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Abstract

Nocturnal studies of fish assemblages are relatively rare, particularly at depths greater than 100 m, despite the relevance of diel shifts in habitat usage to fisheries management. This study assesses fish diversity and abundance from remotely operated vehicle (ROV) video recordings that were collected by industry during the day and at night in the course of a subsea pipeline survey, at 130 m depth. A total of 34,862 fish from 41 species and 25 families were recorded along the 23 km of pipeline. The pipeline was characterised by a high abundance of commercially important snapper (Lutjanidae) and grouper (Epinephelidae) species. The fish assemblage sampled along the pipeline during the day differed markedly to that sampled at night time. Several ubiquitous predatory species, e.g. Epinephelus areolatus, Lutjanus quinquelineatus, Lutjanus russellii, where present during the day but not at night, likely moving off the pipeline to feed in nearby habitats. Structurally complex mesophotic epibenthic habitat forming invertebrates were observed on the pipeline including; mesophotic corals, crinoids (featherstars), gorgonocephalids (basket stars), hydroids, true anemones and sponges, but elsewhere in the region, historical trawling effort is thought to have removed such organisms and extensively modified the original habitat. These complex epibenthic habitats were considered to be important to commercial target species and the modification or loss of these habitats is thought to have negatively impacted the valuable commercial fisheries in the region. This study suggests pipelines can offer a significant epibenthic habitat and refuge for fish, potentially comparable to the historical habitats lost to trawling. Fish diversity and abundance was observed to be consistently greater where a gap/crevice existed beneath the pipeline and many species were frequently observed in conjunction with the complex invertebrate matrix above the pipeline, under spanning sections beneath the pipeline and at the pipeline-sediment interface, regardless of time of day. Further dietary analysis, spatially explicit fisheries modelling and off-pipeline surveys on the natural seafloor are required to further investigate the ecological value of pipelines and its influence in fish behaviour. The study builds knowledge of mesophotic coastal fish ecology and will help to inform discussions regarding the ecological and fisheries implications of decommissioning and the removal of subsea infrastructure.

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... Offshore oil and gas (O&G) infrastructure such as pipelines and platforms have proliferated along continental margins and in the deeper oceans worldwide (Ars and Rios, 2017). These structures are colonised by sessile and motile epibiota, which in turn attract fish and larger fauna (van der Stap et al., 2016;Bond et al., 2018;Thomson et al., 2018;McLean et al., 2019a;Todd et al., 2019). The role these structures play as artificial reefs has attracted greater attention worldwide as they age and as industry considers decommissioning options (Macreadie et al., 2011;Bull and Love, 2019). ...
... However, our data suggests that both whale sharks we detected moved away from the platform receivers at night. Diel movements of fish species driven mostly by feeding and reproduction are well known and the abundance of some fish around offshore infrastructure has been shown to decrease at night (Baggerman, 1980;Lowry and Suthers, 1998;Nagelkerken et al., 2000;Bond et al., 2018). In the Gulf of Mexico, Barker and Cowan (2018) found fish communities in surface waters around lit versus unlit platforms were most abundant during daylight hours, suggesting they utilised the structure during the day for shelter and had an aversion to the lights at night, potentially to avoid predation. ...
... In the Gulf of Mexico, Barker and Cowan (2018) found fish communities in surface waters around lit versus unlit platforms were most abundant during daylight hours, suggesting they utilised the structure during the day for shelter and had an aversion to the lights at night, potentially to avoid predation. On the NWS, predatory fish species that sheltered along pipelines during the day were absent at night, thought to be foraging in adjacent habitats (Bond et al., 2018). As the world's largest fish, the whale sharks we detected may be undertaking similar, nocturnal movements away from the platform, possibly using them as a refuge during the daylight hours. ...
Article
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Subsea infrastructure of the oil and gas industry attracts commercial fish species as well as megafauna including sea lions, turtles, sharks and whales. Potential impacts of this attraction, whether positive or negative, are unknown. As part of a pilot study, we deployed acoustic telemetry equipment around offshore infrastructure to assess its effectiveness in detecting tagged marine animals and to gain insights into patterns of megafauna occurrence around these structures. Acoustic receivers were placed around four oil and gas platforms and on two remotely operated vehicles (ROVs) on Australia’s North West Shelf. Two whale sharks ( Rhincodon typus ) tagged in the World Heritage Ningaloo Reef Marine Park were detected at two platforms, North Rankin A and Pluto, located up to 340 km to the northeast. The shark at North Rankin A was detected infrequently and only 15 times over ∼6 weeks. The shark at Pluto was detected each day of the 24-day deployment, in total 4,894 times. Detections at Pluto platform were highest during the day, with peaks at dusk and dawn. Our study indicates that acoustic telemetry around platforms may be an effective method for understanding how marine megafauna utilise these structures. We recommend collaborating with industry to undertake receiver detection range testing to understand the effectiveness of the method. Furthermore, future studies should co-occur with tagging programs at sites like Ningaloo Reef and around the structures themselves to maximise the probability of detecting animals at these sites, thereby improving our understanding of how marine megafauna interact with these structures.
... Subsea pipelines are an integral component of oil and gas operations and form extensive networks on the seafloor. Despite their prevalence in our oceans there are few environmental studies that assess the ecological role of subsea pipelines as habitat (although see [29][30][31][32][33][34], with the majority of literature focused on oil and gas platforms 14 . Research is now beginning to demonstrate the potential role subsea pipelines may serve in the marine environment. ...
... Studies that have assessed fish associations with subsea pipelines have either used existing industry remotely operated vehicle (ROV) video footage [31][32][33] , small submersibles 34 , or Baited Remote Underwater stereo-Video systems (stereo-BRUVs) 29,30 as a means of sampling. The use of a mini-ROV fitted with a stereo-video system (stereo-ROV) may be a more appropriate sampling approach for assessing fish associations on pipelines, as the stereo camera setup provides per unit area measurements of fish and accurate length data for biomass estimates in situ 12 . ...
... In total, eleven segments of exposed pipeline were surveyed with segment lengths varying between 0.3 and 1.7 km, which was dependent on the level of exposure of the pipeline. Pipeline surveys were completed between 08:30 and 17:00 h to minimise the effects of diel changes in fish behaviour on data collected 31,46 . Quantitative comparisons between the reef and soft sediment habitats were undertaken by dividing continuous footage of the pipelines into 50 m transects, with a minimum 20 m separation between transects to ensure independence. ...
Article
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Offshore 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.
... Fish that move between habitats transport nutrients, serving as nutrient sinks in the systems in which they feed and nutrient sources in the systems where their waste is excreted Shantz et al., 2015). Bond et al. (2018) described diel changes in the behaviour and relative abundance of fish on this pipeline, reporting a much higher relative abundance of Apogonidae (cardinal fishes), Epinephelus areolatus (areolate grouper), Lutjanus quinquelineatus (five-lined snapper) ...
... Moreover, the use of identical methods on and off pipeline avoids the difficulties, and potential confounds, faced by studies that compare fish populations using different assessment methods. Using stereo-BRUVs, we have provided information on the fish assemblage found on the pipeline, recording 26 species, of which 10 were not recorded from the most recent ROV survey by Bond et al. (2018). To date, a total of 48 species and 28 families of teleost fish and sharks have been recorded on the pipeline (Table S1) from this study and the 2013 ROV survey Bond et al., 2018). ...
... Using stereo-BRUVs, we have provided information on the fish assemblage found on the pipeline, recording 26 species, of which 10 were not recorded from the most recent ROV survey by Bond et al. (2018). To date, a total of 48 species and 28 families of teleost fish and sharks have been recorded on the pipeline (Table S1) from this study and the 2013 ROV survey Bond et al., 2018). A future challenge will be to reconcile data obtained by different survey methods (e.g. ...
Article
Information on the potential ecological value of offshore oil and gas infrastructure is required as it reaches the end of its operational life and decisions must be made regarding the best practice option for decommissioning. This study uses baited remote underwater stereo-video systems to assess fish assemblages along an offshore subsea pipeline and in adjacent natural seabed habitats at ∼140 m depth on the North West Shelf of Western Australia. A total of 955 fish from 40 species and 25 families were recorded. Species richness was, on average 25% higher on the pipeline (6.48 ± 0.37 SE) than off (4.81 ± 0.28 SE) while relative abundance of fish was nearly double on the pipeline (20.38 ± 2.81 SE) than in adjacent natural habitats (10.97 ± 1.02 SE). The pipeline was characterised by large, commercially important species known to associate with complex epibenthic habitat and, as such, possessed a biomass of commercial fish ca 7.5 × higher and catch value ca. 8.6 × ($65.11 ± $11.14 SE) than in adjacent natural habitats ($7.57 ± $2.41 SE). This study has added to the knowledge of fish assemblage associations with subsea infrastructure and provides a greater understanding of the ecological and fisheries implications of decommissioning, helping to better inform decision-making on the fate of infrastructure.
... Epibenthic communities on pipelines are often identified by video footage from pipeline inspections and are characterised based on a standard classification scheme (Althaus et al., 2015). Flora and fauna most commonly found on pipelines include encrusting growth (typically coralline microalgae), black and octocorals, cnidarians, crinoids, echinoderms (basket stars and urchins), molluscs (bivalves), and sponges (Bond et al., 2018;McLean et al., 2020). In more complex habitat structures, many of these growth types will coexist forming complex invertebrate communities, which are often correlated to increased fish abundance (Bond et al., 2018). ...
... Flora and fauna most commonly found on pipelines include encrusting growth (typically coralline microalgae), black and octocorals, cnidarians, crinoids, echinoderms (basket stars and urchins), molluscs (bivalves), and sponges (Bond et al., 2018;McLean et al., 2020). In more complex habitat structures, many of these growth types will coexist forming complex invertebrate communities, which are often correlated to increased fish abundance (Bond et al., 2018). ...
... NORM-contaminated products in infrastructure may emit radiation that can penetrate pipeline material to irradiate nearby organisms (Fig. 3). These external-only radiation exposures may be an important exposure pathway as sessile organisms colonise subsea infrastructure to form artificial reefs which also provide habitat to fish and invertebrates (Bond et al., 2018). ...
Article
Thousands of offshore oil and gas facilities are coming to the end of their life in jurisdictions worldwide and will require decommissioning. In-situ decommissioning, where the subsea components of that infrastructure are left in the marine environment following the end of its productive life, has been proposed as an option that delivers net benefits, including from: ecological benefits from the establishment of artificial reefs, economic benefits from associated fisheries, reduced costs and improved human safety outcomes for operators. However, potential negative impacts, such as the ecological risk of residual contaminants, are not well understood. Naturally occurring radioactive materials (NORM) are a class of contaminants found in some oil and gas infrastructure (e.g. pipelines) and includes radionuclides of uranium, thorium, radium, radon, lead, and polonium. NORM are ubiquitous in oil and gas reservoirs around the world and may form contamination products including scales and sludges in subsea infrastructure due to their chemistries and the physical processes of oil and gas extraction. The risk that NORM from these sources pose to marine ecosystems is not yet understood meaning that decisions made about decommissioning may not deliver the best outcomes for environments. In this review, we consider the life of NORM-contamination products in oil and gas systems, their expected exposure pathways in the marine environment, and possible ecological impacts following release. These are accompanied by the key research priorities that need to better describe risk associated with decommissioning options.
... Many of these pipelines have a small diameter, 12 in (305 mm) or less, and transport gas tens of kilometres, while others are up to 42 in (1066 mm) in diameter, connecting offshore fields to onshore processing facilities hundreds of kilometres away. Despite the prevalence of cyclones in the region, much of this pipeline infrastructure lies exposed on the seafloor, providing the opportunity for marine organisms to grow on it and mobile organisms to interact with it (McLean et al. 2017;Bond et al. 2018a). Similarly, commercial fishers can find the exposed pipelines using echo sounders, or locate many of them on marine charts. ...
... Two of these species, L. sebae and E. multinotatus, were in the top three species landed by commercial fisheries in the Pilbara in 2017 (Newman et al. 2019). These commercially valuable species are commonly associated with complex epibenthic invertebrate assemblages (Sainsbury et al. 1997;Newman 2002;Newman and Dunk 2003;Speare and Stowar 2007;Fitzpatrick et al. 2012;McLean et al. 2017), and are known to persist on pipelines in the PTMF (McLean et al. 2017;Bond et al. 2018a). Interrogation of VMS data show fishers target pipelines like Griffin and Echo Yodel most likely because they provide structurally complex habitat favourable for commercially valuable species. ...
... Traditional concepts suggest pipelines go through processes of scour, sagging, and backfilling and eventually self-bury at free-spans or for the entire pipeline (Sumer and Fredsøe 2002). Should this happen on the NWS, pipeline spans may reduce in length and height, and the cover of structurally complex marine growth may decrease, consequently impacting the abundance and species diversity of fish (McLean et al. 2017;Bond et al. 2018a). However, Leckie et al. (2015) described the mature state of a pipeline on the NWS as 'self-lowering' with a pseudostatic profile regularly alternating between buried and spanning. ...
Article
Full-text available
Over 1400 km of oil and gas pipeline infrastructure exists within the boundaries of the Pilbara Trap Managed Fishery (PTMF) operating on the North West Shelf of Australia. Some of this infrastructure has reached the end of its operational life and requires decommissioning. Location and speed data collected from 2008 to 2018 using vessel monitoring systems onboard all trap fishing vessels (n = 3) operating in the PTMF were used to understand how fishing activity near pipelines has changed through time, and to identify the best predictive variables to explain hours spent fishing km−2 week−1. The proportion of fishing activity within 200 m of a pipeline increased over the survey decade and averaged 4.2% across all years. Hours spent fishing km−2 within 200 m of any pipeline was found to be 8.0 h km−2, ~ 11.4 times more than that recorded, on average, for the remaining area of the PTMF (0.7 h km−2), and ~ 4.6 times more than the western portion of the PTMP (1.7 h km−2) where all pipeline infrastructure exists. Fishing activity within 1 km of pipelines increased after their installation, and hence time since installation was the best predictor of fishing. This study demonstrated that trap fishers in the PTMF allocate a small proportion of their time targeting pipeline infrastructure, with the area close to a pipeline experiencing a relatively greater magnitude of fishing than that elsewhere in the PTMF. As such, the results of this study provide decision makers with an understanding of the intrinsic value of this infrastructure to trap fishers.
... Closeup imagery of epibenthic organisms that often form complex "marine growth" habitats on offshore structures is required, whereas for assessments of fish populations greater setback from the structure is necessary for abundance counts. Industry ROVs usually operate on a 24-h schedule, and on an "as-required" basis and as such their timing may bias observations, particularly abundance estimates for species that exhibit diel and/or seasonal changes in behavior and population dynamics (Barker and Cowan, 2018;Bond et al., 2018a). Once imagery is obtained from industry, further challenges can be faced in video formatting for photogrammetric analysis and in spatially linking video to specific infrastructure components. ...
... To facilitate accurate identification of fish, marine growth and other fauna, ROVs should collect at least HD video. Traditionally, industry ROV operations do not require collection of HD imagery and, as a result, analysis of historical imagery for science is hampered by difficulties in species identification and counting due to low image resolution (e.g., Bond et al., 2018a;McLean et al., 2018;Thomson et al., 2018). Most modern ROVs possess the ability to record HD imagery and should do so as TABLE 1 | Key environmental indicators for assessment and the approach for obtaining them using industry ROV. ...
... For example, typical ROV visual inspections of pipeline use multiple cameras to obtain a central, port and starboard view of the pipeline while an AUV usually uses a single, central camera. In this instance, the ability to see, identify and count fish that most often reside underneath or in the crevice between the seabed and pipeline (Bond et al., 2018a;McLean et al., 2018) is removed and the value of the survey for documenting fish populations significantly reduced. Potential limitations in data comparison should also be outlined to industry and rigorous method comparisons could be undertaken. ...
Article
Full-text available
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 1,000 m, there is a great and underutilized 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 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 analyzed 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 use of oil and gas platforms as habitat by fish has been well-documented (e.g. Ajemian et al., 2015aAjemian et al., , 2015bClaisse et al., 2014;Friedlander et al., 2014;Gallaway et al., 2009;Love et al., 2006;Streich et al., 2017;Torquato et al., 2017), however, investigation of the habitat value of pipelines to fish assemblages has received less attention (although see; Bond et al., 2018a, Bond et al., 2018b, Bond et al., 2018cLove and York, 2005;McLean et al., 2017McLean et al., , 2020. Love and York (2005) reported that fish density was nearly six to seven times greater on pipelines compared to the adjacent seafloor in the Santa Barbara Channel, Southern California. ...
... In recent years, ROVs have emerged as an alternative approach for assessing fish assemblages, particularly on artificial structures (e.g. Ajemian et al., 2015b;Andaloro et al., 2013;Consoli et al., 2016;Trenkel et al., 2004), including pipelines (Bond et al., 2018a;McLean et al., 2017McLean et al., , 2020. ROVs are regularly used by the oil and gas industry to inspect subsea infrastructure, including pipelines, for inspection and maintenance purposes. ...
... We avoided concurrent sampling in the same area due to the possible influence of bait used to attract fish to the stereo-BRUVs affecting the stereo-ROV surveys. Surveys were done between 7:30 and 16:00 h to reduce diurnal variations in fish assemblages across the study (Bond et al., 2018a;Myers et al., 2016). Stereo-BRUVs surveys were completed over seven segments of exposed pipe, with four replicates deployed on each segment, where possible ( Fig. 1). ...
Article
We compared and contrasted fish assemblage data sampled by baited remote underwater stereo-video systems (stereo-BRUVs) and stereo-video remotely operated vehicles (stereo-ROVs) from subsea pipelines, reef and soft sediment habitats. Stereo-BRUVs sampled greater fish diversity across all three habitats, with the stereo-ROV sampling ~46% of the same species on pipeline and reef habitats. Larger differences existed in soft sediment habitats, with stereo-BRUVs recording ~65% more species than the stereo-ROV, the majority of which were generalist carnivores. These differences were likely due to the bait used with stereo-BRUVs attracting fish from a large and unknown area. Fish may have also avoided the moving stereo-ROV, an effect possibly magnified in open soft sediment habitats. As a result of these biases, we recommend stereo-ROVs for assessing fish communities on pipelines due to their ability to capture fish in-situ and within a defined sampling area, but caution is needed over soft sediment habitats for ecological comparisons.
... Fish that move between habitats transport nutrients, serving as nutrient sinks in the systems in which they feed and nutrient sources in the systems where waste is excreted Shantz et al., 2015). Bond et al. (2018) suggested that many fish species likely move off subsea pipelines at night to feed and return by day for shelter. For wellheads, Pradella et al. (2014) also noted the absence of many species at night at the structures. ...
... Previous fish research in depths 80-200 m on the NWS of Western Australia is limited to studies on pipelines Bond et al., 2018), wellheads (Fowler et al., 2012;Pradella et al., 2014;Fowler et al., 2015), specific research trawl expeditions and data reported by commercial fisheries operations (e.g. Newman et al., 2015). ...
Article
When production ceases, offshore oil and gas wells are taken out of service which involves safely plugging, abandoning and usually removing most of the associated subsea equipment. This process must consider impacts to marine ecosystems to meet regulatory requirement and for best environmental practice. However, there is a paucity of information globally on the ecosystem value of these structures, despite the many thousands that are installed throughout our oceans. This study provides the first assessment of fish assemblages and habitats formed by colonising invertebrates on oil and gas wellheads and associated infrastructure in depths of 78–825 m on the north west shelf of Western Australia. Video footage was obtained from Remotely Operated Vehicles deployed by industry on 25 wellhead structures, with six surveyed in each of four distinct depth zones: 78–85 m, 125–135 m, 350–395 m and 490–550 m, and one in 825 m depth. A total of 7278 individual fish from 60 species and 35 families were observed. Commercially important lutjanid (snapper) and epinephelid (grouper) species were common and most abundant on well infrastructure to depths of 135 m, but were absent in depths > 350 m. An as yet unidentified species of roughy, recorded here as Gephyroberyx sp. was the most common fish species observed on well infrastructure in depths > 350 m. Two speckled swellsharks (Cephaloscyllium speccum), believed to be endemic to north-west Australia, were observed for the first time in situ. Numerous fish species were observed at depths beyond their known limits and two IUCN vulnerable species were recorded: the grey nurse shark (Carcharias taurus; 135 m depth) and the round ribbontail ray (Taeniura meyeni; 78 m depth). Fish assemblages and colonising invertebrate habitats present on wellheads and associated infrastructure were strongly influenced by depth, age and height of the structures. Older, taller wellheads in depths < 135 m possessed greater abundances of groupers, snappers, site-attached reef species, and transient pelagic fish species. Beyond 350 m depth, the number of species and total fish abundance declined markedly, as did the percent cover of ascidians, black/octocorals, sponges and Gorgonocephalidae (basket stars) observed growing on the infrastructure. Deeper structures were characterised by an abundance of Gephyroberyx sp. and, while these structures had less colonising invertebrate coverage in general, crinoids (490–550 m) and crustacea (barnacles; 350–395 m) were dominant at these depths. With very little known about marine ecosystems in depths > 100 m, or about wellheads as a type of subsea structure, this study demonstrates the ecological value of ROV footage obtained during industry operations and is indicative of the importance of subsea oil and gas infrastructure as a habitat for fish, and potentially as structures with value to fisheries.
... In depths >40 m, the fish assemblage on the pipeline was characterised by large bodied, commercially important species including P. multidens, L. malabaricus, L. russellii, L. sebae and A. spinifer. These species are commonly associated with structurally complex epibenthic invertebrate communities that include sponges and octocorals [15,16,[60][61][62][63][64]. These habitats were once common throughout the north-west shelf region, but were reduced by trawl fishing activities between 1959 and 1990 [16]. ...
... To understand why certain fish associate with pipelines, it may be necessary to investigate the epibenthic invertebrates colonizing O&G pipelines, and the habitat that they create. Comparable studies examining fish assemblages on pipelines on the north-west shelf found a high diversity of fish at 60-80 m depth and 120-130 m depth using ROV footage [15,60]. Fish diversity was positively correlated with invertebrates such as sponges and crinoids growing on the pipeline, providing a complex habitat for fish assemblages [15]. ...
Article
Full-text available
Knowledge of marine ecosystems that grow and reside on and around subsea oil and gas infrastructure is required to understand impacts of this offshore industry on the marine environment and inform decommissioning decisions. This study used baited remote underwater stereo-video systems (stereo-BRUVs) to compare species richness, fish abundance and size along 42.3 km of subsea pipeline and in adjacent areas of varying habitats. The pipeline is laid in an onshore-offshore direction enabling surveys to encompass a range of depths from 9 m nearshore out to 140 m depth offshore. Surveys off the pipeline were performed across this depth range and in an array of natural habitats (sand, macroalgae, coral reef) between 1 km and 40 km distance from the pipeline. A total of 14,953 fish were observed comprising 240 species (131 on the pipeline and 225 off-pipeline) and 59 families (39 on the pipeline and 56 off-pipeline) and the length of 8,610 fish were measured. The fish assemblage on and off the pipeline was similar in depths of
... When these data are made available to researchers, new discoveries can be made, including a better understanding of fish associations with subsea infrastructure (e.g. McLean et al., 2017), marine growth estimates (van der Stap et al., 2016), new behavioural observations of animals (Gates et al., 2017a;Bond et al., 2018a) and, occasionally, even new species observations (Gates et al., 2017b). However, as the priority of industrial ROV operations is to inspect and maintain subsea infrastructure, rigorous scientific protocols are rarely applied in their operating procedures, which can limit inferences made from opportunistic use of this imagery. ...
... The difference may, in part, be due to sampling differences with Bond et al. (2018bBond et al. ( , 2018c utilising baited underwater cameras (stereo-BRUVs) rather than ROV video recordings. However, Bond et al. (2018a) and McLean et al. (2017) utilised ROV video records and still reported P. multidens to be ubiquitous on pipelines. We suspect that the difference may be due to their behaviour. ...
Article
Scientists, industry and regulators are seeking to understand the influence of oil and gas infrastructure in our oceans to mitigate its impacts and maximise environmental benefits. This project equipped a standard work-class ROV with a light-weight stereo-video camera system to collect high definition imagery of fish and habitats formed by marine growth associated with Woodside Energy's Goodwyn Alpha Platform jacket (GWA) 138 km offshore of Dampier, north-west Australia. ROV video surveys were rapidly performed by industry on four faces of the GWA jacket, from the surface to the seabed at 130 m, yielding 1 h and 14 min of imagery. The stereo-video cameras continued to film during standard ROV operations collecting a further 150 h of HD imagery, used to build a comprehensive fish species list. A total of 8676 individual fish from at least 57 species and 20 families, with an estimated combined mass of 8719 kg, were recorded from the vertical transects of four faces of the jacket. An additional 43 fish species from 21 families were recorded via rapid assessment of a subset of the additional, standard ROV operations imagery. The jacket was characterised by abundant Caranx sexfasciatus (bigeye trevally), Pseudanthias spp. (basslets), Heniochus diphreutes (schooling bannerfish), Labridae sp. (wrasse) and Acanthurus spp. (surgeonfish). Several fish important to the demersal scalefish fishery in the region were observed, including: Lutjanus argentimaculatus (mangrove jack), Lutjanus erythropterus (crimson snapper), Lutjanus malabaricus (saddletail snapper), Lutjanus russellii (Moses' snapper). Eleven broad marine growth types were observed with encrusting/enveloping species (brown algae, filamentous mat, coralline algae, calcite) and hard corals (Tubastrea sp.) present in the greatest coverage. Both marine growth and fish assemblages changed markedly with depth. The addition of a lightweight stereo-video system to an industrial ROV and the allocation of short amounts of time for rapid vertical surveys provided important information on the ecology of an oil and gas platform jacket. Future industrial ROV campaigns should consider utilising this approach to gather scientific information that may have value in the context of decommissioning comparative assessments and, more generally, improves our understanding of the impact of oil and gas infrastructure in our oceans.
... Our experiments were conducted during the day when many reef fishes are known to use coral reefs as refuge from predators (Rasher et al. 2017;Bond et al. 2018). In addition to this spatial refuge from predation, prey species can alter their behaviours to avoid exhibiting "risky" behaviours when predators are active, creating temporal refugia from predation (Smith et al. 2019). ...
Article
Predators can exert strong ecological effects on their prey either via consumption or by altering their behaviour and morphology. In marine systems, predators and their prey co‐occur in a three‐dimensional environment, but to date predator‐prey studies have largely focussed on behaviours of prey on horizontal (distance from shelter) rather than vertical (height in water column) axes. We used life‐size shape‐models of a blacktip reef shark Carcharhinus melanopterus (threatening shape‐model), a juvenile coral trout Plectropomus leopardus (non‐threatening shape‐model) and a shape‐control to examine the impact of perceived instantaneous (measured by time to first feeding) versus sustained (measured by time to consume the entire bait) predation threats on the feeding behaviour and three‐dimensional use of space by mesopredatory reef fishes in a coral reef environment. We found that mesopredatory fishes such as red snapper Lutjanus bohar and spangled emperor Lethrinus nebulosus took longer to begin feeding and to consume predation assays (fish baits) at greater distances from the shelter of a patch reef across both horizontal and vertical axes and that this phenomenon was stronger in the vertical axis than the horizontal. The presence of a life‐size shape‐model of a shark, which we used to increase the perception of predator threat, magnified the instantaneous effect compared to non‐threatening models, but not the sustained effect. We found no evidence for a difference in the level of predation risk posed by the shape‐model of the juvenile coral trout (a non‐threatening reef fish) and a negative control (no shape‐model). Our study suggests that mesopredators modify their behaviours in response to the perceived risk of predation across both horizontal and vertical axes away from shelter, and that this response is most severe on the vertical axis, potentially limiting daytime foraging behaviour to a hemisphere around shelter sites. This article is protected by copyright. All rights reserved.
... Most individuals of the species L. russellii were detected in the mangroves and coral reefs, and this multiple habitat use reflects a relaxed day-night shift, with individuals feeding in seagrass beds at night and shifting to sheltered areas (mangrove/ coral reefs) by daytime (Nagelkerken et al., 2000a;Bond et al., 2018). Upeneus tragula and Sillago maculata utilized almost all habitats. ...
Article
Understanding the connectivity of fish among different typical habitats is important for conducting ecosystem-based management, particularly when designing marine protected areas (MPA) or setting MPA networks. To clarify of connectivity among mangrove, seagrass beds, and coral reef habitats in Wenchang, Hainan Province, China, the fish community structure was studied in wet and dry seasons of 2018. Gill nets were placed across the three habitat types, and the number of species, individuals, and body size of individual fish were recorded. In total, 3 815 individuals belonging to 154 species of 57 families were collected. The highest number of individuals and species was documented in mangroves (117 species, 2 623 individuals), followed by coral reefs (61 species, 438 individuals) and seagrass beds (46 species, 754 individuals). The similarity tests revealed highly significant differences among the three habitats. Approximately 23.4% species used two habitats and 11.0% species used three habitats. A significant difference (p<0.05) in habitat use among eight species (Mugil cephalus, Gerres oblongus, Siganus fuscescens, Terapon jarbua, Sillago maculata, Upeneus tragula, Lutjanus russellii, and Monacanthus chinensis) was detected, with a clear ontogenetic shift in habitat use from mangrove or seagrass beds to coral reefs. The similarity indices suggested that fish assemblages can be divided into three large groups namely coral, seagrass, and mangrove habitat types. This study demonstrated that connectivity exists between mangrove-seagrass-coral reef continuum in Wenchang area; therefore, we recommend that fish connectivity should be considered when designing MPAs or MPA network where possible.
... Most individuals of the species L. russellii were detected in the mangroves and coral reefs, and this multiple habitat use reflects a relaxed day-night shift, with individuals feeding in seagrass beds at night and shifting to sheltered areas (mangrove/ coral reefs) by daytime (Nagelkerken et al., 2000a;Bond et al., 2018). Upeneus tragula and Sillago maculata utilized almost all habitats. ...
Article
Understanding the connectivity of fish among different typical habitats is important for conducting ecosystem-based management, particularly when designing marine protected areas (MPA) or setting MPA networks. To clarify of connectivity among mangrove, seagrass beds, and coral reef habitats in Wenchang, Hainan Province, China, the fish community structure was studied in wet and dry seasons of 2018. Gill nets were placed across the three habitat types, and the number of species, individuals, and body size of individual fish were recorded. In total, 3 815 individuals belonging to 154 species of 57 families were collected. The highest number of individuals and species was documented in mangroves (117 species, 2 623 individuals), followed by coral reefs (61 species, 438 individuals) and seagrass beds (46 species, 754 individuals). The similarity tests revealed highly significant differences among the three habitats. Approximately 23.4% species used two habitats and 11.0% species used three habitats. A significant difference (p<0.05) in habitat use among eight species (Mugil cephalus, Gerres oblongus, Siganus fuscescens, Terapon jarbua, Sillago maculata, Upeneus tragula, Lutjanus russellii, and Monacanthus chinensis) was detected, with a clear ontogenetic shift in habitat use from mangrove or seagrass beds to coral reefs. The similarity indices suggested that fish assemblages can be divided into three large groups namely coral, seagrass, and mangrove habitat types. This study demonstrated that connectivity exists between mangrove-seagrass-coral reef continuum in Wenchang area; therefore, we recommend that fish connectivity should be considered when designing MPAs or MPA network where possible.
... These effects may vary over time, relating to environmental conditions and stage of ecological succession (Fujii, 2015;Gates et al., 2019;Todd et al., 2019). Consequently, artificial structures have a potential role in restoring degraded marine ecosystems such as coral reefs (Rinkevich, 2014), mollusc reefs (Walles et al., 2016), algal forests (Gianni et al., 2013) and historically trawled or degraded habitats (Bond et al., 2018a), and have been proposed for restoration of disturbed deep-sea habitats (Cuvelier et al., 2018). ...
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Large structures are introduced into deep-water marine environments by several industrial activities, including hydrocarbon exploitation. Anthropogenic structures can alter ecosystem structure and functioning in many marine ecosystems but the responses on continental margins are poorly known. Here, we investigate the short-term response of benthic megafauna to the installation of a 56 km-long 30 cm diameter pipeline on the Angolan Margin (Block 31) from 700 to 1800 m water depth using remotely operated vehicle imagery. Clear depth-related patterns exist in the density, diversity and community structure of megafauna observed in 2013 prior to pipeline installation. These patterns are altered in a subsequent survey in 2014, three-months after pipeline installation. Significant increases in density, particularly in mid-slope regions are observed. Diversity is generally, but not consistently, enhanced, particularly in the shallower areas in 2014. Clear changes are noted in community structure between years. These changes are primarily caused by increases in the abundance of echinoderms, particularly the echinoid Phormosoma sp. indet. There was no evidence of colonisation of the pipeline in three months by visible fauna. The few large anemones observed attached to the pipe may be able to move as adults. The pipeline appeared to trap organic material and anthropogenic litter, and may enhance available food resources locally as well as providing hard substratum. These results indicate complex and ecosystem-dependent responses to structure installation and caution against simplistic approaches to environmental management.
... Oil and gas infrastructure likely increases, or at least focuses, fish production (Claisse et al., 2014), surrounding benthic biomass, diversity, and connectivity (Macreadie et al., 2011) so their removal may reduce secondary production (Pondella et al., 2015). The particular assemblages supported by these structures varies with structure age, water depth and height on the structure and on different timescales (Fujii, 2015;Bond et al., 2018) so there is potentially variation within and between different basins. It is therefore important to develop a better understanding of faunal assemblages supported by offshore infrastructures in order to understand the effect of their removal. ...
Article
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Decommissioning of oil and gas infrastructure globally has focused attention on its importance as hard substratum on continental shelf and slope habitats. Observational studies are needed to improve understanding of faunal assemblages supported by offshore infrastructure and better predict the effect of removal. Here, we present results from visual inspection and physical sampling of a small oil and gas industry structure decommissioned from an oil field in the North East Atlantic. This is supported by observations of similar structures nearby and by photographs of the surrounding seabed from environmental baseline surveys. The structure supported a reasonably high biomass and diversity of invertebrates (>10 kg and >39 macrofaunal and 17 megafaunal species) and fishes (>20 kg biomass and >4 species). The invertebrate megafaunal species present on the structure were a sub-set of the hard substratum fauna observed on surrounding seabed. Porifera were absent from the structure. Biological succession in the first 2 years occurred as follows. Sparse colonies of the hydroid Obelia sp. stet were early colonisers then subsequent development of thick hydroid turf (Obelia sp. stet. and Halecium sp. stet.) supported an invertebrate assemblage (2654 individuals kg wet mass–1) dominated by saddle oysters [Pododesmus squama (Gmelin, 1791) and Heteranomia sp. stet.)] and scale worms (Harmothoe spp.). Percentage cover of hydroid turf varied significantly over the structure, with most growth on sections exposed to strongest currents. Commercially important fish species present around the structure included Gadus morhua (Atlantic cod), Pollachius virens (saithe) and Lophius piscatorius (monkfish). Studies of artificial structures such as this provide much needed data to understand their role in the ecology of seafloor habitats and inform environmental decision making on all stages of industry from exploration to decommissioning. We show that the ecological role of the decommissioned three-dimensional structures was to enhance the biomass of a sub-set of epifaunal invertebrates found in the area. This supported diverse associated macrofaunal organisms, providing a food source for motile invertebrates and fishes in an area where background hard substratum can be lost through the impacts of drilling.
... The approach constructs all possible combinations of models and excludes models with collinear variables specified by a Pearson's correlation [ 0.28 (Graham 2003). This technique has great utility for ecological applications exploring the influence of environmental factors on the distribution of biota (Bond et al. 2018;Wellington et al. 2018). ...
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Context Whilst the composition and arrangement of habitats within landscape mosaics are known to be important determinants of biodiversity patterns, the influence of seascape patterning and connectivity on temperate reef fish assemblages remains largely unknown. Objectives We examined how habitat patterns at multiple spatial scales (100–1000 m) explained the abundance and diversity of temperate reef fish in a reef-seagrass dominated seascape. Methods Fish assemblages were surveyed using remote underwater videos deployed on 22 reefs in Jervis Bay, NSW, Australia. Using full-subset GAMMs, we investigated if habitat area, edge, structural connectivity and a metric for habitat diversity (Shannon’s diversity index) of reef and seagrass can predict variations in a temperate reef fish assemblage. Results A key finding of the study was that temperate reefs close (< 55 m) to large (> 6.25 ha) seagrass meadows contained greater abundance and diversity of fish. A consistent negative correlation was also found between reef area (> 0.01 ha) and the fish assemblage. The influence of seascape metrics on the abundance of fishes varied with functional traits (trophic groups, mobility and habitat associations). Fish-seascape relationships occurred at a range of spatial scales with no single scale being solely important for structuring the fish assemblage. Conclusions We demonstrate that it is important not to view reef habitats in isolation, rather consider a reefs context to adjacent seagrass when predicting the distribution of temperate reef fish. This finding improves current understanding of the multi-scale factors structuring temperate reef fish assemblages and highlights the importance of reef-seagrass connectivty for the management of temperate marine ecosystems.
... There are numerous examples of other successful shortterm collaborations investigating a range of key questions, including: extent of anthropogenic impacts (Netto et al., 2010); recovery from anthropogenic impacts (Jones et al., 2012), role of infrastructure (Bond et al., 2018); potential impacts on reef-forming corals (Purser, 2015), and characterization of local biodiversity . In the deep-ocean observing context, long-term collaborations are a key focus for further expansion of these synergies. ...
Article
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The deep ocean below 200 m water depth is the least observed, but largest habitat on our planet by volume and area. Over 150 years of exploration has revealed that this dynamic system provides critical climate regulation, houses a wealth of energy, mineral, and biological resources, and represents a vast repository of biological diversity. A long history of deep-ocean exploration and observation led to the initial concept for the Deep-Ocean Observing Strategy (DOOS), under the auspices of the Global Ocean Observing System (GOOS). Here we discuss the scientific need for globally integrated deep-ocean observing, its status, and the key scientific questions and societal mandates driving observing requirements over the next decade. We consider the Essential Ocean Variables (EOVs) needed to address deep-ocean challenges within the physical, biogeochemical, and biological/ecosystem sciences according to the Framework for Ocean Observing (FOO), and map these onto scientific questions. Opportunities for new and expanded synergies among deep-ocean stakeholders are discussed, including academic-industry partnerships with the oil and gas, mining, cable and fishing industries, the ocean exploration and mapping community, and biodiversity conservation initiatives. Future deep-ocean observing will benefit from the greater integration across traditional disciplines and sectors, achieved through demonstration projects and facilitated reuse and repurposing of existing deep-sea data efforts. We highlight examples of existing and emerging deep-sea methods and technologies, noting key challenges associated with data volume, preservation, standardization, and accessibility. Emerging technologies relevant to deep-ocean sustainability and the blue economy include novel genomics approaches, imaging technologies, and ultradeep hydrographic measurements. Capacity building will be necessary to integrate capabilities into programs and projects at a global scale. Progress can be facilitated by Open Science and Findable, Accessible, Interoperable, Reusable (FAIR) data principles and converge on agreed to data standards, practices, vocabularies, and registries. We envision expansion of the deep-ocean observing community to embrace the participation of academia, industry, NGOs, national governments, international governmental organizations, and the public at large in order to unlock critical knowledge contained in the deep ocean over coming decades, and to realize the mutual benefits of thoughtful deep-ocean observing for all elements of a sustainable ocean.
... This is due to the strong dependency of sessile organisms on suitable anchor points. Various consolidated objects, both natural and artificial (e.g., stones, mussel accumulations, shipwrecks, pipelines or construction basements), can provide shelter and substrate for a variety of sessile and mobile species (e.g., [6][7][8]). The sediment composition of the seafloor has a strong influence on the availability of such substrates. ...
Article
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Stony grounds form important habitats in the marine environment, especially for sessile benthic organisms. For the purpose of habitat demarcation and monitoring, knowledge of the position and abundance of individual stones is necessary. This is especially the case in areas with a scattered occurrence of stones in an environment which is otherwise characterized by relatively mobile sandy sediments. Exposed stones can be detected using side-scan sonar (SSS) data. However, apart from laborious manual identification, there is as yet no automated or semi-automated method available for a fast and spatially resolved detection of stones. In this study, a Haar-like feature detector was trained to identify individual stones on an SSS mosaic (~12 km2) showing heterogeneous sediment distribution. The results of this method were compared with those of manually derived stones. Our study shows that the Haar-like feature detector was able to detect up to 62% of the overall occurrence of stones within the study area. Even though the sheer number of correctly identified stones was influenced by, e.g., the type of sediments and the number of grey values of the mosaic, Haar-like feature detectors provide a relatively easy and fast method to identify stones on SSS mosaics when compared to the manual investigation.
... Most individuals of the species L. russellii were detected in the mangroves and coral reefs, and this multiple habitat use reflects a relaxed day-night shift, with individuals feeding in seagrass beds at night and shifting to sheltered areas (mangrove/ coral reefs) by daytime (Nagelkerken et al., 2000a;Bond et al., 2018). Upeneus tragula and Sillago maculata utilized almost all habitats. ...
Article
The length‐weight relationships (LWRs) were studied for eight seagrass fish from Wenchang, China, using gill nets (150*1 m, mesh size 0.5 cm), including Gerres oblongus, Ambassis kopsii, Halichoeres nigrescens, Sillago aeolus, Yongeichthys criniger, Oxyurichthys tentacularis, Lethrinus haematopterus and Hypoatherina tsurugae, in November 2017, March and August 2018. Results suggest that mean LWR parameters b for these eight seagrass fish varied from 2.801 for L. haematopterus to 3.640 for A. kopsii, and r2 valued from .950 for L. haematopterus to 0.993 for H. nigrescens. This study will help us to better understand the ecological parameters these seagrass fish.
... In recent years, many researchers (Benfield et al., 2019;Bond et al., 2018;Corbera et al., 2019;Macreadie et al., 2018;Raoult et al., 2020;Wetz et al., 2020) used ROV devices for samplings, explorations, measurements and recording high quality images and videos. Capocci et al. (2017) categorized the underwater vehicles and investigated the difference between the mid-sized inspection-class and the handheld ROVs. ...
Article
Nowadays, remotely operated vehicle (ROV) is an integral part of the marine industry. In this study, the hydrodynamic performance of a specific model of ROV is evaluated by numerical and experimental simulations in different Reynolds numbers ranging from 39291 to 157163 and various angles of attack from 0° to 45°. Moreover, two rectangular cubic models with fillet and sharp edges are modeled for comparative study. The wind tunnel and the finite volume methods are used for experimental and numerical simulations, respectively, and the Menter's SST k-ω model is employed to simulate the turbulent flow. The leading edge geometry, angle of attack, and Reynolds number are found to be the most effective factors on the drag forces. Additionally, the fillet edge model had better hydrodynamic performance than the ROV and the sharp edge rectangular cubic model considerably.
... com)]. Archival footage is better suited to quantify fish biodiversity (Bond et al., 2018a;McLean et al., 2021). Although, research questions formulated by experts and other stakeholders (Shaw et al., 2018) encompass many themes that are important to make informed decisions (Figure 1), those themes, do not get reflected in the research that has been carried out to date, aside from biodiversity assessments. ...
Article
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Numerous oil and gas (O&G) installations worldwide will need to be decommissioned in the near future. Complete removal of subsea structures is often the default approach although some regions retain structures under rigs-to-reefs programs. Here, we reviewed the published literature to understand the status of global research on decommissioning, and specifically identify gaps in ecological knowledge. We estimated the frequency of different research categories (i.e., themes, and spatial/temporal scales), and tested the assumption that the number of papers across the categories of each research aspect was even in distribution. However, the frequency of studies focusing on biodiversity at a local (≤100 km2) scale (relative to regional and oceanic and pan-oceanic scales) were significantly higher; while other theme categories (e.g., eco-toxicology, connectivity, structural-integrity, restoration and other) were significantly lower than expected. Temporally, ≤1-year studies were more frequent than multi-year studies, but these frequencies did not significantly deviate from the assumed distribution of equal frequencies. We propose that further research be carried out to evaluate the benefits of both retention and removal of structures. Ecological research on decommissioning should extend its focus beyond biodiversity, to include eco-toxicology, structural-integrity, connectivity at larger spatial and temporal scales. This would provide a more holistic assessment of ecological impacts to inform sustainable and equitable development choices in multiple Blue Economy sectors, as we transition from offshore O&G to marine renewables.
... It is possible that circles exist along the EY pipeline, but are out of view, beyond the irregular and steep-sloped depressions which induce disruptions and variation in seafloor hydrodynamics. In addition, fish in general are more abundant where pipeline spans exist (Bond et al., 2018;McLean et al., 2017) which may deter pufferfish from building nests due to egg disturbance or predation. The extent of any such potential effect, however, remains unknown, as only a thin strip of seafloor centred on the umbilical and pipeline was surveyed. ...
Article
In 2011, the enigma of “mystery circles”, small but complex underwater structures first observed by divers from southern Japan in 1995, was solved when a new species of pufferfish, white‐spotted pufferfish (Torquigener albomaculosus Matsuura, 2014), was identified as the responsible agent. To date these circles have been described only from Japan, where they are formed on a sandy seafloor in water depths less than 30 m. A survey of oil field infrastructure on the north‐west shelf of Western Australia in 2018 using a remotely operated vehicle (ROV) and hybrid autonomous underwater vehicle (HAUV) recorded high‐resolution video and bathymetric data of 21 circular formations with similar features to those described in Japan. The circles display dimensions and morphology like those described from Japan, but were observed in water depths between 129 m and 137 m. The HAUV also recorded high resolution photographs which captured a Torquigener sp. fish in the immediate vicinity of the circles. An additional circle and Torquigener sp. was observed in images collected by baited remote underwater stereo‐video (stereo‐BRUV) in a nearby location in 129 m depth. These circles are the first to be found in Australia. The pufferfish species responsible cannot be identified from images collected but is not likely to be T. albomaculatus. Such a discovery not only generates intrigue and wonder amongst scientists and the general public, but also provides an insight into the reproductive behaviour and evolution of pufferfish globally.
... Multiple stereo-BRUVs can be deployed concurrently, with ~10 stereo-BRUV systems providing optimum logistical efficiency for 60-minute deployment times. Crepuscular periods should be avoided due to demonstrated changes in fish behaviour during these times (Myers et al. 2016;Bond et al. 2018a). When sampling in low light conditions, both blue (450-465 nm) and white (550-560 nm) lights can be used. ...
Article
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1. Baited remote underwater stereo‐video systems (stereo‐BRUVs) are a popular tool to sample demersal fish assemblages and gather data on their relative abundance and body‐size structure in a robust, cost‐effective, and non‐invasive manner. Given the rapid uptake of the method, subtle differences have emerged in the way stereo‐BRUVs are deployed and how the resulting imagery are annotated. These disparities limit the interoperability of datasets obtained across studies, preventing broad‐scale insights into the dynamics of ecological systems. 2. We provide the first globally accepted guide for using stereo‐BRUVs to survey demersal fish assemblages and associated benthic habitats. 3. Information on stereo‐BRUV design, camera settings, field operations, and image annotation are outlined. Additionally, we provide links to protocols for data validation, archiving, and sharing. 4. Globally, the use of stereo‐BRUVs is spreading rapidly. We provide a standardised protocol that will reduce methodological variation among researchers and encourage the use of Findable, Accessible, Interoperable, and Reproducible (FAIR) workflows to increase the ability to synthesise global datasets and answer a broad suite of ecological questions.
... However, there also exists oil and gas ROV engineering surveys of platforms and associated infrastructure (i.e., pipelines, subsea equipment and wellheads) conducted as part of routine physical integrity inspections. In the past few years, researchers off western Australia [8][9][10][11][12] and in the North Sea [13,14] have begun to use this archival footage to characterize the biological communities associated with the offshore oil and gas structures. ...
Article
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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.
... Higher diversity and abundance of fish occurs on pipelines that feature spanning (gap between pipeline and seafloor) than on pipelines that rest directly on the seafloor or are part buried . Similarly, fish are more diverse and abundant on pipelines that have been colonised by habitat-forming species such as sponges and corals (Bond et al., 2018b;McLean et al., 2017). These habitats likely offer a significant food source and refuge for fish, but also for invertebrates upon which fish feed Rouse et al., 2019). ...
Article
The value of subsea pipelines as habitat for fish and benthic species is being considered, particularly by the oil and gas industry as they look to decommission seafloor infrastructure reaching the end of production. We investigated fish and benthic communities along a ca.345 km section of offshore pipeline in remote northern Australia to compare pipeline communities with those in surrounding areas and provide context for decommissioning risk assessments. We surveyed pipeline and adjacent natural seabed ecosystems at five locations on the continental shelf using remote video technology to quantify fish and benthic communities and modelled predicted fish communities across the study locations. We found that the pipeline supported turfing and low-relief biota (e.g. coralline algae, ascidians, bryozoans, small/encrusting sponges and soft coral or mixed filter feeder communities) with cover >75%. Pipeline benthic communities differed from those in adjacent ecosystems. Within 6 km of the pipeline, the seabed was predominantly sand/silt with only sparse biota; natural hard substrate (e.g. shoal features within 3 km of the pipeline) supported diverse coral and filter feeder communities (average 10–25% cover). Fish abundance and assemblage composition on the pipeline also differed from those in surrounding high- and low-complexity habitats. This difference was driven by high abundance and biomass of commercially important fish species near the pipeline and sand-affiliated species elsewhere. Our study provides important new insights into the marine communities associated with a subsea pipeline in northern Australia; with this artificial habitat observed to support a subset of species known to inhabit the area, but effectively representing a unique assemblage within the region.
... Offshore oil platform placement and well drilling, submarine pipelaying, and coastal port and refinery construction can mobilize marine sediments and disturb benthic organisms [65,66], resulting in permanent loss of physical habitat and mobilization of contaminants into marine food webs [121]. Coastal oil ports and refineries result in permanent shoreline alteration and loss of productive nearshore habitats such as mangroves, seagrass beds, estuaries, and kelp forests which serve as critical habitats for early life stages of many commercially valuable fishes and invertebrates-serving to increase mortality and potentially decrease fishery productivity. ...
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A quarter of global oil production comes from offshore fields and about 60% of internationally-traded oil travels by tankers. The relationship between oil, fisheries, and coastal communities is documented primarily through case studies in individual jurisdictions and via the impacts of oil spills. Yet, the implications of oil development for fisheries and coastal communities are much broader. This study provides an extensive review of the effects of oil development in relation to four interconnected themes: 1) the environment, including marine habitats and fish; 2) small-scale fisheries and coastal community livelihoods; 3) coastal and ocean spaces, including disputes over territory and infrastructure; and 4) ocean and coastal governance processes. We map spatial overlaps between the oil sector and small-scale fisheries and point to the frequent displacement of fishers from fishing grounds due to increasing coastal traffic and infrastructure, and the catastrophic effects of oil spills on fisheries and coastal economies. Though the oil sector generally has negative impacts on fisheries livelihoods and coastal communities, these effects and their mechanisms vary across locations, ecosystems, species, and specific activities and groups. Overall, this narrative review provides a comprehensive account of the scholarship to date and points to key themes for future research, including intersections between offshore oil and gender, cross-sectoral governance, and the achievement of Sustainable Development Goal 14. Underpinning all of these challenges and potential solutions is a clear need for stronger integration of social and natural science knowledge, perspectives, and tools.
... Offshore oil and gas (O&G) infrastructure provides habitat that can promote biodiversity (Love and York 2005;Bond et al. 2018a;McLean et al. 2017McLean et al. , 2019Todd et al. 2020) and enhance fish production (Smith et al. 2016;Claisse et al. 2019), particularly in environments that are oligotrophic or where natural hard substrates (e.g. reefs) are limited. ...
Article
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.
... Accounting for collinear variables is important for model stability and was especially important in our study because we had multiple correlated explanatory variables ( Figure A.2). The full-subsets approach was developed for ecological applications and has great utility for evaluating the influence of correlated environmental factors on the ecology of biota (McLean et al. 2016;Bond et al. 2018). We used the R package FSSgam 1.11 (Fisher et al. 2018) to generate the best-fitting model(s) for each ocean age year. ...
Article
An improved understanding of the mechanisms influencing productivity of fish populations is critical for accurately determining harvest rates and identifying years of conservation concern. Here we reconstruct yearly scale growth of three Puget Sound (PS) Chum Salmon Oncorhynchus keta stocks over 16 brood years (1997–2012) to better understand how variation in marine growth may be related to environmental factors, intra‐ and interspecific competition, and stock productivity. Generalized additive mixed models identified copepod species richness in the northern California Current and the abundance of PS Pink Salmon O. gorbuscha and Chum Salmon as strong predictors of first‐year growth, the latter indicative of density‐dependent effects as the abundance of local competitors (Pink and Chum salmon) increased. Second‐year growth was negatively related to the Aleutian Low–Beaufort Sea Anticyclone (ALBSA), a recently defined metric of the Aleutian Low, and showed a nonlinear positive to negative relationship with sea surface temperature in the Gulf of Alaska. Puget Sound Chum and Pink Salmon abundances were also significantly related to second‐year growth but did not suggest density‐dependent effects like those observed in ocean year 1. Third‐year growth was closely related to large‐scale climate indicators, demonstrating a nonlinear negative to positive relationship with the North Pacific Gyre Oscillation, a negative relationship with ALBSA, and a negative relationship with North Pacific Pink Salmon abundance when catch statistics indicated that abundance was high. Models indicated that PS Chum Salmon stock productivity (recruits per spawner) was positively correlated with back‐calculated first‐year growth and negatively correlated with second‐ and third‐year growth, suggesting that for brood years whose surviving adults experienced rapid early marine growth, there were cohort survival benefits. As new relationships between large‐scale indicators and Pacific salmon stocks are identified, incorporating these indicators into forecasting efforts is paramount for effective and sustainable management of fishery resources.
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Oil and gas pipelines that lie exposed on the seabed can function as “artificial reefs,” providing habitat for fish and benthic species, including some that are listed under conservation designations. As the offshore hydrocarbon industry matures, operators and national governments must decide whether decommissioned pipelines should be left in situ or removed for onshore disposal. In most jurisdictions, there is a requirement to evaluate the environmental consequences of different pipeline decommissioning options in a comparative assessment. To do this effectively requires an understanding of the associations between pipelines and fauna. Pipeline operators routinely collect video footage for inspection and maintenance purposes using remotely operated vehicles (ROV). This footage has the potential to provide insight into interactions between the marine environment and offshore pipelines. This study uses inspection footage from eight pipelines to quantify the presence and abundance of species and features listed under a number of EU and United Kingdom conservation designations; 12 such features and species were observed on the pipelines or neighboring sediments. The soft coral Alcyonium digitatum was present in the highest densities on pipelines located on mud, while Sabellaria sp. and Echinus esculentus were more common on pipelines in sand. Gadoids, anemones and hermit crabs were also frequently observed around pipelines. The study identifies the limitations to the use of industry ROV footage for ecological purposes, but shows that with consideration of taxon size, image resolution, ROV speed and altitude, this can be a valuable approach to gain additional insights into environment-infrastructure interactions. The results suggest that removal of pipelines will remove established colonies of epibenthic species, some of which have conservation value. The ecological significance of this loss, however, must be weighed against the broader considerations during pipeline decommissioning including cost, technical feasibility and impacts to other marine users.
Chapter
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In recent times, decommissioning of offshore platforms has become an even more discussed topic, for its relevant environmental, social, and economic repercussions. In particular, by carrying out economic considerations, all the divestiture possibilities applicable to an offshore platform and the relative sustainable business models (SBMs) will be analyzed in a wide framework of the circular economy and sustainable principles. In this scenario, sustainable decommissioning (SD) of offshore platforms process refers to multidimensional and interdisciplinary challenges, which requires a deep understanding of technical, legal, economic, financial, social, and environmental variables. The decommissioning of these structures is an issue that has gained a great deal of international attention and will require in the next years an open dialogue and exchange between institutions, oil and gas companies, enterprises, and the environment.
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Offshore platforms, subsea pipelines, wells and related fixed structures supporting the oil and gas (O&G) industry are prevalent in oceans across the globe, with many approaching the end of their operational life and requiring decommissioning. Although structures can possess high ecological diversity and productivity, information on how they interact with broader ecological processes remains unclear. Here, we review the current state of knowledge on the role of O&G infrastructure in maintaining, altering or enhancing ecological connectivity with natural marine habitats. There is a paucity of studies on the subject with only 33 papers specifically targeting connectivity and O&G structures, although other studies provide important related information. Evidence for O&G structures facilitating vertical and horizontal seascape connectivity exists for larvae and mobile adult invertebrates, fish and megafauna; including threatened and commercially important species. The degree to which these structures represent a beneficial or detrimental net impact remains unclear, is complex and ultimately needs more research to determine the extent to which natural connectivity networks are conserved, enhanced or disrupted. We discuss the potential impacts of different decommissioning approaches on seascape connectivity and identify, through expert elicitation, critical knowledge gaps that, if addressed, may further inform decision making for the life cycle of O&G infrastructure, with relevance for other industries (e.g. renewables). The most highly ranked critical knowledge gap was a need to understand how O&G structures modify and influence the movement patterns of mobile species and dispersal stages of sessile marine species. Understanding how different decommissioning options affect species survival and movement was also highly ranked, as was understanding the extent to which O&G structures contribute to extending species distributions by providing rest stops, foraging habitat, and stepping stones. These questions could be addressed with further dedicated studies of animal movement in relation to structures using telemetry, molecular techniques and movement models. Our review and these priority questions provide a roadmap for advancing research needed to support evidence‐based decision making for decommissioning O&G infrastructure. Offshore platforms and related fixed structures supporting the oil and gas (O&G) industry are prevalent in all oceans. We review current knowledge on the role of O&G infrastructure in maintaining, altering or enhancing ecological seascape connectivity. There is a paucity of studies assessing connectivity and O&G structures. We discuss existing knowledge and identify critical knowledge gaps for decision‐making, such as the need to understand how O&G structures modify and influence movement patterns of mobile species and dispersal. Our review and priority questions provide a roadmap for advancing research needed to support evidence‐based decision‐making for decommissioning O&G infrastructure.
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The decommissioning of offshore oil and gas platforms typically involves removing some or all of the associated infrastructure and the consequent destruction of the associated marine ecosystem that has developed over decades. There is increasing evidence of the important ecological role played by offshore platforms. Concepts such as novel ecosystems allow stakeholders to consider the ecological role played by each platform in the decommissioning process. This study focused on the Wandoo field in Northwest Australia as a case study for the application of the novel ecosystem concept to the decommissioning of offshore platforms. Stereo-baited remote underwater video systems were used to assess the habitat composition and fish communities at Wandoo, as well as two control sites: a sandy one that resembled the Wandoo site pre-installation, and one characterized by a natural reef as a control for natural hard substrate and vertical relief. We found denser macrobenthos habitat at the Wandoo site than at either of the control sites, which we attributed to the exclusion of seabed trawling around the Wandoo infrastructure. We also found that the demersal and pelagic taxonomic assemblages at Wandoo more closely resemble those at a natural reef than those which would likely have been present pre-installation, but these assemblages are still unique in a regional context. The demersal assemblage is characterized by reef-associated species with higher diversity than those at the sand control and natural reef control sites, with the pelagic community characterized by species associated with oil platforms in other regions. These findings suggest that a novel ecosystem has emerged in the Wandoo field. It is likely that many of the novel qualities of this ecosystem would be lost under decommissioning scenarios that involve partial or complete removal. This study provides an example for classifying offshore platforms as novel ecosystems.
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In 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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Coral reef ecosystems are under increasing anthropogenic pressures making it ever more important to monitor changes in fish communities to implement appropriate management. In contrast to long-term spatial and temporal variation which has been extensively documented, little work has been carried out to identify variability in fish assemblages on short time scales, with few studies testing patterns of fish assemblages between and within days. Here we investigated the diurnal changes in species richness, relative abundance and assemblage composition in a shallow coral reef fish community in Egypt. To do so, a section of coral reef was filmed during the morning (0600 h), midday (1000 and 1400 h) and afternoon (1800 h) over eleven days. Dusk (0600 h) and dawn samples (1800 h) showed higher species richness compared to late morning (1000 h) and mid-day samples (1400 h) and borderline significantly higher numbers of total individuals, likely associated with feeding activity and predator avoidance. Assemblage composition varied across days and time-of-day, showing greater variability during dusk and dawn associated with a transition between day-time and night-time assemblages. Our results have implications for designing coral reef fish surveys, emphasising that short-term changes in fish communities should be considered when designing experiments to monitor fish assemblages over time. Where possible, we suggest increasing replication within sites and time scales or randomising data within a specific time window at all sites, looking to exclude dusk and dawn.
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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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Subsea pipelines have been installed in all major hydrocarbon basins across the globe to support the offshore Oil & Gas (O&G) industry. These artificial structures provide hard substratum that can be colonised and utilised by sessile and mobile organisms. The present study utilises industry-collected remotely operated vehicle (ROV) video to assess fish species richness and abundance, and marine growth type, extent and complexity along sections of a subsea gas pipeline, in 56-82 m depth, that traverses the Australian Commonwealth Montebello Marine Park (MMP). A total of 7493 fish from 81 species and 33 families were recorded from 606 analysed 10 m transects spaced across sections of the pipeline. Of these 81 species, 27 are considered fishery-target species in the Pilbara Demersal Scalefish fishery (PDSF), with select commercial fishing activities permitted with authorisation within the Marine Park. A moderate abundance (175) of sub-adult red emperor (Lutjanus sebae), a fishery-indicator species, were observed along the pipeline. Eleven different categories of marine growth habitat were observed, with the pipeline possessing quite uniform coverage of encrusting marine growth (coralline algae, bryozoans, ascidians, etc.) with patchy occurrences of more structurally complex sponges and black/octocoral forms. Fish species richness and abundance of the commercially targeted Moses' snapper (Lutjanus russellii) were correlated positively with increasing cover of sponges. The pipeline itself had very few spans and was never more than fractionally buried. Despite the somewhat homogenous habitats, depths, and position of the pipeline relative to the seafloor, presence of a field joint indent had a positive influence on the abundance of some common and commercially important fish species. This study demonstrates the ecological value of ROV footage obtained during industry inspection operations that were conducted for reasons unrelated to the determination of ecological information. The pipeline offers a corridor of hard bottom habitat within a marine park that facilitates epibiotic growth and the presence of reef-associated species in a region characterised by sandy sediments. Results indicate the potential importance of subsea O&G infrastructure as a habitat for fish, and in consequence, potentially also as structures with value to fisheries.
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The ecological role of subsea pipelines is an important factor in the consideration of decommissioning options. Several studies have assessed the marine communities associated with subsea pipelines on Australia’s North West Shelf (NWS), considering the influence of factors such as water depth, substrate type, pipeline diameter and pipeline position on fish assemblages. Less is known about the artificial rock berms used to stabilise pipelines. The Wandoo field on the NWS consists of an unmanned monopod and a concrete gravity structure, with three pipelines connecting these structures: a 4″ Gas Flowline, an 8″ Test Flowline and a 12″ Production Flowline. These pipelines are buried, exposed or span the seabed and are supported by rock berms at regular intervals. We present a novel frame-based, timed-count method to assess the fish communities associated with subsea pipelines utilising archival remotely operated vehicle footage that lacks geospatial data. We apply this approach to a pipeline in the Wandoo field to document variation in the fish assemblage with pipeline position (buried, exposed, span or covered by rock berm). Overall, diversity and abundance were higher on pipeline covered by rock berms than on the other pipeline positions. We hypothesise that rock berms are effectively artificial reefs, providing complex habitat structure and facilitating growth of macrobenthos communities that are associated with higher fish diversity. We demonstrate that rock berms can increase the ecological value of subsea pipelines and should therefore be a priority area for future ecological surveys.
Conference Paper
This paper describes the potential global scientific value of video and other data collected by Remotely Operated Vehicles (ROVs). ROVs are used worldwide, primarily by the offshore oil and gas industry, to monitor the integrity of subsea infrastructure and, in doing so, collect terabytes of video and in situ physical data from inaccessible regions and poorly understood marine environments. The paper begins by describing how recent ROV surveys for projects in Australia have gained a new dimension by involving marine scientists in their interpretation. A previously unrecognised influence of marine life on oil and gas pipelines was uncovered, triggering new collaborations between industry and marine science. This new collaboration prompted a team of international engineers and marine scientists to gather together with West Australian based members of the oil and gas sector and ROV operators, to examine the global scientific value of ROV-collected data. If made available for research, these data have immense value for science to quantify the marine ecology and assist good stewardship of this environment by industry. It was found that most ROV operations are conducted by industry in a way that fulfils immediate industry requirements but which can confound scientific interpretation of the data. For example, there is variation in video resolution, ROV speed, distance above substrate and time (e.g. both seasonal and time of day), and these variations can limit the quantitative conclusions that can be drawn about marine ecology. We examined potential cost-effective, simple enhancements to standard ROV hardware and operational procedures that will increase the value of future industrial ROV operational data, without disrupting the primary focus of these operations. The ecological value of existing ROV data represents an immense and under-utilized resource with worldwide coverage. We describe how ROVs can unravel the mysteries of our oceans, yield scientific discoveries, and provide examples of how these data can allow quantification of the ecological value of subsea infrastructure. By using these data, we can greatly improve our knowledge of marine biodiversity on and around offshore infrastructure and their environmental impact on marine ecosystems, both of which are particularly important in the consideration and selection of decommissioning strategies. Predicting the environmental consequences of removing or retaining subsea structures after decommissioning relies on an understanding of the ecological communities that have developed in association with these structures during their operational lives. Making industrial ROV data available for scientific research, and collating it in the future using modified protocols, would provide a very positive contribution to both science and industry, allowing the environmental impacts of subsea infrastructure to be quantified. It will also allow industry to contribute to a broader scientific understanding of our oceans, given the location of ROVs in areas that can rarely be accessed by independent researchers. This would provide novel and valuable information about under-researched and little known regions of the world's oceans.<br/
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Full-subsets information theoretic approaches are becoming an increasingly popular tool for exploring predictive power and variable importance where a wide range of candidate predictors are being considered. Here, we describe a simple function in the statistical programming language R that can be used to construct, fit, and compare a complete model set of possible ecological or environmental predictors, given a re- sponse variable of interest and a starting generalized additive (mixed) model fit. Main advantages include not requiring a complete model to be fit as the starting point for candidate model set construction (meaning that a greater number of predictors can potentially be explored than might be available through functions such as dredge); model sets that include interactions between factors and continuous nonlinear pre- dictors; and automatic removal of models with correlated predictors (based on a user defined criterion for exclusion). The function takes continuous predictors, which are fitted using smoothers via either gam, gamm (mgcv) or gamm4, as well as factor vari- ables which are included on their own or as two- level interaction terms within the gam smooth (via use of the “by” argument), or with themselves. The function allows any model to be constructed and used as a null model, and takes a range of arguments that allow control over the model set being constructed, including specifying cyclic and linear continuous predictors, specification of the smoothing algorithm used, and the maximum complexity allowed for smooth terms. The use of the function is dem- onstrated via case studies that highlight how appropriate model sets can be easily constructed and the broader utility of the approach for exploratory ecology.
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Imagery collected by still and video cameras is an increasingly important tool for minimal impact, repeatable observations in the marine environment. Data generated from imagery includes identification, annotation and quantification of biological subjects and environmental features within an image. To be long-lived and useful beyond their project-specific initial purpose, and to maximize their utility across studies and disciplines, marine imagery data should use a standardised vocabulary of defined terms. This would enable the compilation of regional, national and/or global data sets from multiple sources, contributing to broad-scale management studies and development of automated annotation algorithms. The classification scheme developed under the Collaborative and Automated Tools for Analysis of Marine Imagery (CATAMI) project provides such a vocabulary. The CATAMI classification scheme introduces Australian-wide acknowledged, standardised terminology for annotating benthic substrates and biota in marine imagery. It combines coarse-level taxonomy and morphology, and is a flexible, hierarchical classification that bridges the gap between habitat/biotope characterisation and taxonomy, acknowledging limitations when describing biological taxa through imagery. It is fully described, documented, and maintained through curated online databases, and can be applied across benthic image collection methods, annotation platforms and scoring methods. Following release in 2013, the CATAMI classification scheme was taken up by a wide variety of users, including government, academia and industry. This rapid acceptance highlights the scheme's utility and the potential to facilitate broad-scale multidisciplinary studies of marine ecosystems when applied globally. Here we present the CATAMI classification scheme, describe its conception and features, and discuss its utility and the opportunities as well as challenges arising from its use.
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Animal-derived nutrients play an important role in structuring nutrient regimes within and between ecosystems. When animals undergo repetitive, aggregating behavior through time, they can create nutrient hotspots where rates of biogeochemical activity are higher than those found in the surrounding environment. In turn, these hotspots can influence ecosystem processes and community structure. We examined the potential for reef fishes from the family Haemulidae (grunts) to create nutrient hotspots and the potential impact of these hotspots on reef communities. To do so, we tracked the schooling locations of diurnally migrating grunts, which shelter at reef sites during the day but forage off reef each night, and measured the impact of these fish schools on benthic communities. We found that grunt schools showed a high degree of site fidelity, repeatedly returning to the same coral heads. These aggregations created nutrient hotspots around coral heads where nitrogen and phosphorus delivery was roughly 10 and 7 times the respective rates of delivery to structurally similar sites that lacked schools of these fishes. In turn, grazing rates of herbivorous fishes at grunt-derived hotspots were approximately 3 times those of sites where grunts were rare. These differences in nutrient delivery and grazing led to distinct benthic communities with higher cover of crustose coralline algae and less total algal abundance at grunt aggregation sites. Importantly, coral growth was roughly 1.5 times greater at grunt hotspots, likely due to the important nutrient subsidy. Our results suggest that schooling reef fish and their nutrient subsidies play an important role in mediating community structure on coral reefs and that overfishing may have important negative consequences on ecosystem functions. As such, management strategies must consider mesopredatory fishes in addition to current protection often offered to herbivores and top-tier predators. Furthermore, our results suggest that restoration strategies may benefit from focusing on providing structure for aggregating fishes on reefs with low topographic complexity or focusing the restoration of nursery raised corals around existing nutrient hotspots.
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Should we "reef" obsolete oil platforms? Claisse et al. (1) show that not only do oil platforms produce fish, but they do so at a rate far greater than our most productive marine habitats, such as coral reefs and mangroves. Because this information may be used to jus-tify increased "reefing" of obsolete oil infra-structure worldwide, we offer some caveats. Although Claisse et al.'s (1) production estimates further our understanding of the habitat value of oil platforms, they bring us little closer to deciding the fate of these struc-tures worldwide. It has been known for more than a decade that platforms are capable of providing valuable habitat for fish, yet habitat value appears to vary greatly among plat-forms, even among those located in similar ecological settings (2). This conclusion is sup-ported by the total production values in fig-ure 3 of Claisse et al. (1), with some platforms off California producing nearly nine times more fish biomass than others. Productivity data for one platform therefore cannot be used to infer the productivity of other plat-forms. Crucially, this means that the produc-tivity values obtained by Claisse et al. (1) should not be used to inform "rigs-to-reefs" decisions for the remaining 11 platforms off California, nor should they be used to inform rigs-to-reefs policies in other regions of the world. Given that even the least productive platform off California was more productive than surrounding natural reefs (1), why not just convert all platforms into artificial reefs? Because habitat value is only one of many factors that must be considered when making rigs-to-reefs decisions. Other factors include biodiversity value besides fish, po-tential contamination, and impacts on soft-bottom communities, as well as stakeholder impacts (e.g., loss of trawling grounds) and financial costs (including those to the tax-payer) (3). These factors and many others must be weighed against each other to deter-mine the net best decommissioning solution, which may not be a rigs-to-reefs conversion if the habitat benefits are outweighed by other negative impacts (4). We argue that a holistic approach should be taken to decommissioning decisions for oil platforms. Research to date has been overly focused on a small number of factors relating to the decision, such as fish production. More effort is required to identify the full range of factors that need to be considered and to integrate these into the decision process. Formal decision frameworks will be essential in this regard. Multicriteria decision frame-works are capable of handling the complex tradeoffs generated by multiple competing factors and have already been used for decades to solve similar decision problems in the fields of forestry and waste manage-ment (5). These frameworks also reduce bias and increase transparency of the decision process, which is particularly important for offshore decommissioning decisions due to the involvement of strongly conflicting stake-holder groups (e.g., commercial fishers and recreational anglers) (2, 4). If a holistic approach is not adopted, decommissioning options for platforms will likely remain highly regulated, and rigs-to-reefs will be viewed as little more than a controversial cost-saving stunt by the oil and gas industry.
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Little is known regarding bias attributable to fish behavior for visual transects conducted using underwater vehicles (UVs). Experiments were conducted under 2 ambient illuminations to assess the behavioral responses of 7 north Pacific Ocean groundfish species to a light stimulus that simulated the approach of a UV. Species included sablefish Anoplopoma fimbria, Pacific halibut Hippoglossus stenolepis, lingcod Ophiodon elongatus and 4 species in the genus Sebastes: blue rockfish S. mystinus, black rockfish S. melanops, copper rockfish S. caurinus and quillback rockfish S. maliger. Movement, as well as general activity, varied greatly between species. The most active species, sablefish, became agitated and moved away from the looming light source, while the least active species, Pacific halibut and lingcod, typically remained stationary. Of the 4 rockfish species, 2 demonstrated a strong response to ambient light level. Black rockfish and blue rockfish moved away from the looming light source, but avoidance was delayed under high ambient light. Bias probably differs among species, being greatest for those that are highly active and mobile, like sablefish. Further, ambient light may modulate bias, such that researchers need to be cautious about comparing results for surveys conducted at different depths and/or times of day.
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Secondary (i.e., heterotrophic or animal) production is a main pathway of energy flow through an ecosystem as it makes energy available to consumers, including humans. Its estimation can play a valuable role in the examination of linkages between ecosystem functions and services. We found that oil and gas platforms off the coast of California have the highest secondary fish production per unit area of seafloor of any marine habitat that has been studied, about an order of magnitude higher than fish communities from other marine ecosystems. Most previous estimates have come from estuarine environments, generally regarded as one of the most productive ecosystems globally. High rates of fish production on these platforms ultimately result from high levels of recruitment and the subsequent growth of primarily rockfish (genus Sebastes) larvae and pelagic juveniles to the substantial amount of complex hardscape habitat created by the platform structure distributed throughout the water column. The platforms have a high ratio of structural surface area to seafloor surface area, resulting in large amounts of habitat for juvenile and adult demersal fishes over a relatively small footprint of seafloor. Understanding the biological implications of these structures will inform policy related to the decommissioning of existing (e.g., oil and gas platforms) and implementation of emerging (e.g., wind, marine hydrokinetic) energy technologies.
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It has been speculated that some deep-sea fishes can display large vertical migrations and likely doing so to explore the full suite of benthopelagic food resources, especially the pelagic organisms of the deep scattering layer (DSL). This would help explain the success of fishes residing at seamounts and the increased biodiversity found in these features of the open ocean. We combined active plus passive acoustic telemetry of blackspot seabream with in situ environmental and biological (backscattering) data collection at a seamount to verify if its behaviour is dominated by vertical movements as a response to temporal changes in environmental conditions and pelagic prey availability. We found that seabream extensively migrate up and down the water column, that these patterns are cyclic both in short-term (tidal, diel) as well as long-term (seasonal) scales, and that they partially match the availability of potential DSL prey components. Furthermore, the emerging pattern points to a more complex spatial behaviour than previously anticipated, suggesting a seasonal switch in the diel behaviour mode (benthic vs. pelagic) of seabream, which may reflect an adaptation to differences in prey availability. This study is the first to document the fine scale three-dimensional behaviour of a deep-sea fish residing at seamounts.
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Artificial reefs are used by many fisheries managers as a tool to mitigate the impact of fisheries on coastal fish communities by providing new habitat for many exploited fish species. However, the comparison between the behavior of wild fish inhabiting either natural or artificial habitats has received less attention. Thus the spatio-temporal patterns of fish that establish their home range in one habitat or the other and their consequences of intra-population differentiation on life-history remain largely unexplored. We hypothesize that individuals with a preferred habitat (i.e. natural vs. artificial) can behave differently in terms of habitat use, with important consequences on population dynamics (e.g. life-history, mortality, and reproductive success). Therefore, using biotelemetry, 98 white seabream (Diplodus sargus) inhabiting either artificial or natural habitats were tagged and their behavior was monitored for up to eight months. Most white seabreams were highly resident either on natural or artificial reefs, with a preference for the shallow artificial reef subsets. Connectivity between artificial and natural reefs was limited for resident individuals due to great inter-habitat distances. The temporal behavioral patterns of white seabreams differed between artificial and natural reefs. Artificial-reef resident fish had a predominantly nocturnal diel pattern, whereas natural-reef resident fish showed a diurnal diel pattern. Differences in diel behavioral patterns of white seabream inhabiting artificial and natural reefs could be the expression of realized individual specialization resulting from differences in habitat configuration and resource availability between these two habitats. Artificial reefs have the potential to modify not only seascape connectivity but also the individual behavioral patterns of fishes. Future management plans of coastal areas and fisheries resources, including artificial reef implementation, should therefore consider the potential effect of habitat modification on fish behavior, which could have key implications on fish dynamics.
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Day-night changes in fish communities were quantified in 6 associated shallow-water biotopes within a single bay: mangroves, seagrass beds, algal beds, channel, fossil reef boulders, and notches in fossil reef rock. All biotopes, except the algal beds, showed a strong reduction in fish density and species richness at night, caused by absence of diurnally active fishes and migrations of Haemulidae and Lutjanidae to the seagrass beds. The fish fauna of the different biotopes showed a relatively high dissimilarity between day and night. This dissimilarity is largely caused by absence of Acanthuridae, Chaetodontidae, Labridae, Pomacentridae, Scaridae and Sparidae at night. These fishes seek shelter at night in, amongst others, the channel, notches and boulders. The balloonfish Diodon holocanthus utilised almost all biotopes as shelter as well as feeding sites. The wide distribution of its preferred food (molluscs) probably explains its distribution in most biotopes at night. The nocturnally active Haemulidae and Lutjanidae, on the other hand, migrated from their daytime shelter sites to the seagrass beds at night to feed. Some of these fishes also migrated to the algal beds to feed. The preference of Haemulidae and Lutjanidae for the seagrass bed as a feeding biotope, instead of other bay biotopes, appears to be related to the relatively high availability of their preferred food (Tanaidacea and Decapoda) as determined by digestive tract analysis. Other bay biotopes showed much lower densities of such food items compared to the seagrass beds.
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The pelagic Sargassum community of the western Atlantic Ocean is species rich, with high densities of predatory fishes and invertebrates living in close association with the floating seaweed. Little, however, is known about predator-prey interactions among Sargassum inhabitants and the factors that might help maintain this species richness. To assess how predators may affect the abundance of sessile Sargassum epiphytes, and how these epiphytes may defend themselves against predators, we examined interactions between the most abundant small predator associated with Sargassum mats, the filefish Monacanthus hispidus, and 4 epiphytic hydroid species. This fish was the only Sargassum-associated predator to significantly consume hydroids in initial assays. When filefish were given a simultaneous choice of all 4 hydroid species, they consumed 40 to 45% of 3 species (Clytia noliformis, Aglaophenia latecarinata, and Tridentata turbinata), but consumed less than 5% of the fourth species, Tridentata marginata. Filefish consistently rejected small portions of T. marginata colonies, but consumed a palatable control food. Bioassay-guided fractionation of T. marginata extract resulted in the isolation of a single deterrent secondary metabolite, tridentatol A. Three additional metabolites (tridentatols B to D) had no effect on filefish feeding. In addition to the defensive role of tridentatol A, the tridentatols (A to D) strongly absorb damaging solar ultraviolet (UV) radiation, and thus may function as sunscreens. To our knowledge, this is the first demonstration of chemical defenses among the pelagic Sargassum fauna, and the first report that a hydroid secondary metabolite deters consumers. Prey chemical defenses are an important factor in maintaining species richness in many predator-rich communities, but despite being chemically defended from predators, T. marginata was far less abundant than any of the other, more palatable, hydroids. The factors that allow high-preference hydroids to persist in such a predator-rich community remain unknown.
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Fish communities and other ecological variables were sampled for 6 mo (May to October) in successive years (1979, 1980) at vegetated and non-vegetated areas in 2 distinctively different littoral zones (an open bay and a protected cove) of mid-salinity Chesapeake Bay, USA. Fish abundance, biomass and species richness were h~gher in vegetated areas at both sites, and were significantly correlated with macrophyte biomass Diel patterns of fish abundance varied, but highest catches generally occurred at dusk or at night. At one sampling site fish assemblages were dominated by smaller individuals in the vegetated area, suggesting an attraction of juveniles to macrophyte beds for food or refuge from predation. Larger piscivorous fish, which were also caught in greater numbers in vegetated areas, may have been attracted there by higher densities of forage fish. At the cove site the biomass of Paleomonetes sp. was comparable to that of the fish community towards the end of the plant growing season. Benthic infauna were also more abundant in vegetated areas at both sites, and stomach analyses indicated these organisms to be the dominant food resources for common fishes. Diets were generally non-selective in non-vegetated areas while highly selective for epiphytic fauna in macrophyte beds. Fish stomachs were also significantly fuller in vegetated areas, indicating generally greater feeding success. Fish production varied among major species but was higher overall at vegetated areas, following the seasonal patterns of primary production. Most of the differences in fish production between areas were attributable to higher instantaneous growth rates rather than higher biomass. It appears that the greater abundance and species richness of fish assemblages in vegetated areas of this region of Chesapeake Bay resulted from the attractiveness of these habitats as rich sources of preferred foods.
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The feeding mechanism of the euryaline basket star Gorgonocephalus arcticus (Leach) from the Bay of Fundy is described from in situ and laboratory observations of feeding behaviour, analysis of gut contents, and examination of the anatomy and microanatomy of the arms. Gorgonocephalus arcticus, which is abundant in areas of moderate to strong current flow, is a fortuitous predatory suspension feeder, coiling and bending its arms to capture prey. The predominant food item in the gut was the euphausiacean Meganyctiphanes norvegica. Food capture by arm bending and coiling is assisted by the adherence of food to rings of sharp hooks on the arm. The role of the tube feet in food capture appears to be minor. Owing to the form of the feeding fan, the animal is adapted for life in strong currents. There is morphological evidence for the presence of mutable collagenous tissues which may be important in maintaining the feeding fan.
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An oil pipeline and its surrounding seafloor, located in the Santa Barbara Channel, southern California, were surveyed for fishes using a manned research submersible. The parts of the pipeline and seafloor surveyed were situated in waters 95–235 m deep. Some sections of the surveyed pipe were covered with both sessile and motile invertebrates, such as sea anemones (Metridium cf. farcimen) and sea urchins (Allocentrotus fragilis), sea stars (particularlyHippasteria cf. spinosa andStylasterias cf. forreri ), basket stars (Gorgonocephalus eucnemis ), spot prawns (Pandalus platyceros), and king crabs (Paralithodes californiensis). Based on differences in fish assemblages, four habitats (shallow and deep pipeline and shallow and deep seafloor) were categorized. Fish densities along the shallow portion of the pipeline were about seven times higher than on the adjacent seafloor and densities along the deep pipeline portion were nearly six times that of the deeper seafloor. Along the pipeline, rockfishes comprised 84% of the fishes and included 22 species. Unidentified sanddabs (probably most or all Citharichthys sordidus), forming 33.2%, and combfishes (Zaniolepis frenata and Z. latipinnis), comprising 19% of the total, were most often observed on the seafloor. Most of the fishes living on the pipeline were either juveniles of such larger taxa as blackgill (Sebastes melanostomus), flag (S. rubrivinctus), and vermilion (S. miniatus) rockfishes, cowcod (S. levis), and lingcod (Ophiodon elongatus), or diminutive species such as halfbanded (S. semicinctus) and stripetail (S. saxicola) rockfishes, combfishes (Zaniolepis spp.), and poachers (Family Agonidae). Higher densities of fishes were often noted in areas of the pipeline that had been undercut. Of particular interest were the relatively high densities of juvenile cowcod along the deeper parts of the pipeline, densities that were far higher than any seen at over 80 natural outcrops and at ten platforms. We suggest that, in the process leading to oil platform and pipeline decommissioning, it is important to understand the role that human-made structure plays as fish habitat.
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Summary. Recent work by Reiss and Ogden provides a theoretical basis for sometimes preferring restricted maximum likelihood (REML) to generalized cross-validation (GCV) for smoothing parameter selection in semiparametric regression. However, existing REML or marginal likelihood (ML) based methods for semiparametric generalized linear models (GLMs) use iterative REML or ML estimation of the smoothing parameters of working linear approximations to the GLM. Such indirect schemes need not converge and fail to do so in a non-negligible proportion of practical analyses. By contrast, very reliable prediction error criteria smoothing parameter selection methods are available, based on direct optimization of GCV, or related criteria, for the GLM itself. Since such methods directly optimize properly defined functions of the smoothing parameters, they have much more reliable convergence properties. The paper develops the first such method for REML or ML estimation of smoothing parameters. A Laplace approximation is used to obtain an approximate REML or ML for any GLM, which is suitable for efficient direct optimization. This REML or ML criterion requires that Newton–Raphson iteration, rather than Fisher scoring, be used for GLM fitting, and a computationally stable approach to this is proposed. The REML or ML criterion itself is optimized by a Newton method, with the derivatives required obtained by a mixture of implicit differentiation and direct methods. The method will cope with numerical rank deficiency in the fitted model and in fact provides a slight improvement in numerical robustness on the earlier method of Wood for prediction error criteria based smoothness selection. Simulation results suggest that the new REML and ML methods offer some improvement in mean-square error performance relative to GCV or Akaike's information criterion in most cases, without the small number of severe undersmoothing failures to which Akaike's information criterion and GCV are prone. This is achieved at the same computational cost as GCV or Akaike's information criterion. The new approach also eliminates the convergence failures of previous REML- or ML-based approaches for penalized GLMs and usually has lower computational cost than these alternatives. Example applications are presented in adaptive smoothing, scalar on function regression and generalized additive model selection.
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Sediment transport-induced changes to the embedment of three 26 km long sections of subsea pipeline are analysed and subsequently explained using model scale experiments. Rather than the scour and scour-induced sinking and sagging traditionally thought to dominate post-lay pipeline spanning and embedment change, the change for these pipelines is shown to be caused by sedimentation. The pipelines traverse a range of metocean and soil conditions; the variation in embedment correlates well with the variation in metocean conditions, with most change occurring in an area where multidirectional high-velocity short-duration flows associated with internal waves propagate at near-perpendicular angles to the pipeline. To understand the mechanism driving these changes, a series of model scale tests in O-tube flumes have been completed under flow conditions mimicking those recorded in the field. Good agreement is found between the field and laboratory results, both in terms of the process timescale and the post-sedimentation profile. The consistency of the embedment changes between the pipelines, their correlation with metocean conditions, and the ability to replicate these changes in model scale tests suggests that such changes can be accounted for in more effective pipeline design. Spans are relatively rare along the pipelines but where they do occur fish rather than scour are shown to be the principal agent of span formation.
Conference Paper
This paper deals with the risk to human lives, installations and the environment that trawling activity within the platform safety zones may cause. Due to the high consequences associated with failures of pipelines and subsea installations in the vicinity of offshore platforms, the zone around (manned) platforms are in some design codes, such as the DNV-OS-F101 for submarine pipelines [1], defined as a safety zone. Such a zone implies that pipelines and risers are designed to a higher target probability of failure, i.e. an extra safety margin is incorporated. To further reduce the probability of failure and, hence, increase the safety, extreme load like trawl interference may be avoided by declaring the safety zone as a trawl-free zone. This means that no fishing gear, such as bottom trawl gear, shall intrude this zone. Because this zone is defined as a trawl free zone, it is common practice not to consider trawl loads within this area, i.e. pipelines and subsea installations are not necessarily designed as over-trawlable. The paradox is that in some areas with extensive trawling, the manoeuvring of trawlers may easily cause the bottom trawl gear to intrude the safety zone and thereby expose the trawler, its crew and the platform with its crew to significant risks. This paper discusses one case where a trawl caused some damage to subsea installations well within the safety zone. It is demonstrated how the bottom gear may intrude the safety zone as the trawler round the platform zone. Different measures to avoid this behaviour or remove/reduce the associated risk are also discussed with background in the real case. Copyright © 2004 by ASME Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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Most organisms, particularly those living at higher latitudes, produce their offspring only in that season of the year in which food is most abundantly present for prosperous growth. Survival of the species therefore depends on a proper timing of the onset as well as termination of the breeding period. It has been believed for a long time, that breeding was controlled solely by external factors, such as photoperiod and temperature. However, it is now known that the correct timing of the breeding season often depends on a co-operation between external factors and endogenous rhythms, circadian and/or circannual.
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Marine reserves provide a large-scale manipulation of predator densities, which provides a means to investigate the potential effects of predation. The effects of reef-associated predators were examined in northeastern New Zealand by comparing soft-sediment assemblages at sites having different densities of large predators. Large rock lobsters (Jasus edwardsii) were 3.8 times more abundant, and large snapper (Pagrus auratus) 12 times more abundant, on average, at reserve sites compared with non-reserve sites. The overall structure of infaunal communities differed between areas with high predator densities (reserve) and those with lower densities (fished). Sites with consistently higher densities of snapper and lobster were found to have a lower biomass of two bivalve species, and the greatest decreases were found near the reef edge (2-5 m). For several fauna a strong gradient in their density with distance from the reef was observed at both reserve and nonreserve sites. The hermit crab Pagurus novizelandiae occurred more frequently near the reef edge, while the heart urchin Echinocardium cordatum and bivalve Dosinia subrosea occurred more frequently farther away from the reef. The results suggest that certain species in this assemblage are affected differently by a combination of physical and biological forces. We conclude that, where reef predators are removed by fishing pressure, a resultant indirect effect is an increase in prey species in adjacent soft-sediment assemblages.
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Stock assessments of tropical demersal teleost fisheries generally rely on fishery-dependent samples of age structure. Baited remote underwater stereo-video (stereo-BRUV) systems can provide fishery independent information on the biases and selectivity of particular fishing gears in relation to the length distribution of what is potentially available for capture. In the tropical demersal fishery off northwestern Australia the length distributions of 12 species sampled by standard commercial fish traps and stereo-BRUVs were compared using kernel density estimation techniques. We found no significant differences in the shape of the length distributions sampled by either method. However, the location (mean length) of the length distribution of seven of the 11 target species and the one bycatch species differed between the sampling methods. A family-specific trend was exhibited, likely due to the ambush behaviour of larger epinephelids in traps and the saturation of the field of view of stereo-BRUV by schools of smaller lutjanids. However, the difference in mean length was not biologically significant for these families. These results indicate that samples of target species derived from commercial trap catches are likely to provide representative and robust estimates of vital population statistics and life history parameters.
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Few in situ observations have been made of deepwater corals and, therefore, little is known about their biology or ecological significance. Deepwater corals (Primnoa spp.) were observed from a manned submersible at 11 sites in the Gulf of Alaska from 1989 to 1997 at depths of 161–365 m. We identified 10 megafaunal groups that associate with Primnoa to feed on the coral, use the coral branches for suspension feeding, or for protection. Predators on Primnoa polyps included sea stars, nudibranchs, and snails. Sea stars were the main predators, consuming 45% and 34% of the polyps at two sites. Suspension-feeders included crinoids, basket stars, anemones, and sponges. Most suspension-feeders observed at depths >300 m were associated with Primnoa. Protection seekers included rockfish, crab, and shrimp. Six rockfish species were either beneath, among, or above Primnoa. Shrimp were among the polyps, and a pair of mating king crabs were beneath Primnoa. These observations indicate Primnoa are important components of the deepwater ecosystem and removal of these slow-growing corals could cause long-term changes in associated megafauna.
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This study provides the first assessment of fish associations with oil and gas structures located in deep water (85-175 m) on Australia's north-west continental shelf, using rare oil industry video footage obtained from remotely operated vehicles. A diverse range of taxa were observed associating with the structures, including reef-dependent species and transient pelagic species. Ten commercially fished species were observed, the most abundant of which was Lutjanus argentimaculatus, with an estimated biomass for the two deepest structures (Goodwyn and Echo) of 109 kg.
Chapter
Diel vertical migrations are cyclic changes in the position of aquatic organisms in the water column that occur with 24-h periodicity. Such movements occur at various stages of the development of teleosts, although they are often more evident during the first year of life. Despite frequent study, fundamental questions concerning the nature of diel vertical migrations remain. For example, most life-history traits exhibit phenotypic plasticity in response to environmental factors during the development. From the fisheries viewpoint, an understanding of diel vertical migration is critical for surveys of abundance at all life-history stages. Such surveys of exploited populations of adult fish have long been employed during the stock assessment process and are becoming increasingly significant, particularly, in light of the difficulties associated with obtaining reliable commercial fishery statistics. This chapter presents a review of the studies of diel vertical migration of marine fish species. The extent to which fish exhibit plasticity in their patterns of diel migrations is examined, both with respect to varying environmental conditions and ontogeny. Most importantly, the chapter also assesses whether the patterns of diel vertical migration fits the criteria for endogenous circadian rhythms. Finally, it attempts to address whether the observed diel periodicity in depth occupied is a result of the endogenous effects whereby the periodicity is derived from the fishes' biochemistry or biophysics, rather than more direct effects of environmental stimuli, such as changes in light and temperature providing a cue for certain behavior.
Article
Effects of three different light wavelengths (blue, red and white) were assessed on the composition, abundance and behaviour of nocturnal fish at the Houtman Abrolhos Islands, Western Australia. The effects of fishing were also considered by further examining the combined effects of lighting and fishing (open vs. closed areas). Data were collected using baited remote underwater stereo-video systems (stereo-BRUVs), which were equipped with red (620–630 nm), white (550–560 nm) or blue (450–465 nm) lights. The total number of individuals, relative abundance of fish and assemblage composition differed under each lighting condition and fishing status. The greatest number of individuals was observed on samples illuminated by red lights (43% of all individuals surveyed). The species Apogon doederleini, Gymnothorax woodwardi, and Pempheris klunzingeri were each more abundant and spent longer in the field of view of the cameras using red lights. In contrast to white and blue light, the wavelength of red light is thought to be beyond the visual sensitivity of these fish species, and may not have affected their behaviour. The heavily targeted species, Pagrus auratus, were twice as abundant on stereo-BRUVs illuminated by blue lights and white lights than on red lights, but only in areas closed to fishing. This higher abundance on blue and white lights may have been due to the attraction of baitfish to these lights. In addition to the effects of lighting, clear effects of fishing were noted on nocturnal populations of P. auratus. Light wavelength can influence observations and measurements made of a nocturnal fish assemblage, and therefore careful consideration of choice of light wavelength should be made for nocturnal studies using artificial illumination on stereo-BRUVs.
Article
2 ABSTRACf Predation pressures from fishes have influenced major evolutionary trends among shallow-water zooplankters, as concluded from study at Santa Catalina Island, Calif. The predominant zooplank­ tivorous fishes near shore are actinopterygians, an evolutionary line that has centered around generalized visually feeding, large-mouthed predators. Historically, zooplankters threatened by these fishes have faced selective pressures favoring reduced size, transparency, and/or nocturnal planktonic habits. At present, most zooplankters in the nearshore water column by day are very small «2 mm, approximately); included are c1adocerans, copepods, and various larval forms. Their small size precludes capture by most large-mouthed fishes, thus providing protection in daylight, when the visual sense of generalized predatory fishes is most effective. Larger zooplankters in the water column by day, for example chaetognaths, tend to be transparent. The advantage of transparency to organisms threatened by visually feeding predators is obvious, and is only briefly mentioned here. Zooplankters having sizes (most >2 mm) and other features making them vulnerable to large-mouthed fishes tend to enter the water column only at night, when darkness offers some security from visually feeding predators. Included are polychaetes, mysids, cumaceans, gammaridean and caprellid amphipods, tanaids, isopods, and carideans. Because successful defensive features of prey create pressures that modify the offensive features of predators, the tendencies toward reduced size and nocturnal habits among zooplankters have generated appropriate adaptations among planktivorous fishes. Fishes that prey as adults on zooplankters during the day (e.g., blacksmith, Chromis punctipinnis) have specialized features, including a small highly modified mouth, that permit even relatively large individuals to take the tiny organisms which constitute the daytime zooplankton. Some other fishes are diurnal planktivores only as small juveniles and assume different feeding habits as they grow larger (e.g., kelp perch, Brachyistius frenatus; seliorita, Oxyjulis californica; smaller juvenile olive rockfish, Sebastes serranoides). Fishes that prey on zooplankters at night (e.g., larger juvenile olive rockfish; kelp rockfish, Sebastes atrovirens; queenfish, Seriphus politus; walleye surfperch, Hyperprosoponargenteum; and salema, Xeniatius californiensis) take the larger organisms that join the zooplankton after dark. In their feeding morphologies and body form, these large-mouthed fishes have diverged less than their diurnal counterparts from the generalized predators that give rise to them all. They have, however, acquired specialized features, including large eyes, suited to detect and capture prey in the dark.
Article
Construction of jetties along the Texas coast has provided hard substrate biota with suitable habitats for attachment that is otherwise scarce. Although similar to natural hard bottom environments such as coral reefs or offshore banks, jetties in temperate or subtropical areas are subjected to substantially more environmental instability including swift channelized currents, terrestrial runoff, maintenance dredging, fluctuating temperatures, and swells from ship and recreational boat traffic. The gorgonian coral Leptogorgia virgulata, found on south Texas jetties, is constantly exposed to the variable salinity and sediment loads associated with these jetty systems. In this study, L. virgulata was collected from the Aransas Pass jetties near Corpus Christi, Texas and experimentally tested to determine their ability to tolerate a range of salinities and sediment loads over 14days. In response to salinity, L. virgulata showed significant tissue loss (p
Article
Cardinalfishes (family Apogonidae) form a major component of nocturnal planktivore assemblages on coral reefs. In order to assess their trophic role on reefs, we examined diet, diel feeding behaviour and nocturnal foraging in 7 species in the lagoon at One Tree Reef, Great Barrier Reef, Australia. Be