Video Surveys Research Articles

The role of emergent physical and chemical properties of Florida spring complexes in predicting fish assemblage structure

Florida spring complexes (springs and their associated runs) represent patches of clear, cool freshwater habitat in a landscape of tannin-stained wetlands, streams, and rivers. These spring complexes differ in morphology, water quantity and quality, and biotic characteristics as well as in their connections to other water bodies. The purpose of this study was to determine whether watershed effects or emergent physical, chemical, and biologic properties of Florida spring complexes would predict fish assemblage structure. Spring complex morphology and water quality metrics were collected from water managers or from the literature, with the exception of dissolved oxygen, which was measured in situ. Fish data were collected by video surveys using GoPro® cameras on stationary tripods at 2 to 5 locations on the banks of each spring complex. Videos were analyzed for the total number of individuals of each species/video, species richness, and diversity. The environmental characteristics of spring complexes differed between watersheds, as the St Johns River spring complexes, which are near the east coast, differed from watersheds closer to the west coast of Florida. However, specific characteristics that discriminated between springs, like low dissolved oxygen concentration or abundant macrophytes, crossed watershed boundaries. Fish assemblages also differed between the St Johns River and western watersheds, but the differences were more subtle than the differences in environmental characteristics, and the characteristics of individual spring complexes also predicted fish assemblage structure. Conductivity, dissolved oxygen concentration, and macrophyte coverage best explained the variation in the fish assemblage structure among spring complexes. The overlap in spring complex fish assemblages across watersheds may be the result of the geologic youth of the freshwater fish assemblages, the high degree of hydrologic connectivity between water bodies, and possible impairment of spring complexes in Florida.

Deep-sea biodiversity at the extremes of the Salas y Gómez and Nazca ridges with implications for conservation.

The Salas y Gómez and Nazca ridges are underwater mountain chains that stretch across 2,900 km in the southeastern Pacific and are recognized for their high biodiversity value and unique ecological characteristics. Explorations of deep-water ecosystems have been limited in this region, and elsewhere globally. To characterize community composition of mesophotic and deep-sea demersal fauna at seamounts in the region, we conducted expeditions to Rapa Nui (RN) and Salas y Gómez (SyG) islands in 2011 and Desventuradas Islands in 2013. Remote autonomous baited-cameras were used to conduct stationary video surveys between 150–1,850 m at RN/SyG (N = 20) and 75–2,363 m at Desventuradas (N = 27). Individual organisms were identified to the lowest possible taxonomic level and relative abundance was quantified with the maximum number of individuals per frame. Deployments were attributed with associated environmental variables (temperature, salinity, dissolved oxygen, nitrate, silicate, phosphate, chlorophyll-a, seamount age, and bathymetric position index [BPI]). We identified 55 unique invertebrate taxa and 66 unique fish taxa. Faunal community structure was highly dissimilar between and within subregions both for invertebrate (p < 0.001) and fish taxa (p = 0.022). For fishes, dogfish sharks (Squalidae) accounted for the greatest dissimilarity between subregions (18.27%), with mean abundances of 2.26 ± 2.49 at Desventuradas, an order of magnitude greater than at RN/SyG (0.21 ± 0.54). Depth, seamount age, broad-scale BPI, and nitrate explained most of the variation in both invertebrate (R2 = 0.475) and fish (R2 = 0.419) assemblages. Slightly more than half the deployments at Desventuradas (N = 14) recorded vulnerable marine ecosystem taxa such as corals and sponges. Our study supports mounting evidence that the Salas y Gómez and Nazca ridges are areas of high biodiversity and high conservation value. While Chile and Peru have recently established or proposed marine protected areas in this region, the majority of these ridges lie outside of national jurisdictions and are under threat from overfishing, plastic pollution, climate change, and potential deep-sea mining. Given its intrinsic value, this region should be comprehensively protected using the best available conservation measures to ensure that the Salas y Gómez and Nazca ridges remain a globally unique biodiversity hotspot.

Assessing the ecological risk to deep-sea megafaunal assemblages from seafloor massive sulfide mining using a functional traits sensitivity approach

The deep sea is subject to multiple anthropogenic disturbances, to which may soon be added mining of hydrothermally-formed seafloor massive sulfides (SMS). As a first step towards a full Ecological Risk Assessment (ERA) for SMS mining, ecological sensitivity to mining activities was assessed based on the functional traits of benthic megafaunal taxa. Faunal distribution and abundance data at two different spatial scales (within seamount and within site) were used from two video surveys conducted at un-fished SMS deposit-hosting seamounts on the Kermadec Volcanic Arc, New Zealand. For each of the 157 taxa identified in the seamount and site surveys, sensitivity was scored for six functional traits: adult size, environmental position, living habit, feeding habit, mobility, and structural fragility. Sensitivity (very low, low, intermediate, high, very high) was scored separately for three mining disturbances: passage of mining vehicles along the seafloor, sediment plumes generated by mining activity, and mineral extraction. The effects of different abundance and diversity weightings on the results were explored and transformations chosen based on ecological rationale. Sensitivity to mining impacts was summed within samples and mapped to show the spatial distribution of sensitivity. Samples (assemblages) consisted of 173 individual 200 m transects for seamount survey data and 153 individual 15 m transects for site survey data. For both spatial scales, the sensitivity of taxa and the sensitivity summed within each sample (assemblage) was greatest to mineral extraction, followed by plume impacts, and least sensitive to vehicle impacts. The location of most very highly sensitive assemblages coincided with the occurrence of hydrothermal vent taxa or previously mapped locations for hydrothermally active habitat. Highly sensitive assemblages occurred at hydrothermally inactive sulfide structures, such as chimneys, and other locations where assemblages were dominated by fragile, sessile, suspension-feeding taxa, such as scleractinian branching corals. The approach taken here illustrates spatial patterns in sensitivity within seamounts and sites and provides an important first step towards a more comprehensive ERA. This type of assessment has the potential to inform decisions on spatial management of SMS mining activities, and the suitable placement of area-based management measures, such as protected areas.

Assessing the impact of trawling on benthic megafauna: comparative study of video surveys vs. scientific trawling

Abstract Most studies about benthic community use small-scale sampling methods focused on the infauna such as grabs or box-corers. The benthic data collected by scientific trawl surveys in all European waters, in the frame of the Common Fishery Policy Data Collection Multiannual Program, can be used to study the impact of large-scale fisheries such as trawling. However, the catchability of trawls is very dependent on the nature of the seabed as well as resulting ground-gear adaptations. Due to its non-destructive nature and its ability to focus on benthic macro-epifauna, towed video sampling appears to be a good alternative to monitor the impact of trawling on benthic communities. In the present work, we studied the influence of fishery induced seabed abrasion and video characteristics on nine indices, which can be used to monitor the effect of trawling on benthic communities, was studied. Among them, three indices specific to fishery effect detection based on biological traits appeared to be the best performing benthic indices with video data: modified-Trawling Disturbance Index, partial-Trawling Disturbance Index, and modified sensitivity index. The effectiveness of these indices to monitor the effect of trawling was evaluated and compared between trawl and video sampling. This work has highlighted that video sampling could be a good alternative, or at least a complementary method, to scientific trawling to monitor the effect of trawling on benthic communities in European waters.

Baited Remote Underwater Video Surveys to assess relative abundance of sharks and rays in a long standing and remote marine protected area in the Arabian Gulf

Marine Protected Areas (MPAs) are increasingly advocated for the protection of key functional groups like elasmobranchs (sharks and rays). However, substantial uncertainty remains regarding which species can benefit from MPAs, crucial information to support policy and management plans. Using Baited Remote Underwater Video Surveys (BRUVS), a study was conducted on Sir Bu Nair Island in the United Arab Emirates encompassing a range of depths and habitat types within the MPA borders. A total of 96 deployments with 117 video hours recorded were analysed to assess the diversity, relative abundance and habitat associations of elasmobranchs. Surveys recorded 40 elasmobranchs including two species of sharks and seven species of rays. Overall, catch per unit effort for elasmobranchs was slightly higher overall, lower for sharks, and higher for rays compared to a similar study using BRUVS across United Arab Emirates waters. Two reef-associated species in early life stages, blacktip reef shark (Carcharhinus melanopterus) and Halavi guitarfish (Glaucostegus halavi) listed as Near Threatened and Critically Endangered on the IUCN Red List of Threatened Species respectively showed the highest frequency of occurrence of species representing 44.4% of all sightings. These results show the value of this MPA in protecting critical habitats for elasmobranchs while suggesting its limitation in protecting adult life stages and other elasmobranchs with wider ranging movements that are likely threatened by fishing in waters adjacent to the MPA. This study provides critical information to support the development of a Sir Bu Nair management plan and highlights further research needs around the island. Finally, it reinforces the need of additional management measures to protect and promote the recovery of elasmobranchs in the United Arab Emirates and broader Arabian Gulf.

Tropicalization and kelp loss shift trophic composition and lead to more winners than losers in fish communities.

Climate-mediated species redistributions are causing novel interactions and leading to profound regime shifts globally. For species that expand their distribution in response to warming, survival depends not only on their physiological capacity, but also on the ability to coexist or be competitive within the established community. In temperate marine reefs from around the world, the range expansion of tropical species, known as 'tropicalization', has been linked to the disappearance of temperate habitat-forming kelps and shifts to dominance by low-biomass turfing algae. The consequences of these range expansions and habitat changes on resident fish communities are, however, unclear. Here, we use data derived from baited remote underwater video (BRUV) surveys to analyse changes in diversity and abundance of marine fishes over a 17-year period in warming reefs that have experienced kelp loss (occurring c. 2009). Despite the loss of kelp, we found that species richness and overall abundance of fishes (measured as probability of occurrence and relative abundance), including both tropical and temperate species, increased through time. We also found dramatic shifts in the trophic composition of fish assemblages. Tropical herbivorous fish increased most markedly through time, and temperate-associated planktivores were the only group that declined, a potential consequence of tropicalization not previously identified. At the species level, we identified 22 tropical and temperate species from four trophic guilds that significantly increased in occurrence, while only three species (all temperate associated) declined. Morphological trait space models suggest increases in fish diversity and overall occurrence are unlikely to be driven by uniqueness of traits among tropical range expanders. Our results show more winners than losers and suggest that pathways of energy flow will change in tropicalized systems, as planktonic inputs become less important and a higher proportion of algal productivity gets consumed locally by increasingly abundant herbivores.

Fine-scale responses of mobile invertebrates and mesopredatory fish to habitat configuration

As habitat-forming species continue to decline globally, it is important to understand how associated communities respond to habitat loss and fragmentation. Changes in the density and spatial configuration of habitat have important consequences for associated communities. However, tests of these factors are often confounded by morphological variation of habitat-formers, which can be resolved by using standardised habitat-mimics. Furthermore, few studies have incorporated the role of predators in mediating the observed effects. To test whether predators mediate the abundance of invertebrates among algal habitats of varying configuration (isolated vs patches, and positions within patches), we placed macroalgal mimics into subtidal estuarine habitats for one month to sample epifaunal communities. At the same time, we conducted underwater video surveys of fish communities to quantify fish communities and their feeding behaviour among the artificial habitats. Isolated habitats did not differ from patch habitats, however, patch edges had the highest epifaunal abundance, where fish were least commonly observed. Observed fish feeding was highest in the middle of patches and increased fish observations and feeding in habitats with reduced epifaunal communities suggest that mesopredatory fish are mediating epifauna in patches, with predation pressure altered by the spatial configuration of the habitat. This contrasts to previous studies that focus on predators that congregate outside patches and suggest that fragmentation leads to reduced invertebrate abundance at habitat edges in contrast to centres. However, this study highlights that in habitat patches housing small mesopredators that also benefit from the increased structure, the centre of the patch experiences higher predation and therefore fewer epifauna in contrast to patch edges and individual algal mimics.

Diel vertical movements and feeding behaviour of blue humphead parrotfish Scarus ovifrons in a temperate reef of Japan.

The feeding ecology of scarinine parrotfishes on tropical coral reefs has received considerable attention in the past few decades; nonetheless, relatively few studies have been conducted in high-latitude reefs. Among the Indo-Pacific Scarus species, Scarus ovifrons is unique, being largely restricted to the warm temperate waters of Japan. Nonetheless, there is very little information available on the feeding ecology of this species. In this study, the authors used acoustic telemetry to detect the diel vertical movement patterns of S. ovifrons, video survey to detect its feeding depths and substrata and focal follow survey and genetic analysis to identify algae composition on the feeding scars at Kashiwajima Island, southwestern Japan (32° 46' N, 132° 38' E). Acoustic telemetry revealed that S. ovifrons spent most of its time in shallow water (<10 m) during the day and slept in deeper water (10-15 m) at night. Video and focal follow surveys revealed that most fishes of various sizes regularly took bites on epilithic algae and detrital materials on rocky substrata at depths of <10 m, but large fishes (>40 cm total length) sometimes took bites directly on live corals (Acropora solitaryensis) at the 5 m depth zone where live tabular corals dominated the benthos. Molecular phylogenetic analyses revealed that epilithic algae collected from feeding scars were mainly composed of Rhodophyta, and coralline algae were less often targeted. Overall, this study revealed that S. ovifrons feeds mostly at depths <10 m, and the feeding algae substrata of the species are similar to those of tropical coral reef parrotfishes.

The influence of shark behavior and environmental conditions on baited remote underwater video survey results

Baited remote underwater video systems (BRUVS) have become an important and frequently used tool by resource managers to monitor relative abundances for a variety of marine species. As with any abundance survey method, fundamental assumptions of the technique are that counts derived from videos accurately reflect true changes to abundances, while being robust to changes in density-independent factors. We tested these assumptions using a newly developed spatially-explicit individual-based simulation model for two of the most commonly used video survey metrics of relative abundance; MaxN and MeanCount. Simulating a 1-km2 area over a 60-min BRUV deployment targeting elasmobranch species, we evaluated how resulting estimates of each metric were influenced by swimming speed, relative directness of movement patterns, relative attraction strength to bait, bait plume size, and camera visibility range while shark density was held constant. By simulating both standard (120°) and full-spherical (FS; 360°) fields of view (FOV), we were also able to explore if newly developed FS cameras could help reduce the impact of these density-independent factors. Results from both generalized linear models and visual inspection of simulations indicated that density as well as non-density-related factors were highly significant in predicting camera counts, regardless of the camera's FOV or count metric used. Collectively, these findings illustrate that video survey metrics are sensitive to factors unrelated to changes in density, and researchers should carefully consider their potential influence on survey results as well as potential management decisions based on these data.

Rapid relative increase of crustose coralline algae following herbivore exclusion in a reef of El Salvador.

The Eastern Tropical Pacific (ETP) is one of the most isolated and least studied regions in the world. This particularly applies to the coast of El Salvador, where the only reef between Guatemala and Nicaragua, called Los Cóbanos reef, is located. There is very little published information about the reef’s biodiversity, and to our knowledge, no research on its ecology and responses to anthropogenic impacts, such as overfishing, has been conducted. The present study, therefore, described the benthic community of Los Cóbanos reef, El Salvador, using the Line-Point-Intercept-Transect method and investigated changes in the benthic community following the exclusion of piscine macroherbivores over a period of seven weeks. Results showed high benthic algae cover (up to 98%), dominated by turf and green algae, and low coral cover (0–4%). Porites lobata was the only hermatypic coral species found during the surveys. Surprisingly, crustose coralline algae (CCA) showed a remarkable total cover increase by 58%, while turf algae cover decreased by 82%, in experimental plots after seven weeks of piscine macroherbivore exclusion. These findings apparently contradict the results of most previous similar studies. While it was not possible to ascertain the exact mechanisms leading to these drastic community changes, the most likely explanation is grazing on turf by small grazing macroherbivores that had access to the cages during the experiment and clearing of CCA initially covered by epiphytes and sediments. A higher CCA cover would promote the succesful settlement by corals and prevent further erosion of the reef framework. Therefore it is crucial to better understand algal dynamics, herbivory, and implications of overfishing at Los Cóbanos to avoid further reef deterioration. This could be achieved through video surveys of the fish community, night-time observations of the macroinvertebrate community, exclusion experiments that also keep out herbivorous macroinvertebrates, and/or experimental assessments of turf algae/CCA interactions.

A Multi-band Forced-photometry Catalog in the ELAIS-S1 Field

Abstract The ELAIS-S1 field will be an Legacy Survey of Space and Time Deep Drilling field, and it also has extensive multiwavelength coverage. To improve the utility of the existing data, we use The Tractor to perform forced-photometry measurements in this field. We compile data in 16 bands from the DeepDrill, VIDEO, DES, ESIS, and VOICE surveys. Using a priori information from the high-resolution fiducial images in VIDEO, we model the images in other bands and generate a forced-photometry catalog. This technique enables consistency throughout different surveys, deblends sources from low-resolution images, extends photometric measurements to a fainter magnitude regime, and improves photometric-redshift estimates. Our catalog contains over 0.8 million sources covering a 3.4 deg2 area in the VIDEO footprint and is available at 10.5281/zenodo.4540178.

Range extension of the Critically Endangered shorttail nurse shark Pseudoginglymostoma brevicaudatum (Orectolobiformes: Ginglymostomatidae) to include Mozambique, with implications for management

The Critically Endangered shorttail nurse shark Pseudoginglymostoma brevicaudatum (Gunther, 1866) is a small-bodied Orectolobiform shark found only in the Western Indian Ocean (WIO). We report here on a significant range extension for P. brevicaudatum based on four records of the species in southern Mozambique, recorded during research surveys, including a specimen collected in 1967 and video surveys in 2019, and opportunistic assessments of shore-angler photographic catch records. These are the first records of P. brevicaudatum in Mozambique. The potential factors for this range extension and its implications for the management of this species are discussed. We also present morphological descriptions of the first recorded P. brevicaudatum specimen from Mozambique and of the dentition of this species (based on samples from Madagascar), and comment on the current status of knowledge and knowledge gaps for this species. Owing to its poor conservation status, limited inshore distribution and potential and confirmed fishery threats, improved knowledge and conservation should be considered priorities for P. brevicaudatum.

The National Geographic Society Deep-Sea Camera System: A Low-Cost Remote Video Survey Instrument to Advance Biodiversity Observation in the Deep Ocean

There is a growing need for marine biodiversity baseline and monitoring data to assess ocean ecosystem health, especially in the deep sea, where data are notoriously sparse. Baited cameras are a biological observing method especially useful in the deep ocean to estimate relative abundances of scavenging fishes and invertebrates. The National Geographic Society Exploration Technology Lab developed an autonomous benthic lander platform with a baited camera system to conduct stationary video surveys of deep-sea megafauna. The first-generation landers were capable of sampling to full ocean depth, however, the form factor, power requirements, and cost of the system limited deployment opportunities. Therefore, a miniaturized version (76 cm × 76 cm × 36 cm, 18 kg in air) was developed to provide a cost-effective method to observe ocean life to 6000 m depth. Here, we detail this next-generation deep-sea camera system, including the structural design, scientific payload, and the procedures for deployment. We provide an overview of NGS deep-sea camera system deployments over the past decade with a focus on the performance improvements of the next-generation system, which began field operations in 2017 and have performed 264 deployments. We present example imagery and discuss the strengths and limitations of the instrument in the context of existing complementary survey methods, and for use in down-stream data products. The key operational advantages of this new instrument are spatial flexibility and cost-efficiency. The instrument can be hand-deployed by a single operator from a small craft concurrent with other shipboard operations. The main limitation of the system is battery power, which allows for 6 h of continuous recording, and takes up to 8 h to recharge between deployments. Like many baited-camera methods, this instrument is specialized to measure the relative abundance of mobile megafauna that are attracted to bait, which results in a stochastic snapshot of the species at the deployment location and time. The small size and ease of deployment of this next-generation camera system allows for increased sample replication on expeditions, and presents a path forward to advance cost-effective biological observing and sustained monitoring in the deep ocean.

A search for X-ray absorbed sources in the 3XMM catalogue using photometric redshifts and Bayesian spectral fits

Since its launch in 1999, the XMM-Newton mission has compiled the largest catalogue of serendipitous X-ray sources, with the 3XMM being the third version of this catalogue. This was possible thanks to the combination of a large effective area (5000 cm2 at 1 keV) and a wide field of view (30 arcmin). The 3XMM-DR6 catalogue contains about 470 000 unique X-ray sources over an area of 982 deg2. A significant fraction of these (100 178 sources) have reliable optical, near-(NIR), and mid-infrared (MIR) counterparts in the SDSS, PANSTARRS, VIDEO, UKIDSS, and WISE surveys. In a previous paper we presented photometric redshifts for these sources using the TPZ machine-learning algorithm. About a quarter of these (22 677) have adequate photon statistics, meaning that a reliable X-ray spectrum can be extracted. Owing to both the X-ray counts selection and the optical counterpart constraint, the sample above is biased towards the bright sources. Here, we present XMMFITCAT-Z: a spectral fit catalogue for these sources using the Bayesian X-ray Analysis technique. To demonstrate the potential of the present catalogue, we comment on the optical and MIR colours of the 765 X-ray absorbed sources with NH &gt; 1022 cm−2. We show that a considerable fraction of X-ray-selected AGNs would not be classified as AGNs following the MIR W1–W2 versus W2 selection criterion. These are AGNs with lower luminosities, where the contribution of the host galaxy to the MIR emission is non-negligible. Only one-third of obscured AGNs in X-rays present red colours or r–W2 &gt; 6. Also, it appears that the r–W2 criterion, often used in the literature for the selection of obscured AGNs, produces very different X-ray absorbed AGN samples compared to the standard X-ray selection criteria.

Distribution and ontogenetic habitat shifts of reefassociated shark species in the northeastern Caribbean

Understanding how reef-associated sharks utilise coastal reef habitats throughout their ontogeny is essential for their effective management. In this study, we assessed the distribution of sharks in the northern Caribbean Netherlands (Saba, Saba Bank and St Eustatius) and ontogenetic shifts in habitat and depth use of the 2 most observed species: Caribbean reef shark Carcharhinus perezi and nurse shark Ginglymostoma cirratum. We used stereo baited remote underwater video (stereo-BRUV) surveys at 376 sites. A total of 126 shark sightings (6 species) were recorded, with C. perezi (n = 72) and G. cirratum (n = 42) most frequently observed. The probability of recording at least 1 shark per deployment ranged from 0.19 to 0.37 and is comparable with shark occurrences in the small number of other stereo-BRUV studies in the Wider Caribbean Region. Habitat type was the most important factor driving reef-associated shark occurrences, with the highest probability of observing C. perezi and G. cirratum in soft-coral habitat. Additionally, occurrences of C. perezi were significantly influenced by the management zone, with highest probabilities of occurrence in no-fishing zones. Almost all observed reef-associated sharks (95.6%) were juveniles, indicating that the study area may be a nursery area. Overall, both species were observed in deeper waters with increasing size, indicating ontogenetic shifts in depth use. Our findings imply that protected areas should not be limited to a single habitat or depth, but focus on protecting a large area with the range of habitats and depths necessary for reef-associated sharks to complete their life cycle.

The marine fishes of St Eustatius Island, northeastern Caribbean: an annotated, photographic catalog.

Sint Eustatius (Statia) is a 21 km2 island situated in the northeastern Caribbean Sea. The most recent published sources of information on that island’s marine fish fauna is in two non-governmental organization reports from 2015–17 related to the formation of a marine reserve. The species-list in the 2017 report was based on field research in 2013–15 using SCUBA diving surveys, shallow “baited underwater video surveys” (BRUVs), and data from fishery surveys and scientific collections over the preceding century. That checklist comprised 304 species of shallow (mostly) and deep-water fishes. In 2017 the Smithsonian Deep Reef Observation Project surveyed deep-reef fishes at Statia using the crewed submersible Curasub. That effort recorded 120 species, including 59 new occurrences records. In March-May 2020, two experienced citizen scientists completed 62 SCUBA dives there and recorded 244 shallow species, 40 of them new records for Statia. The 2017–2020 research effort increased the number of species known from the island by 33.6% to 406. Here we present an updated catalog of that marine fish fauna, including voucher photographs of 280 species recorded there in 2017 and 2020. The Statia reef-fish fauna likely is incompletely documented as it has few small, shallow, cryptobenthic species, which are a major component of the regional fauna. A lack of targeted sampling is probably the major factor explaining that deficit, although a limited range of benthic marine habitats may also be contributing.

The biodiversity of fishes at the Islas Marías Biosphere Reserve, Mexico, as determined by baited remote underwater video

The Islas Marías Biosphere Reserve, made up of 4 islands in Pacific waters off central Mexico, supports a large diversity of marine life. However, scientific research was restricted for decades by the occupation of Isla María Madre by the Federal Penitentiary Colony of Mexico from 1905 to 2019. Aside from a list of coastal fish species published in 2011, little has been published about the fish biodiversity in the area. While the limited access to the archipelago may have acted as a de-facto marine reserve, there is evidence that fishing continued both legally for the benefit of the colony and illegally by trespassing vessels. In order to establish baseline ecological data for future conservation planning, we used baited remote underwater video (BRUV) surveys at all 4 islands during 3 expeditions to the archipelago in 2018. A total of 131 BRUV surveys representing ~150 h of footage were analyzed to create the most current compilation of species and abundance data on coastal marine fishes at Islas Marías. Ninety-nine species were identified, 3 of which were additions to the previous assessment. We found strong separation of fish communities based on both habitat and depth, and an association between hard-bottom habitats and high biodiversity of reef fishes. With the declaration of Islas Marías as a natural reserve and relocation of the prison in 2019, there is an opportunity for the reserve to become a priority area for marine conservation on the Pacific coast of Mexico. Spatial analyses of fish biodiversity at Isla María Cleofas can help develop sustainable management strategies at a time when the governmental jurisdiction of the iconic archipelago is uncertain.

A Video Survey on Minimal Risk Maneuvers and Conditions

Known issues at higher automation levels are hoped to be solved by the systems capability to automatically perform maneuvers in order to achieve a so-called minimal risk condition. In this paper, we contribute to this developing research field and emphasize the driver’s perspective. We have conducted a video survey with 49 participants showing different forms of maneuvers. The results show that drivers favor evasive maneuvers over coming to standstills and maneuvers to the left over right. However, the desired condition to be achieved is mainly the standstill on a shoulder lane. These conflicts should be considered for designing such systems and further investigated with different methodologies, such as driving simulators.

Understanding growth and age of red tree corals (Primnoa pacifica) in the North Pacific Ocean.

Massive, long-lived deep-sea red tree corals (Primnoa pacifica) form a solid, layered axis comprised of calcite and gorgonin skeleton. They are abundant on the outer continental shelf and upper slope of the Northeast Pacific, providing habitat for fish and invertebrates. Yet, their large size and arborescent morphology makes them susceptible to disturbance from fishing activities. A better understanding of their growth patterns will facilitate in-situ estimates of population age structure and biomass. Here, we evaluated relationships between ages, growth rates, gross morphological characteristics, and banding patterns in 11 colonies collected from depths of ~141–335 m off the Alaskan coast. These corals ranged in age from 12 to 80 years old. They grew faster radially (0.33–0.74 mm year-1) and axially (2.41–6.39 cm year-1) than in previously measured older colonies, suggesting that growth in P. pacifica declines slowly with age, and that basal diameter and axial height eventually plateau. However, since coral morphology correlated with age in younger colonies (< century), we developed an in-situ age estimation technique for corals from the Northeast Pacific Ocean providing a non-invasive method for evaluating coral age without removing colonies from the population. Furthermore, we determined that annual bands provided the most accurate means for determining coral age in live-collected corals, relative to radiometric dating. Taken together, this work provides insight into P. pacifica growth patterns to inform coastal managers about the demographics of this ecologically important species. With this new ability to estimate the age of red tree corals in-situ, we can readily determine the age-class structure and consequently, the maturity status of thickets, using non-invasive video survey techniques when coupled with mensuration systems such as lasers or stereo-cameras. Enhanced surveys could identify which populations are most vulnerable to disturbance from human activities, and which should be highlighted for protection.

Shore-fish assemblage structure in the central Philippines from shallow coral reefs to the mesophotic zone

Connectivity between shallow coral reefs and adjacent deeper habitats may be crucial to reef ecosystem stability. However, deeper habitats such as mesophotic coral ecosystems (MCEs) remain understudied. We investigated the depth structuring of shore-fish assemblages in the central Philippines across shallow (10-30 m) and mesophotic (upper: 30-60 m, lower: 60-90 m) depth zones. Baited video surveys in two coastal sites similar to 30 km apart showed strong declines with depth in fish species richness and abundance including fishery target species. Corallivores, herbivores/detritivores, omnivores and planktivores showed the strongest declines. Invertivores and generalist carnivores dominated abundance at mesophotic depths. Data from the coastal sites were analysed with published data from an offshore island (Apo Island) < 25 km away to provide broader insights on spatial variability of shore-fish depth structuring. The percentages of species that overlapped shallow and mesophotic depths were much lower in coastal sites (9-13%, 9-11%) than the island (20-26%), suggesting higher potential vertical connectivity in the latter. Mean assemblage similarities (Bray-Curtis) between shallow and mesophotic depth zones were found to be low at all sites (0.3-19.6) and decreased with depth. Fish assemblages gradually differed across depth zones at coastal sites but mesophotic assemblages at the island were more similar to the shallow coastal assemblages. Strong correlations between fish assemblages and benthic habitat were detected, suggesting that higher cover of rocky substratum at mesophotic depths facilitates vertical connectivity at the island. Our findings highlight benthic habitat as a driver of spatial variation in the depth structuring and vertical connectivity of shore-fish assemblages.