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Sea-cage fish farms cause wild fish to aggregate nearby. Nevertheless, it is still not clear to what extent the attraction effect around sea-cage fish farms varies according to the type and size of the reared species. We examined this attraction effect in six sea-cage fish farms across the Aegean Sea using an integrated approach combining these variables with seasonal and spatial factors. Six 5-minute rapid visual counts were conducted on each farm complex for comparing the wild fish aggregations around the sea-cages concerning both cultivated species (seabass and seabream) and their sizes (adult and juvenile). We counted a total of 509,061 fishes, representing 36 species and 18 families. While 292,377 fish belonging to 34 species were counted in seabass cages, 216,684 fish belonging to 27 species were counted at seabream cages. In addition, 160,192 fish belonging to 28 species were counted around the juvenile cages, while 348,869 fish belonging to 34 species were counted at adult fish cages. The study shows that wild fish communities are formed around the sea-cages where seabass and seabream are reared in both adult and juvenile sizes in the Aegean Sea. According to our results, the fish species reared in the cages do not have a statistically significant effect on the wild fish community structure around the cages, whereas fish size, which was correlated with cage biomass and a longer history of feeding, had a strong effect. Other factors affecting the wild fish community structure around the cages are the season and the location of the cages. [ABSTRACT FROM AUTHOR]

The weight of marine litter has been marginally considered in comparison to counting and categorizing items. However, weight determines litter dynamics on water and coasts, and it is an essential parameter for planning and optimizing clean-up activities. This work reviewed 80 publications that reported both the number and weight of beached macro-litter worldwide. On average, a litter item weighed 19.5 ± 20.3 g, with a median weight of 13.4 g. Plastics composed 80% by number and 51% by weight of the global litter bulk. A plastic item weighed 12.9 ± 13.8 g on average, with a median weight of 9 g. The analysis based on continents and on water bodies returned similar values, which can be used to estimate litter weight on beaches from past and future visual census surveys, and from remote sensing imagery. Overall, this work can improve litter monitoring reports and support dynamics modelling, thereby contributing for environmental protection and mitigation efforts. [Display omitted] • Analysis of 80 papers on beached litter abundance and weight over the past 24 years. • Around 3.4 million of items and a total weight of 27.9 tons were considered. • The median weight of an item varied from 8.6 g (Europe) to 19.6 g (Oceania). • On coasts, the median weight varied from 9.2 g (Atlantic) to 21 g (Pacific). • Plastics constituted 80% by number and 51% by weight of the global litter bulk. [ABSTRACT FROM AUTHOR]

We conducted an integrated survey combining visual census and baited remote underwater video survey on the coral reefs in the northeastern Red Sea and examined their health by comparing the baseline information from two decades ago. The mean coverage of the corals of all stations was 36 %, including 32 % stony corals and 4.0 % soft corals, significantly higher and lower to previous baseline. Observed high proportion of dead corals indicated the occurrence of the events of mass mortality, and the heating events were the most likely cause. Similar levels of coral coverage compared to two decades ago indicated their resilience to past events with mass coral mortality. Small proportions of macroalgae and sea urchins indicated that they might be controlled by their predators frequently observed in both visual census and underwater video survey. Regular monitoring and careful development plans are needed to safeguard these invaluable reefs. • Nearshore reefs had similar coverages of corals compared to two decades ago. • Observed high proportion of dead corals indicated mass mortality events. • Similar levels of corals indicate the resilience to previous mortality events. • This resilience might be contributed by the fish to control corals' competitors. [ABSTRACT FROM AUTHOR]

Abstract Abundance and qualitative composition of benthic marine litter were investigated in a coastal area of the central Mediterranean Sea. Almost 30 km of video footage, collected by a Remotely Operated Vehicle between 5 and 30 m depth, were analyzed. Litter density ranged from 0 to 0.64 items/m2 with a mean of 0.11 (±0.16) items/m2. General wastes, made up almost entirely of plastic objects, were the dominant sources of debris representing 68% of the overall litter. The remaining 32% consisted of lost or abandoned fishing gears. Synthetic polymers, considering both fishing gears and general waste, represented 73% of total debris items. Our results are comparable with litter amounts reported in other Mediterranean sites at similar depths. Overall, the results are discussed in terms of monitoring strategy, to support the implementation of the Marine Strategy Framework Directive (2008/56/EC) for descriptor 10 and the Mediterranean UN Environment (UNEP/MAP) regional Plan on Marine Litter. Highlights • A total of 56 litter items were observed by ROV on a shallow area of 59,616 m2. • The mean density of marine litter for the whole area was 0.11 items 100 m−2. • General wastes represented 67.86% of the overall density. • 73% of all marine litter items was composed by plastics. • Ropes, disposable crockeries and papers accounted for 50% of the total density. [ABSTRACT FROM AUTHOR]

Abstract Many marine animals around the world are threatened by a variety of anthropogenic activities, yet there is often a paucity of data to monitor patterns in abundance and distribution or to evaluate human interventions. The new citizen science program eOceans helps to fill this gap by gathering observations of various marine animals from worldwide ocean explorers. In 2012, a dedicated Thailand-wide census of sharks, and other animals, began as a collaboration between eOceans scientists and the dive tourism industry. Using the observations from 9524 dives (9357 h underwater) logged by 169 divers on 153 sites, we describe the spatial and temporal patterns of sharks in coastal Thailand. A total of 12 shark species were encountered, most commonly (67%) as individuals, and were observed on 11% of all dives, on 59% of sites, in all months and years. The two most frequently encountered species were blacktip reef (Carcharhinus melanopterus) and leopard sharks (Stegostoma fasciatum). Many species had peak encounter rates in summer, but aggregated in various seasons in different years. Mating events and nursery sites were rarely observed, and only for blacktip reef and whitetip reef (Triaenodon obesus) sharks. These results could be of value to species- or region-specific biologists, ecologists and fisheries scientists, as well as to managers and policy makers that could use the findings to monitor future trends and prioritize conservation strategies. Moreover, this study highlights the value that collaborative citizen science projects could have in support of marine science, management and conservation efforts worldwide. Highlights • Longitudinal sampling, 9524 dives on 153 sites across 5 years, provided spatiotemporal patterns of sharks in Thailand. • Twelve shark species were encountered, most as individuals, on 59% of sites. • Endangered Stegostoma fasciatum and Carcharhinus melanopterus were among most frequently encountered species. • Highlights the value of eOceans citizen science data for informing marine science, management, and conservation. • Demonstrates the success of collaborative programs that combine the diversity of expertise that exists within communities. [ABSTRACT FROM AUTHOR]

Fish cages attract a high variety of wild fish, and therefore are similar to fish aggregation devices. Aquaculture cages enhance local fisheries, with a more diverse and abundant fish assemblages compared to control stations, not influenced by fish cages. Previous studies have been mainly focused on taxonomic and ecological indices, such as species richness, individual abundances or Shannon-Weaver index. In the present study, we explore if functional diversity may be feasible to understand the consequences of changes in the composition of fish aggregates around cages. We studied fish aggregates from three cages on the coast of Tenerife (Canary Islands, Atlantic Ocean) over several years. All fishes were identified and counted using rapid visual counts (RVCs) in cage and control stations. An increase of species richness and individual abundance occurred in fish aggregates around the studied cages persisting over time. Functional diversity showed increase on cage stations, with higher values of functional evenness and functional divergence relative to control stations. A slight dissimilarity in the taxonomic composition was only observed in the eastern farm. In terms of functional diversity, the studied aquaculture cages exhibited a slight increase in wild fish aggregates over time. These results are similar to previous studies based on taxonomic and ecologic diversity in which a long lasting effect was observed on wild fish aggregates. Thus, aquaculture cages might be considered as a figure of conservation or fishery interest. Statement of relevance Our results showed a functionally diverse fish community around offshore cages. Thus, aquaculture leases could work as a “reservoir”, promoting the development of diverse fish assemblages, as marine protected areas (MPAs) are designed for. The development of aquaculture offshore cages might include their positive effects on wild fish aggregates, with a “buffer” fish-ban zone to protect fish stocks from the fishermen. [ABSTRACT FROM AUTHOR]

Floating litter in the estuarine system of Santos-São Vicente is common and is part of day-to-day activities of various users of the area. The objective of the present study was to carry out a quali-quantitative evaluation of the occurrence of floating litter, to infer their sources, and to identify environmental factors that are likely to control occurrence and distribution, with particular emphasis on the effects of tidal regimes. Six sampling stations were selected along the aforementioned estuary and visited monthly between July 2010 and January 2012. Floating litter was counted from a fixed sampling station. Plastics prevailed (89.64%) and their main source was domestic activities (55.41%). More litter was found during ebb spring tides, with higher concentrations obeying confluence patterns of the estuary's channels. Results indicated that occurrence can be attributed to the deficiency in basic sewage system in the area and the deliberate disposal into the estuary by the local population. [ABSTRACT FROM AUTHOR]

Abstract: A lure assisted, visual census, belt transect method has been developed and compared with the traditional visual census. Presentation of a lure was predicted to improve visibility of fish that are difficult to detect or identify. These include species hidden within three dimensional structures, buried in or camouflaged with the substratum, and fast swimming. A snorkeler presenting an artificial lure near the seabed along 3-m transects recorded all fish visiting the lure or present near the lure''s path. Totals of 1527 lure-assisted transects and 1292 lure-absent transects intersecting a diversity of benthic habitats were carried out at thirty sites spanning the Croatian Adriatic coast in spring 2010. More than half the observed fish visited the lure, and lure presentations increased the probability of census for 76% of the 58 observed taxa. The overall significantly higher fish density at lure-assisted transects than at lure-absent transects was also significant within all common habitat types and for the entire investigated depth range (0.25–9m). The positive effect of the lure on estimates of density was significant for 33% of taxa, including: ambush predators (Trachinus draco), fast moving cruise-chase predators (Sparidae), predators chasing prey from a hidden waiting position (Coris julis and Serranidae) or from a position of camouflaging against bare sand (Gobiidae). Adding lure presentation to regular visual census is logistically simple and flexible in the detail of its design and application. [Copyright &y& Elsevier]

Abstract: Fish communities associated with a series of artificial reefs deployed in three estuaries in southeastern Australia (151° 34′ E, 33° 7′ S to 150° 37′ E, 35° 8′ S) were surveyed using both Baited Remote Underwater Video (BRUV) and Underwater Visual Census (UVC). Abundance estimates, frequency of observations, and species indicators (richness and diversity) provided the basis for comparison between methods. UVC recorded significantly greater numbers of species in all estuaries and significantly greater species richness and diversity at two of the three estuaries. Variation in the number and frequency of species detected by each method directly related to the ecological niche and behaviour of each species. UVC provided better estimates of the rare or cryptic reef associated species. BRUV sampled a smaller proportion of species overall but did observe key recreational species such as Acanthopagrus australis, Pagrus auratus and Rhabdosargus sarba with increased frequency, although the presence of large numbers of schooling species such as Pelates sexlineatus reduced the detection frequency of these species. In summary, results indicate that BRUV is an effective method for recording species associated with artificial reefs with the exception of cryptic species that are located within the reef structure itself. BRUV techniques complement UVC by providing increased coverage of species known to be diver averse as well as providing important information regarding behaviour of the species identified. Given the limitation of each method, it is recommended that monitoring plans for artificial structures should adopt a multi-method approach utilising BRUV and UVC where possible. [Copyright &y& Elsevier]

Abstract: Quantification and comparisons of the structure of subtidal marine communities are essential for answering a suite of basic and applied ecological questions. However, time constraint associated with sampling underwater by scuba diving is a major obstacle to achieve adequate sampling effort. We tested a technique for rapid-assessment of hard substrate epibenthic communities, based on counts of the frequency of different taxa within sampling units (quadrats). This technique was compared to a broadly used technique, based on visual estimation of percent cover of taxa, to determine whether a significant amount of information is lost when using the rapid assessment technique. We applied both techniques in three case studies from the Ligurian Sea, in the NW Mediterranean. Field measurements showed that the same communities can be surveyed twice as fast with the frequency-count compared to the cover-estimation. Structural variables of communities as species richness and diversity yield almost identical values with the two techniques while dominance showed underestimated by frequency-count when compared to the cover-estimation. Multivariate analyses indicated that the two techniques yield similar results, highlighting similar patterns of variation in all three case studies, particularly when data are transformed (square-root or fourth-root transformation). Our findings suggest that applying the frequency-count technique to the assessment of benthic communities is an effective strategy for increasing sampling effort when working underwater at depth. [ABSTRACT FROM AUTHOR]

Abstract: The effects of sewage outfalls on subtidal fish assemblages were studied along the NW coasts of Malta (Sicily channel, Mediterranean Sea) by means of underwater visual census. The presence of two spatially distinct outfalls discharging untreated wastewaters allowed to use a balanced symmetrical after control/impact (ACI) design that consisted of two putatively impacted locations and two controls, with four sites nested in each location. Surveys were performed in 2006 at two random dates. The study highlighted significant changes at both assemblage and individual species levels. Fish assemblages structures were different between controls and sewages, where total abundance of fish were higher. The responses of individual species to sewage pollution were mostly related to an anomalous increase of two small opportunistic species i.e. Gobius bucchichii and Parablennius rouxi and to a decrease of species of the genus Symphodus, particularly S. roissali and S. ocellatus. Moreover in correspondence of the outfalls, significant changes of the fish size distribution were detected for several species. These results support the use of fish assemblages as biological indicators for marine coastal waters and demonstrated the possibility to obtain sharp signals of environmental impact from some individual fish species. [Copyright &y& Elsevier]

Abstract: Artificial reefs have been deployed worldwide in shallow marine environments to enhance attraction and capture of fish, but, despite their potential as a fishery management option, few studies addressed whether fish assemblages will change with distance from a reef. We experimentally assessed the relationship between fish abundance and richness to increased distance (0, 25, 100, and 300m) to reef balls deployed on a flat and homogeneous bottom, 9-m deep, on the north coast of Rio de Janeiro, Southeastern Brazil. A total of thirty fish species was associated with the reefs and the variation in species composition with sampling period or technique did not account for changes in fish assemblages with reef distance. Fish abundance and richness were significantly greater at the nearest distances (0m and 50m) to the reefs than at 300m, but while the first dependent variable decreased exponentially with reef distance the later diminished linearly. Fish responses to reef distance were clearly species-specific and the tomtate (Haemulon aurolineatum — the dominant species that probably used the reefs for shelter purposes) strongly influenced the exponential decreasing pattern found for the total number of fishes and abundance of Haemulidae. The abundance of the close congener Haemulon steindachneri, and of Chaetodon striatus, Serranus flaviventris and serranid species as a group also decreased, but linearly, with reef distance, probably related to variation in home-range. Acanthurus chirurgus and Scorpaena isthmensis decreased linearly in number with reef distance, probably due to feeding rather than refuge purposes. The abundance of Isopisthus parvipinnis tended to increase with reef distance, suggesting that artificial reefs might be unprofitable for those species less dependent on clear water or structurally complex habitats to obtain refuge or food. Overall, our study indicates that artificial reefs are a promising management tool to enhance fish capture in the oligotrophic waters and structureless bottoms of the north coast of Rio de Janeiro, but with varied rates of success, depending on the target species and fishing distance from the reefs. [Copyright &y& Elsevier]

Abstract: Since 1972, the UNESCO “World Heritage Convention” offers an international canvas for conservation and management that targets areas of high cultural and environmental significance. To support the designation of areas within the 36.000km2 of New Caledonia coral reefs and lagoons as a World Heritage Site, the natural value and diversity of the proposed zones needed to be demonstrated. To exhaustively identify each configuration of shallow habitats, high resolution remote sensing images were used to select the sampling sites. This optimal scheme resulted in the selection of nearly 1300 sampling sites, and was then simplified to render its application realistic. In the final sampling plan, only the most common or the most remarkable coral zones were selected. Following this selection, in situ habitat and fish surveys were conducted in 2006–2008 in five large areas spanning a 600km-long latitudinal gradient. Habitats were described using line-intercept transects in parallel with underwater visual census of indicator and commercial coral reef fish species. We report here on the results achieved in terms of: (i) the actual diversity of coral habitats captured by the remote sensing based sampling strategy, (ii) the different reef fish communities captured from the different sites, and (iii) how well they represent New Caledonia diversity. We discuss the possible generalization of this scheme to other sites, in the context of World Heritage Site selection and for other large-scale conservation planning activities. [ABSTRACT FROM AUTHOR]

Abstract: Fish communities and habitat structures were evaluated by underwater visual censuses a rocky location impacted by thermal discharge (I) and at two control locations, one in a Sargassum bed (C1) and the other in a rocky shore with higher structural complexity (C2). Habitat indicators and fish communities exhibited significant differences between the impacted and control locations, with the impacted one showing a significant decrease in fish species richness and diversity, as well as a decrease in benthic cover. At the I location, only 13 fish species were described, and the average water temperature was 32±0.4°C, compared with 44 species at C1 (25.9±0.3°C) and 33 species at C2 (24.6±0.2°C). Significant differences in fish communities among locations were found by ANOSIM with Eucinostomus argenteus, Mugil sp. and Haemulon steindachneri typical of location I, while Abudefduf saxatilis, Stegastes fuscus and Malacoctenus delalandi were typical of the control locations. Our study shows that thermal pollution alters benthic cover and influences fish assemblages by altering composition and decreasing richness. [Copyright &y& Elsevier]

Abstract: Marine protected areas (MPAs) could be useful as fisheries management tools for the exportation of pelagic eggs, larvae and adult fish. A decreasing gradient of fish biomass across MPAs boundary may indicate export. We determine whether gradients of decreasing biomass of fish assemblage occurred in Tabarca Marine Reserve over two habitats with different continuity across the boundaries, to test if the patchy nature of the marine environment might act as a barrier for the fish export. In general, significant decreasing gradients in total fish biomass and biomass of some species were observed on P. oceanica and rocky substrates, independently of their different continuity through the reserve boundaries. Changes in the multivariate structure of the fish assemblage were correlated with the distance from integral reserve. All of these results support the hypothesis that the exportation of adult fish from Tabarca Marine Reserve occurs, and this process may influence the surrounding fished areas. [Copyright &y& Elsevier]

Marine protected areas (MPAs) are considered as an effective tool in marine coastal management, and considered able to enhance local fisheries through adult fish spillover. Indirect evidence of fish spillover could be obtained by horizontal gradients in fish abundance. To address this question, the existence of gradients of fish abundance and biomass across marine reserve boundaries was assessed in six Mediterranean MPAs using underwater visual censuses performed at various distances from the core of the MPA, in integral reserve (IR), to buffer zone (BZ) and fished areas. A reserve effect was evidenced with higher values of fish species richness (×1.1), abundance (×1.3), and biomass (×4.7) recorded inside MPAs compared to adjacent fished areas. Linear correlations revealed significant negative gradients in mean fish biomass in all the reserves studied after the effect of habitat had been removed, whereas negative gradients in abundance were less conspicuous. Generalized additive models suggested two main patterns of biomass gradients, with a sharp decrease at the IR–BZ boundary or at the BZ–fished area boundary. It was estimated that fish spillover beneficial to local fisheries occurred mostly at a small spatial scale (100s of metres). The existence of regular patterns of negative fish biomass gradients from within MPAs to fished areas was consistent with the hypothesis of adult fish biomass spillover processes from marine reserves and could be considered as a general pattern in this Mediterranean region. [Copyright &y& Elsevier]

Abstract: A baited underwater video (BUV) system for the study of reef-associated fish populations on shallow (10–20 m) rocky habitats in the western Mediterranean was assessed at four locations in Spain and two in France. We describe the apparatus and optimal deployment times for video sampling. Different species had different response times to the bait, with four response groups identified. Examination of species accumulation curves and fish abundance estimates over time revealed that a period of approximately 20 min deployment was sufficient to capture most species on video. The technique sampled a wide variety of species, with 51 species belonging to 33 families recorded. Nine species of fish appeared regularly at the bait in relatively high numbers, and consist of six carnivores (Serranus cabrilla, Serranus scriba, Coris julis, Diplodus annularis, Diplodus vulgaris, Thalassoma pavo), two planktivores (Chromis chromis, Boops boops) and one omnivore (Oblada melanura). However, abundance estimates for other species were generally very low (mean <1 per location). Comparison of results from BUV with those obtained by Underwater Visual Census (UVC) at the same locations suggests that although BUV estimates species richness reliably, UVC is the more suitable technique for estimating the abundance of shallow-water reef fish in the Mediterranean. BUV improvements are suggested to optimise its use in deeper waters where UVC using scuba is inoperable. [Copyright &y& Elsevier]

Abstract: Monthly visual surveys of reef fish populations in the Florida Keys were conducted from May to September of 1999 and April to December of 2000 using both strip transect and stationary point count sampling methods. Each month divers using SCUBA conducted three 10m×30m transect surveys and three 5m radius stationary point counts at 26 sites selected using a habitat based, stratified random design procedure. During both sampling procedures divers enumerated and assigned to 5cm size increments all groupers (Serranidae), snappers (Lutjanidae), hogfish (Labridae), angelfish (Pomacanthidae), butterflyfish (Chaetodontidae), triggerfish (Balistidae), and a few other species of recreational or commercial importance. The rationale behind this sampling design was to assess the differential vulnerability of the various species and size classes to the lower behavioral disturbance/smaller area point count technique as compared to the higher disturbance/larger area transect method, and to assess which method would produce the highest density estimates and census the largest number of individuals per unit of sampling effort for size structure determinations. Although both types of samples required about the same amount of diver effort to complete, approximately 1.5 times more individuals were recorded during transect surveys. However, since transect surveys encompassed 4.3 times as much area as point counts, observed densities averaged about three times higher for point count samples. There was considerable variation among species with respect to this pattern, with total numbers of individuals for the 10 most abundant species ranging from about equal to 4.5 times higher during transect surveys, while densities ranged from nearly equal to about 6 times higher during point counts. Length frequencies within species were generally very similar between the two methods, though a higher proportion of larger individuals was recorded for a few species during transect surveys. Since previous studies have strongly indicated that visual census techniques produce underestimates of true reef fish densities, the higher and presumably more accurate density estimates provided by the point count method, along with other factors such as presumed increases in accuracy of counts and size estimates associated with increased observation time of individual fishes, led us to select this method for our future surveys. [Copyright &y& Elsevier]

Abstract: We investigated spatio-temporal variability in the population structure of the parrotfish, Sparisoma cretense (Linnaeus, 1758), throughout the Canarian Archipelago (eastern Atlantic Ocean) with underwater visual transects. By means of a multiscaled hierarchical sampling design spanning three orders of magnitude of spatial variability (from 10s of meters between replicated 100m2 transects to 100s of kilometres among islands) and four sampling times (twice a year in 2003 and 2004); we related differences between islands to differences in the degree of fishing pressure. The mean abundance of parrotfish across all counts was 6.79±0.46 ind 100m−2 (mean±S.E., n =768 transects), while the mean biomass was 593.81±45.61g 100m−2 (mean±S.E., n =768). Abundances and biomasses of S. cretense clearly differed between islands, although they were relatively consistent between the sampling times. The different abundances and biomasses observed between islands were correlated with fishing pressure, providing evidence that fishing was responsible for the inter-island differences. Differences in the size-structure between the eastern and western islands suggest differences in the recruitment periodicity at both groups of islands, which could be related to large-scale spatial variation in the oceanographic conditions across an east–west gradient along the Canary Islands. [Copyright &y& Elsevier]

Man-made defence structures (e.g., breakwaters, jetties) are becoming common features of marine coastal landscapes all around the world. The ecology of assemblages of species associated with such artificial structures is, however, poorly known. In this study, we evaluated the density and size of fish predators of echinoids (i.e., Diplodus sargus, Diplodus vulgaris, Sparus aurata), and the density of sea urchins (i.e., Paracentrotus lividus) at defence structures (i.e., breakwaters) inside and outside the marine protected area of Miramare (northern Adriatic Sea) in order to: (1) assess possible differences in fish predator density and size between protected and fished breakwaters; (2) assess whether fish predation may have the potential to affect sea urchin density in artificial rocky habitats. Surveys were carried out at four random times over a period of two years. Total density, and density of medium- and large-sized individuals of the three predatory fishes were generally greater at the protected than at the fished breakwaters, whereas no differences were detected in the density of small-sized individuals. Density of the sea urchin P. lividus did not show any difference between protected and fished breakwaters. The results of this study suggest that: (1) protection may significantly affect predatory fishes in artificial rocky habitats; (2) differences in predatory fish density, and size may be unrelated with the density of the sea urchin P. lividus; (3) protected artificial structures such as breakwaters, originally planned for other purposes, could represent a potential tool for fish population recovery and enhancement of local fisheries. [Copyright &y& Elsevier]

Most methods for assessing reef fish assemblages at night require artificial light, but the use of different colors of light may influence the results. We used data from 135 underwater visual censuses (UVCs) performed with different colors of light (red, blue and white) to evaluate the structure of fish assemblages on subtropical rocky reefs along three depth intervals. We did not detect any effect of the color of light on total density or fish species richness per transect, nor on the structure of the entire assemblage. However, the density of some of the most abundant species varied according to the color used. Red light showed the highest values of frequency of occurrence for most species, while the white light resulted in decreased abundance of some fish species. Our results emphasize the importance of choosing the color of light depending on the type of studies to be conducted. This will depend on the objectives of the research (e.g. inventory, behavior or community dynamics) and the target fish fauna (e.g. mobile or sedentary). • Light color for night UVCs depends on the objective of the study • White, red and blue colors work well to evaluate the nocturnal fish assemblage • Density of some of the most abundant species varied according to the color used • Red light should be preferred to assess behavioral aspects of nocturnal fish [ABSTRACT FROM AUTHOR]

Abstract: A system for visual surveys of bottom fishes, assembled from readily available components, is described. A camera and a depth sounder transducer are mounted on a towed body. The camera captures the images, and the depth sounder measures the distance between the camera and the bottom. A video recorder is used to record the data—the video channel for the image, and the audio channel for distance information, which is dictated from the depth sounder display into a microphone. A relationship between distance and magnification is used to estimate the width of the survey path and the size of surveyed objects. A comparison of round goby (Apollonia melanostoma) density estimated by repeated seining and use of the underwater visual apparatus showed that the smallest individuals are underrepresented by the visual assessment, but the visual method detects about 85% of the 50 mm TL or larger gobies. [Copyright &y& Elsevier]