Reef habitat type.
Photo: Dr Owen M. Exeter.
The footage comes from the Isles of Scilly, a protected area lying just off the tip of Cornwall in the far southwest of Britain. Thanks to the Gulf Stream, these islands enjoy a climate that feels almost Mediterranean — a rare treat for the UK!
A team from the University of Exeter’s Centre for Ecology and Conservation set up remote cameras around the islands to see what they could capture. This was a proof-of-concept project designed to test new ways of monitoring coastal ecosystems. The results didn’t disappoint. Their findings have just been published open-access in the Ecological Society of America’s journal Ecological Applications.
Catsharks filmed by the remote underwater camera.
Credit: Dr. Owen M. Exeter.
The Isles of Scilly^ Formation & Ecology.If you’d like the full story, Exeter University has also put out a news release about the project, which highlights just how valuable this approach could be for the future of marine conservation.
- Geological Origins
The Isles of Scilly are the westernmost granite outcrops of the Cornubian Batholith, a huge mass of granite formed around 290 million years ago during the late Carboniferous to early Permian period. Rising seas at the end of the last Ice Age (~10,000 years ago) drowned low-lying land, leaving the present archipelago of about 140 islands and islets, of which five are inhabited.- Climate
The surrounding seas are warmed by the Gulf Stream, giving the islands a mild, oceanic climate. Winters are frost-free and summers are cooler than on the mainland, creating conditions closer to those of the Mediterranean than most of Britain.- Habitats
Despite their small size, the islands host a mosaic of habitats:
- Heathlands on higher ground, dominated by heather and gorse.
- Coastal grasslands grazed by seabirds and rabbits.
- Rocky shores, kelp forests, and seagrass beds underwater, supporting diverse marine life.
- Freshwater pools and wetlands, home to migratory birds.
- Biodiversity Highlights
The seas around the Scillies are particularly rich, with species such as grey seals, seahorses, and colourful wrasse. Birdlife is also exceptional — the islands lie on major migratory flyways, attracting both seabird colonies and rare vagrants.- Conservation
Much of the land and surrounding waters are protected for their ecological importance. The Isles are a designated Area of Outstanding Natural Beauty (AONB) and part of several Marine Conservation Zones, helping safeguard their fragile ecosystems.
Scilly Isles cameras give glimpse of ‘natural’ UK waters
Underwater cameras around the Isles of Scilly have given scientists a glimpse of how sea life can thrive in well-protected UK waters.
Despite widespread degradation of UK seas from destructive fishing, pollution, and climate change, the waters surrounding the Isles of Scilly appear to be bucking the trend.
This new study used baited underwater cameras and found the Isles of Scilly’s waters support vibrant marine life including sharks, lobsters, octopuses and bluefin tuna.
The researchers say these relatively low-cost camera systems could be used to improve the monitoring and effectiveness of Marine Protected Areas (MPAs) – helping restore thriving seas around the UK.
The study was led by the University of Exeter, working with the Isles of Scilly Inshore Fisheries and Conservation Authority and Natural England.The richness and variety of marine life around the Isle of Scilly is wonderful to see. Our cameras recorded nearly 12,000 individual animals, from 64 species, including large populations of commercially targeted species such as lobsters and small sharks. We also saw bluefin tuna – which have recently returned to UK waters after largely disappearing due to overfishing.
Dr Owen M. Exeter, lead author
Centre for Ecology and Conservation
Faculty of Environment, Science and Economy
University of Exeter, Penryn, Cornwall, UK.
‘Healthy seas’
While the site isn’t entirely untouched by human activity, the team describes it as one of the UK’s most ‘near-natural’ marine ecosystems – largely protected from destructive practices such as bottom trawling, and with relatively low human impact due to the archipelago’s small population and well-managed fisheries.
These waters haven’t recovered from severe damage – they’ve remained in comparatively good condition. By studying ecosystems like this, we can start to understand what a healthy UK marine environment should look like. This gives us a crucial reference point as we work to restore degraded areas elsewhere.
Dr Owen M. Exeter.
The findings suggest that complex seabed habitats, such as reefs and mixed sediments which can be damaged by bottom trawling, host especially high biodiversity, underlining the importance of protecting these areas.
Bottom trawling – a focus of the recent David Attenborough film, Ocean – is permitted in some UK MPAs but the government is considering extending a ban to more areas.
‘Great option’
The cameras used in the study, known as Baited Remote Underwater Video Systems (BRUVs), offer a powerful tool for assessing whether MPAs are delivering measurable benefits for marine biodiversity when bottom trawling is excluded.
MPAs are only as effective as the protections and monitoring in place to support them. These camera systems allow us to track changes in species diversity and abundance over time, giving us vital evidence on whether conservation measures are working. They’re non-destructive, relatively inexpensive, and scalable – making them a great option for regular biodiversity assessments across large areas of our coastal seas.
Associate Professor Dr Kristian Metcalfe, co-author.
Centre for Ecology and Conservation
Faculty of Environment, Science and Economy
University of Exeter, Penryn, Cornwall, UK.
Gray SealDr Owen M. ExeterWe have been really pleased to support Owen’s work for this PhD. BRUVs can provide invaluable evidence to help improve our understanding of the condition and effectiveness of our Marine Protected Areas. This project has really demonstrated how BRUVs could be a consistent, non-invasive and low-cost way to monitor these critical marine ecosystems long-term.
Julie Webber, co-author
Natural England, York, UK.
The research has informed the Isles of Scilly being designated as an Important Shark and Ray Area (ISRA).
This recognition highlights the region’s significance for four shark species (primarily catsharks, with supporting species nursehounds, blue sharks, and porbeagle sharks) and provides an important tool to guide conservation and management efforts.
ISRAs are not regulatory or restrictive, but rather reflect areas of ecological interest and serve as a science-based framework to inform decision-making and strengthen the case for future funding and conservation initiatives.
The camera systems used in the study, developed by Blue Abacus, have two cameras that can be used estimate the size of individuals, providing rich ecological data for long-term marine monitoring.
Dr Exeter’s work was funded by a Natural Environment Research Council GW4+ Doctoral Training Partnership PhD Studentship – a case partnership between the Isles of Scilly Inshore Fisheries and Conservation Authority and Natural England.
Publication:
Crawfish filmed by the underwater camera.
Credit: Dr. Owen M. Exeter.
Bluefin tuna filmed by the underwater camera.
Credit: Dr. Owen M. Exeter
AbstractThe Isles of Scilly offer a rare glimpse into the quiet abundance of Britain’s coastal waters, where the interplay of geology, ocean currents, and climate has created a haven of biodiversity. Formed from ancient granite, these islands sit at the crossroads of land and sea, shaped by the rising tides of the Holocene and bathed in the softening influence of the Gulf Stream. The result is a landscape and seascape of striking richness, where subtleties of light, colour, and life combine in ways more often associated with the Mediterranean than the far-flung edge of Britain.
Marine protected areas (MPAs) often lack adequate data on the status of marine assemblages to support evidence-based management. Stereo baited remote underwater video (BRUV) systems offer a powerful, low-cost tool for collecting ecological data, yet they remain underutilized in the North East Atlantic, especially compared to more invasive methods such as fisheries surveys. Here, we demonstrate how a spatially comprehensive stereo-BRUV survey can generate benchmark data to support MPA management at an ecosystem scale, using an ecologically distinct oceanic archipelago as a case study. The archipelago's habitats were found to support high abundances of regionally targeted commercial species, including benthic catsharks (Scyliorhinidae) and European spiny lobster (Palinurus elephas), with ~12,000 individuals recorded representing 64 species and 44 families. Deeper, topographically complex reefs were found to support higher levels of richness and biomass, with sediment-specific increases in depth also driving demersal abundance. Stereo technology was additionally able to provide body size data for 43 species, with remoteness and shelter from exposure found to be common drivers of increased body size for indicator taxa. Survey results represent a contemporary benchmark for measuring changes in local MPA management, fisheries practices, and climate change impacts. The results also illustrate how spatially robust sampling methods and stereo-BRUV systems can facilitate more holistic, fisheries-independent data collection in UK and European waters.
INTRODUCTION
Marine ecosystems are increasingly being impacted by human activities (Halpern et al., 2019; O'Hara et al., 2021), with destructive fishing practices, pollution, and climate change (Anthony et al., 2008; Wernberg et al., 2011), leading to habitat degradation, species decline (Christiansen et al., 2020; Dulvy & Reynolds, 2002; Pacoureau et al., 2021.1), and food insecurity for coastal communities (Belhabib et al., 2015; Sumaila & Vasconcellos, 2000). To mitigate against these impacts, a variety of spatial management initiatives have been explored, including marine spatial planning (MSP) and ecosystem-based management (EBM) (Douvere, 2008.1), aiming to improve the sustainability of human activities and alleviate pressures on marine ecosystems.
Marine protected areas (MPAs) have become one of the primary tools for implementing spatial conservation management at sea (Grorud-Colvert et al., 2021.2). International treaties and initiatives such as the Convention on Biological Diversity Kunming–Montreal Global Biodiversity Framework have targeted 30% of the world's oceans to be conserved by 2030, driving an increase in designations globally (Sala et al., 2018; Thomas et al., 2014). When properly designed and effectively enforced (Canty et al., 2024), MPAs have been shown to increase fish biomass (Aburto-Oropeza et al., 2011.1; Goetze et al., 2021.8; Sala & Giakoumi, 2018.1), conserve threatened species (Davidson & Dulvy, 2017; Roberts et al., 2021.3), allow recovery of marine habitats (Davies, Holmes, Attrill, & Sheehan, 2022; Davies, Holmes, Bicknell, et al., 2022.1; Medrano et al., 2020.1; Sheehan et al., 2013), and potentially buffer the impacts of climate change (Ling & Johnson, 2012). They have also been recognized for having secondary benefits to coastal communities and fisheries through processes such as the spillover of adult fish (Lenihan et al., 2021.4; Medoff et al., 2022.2), larval dispersion (Christie et al., 2010; Green et al., 2015.1), and alternative income opportunities (Nowakowski et al., 2023; Pham, 2020.2).
The effectiveness of MPAs and other spatial management interventions is, however, often limited by poor design (Agardy et al., 2011.2; Conners et al., 2022.3), inadequate management (Claudet et al., 2020.3; Sala et al., 2018), and insufficient long-term monitoring (Addison, 2011.3). Many of these issues stem from a lack of basic data on the diversity, distribution, and abundance of habitats and species that MPAs are designated to protect (Espinoza et al., 2020.4; Metcalfe et al., 2013.1; Rees et al., 2020.5). This paucity of data is often attributed to the difficulties and costs associated with collecting marine data, particularly in remote locations, for mobile taxa, and in temperate systems due to weather and visibility (Noble-James et al., 2023.1; Wilding et al., 2017.1). Without adequate baseline or benchmark data, however, the ability to detect changes in the health and status of marine communities, and therefore track MPA effectiveness in the face of changing management policies, human pressures, or climate change, remains challenging (Ban et al., 2023.2; Espinoza et al., 2024.1). Developing cost-effective approaches for assessing the marine environment, particularly identifying areas of elevated diversity and essential habitat, is therefore essential for evidence-based marine management (Espinoza et al., 2020.4; Hyvärinen et al., 2021.5).
Recent advances in remote camera technologies have improved the accessibility and cost of easily repeatable survey methods for marine monitoring (Bicknell et al., 2016; Perkins et al., 2021.6). Baited remote underwater video (BRUV) systems have proven particularly effective for assessing the health and status of marine assemblages (Espinoza et al., 2020.4; White et al., 2013.2), species–habitat associations (Brown et al., 2022.4), and management interventions across various marine systems globally (Albano et al., 2021.7; Goetze et al., 2021.8). BRUV systems are also considered low impact (Whitmarsh et al., 2017.2), making them more compatible with MPA objectives than invasive methods such as scientific fishing surveys (Trenkel et al., 2019.1). The advancement of stereo BRUV (dual camera) technology also allows for the recording of length data that can be used to derive biomass estimates, thereby ensuring that outputs can be aligned with fisheries-dependent data (Letessier et al., 2024.2; Meeuwig, 2021.9). Additionally, BRUV systems are considered safe and applicable across a range of habitats (Whitmarsh et al., 2017.2), including those less suitable for traditional underwater visual census dive surveys (Baremore et al., 2023.3; Bouchet & Meeuwig, 2015.2), which can be resource intensive in terms of personnel, cost, and time and limited by depth and safety considerations (but are known to record smaller and more cryptic species compared to BRUV systems; Lowry et al., 2012.1). Despite their low cost, accessibility, and repeatable nature, BRUV application has been limited to a relatively small number of sites and surveys in UK waters to date (i.e., Clark et al., 2024.3; Davies, Holmes, Attrill, & Sheehan, 2022; Davies, Holmes, Bicknell, et al.,2022.1; Unsworth et al., 2014.2). Wider incorporation of BRUV systems into UK marine monitoring programs has the potential to generate comprehensive modern benchmarks which are often lacking for existing MPAs (Hill et al., 2018.2). They also have the potential to improve knowledge of local environmental and anthropogenic drivers of marine assemblages (Brown et al., 2022.4; Furness & Unsworth, 2020.6) and allow regional or national assessments of MPA effectiveness if methods are standardized (Canty et al., 2024; Goetze et al., 2021.8).
Here, we present the largest scale stereo BRUV survey conducted to date in the UK across the Isles of Scilly archipelago and its MPAs. Despite being considered a regionally unique biodiversity hotspot (Lewis et al., 2008.2; Warwick et al., 2003), there exist limited data on the local diversity and abundance of marine teleost fish, elasmobranchs, and macroinvertebrates (Exeter et al., 2024.4). Understanding the current health of the archipelago at an ecosystem level therefore remains challenging, and the impacts of novel threats such as habitat regime shifts from invasions (Barrett et al., 2007) and climate change (Smale et al., 2019.2), noise pollution, and shifts in fishing practices are hard to quantify. Long-term application of BRUV surveys can therefore address this knowledge gap and complement ongoing annual monitoring of other conservation features (i.e., seabird colonies and seagrass bed health; Exeter et al., 2024.4). This study therefore adopts a spatially balanced probabilistic sampling approach to survey the archipelago's mobile marine assemblages and: (1) establish a modern benchmark of local marine species from which future changes can be measured against; (2) explore the spatial and environmental drivers of species richness, abundance, diversity, biomass, and indicator species body length; and (3) evaluate the effectiveness of large-scale stereo BRUV for surveying in UK waters. Findings from this study will contribute to the archipelago's future MPA management and enhance the knowledge base of drivers of marine diversity within isolated archipelago systems. Given BRUV systems are an underutilized monitoring tool in the domestic English waters, this study also highlights the value of spatially comprehensive stereo BRUV surveys for UK MPA monitoring.
FIGURE 1.
Map of study area with (A) the United Kingdom and surrounding bathymetry (Global Bathymetric Chart of the Oceans (GEBCO) data) with an inset (red box) indicating the extent of (B) the Southwest UK peninsula and insets of (C) the Seven Stones Reef, and (D) the Isles of Scilly inshore zone, with bathymetry < 40 m highlighted and inhabited islands indicated by a gray arrow at their centroid. GRTS survey locations indicated by blue (reef) and orange (sediment) points. Marine Conservation Zone boundaries (green solid polygons) and the Special Area of Conservation (green outline) are also shown, with examples of designated feature habitat types Reefs (E) and Subtidal sediments (F).
Photo credits for (E) and (F): Owen M. Exeter.
FIGURE 2
Proportion of total deployments observed and relative abundance of the top 10 most commonly occurring families (A, B) and species (C, D). Note, Relative abundance axis capped at MaxN 15 for clarity, but Ammodytidae spp. and Pollachius pollachius include observed values >15.
FIGURE 3
Length frequencies for indicator taxa of interest. Red dashed line indicates commercial or recreational minimum landing sizes within the Isles of Scilly six nautical mile inshore fisheries zone (note both male and female minimum landing size shown for C. Pagurus). Blue dashed lines indicate length of maturity sourced from FishBase or Marlin (www.marlin.ac.uk) if not available.
Species illustrations by Emma Wood.
FIGURE 4
Mean values for (A) demersal richness, (B) demersal relative abundance, (C) Shannon–Wiener Diversity Index, and (D) total biomass for all deployments at a 1 km2 hexagonal grid cell resolution. All intervals displayed using a Natural Breaks (Jenks) function. Maps generated in ArcPro (v3.1) and Mapbox.
Exeter, Owen M., Annette C. Broderick, Xavier A. Harrison, Francesco Garzon, Sarah Morcom, Ricky Pender, Trudy Russell, et al. 2025.
Application of Spatially Robust Stereo-BRUV Sampling for Quantifying Fish Assemblages in UK Marine Protected Areas. Ecological Applications 35(6): e70104. https://doi.org/10.1002/eap.70104
Copyright: © 2025 The authors.
Published by John Wiley & Sons, In. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
Beneath the surface, kelp forests sway in tidal rhythms, sheltering wrasse, pollack, and delicate seahorses, while shoals of smaller fish weave their way through seagrass meadows. Grey seals, curious and agile, patrol these waters, reminders that even at the margin of Europe there remain places where the great dramas of predator and prey unfold daily. Above the tideline, seabirds wheel and call, linking ocean and sky, while migratory species pause here on journeys that span continents, guided by instinct older than civilisation itself.
What these images and videos capture is not merely the beauty of the Isles but something larger: a fleeting glimpse of the intricate web that sustains life on our planet. To watch these creatures is to be reminded that humans, too, are part of this fabric, dependent upon the same oceans and currents that nourish the smallest plankton and the mightiest whale. The Isles of Scilly thus stand not only as a sanctuary for wildlife but as a testament to the continuity of life itself — fragile, resilient, and endlessly astonishing.
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