Baited Remote Underwater Video Stations Research Articles

Untangling Coastal Diversity: How Habitat Complexity Shapes Demersal and Benthopelagic Assemblages in NW Iberia

Understanding species–habitat relationships is essential for ecosystem-based conservation. This study explores the significance of habitat characteristics and complexity for demersal and benthopelagic communities within a patchwork of coastal habitats, including rocky seabed, macroalgae formations, sandy bottoms, and a combination of rock and sand areas. Species and habitats were surveyed along the north-west (NW) Iberian continental shelf area of Viana do Castelo using baited remote underwater video stations (BRUVS). We found significant differences (p < 0.05) in species assemblages across habitats, with rocky substrates showing the highest diversity and abundance. Sand habitats showed the lowest species richness and abundance, underscoring the importance of habitat complexity to support marine life. Our study also emphasises the role of specific species in shaping the communities, identifying key species such as Trisopterus luscus, Diplodus vulgaris, and Ctenolabrus rupestris as the three most abundant in the region and significant contributors to the observed dissimilarities between habitats. By elucidating the impact of habitat complexity on marine life, our results offer essential baseline data, which serve as a kick-start point to inform sustainable management and conservation strategies for the long-term health and productivity of these vital ecological systems in the North-East Atlantic.

Elasmobranch diversity around the southern Caribbean island of Tobago: opportunities for conservation in a regional trade hub

Abstract Sharks are scarce in much of the Caribbean due to widespread depletion. Trinidad and Tobago, in the southern Caribbean, is a shark meat consumer and international exporter of dried shark fins. Despite limited fisheries management there is a small Marine Protected Area (MPA; 7 km2) in urbanised southwest Tobago, but its effect on sharks and rays (elasmobranchs) is unknown. The rural northeast is a recently designated UNESCO Man and the Biosphere Reserve with a significant marine component and plans for a large MPA, but no baseline data for elasmobranchs exist. Given the local importance of elasmobranchs and a newly drafted Sustainable Shark and Ray Management Plan, we used baited remote underwater video stations within a 40 m depth contour at 270 randomly generated points around Tobago to: (i) establish a baseline of species richness and relative abundance, (ii) investigate the influence of season, habitat relief, depth and water temperature on relative abundance, and (iii) investigate spatial variation in relative abundance. Caribbean reef sharks, nurse sharks, and southern stingrays were observed at all sites, the latter two more frequently in the urbanised southwest. Shark diversity was unexpectedly high in the northeast, driven by rarer species (sharpnose, smoothhound, tiger, scalloped hammerhead, great hammerhead) only observed there. Habitat relief, depth and season likely influence relative abundance of elasmobranchs around Tobago, but research is needed to elucidate species-level effects. Shark species richness in northeast Tobago is high for the Caribbean, warranting research attention, while the larger MPA presents an opportunity to strengthen elasmobranch management.

Baited remote underwater video stations as a potential tool for assessing coastal rocky fishes in Chile

AbstractCoastal rocky fish species support important fishing activities, but basic information is lacking for many before catches decline. Monitoring and management of coastal rocky fish species is urgently needed in Chile, but knowledge of these species is fragmentary at best. Performance of Baited Remote Underwater Video Stations (BRUVS) for assessing rocky fish assemblages was evaluated in south‐central Chile. Seven medium‐ to large‐sized exploited species dominated fish assemblages in the survey area, including five small cryptic rocky reef fishes, one agnathan and a catshark species. These seven species represented 78% of the species targeted by commercial fishing in the survey area. Furthermore, this tool provided new information on behaviour of rocky fish species. The simple, inexpensive and light nature of single‐camera BRUVS may be crucial for maintaining monitoring programs along remote areas of Chile.

Feeding, agonistic and cooperative behavioural responses of shallow-water benthic marine scavengers

ABSTRACT Baited remote underwater video station (BRUVS) investigations of benthic scavenging by fish and invertebrates were conducted in an Irish sea lough. Mackerel (Scomber scombrus) baits were deployed under natural light during the day and under dim red light at night. Ethograms for feeding mechanisms and agonistic behaviours were established for four abundant scavengers (two crabs: the harbour crab Liocarcinus depurator, and the European green crab Carcinus maenas; two fish: the shanny Lipophrys pholis, and the small-spotted catshark Scyliorhinus canicula). Crabs’ feeding mechanisms were similar, with differences reflecting their morphologies. Feeding bouts lasted minutes/tens of minutes. Intraspecific agonistic responses were mild and did not result in mutilation or mortality. Feeding mechanisms on macerated baits focussed on ‘chewing’ (combined use of chelipeds and mouthparts to feed continuously); agonistic behaviour was reduced, especially at night when balls of crabs showed ‘cooperative feeding’. Fish feeding bouts lasted for a few seconds in all cases. Shannies showed anticipatory agonistic behaviour (bait ‘guarding’ and ‘patrolling’ by large shannies) before bait maceration. Catsharks exhibited no intraspecific agonistic behaviour but removed large bait morsels by ‘biting’, ‘chewing’ and ‘spinning’. The common prawns Palaemon serratus only scavenged at night and were invisible to other scavengers; they showed no agonistic behaviours. Kleptoparasitism amongst the scavenger guild was common but intra-community predation was extremely rare. Phoretic feeding on bait scraps by red-speckled anemones (Anthopleura ballii) attached to the carapaces of the edible crab Cancer pagurus was observed.

Fine-scale variation in the proximity of baited remote underwater video stations (BRUVS) to rocky reefs reveals changes in the structure of temperate fish assemblages

We investigated changes in the structure of coastal fish assemblages in Northern Patagonia, Southwestern Atlantic, by using baited remote underwater video stations (BRUVS) deployed at increasing distances from rocky reefs: 0–5 m, 15–20 m and 50–60 m. We estimated species richness and abundance (total and by preferred habitat type) and searched for diagnostic species in each distance range. We recorded 14 taxa across 11 families in 19 areas surveyed. Species richness and abundance were higher on reef ledges and decreased with distance from them, at a finer spatial scale than previously reported. Acanthistius patachonicus and Sebastes oculatus were indicative of reef ledges; they were less abundant at 15–20 m and disappeared at 50–60 m. Callorinchus callorynchus and Odontesthes spp. occurred only at distances >15–20 m from the reefs, while Galeorhinus galeus was distributed homogeneously throughout the surveyed area. Our findings have practical implications for monitoring ecotone demersal habitats with BRUVS.

Checklist of coral reef fishes of Darvel Bay, Sabah, Malaysian Coral Triangle, with a note on the biodiversity and community structure.

The Darvel Bay is a large semi-enclosed bay with spectacular natural land and seascape. The inward side of the Bay has only been recently known to be an important foraging ground for the endangered, threatened and protected (ETP) elasmobranch species, such as the Whale Shark and mobulid rays. Following a recent scientific expedition, we present a checklist of the coral reef fishes of Darvel Bay. A note on the biodiversity and community structure is presented, based on our analysis using diversity indices, univariate and multivariate approaches. Seven natural coral reefs comprising two fringing reefs and five patch reefs, were surveyed at 10 m depth using underwater visual census (UVC) and baited remote underwater video station (BRUVS) methods. A diverse list of 66 species of reef fishes from 17 families is recorded. However, this is overwhelmingly dominated by the small-sized omnivorous damselfish, family Pomacentridae (62%; N = 1485 individuals). Species richness and abundance were observed to increase at sites surveyed furthest from the coast within the Bay. Significantly distinct reef fish assemblages were observed between three priori groups, based on proximity to shore (ANOSIM, R = 0.65, p < 0.05). SIMPER analysis further revealed that 22 species of the total reef fish species recorded drive 76% dissimilarities between the groups. The pattern of the reef fish communities observed, reflected as a logseries distribution model, is that commonly found in disturbed habitats or habitats characterised by restricted resources in a community, where the dominant species takes up a high proportion of available resources. The ecological indices (Shannon-Wiener Diversity Index, 2.05; Simpson Index of Diversity, 0.79; Simpson Dominance Index, 0.20; and Pielou's Evenness Index, 0.43), all reflect the relatively low diversity and uneven species distribution of the reef fish community. We conclude that the present status of the coral reef fish community dominating Darvel Bay as having undergone a rapid shift in structure following intense and rampant fishing pressure, as reported by the media.

Accelerating Species Recognition and Labelling of Fish From Underwater Video With Machine-Assisted Deep Learning

Machine-assisted object detection and classification of fish species from Baited Remote Underwater Video Station (BRUVS) surveys using deep learning algorithms presents an opportunity for optimising analysis time and rapid reporting of marine ecosystem statuses. Training object detection algorithms for BRUVS analysis presents significant challenges: the model requires training datasets with bounding boxes already applied identifying the location of all fish individuals in a scene, and it requires training datasets identifying species with labels. In both cases, substantial volumes of data are required and this is currently a manual, labour-intensive process, resulting in a paucity of the labelled data currently required for training object detection models for species detection. Here, we present a “machine-assisted” approach for i) a generalised model to automate the application of bounding boxes to any underwater environment containing fish and ii) fish detection and classification to species identification level, up to 12 target species. A catch-all “fish” classification is applied to fish individuals that remain unidentified due to a lack of available training and validation data. Machine-assisted bounding box annotation was shown to detect and label fish on out-of-sample datasets with a recall between 0.70 and 0.89 and automated labelling of 12 targeted species with an F1 score of 0.79. On average, 12% of fish were given a bounding box with species labels and 88% of fish were located and given a fish label and identified for manual labelling. Taking a combined, machine-assisted approach presents a significant advancement towards the applied use of deep learning for fish species detection in fish analysis and workflows and has potential for future fish ecologist uptake if integrated into video analysis software. Manual labelling and classification effort is still required, and a community effort to address the limitation presented by a severe paucity of training data would improve automation accuracy and encourage increased uptake.

Preliminary evidence of early Reef Cube® enhancements to mobile benthic ecosystems

Reef Cubes® are ecological engineering units, intended to restore biodiversity while serving functions to marine engineers. Ecological engineering must be backed by quantitative scientific evidence. Here, preliminary results of the Reef Enhancement for Fisheries at Aquaculture Sites (REFAS) project are presented. 11 Clusters of Reef Cubes® were deployed in June 2021. Sampling was undertaken before and after in the Spring and Autumn of 2021, in daylight and at night-time. Guided Baited Remote Underwater Video Station (BRUVS) surveys were completed with a modified BlueROV2. All mobile benthic and demersal species were identified during a 30-minute window and quantified in terms of Max-N. Biodiversity indices, rarefaction curves and multivariate community compositions were compared at reef and non-reef sites before and after build. Average species richness, Pielou’s evenness, Simpson’s and Shannon’s indices were similar between reef and non-reef sites. Seasonal increases of total abundance and total species were found, and these were significantly greater at reef sites. There were also significant differences in the community compositions of the reef and non-reef sites that were not observed before the build. These results are significant for the implications of using Reef Cubes® and indicate that Reef Cubes® could be a potential tool for biodiversity remediation.

First use of baited remote underwater video stations to assess fish diversity in the Metropolitan Region of Recife, Northeastern Brazil

Introduction: Video techniques are used worldwide to study marine communities. As elsewhere, the use of remote underwater videos has recently increased in Brazil and there is a need for information about their advantages, disadvantages, and reliability in tropical habitats. Objective: To evaluate the use of baited remote underwater video stations (BRUVS) in fish diversity research in a tropical habitat. Methods: We used baited video stations to record the fishes and their relationship with habitat type, underwater visibility and depth, in 79 random sites in the Metropolitan Region of Recife, Northeastern Brazil (11 days in November 2017). Results: We recorded 3 286 individuals (65 taxa, 29 families) along a 25 km section of the shoreline, 10.2 to 28.6 m depth. The Clupeidae dominated numerically, followed by Haemulidae, Carangidae, and Lutjanidae; by species, Haemulon aurolineatum, Ophistonema oglinum, Haemulon steindachneri, Lutjanus synagris and Caranx crysos. The highest mean number of species was detected over sediment close to shipwrecks, but we found no differences among the mean number of individuals between habitat types. More species and individuals were observed at a depth of 20-25 m depth. The highest mean number of species was in 2-3 m of visibility, and the highest number of individuals within 4-5 m. Conclusions: Video recording seemed to be a valid method, and indicated that —besides being relatively diverse— the local fish community is dominated by a few species of small and medium-sized mesopredators, and a few top predators.

A first assessment of the distribution and abundance of large pelagic species at Cocos Ridge seamounts (Eastern Tropical Pacific) using drifting pelagic baited remote cameras.

Understanding the link between seamounts and large pelagic species (LPS) may provide important insights for the conservation of these species in open water ecosystems. The seamounts along the Cocos Ridge in the Eastern Tropical Pacific (ETP) ocean are thought to be ecologically important aggregation sites for LPS when moving between Cocos Island (Costa Rica) and Galapagos Islands (Ecuador). However, to date, research efforts to quantify the abundance and distribution patterns of LPS beyond the borders of these two oceanic Marine Protected Areas (MPAs) have been limited. This study used drifting-pelagic baited remote underwater video stations (BRUVS) to investigate the distribution and relative abundance of LPS at Cocos Ridge seamounts. Our drifting-pelagic BRUVS recorded a total of 21 species including elasmobranchs, small and large teleosts, dolphins and one sea turtle; of which four species are currently threatened. Depth of seamount summit was the most significant driver for LPS richness and abundance which were significantly higher at shallow seamounts (< 400 m) compared to deeper ones (> 400m). Distance to nearest MPA was also a significant predictor for LPS abundance, which increased at increasing distances from the nearest MPA. Our results suggest that the Cocos Ridge seamounts, specifically Paramount and West Cocos which had the highest LPS richness and abundance, are important aggregation sites for LPS in the ETP. However, further research is still needed to demonstrate a positive association between LPS and Cocos Ridge seamounts. Our findings showed that drifting pelagic BRUVS are an effective tool to survey LPS in fully pelagic ecosystems of the ETP. This study represents the first step towards the standardization of this technique throughout the region.

Successful parks for sharks: No-take marine reserve provides conservation benefits to endemic and threatened sharks off South Africa

Sharks are among the most threatened vertebrates on the planet. Marine protected areas (MPAs) have been widely established and promoted as a shark conservation tool. However, the geographic ranges of most imperiled shark species (endemic and threatened) fall outside the current global networks of MPAs, leaving the protective benefits of this tool questionable for the shark species of highest conservation concern. The Western Cape of South Africa is a hotspot for endemic and threatened shark species. Here, we examined the potential protective benefit of a no-take marine reserve (the De Hoop MPA) for imperiled shark species using baited remote underwater video stations (BRUVS). Eleven shark species were documented, with six of 11 species (55%) classified as threatened with extinction by the International Union for the Conservation of Nature. The composition of the shark assemblage was dominated by small to mid-sized species, including small endemics. Species-specific habitat preferences were identified, with all these habitats represented in the MPA. Frequency of occurrence and relative abundance of sharks on BRUVS were significantly higher inside the De Hoop MPA than outside. Both protected and commercially exploited sharks species exhibited higher relative abundance inside the MPA. Relative abundance also increased inside the MPA with increasing distance from the reserve boundaries. Our findings suggest that no-take MPAs can be an effective tool for protecting shark species of conservation concern, including threatened endemics, particularly if the MPA adequately incorporates their preferred habitats.

Habitat type and complexity drive fish assemblages in a tropical seascape.

Inshore marine seascapes support a diversity of interconnected habitats and are an important focus for biodiversity conservation. This study examines the importance of habitat attributes to fish assemblages across a mosaic of inshore habitats: coral reefs, rocky reefs, macroalgae beds and sand/rubble beds. Fishes and benthic habitats were surveyed at 34 sites around continental islands of the central Great Barrier Reef using baited remote underwater video stations (BRUVS). Species richness was influenced foremost by habitat type and also by structural complexity within habitat types. The most speciose assemblages occurred in coral and rocky reef habitats with high structural complexity, provided by the presence of coral bommies/overhangs, boulders and rock crevices. Nonetheless, macroalgae and sand/rubble beds also supported unique species, and therefore contributed to the overall richness of fish assemblages in the seascape. Most trophic groups had positive associations with complexity, which was the most important predictor for abundance of piscivorous fishes and mobile planktivores. There was significant differentiation of fish assemblages among habitats, with the notable exception of coral and rocky reefs. Species assemblages overlapped substantially between coral and rocky reefs, which had 60% common species, despite coral cover being lower on rocky reefs. This suggests that, for many species, rocky and coral substrates can provide equivalent habitat structure, emphasizing the importance of complexity in providing habitat refuges, and highlighting the contribution of rocky reefs to habitat provision within tropical seascapes. The results of this study support an emerging recognition of the collective value of habitat mosaics in inshore marine ecosystems.

First record of a potential neonate tiger shark (Galeocerdo cuvier) at a remote oceanic island in the Eastern Tropical Pacific.

Tiger sharks (Galeocerdo cuvier) play an important ecological role as top predators, yet knowledge of their reproductive ecology is scarce. Here, the authors report the first observation of a potential neonate G. cuvier at Cocos Island, a predator-dominated oceanic island in the Eastern Tropical Pacific (ETP). The individual was detected using baited remote underwater video stations (BRUVS). The cameras also detected female individuals potentially pregnant, suggesting that parturition may take place at or near the island. Nonetheless, it is still unclear if the presence of a single neonate is an isolated event or evidence that the species is using the island for reproduction.

Comparability and complementarity of reef fish measures from underwater visual census (UVC) and baited remote underwater video stations (BRUVS)

The much-publicized threats to coral reef systems necessitate a considered management response based on comprehensive ecological data. However, data from large reef systems commonly originate from multiple monitoring programs that use different methods, each with distinct biases that limit united assessments of ecological status. The effective integration of data from different monitoring methods would allow better assessment of system status and hence, more informed management. Here we examine the scope for comparability and complementarity of fish data from two different methods used on Australia's Great Barrier Reef (GBR): underwater visual census (UVC) and baited remote underwater video stations (BRUVS). We compared commonly reported reef fish measures from UVC and BRUVS on similar reef slope habitats of three central GBR reefs. Both methods recorded similar estimates of total species richness, although ~30% of recorded species were not common to both methods. There were marked differences between methods in sub-group species richness, frequency of species occurrences, relative abundances of taxa and assemblage structure. The magnitude and orientation of inter-method differences were often inconsistent among taxa. However, each method better categorized certain components of fish communities: BRUVS sampled more predatory species in higher numbers while UVC was similarly better at sampling damselfishes (Pomacentridae). Our results suggest limited scope for direct or adjusted comparisons of data from UVC and BRUVS. Conversely, complementary aspects of the two methods confirm that their integration in monitoring programs will provide a more complete and extensive assessment of reef fish status for managers than from either method alone.

Uso de BRUVS para describir el ensamble de peces y su estacionalidad en dos caletas marinas poco profundas dentro de áreas protegidas de la Patagonia, Argentina

Baited Remote Underwater Video Stations (BRUVS) complemented with fishing methods were used to describe the fish assemblage and its seasonal pattern in two marine inlets from Patagonia. The combined results for BRUVS and fishing sessions identified 13 fish species. Our results agree with the biogeographic schemes proposed for the southern Southwest Atlantic. The fish species belonging to the Argentine Biogeographic Province presented a seasonal pattern with a peak of maximum abundance (Notorynchus cepedianus and Galeorhinus galeus) or were recorded during warm months only (Mustelus schmitti, Myliobatis goodei, and M. ridens), coinciding with the general latitudinal pattern expected for fish species richness. The use of BRUVS in this study allowed for the assessment of different fish species and wide range of sizes, from large sharks (N. cepedianus) to small cryptic species (Patagonotothem sp.). However, three of 13 species were only recorded by fishing methods, like it was the case for M. ridens. The record of M. ridens is the first in Patagonian waters, extending its distribution for c. 180 km south of the previously known southern limit. This study contributes to filling large data gaps along the Southwest Atlantic regarding the description and understanding of the temporal dynamics of fish assemblages in particular environments within protected areas.

Mangrove fish assemblages reflect the environmental diversity of the Galapagos Islands

Mangroves are important habitats for a variety of ecologically, commercially and culturally important fishes. However, little is known about their role within the Tropical Eastern Pacific (TEP), and particularly in the Galapagos Archipelago, the westernmost limit for mangroves in the Americas, and the only oceanic islands in the TEP where mangroves are present. We describe patterns of fish composition in the 2 Galapagos bioregions where mangroves are present and assess potential environmental factors influencing fish community composition. Underwater Visual Census and Stereo Baited Remote Underwater Video stations (stereo-BRUVS) were used to sample fish communities. We identified 35029 fish representing 93 species, 67 genera and 36 families. Pomacentridae, Mugilidae, Haemulidae and Lutjanidae were the most common families. Juveniles made up 43% of the fish, 30 species were of importance to local artisanal fisheries and 80% of species were associated with reef habitats, suggesting mangroves in Galapagos may provide nursery habitats for economically valued species. Fish assemblage composition varied across bioregions, with 6 taxa responsible for driving these differences, including species of economic importance:Lutjanus novemfasciatusandMycteroperca olfax. Species richness was 17% higher in the Central-Southeastern than in the Western region; while higher species richness, Shannon-Wiener diversity and Pielou’s evenness were detected with BRUVS than through visual censuses. Our results highlight the role of mangroves as a habitat for a unique fish community composed of young, endemic and commercially important species, whose composition is likely driven by the isolation of the islands and its location in a convergence zone.

Varying reef shark abundance trends inside a marine reserve: evidence of a Caribbean reef shark decline

Spatial comparisons of reef shark abundance inside and outside marine protected areas (MPAs) are common and generally report positive MPA effects, yet few studies have tracked abundance trends over long time periods. This is problematic because inside:outside comparisons at a single point in time cannot evaluate whether populations are declining. In Belize, the Caribbean reef shark Carcharhinus perezi is one of the most fished shark species and is more abundant inside MPAs. Although the relative abundance of C. perezi was stable inside Glover’s Reef Marine Reserve (GRMR) from 2001 to 2013, using standard baited remote underwater video station surveys, we document a decline in relative abundance inside the no-take marine reserve from 2009 to 2019. We used a negative binomial generalized linear model and model averaging to test the effect of year, depth, and water temperature on C. perezi and nurse shark Ginglymostoma cirratum relative abundance. While model-averaged results indicated a C. perezi decline, G. cirratum remained stable from 2009 to 2019. We hypothesize that the C. perezi decline is a result of fishing along the edge of GRMR, while G. cirratum stability is related to their behavior and nationwide protection. Given the dynamic nature of fisheries regulations, economic pressures, and site-specific environmental conditions, our results emphasize the need for standardized long-term monitoring of reef sharks inside and around MPAs globally.

Comprehensive assessment of shallow surf zone fish biodiversity requires a combination of sampling methods

Surf zones of sandy beaches are crucial environments for numerous fishes but one of the most challenging habitats when it comes to sampling, due to high-energy currents and waves. In this study, we compared the efficiency of 2 methods currently used to sample the biodiversity of shallow surf zone fish communities: the traditional method of beach seine nets and the more recently introduced surf zone Baited Remote Underwater Video Stations (surf-BRUVS). We applied both sampling strategies at 67 sites along 27 sandy beaches with different environmental characteristics in southeastern Brazil. We compared overall abundance, species richness, and beta (turnover) and functional trait diversity recorded from both methods. Our results showed that seine nets captured a higher species richness, greater abundance, greater functional richness and more functionally singular species than surf-BRUVS, particularly in areas with low wave energy. Beta diversity analyses, however, showed a clear difference in assemblage composition detected by each method regardless of environmental conditions, mainly driven by species turnover and variations in abundance. Only seine nets captured small species (&lt;10 cm total length), while surf-BRUVS were more effective in recording larger species. Our results suggest that shallow surf zone assemblages sampled with surf-BRUVS and beach seine nets are almost totally taxonomically and highly functionally divergent, and the application of both methods provides complementary results. Additionally, the non-extractive nature of surf-BRUVS presents an opportunity for sampling vulnerable areas or species. However, when using a single method, researchers should take into consideration each method’s biases and be aware that biodiversity may be underestimated for certain groups.

Drivers of reef fish assemblages in an upwelling region from the Eastern Tropical Pacific Ocean

Reef fish assemblages are exposed to a wide range of anthropogenic threats as well as chronic natural disturbances. In upwelling regions, for example, there is a seasonal influx of cool nutrient-rich waters that may shape the structure and composition of reef fish assemblages. Given that climate change may disrupt the natural oceanographic processes by altering the frequency and strength of natural disturbances, understanding how fish assemblages respond to upwelling events is essential to effectively manage reef ecosystems under changing ocean conditions. This study used the baited remote underwater video stations (BRUVS) and the traditional underwater visual census (UVC) to investigate the spatiotemporal patterns of reef fish assemblages in an upwelling region in the North Pacific of Costa Rica. A total of 183 reef fish species from 60 families were recorded, of which 166 species were detected using BRUVS and 122 using UVC. Only 66% of all species were detected using both methods. This study showed that the upwelling had an important role in shaping reef fish assemblages in this region, but there was also a significant interaction between upwelling and location. In addition, other drivers such as habitat complexity and habitat composition had an effect on reef fish abundances and species. To authors' knowledge, this is the first study in the Eastern Tropical Pacific that combines BRUVS and UVC to monitor reef fish assemblages in an upwelling region, which provides more detailed information to assess the state of reef ecosystems in response to multiple threats and changing ocean conditions.

Repeatability of baited remote underwater video station (BRUVS) results within and between seasons.

Baited remote underwater video stations (BRUVS) are increasingly being used to evaluate and monitor reef communities. Many BRUVS studies compare multiple sites sampled at single time points that may differ from the sampling time of another site. As BRUVS use grows in its application to provide data relevant to sustainable management, marine protected area success, and overall reef health, understanding repeatability of sampling results is vital. We examined the repeatability of BRUVS results for the elasmobranch community both within and between seasons and years, and explored environmental factors affecting abundances at two sites in Indonesia. On 956 BRUVS, 1139 elasmobranchs (69% rays, 31% sharks) were observed. We found consistent results in species composition and abundances within a season and across years. However, elasmobranch abundances were significantly higher in the wet season. The elasmobranch community was significantly different between the two sites sampled, one site being more coastal and easily accessed by fishermen. Our results demonstrate that while BRUVS are a reliable and repeatable method for surveying elasmobranchs, care must be taken in the timing of sampling between different regions to ensure that any differences observed are due to inherent differences amongst sampling areas as opposed to seasonal dissimilarities.