with natural habitats

Bulletin of Marine Science ◽

10.5343/bms.2018.0061 ◽

2019 ◽

Vol 95 (4) ◽

pp. 477-514 ◽

Cited By ~ 4

Author(s):

Milton S Love ◽

Jeremy T Claisse ◽

Alexa Roeper

Keyword(s):

Oil And Gas ◽

Fish Assemblages ◽

Habitat Type ◽

Geographic Location ◽

Natural Habitats ◽

Central California ◽

Shell Mounds ◽

Young Of The Year ◽

Offshore Oil And Gas ◽

Offshore Oil

Between 1995 and 2013, we surveyed fishes living around 23 California offshore oil and gas platforms (midwaters, bases, and shell mounds) and 70 natural habitats. These platforms were distributed between about Point Arguello, central California, and Huntington Beach, southern California, had seafloor depths between 49 and 363 m, and were surveyed between one and 16 times. A total of 1,526,437 fishes were observed. Fish densities were highest around platform bases, followed by platform midwaters, shell mounds, and natural habitats. Of all fishes observed, 90.4% were in the genus Sebastes. Water depth was the strongest driver of the fish species assemblages, although habitat type and geographic location were also important. Most of the fishes living around platforms and natural habitats were relatively small, primarily ≤20 cm in length. Many of these individuals were the juveniles of larger taxa or the juveniles and adults of dwarf species. Larger fishes were less common and these were most often found around platform bases and on natural habitats. Most young-of-the-year (YOY) fishes occurred at water depths of ≤150 m at all four habitats. At platforms, YOY densities were highest in platform midwaters and bases. On average, densities of these young fishes were somewhat higher compared to natural habitats and it is likely that many, although not all, California platforms play a significant role as nursery grounds for a variety of fishes, particularly for a number of Sebastes species.

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A comparison of two remotely operated vehicle (ROV) survey methods used to estimate fish assemblages and densities around a California oil platform

PLoS ONE ◽

10.1371/journal.pone.0242017 ◽

2020 ◽

Vol 15 (11) ◽

pp. e0242017

Author(s):

Milton S. Love ◽

Mary M. Nishimoto ◽

Scott Clark ◽

Li Kui ◽

Azivy Aziz ◽

...

Keyword(s):

Structural Integrity ◽

Oil And Gas ◽

Fish Assemblages ◽

Survey Methods ◽

Fish Habitat ◽

Species Assemblages ◽

Fish Diversity ◽

Structural Method ◽

Remotely Operated Vehicle ◽

Integrity Assessment

Offshore oil and gas platforms have a finite life of production operations. Once production ceases, decommissioning options for the platform are assessed. The role that a platform’s jacket plays as fish habitat can inform the decommissioning decision. In this study, conducted along the crossbeams of a California platform jacket and using an ROV, we compared estimates of fish diversity and densities determined from a targeted “biological” survey with those from a replicated “structural” survey. We found that the water column fish species assemblages characterized by the two methods were similar. By contrast, the two survey methods yielded different species assemblages inhabiting the crossbeam at the platform jacket base. This difference occurred because, at least off California, the platform jacket base species diversity tends to be highest where the bottom crossbeam is undercut, creating sheltering sites for many species. Because the structural method inadequately imaged the seafloor-crossbeam interface, particularly where a gap occurred between crossbeam and seafloor, substantial numbers of fishes were not visible. While we cannot extrapolate from this study to all platforms’ worldwide, it is clear that routine platform structural integrity surveys may be a valuable source for opportunistic marine community surveys. Intentional planning of the structural survey to incorporate relatively minor variations (e.g., maintaining fixed ROV distance from the infrastructure and consistent 90° camera angle) coupled with a deliberate consideration of the platform ecology (e.g., positioning the ROV to capture the seafloor-crossbeam interface) can substantially improve the effects on fish assemblage assessments from routine structural surveys without compromising the integrity assessment. We suggest that these biases should be both acknowledged and, understood when using routine structural surveys to inform platform ecology assessment. Additional consideration may be given to structural surveys that incorporate incremental adjustments to provide better data applicability to biological assessments.

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Fish Assemblages Associated With Oil and Gas Platforms in the Gulf of Thailand

Frontiers in Marine Science ◽

10.3389/fmars.2021.664014 ◽

2021 ◽

Vol 8 ◽

Author(s):

Euan S. Harvey ◽

Stephanie L. Watts ◽

Benjamin J. Saunders ◽

Damon Driessen ◽

Laura A. F. Fullwood ◽

...

Keyword(s):

Coral Reef ◽

Oil And Gas ◽

Fish Assemblages ◽

Economic Value ◽

Offshore Structures ◽

Economic Benefits ◽

Gulf Of Thailand ◽

Reference Sites ◽

Remotely Operated Vehicle ◽

Offshore Oil And Gas

Decommissioning of offshore oil and gas structures is either occurring, or imminent in most regions of the world. Most jurisdictions require that offshore structures be removed for onshore disposal. However, there is growing interest in understanding the ecological and socio-economic benefits of leaving structures in the water. Descriptions of how fish utilize the vertical structure created by wellhead platform jackets (platforms) will provide insights into possible outcomes of decommissioning alternatives, such as full removal, leave in situ, or translocation to a designated reefing site. We surveyed fish assemblages associated with seven platforms and five reference sites located ∼150 km offshore in the central Gulf of Thailand. The platforms spanned the entire water column (∼75 m) and were a mix of three and four legged structures. We used a Remotely Operated Vehicle (ROV) fitted with an underwater stereo video system to quantify the abundance, size, biomass, and economic value of fish associated with the platforms. We recorded 43 species of fish on the platforms and five reference sites with most fishes on platforms categorized as coral-reef or coral-reef-associated species. We observed a strong vertical zonation in the fish assemblage on the platforms. The Regal demoiselle (Neopomacentrus cyanomos) was numerically dominant (75% of all fish observed). We measured 3,933 kg of fish on the platforms with Caranx sexfasciatus accounting for 76.12% of that. We conservatively estimate each platform had a scaled mean biomass of ∼2,927 kg and the fished species had scaled mean economic value of 175,500 Thai Baht per platform. We estimated that the biomass of fish associated with the seven platforms was at least four times higher per unit area than some of the world’s most productive coral reefs.

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