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The stress on the marine environment caused by industrialization in developing economies is indisputable. The Aliağa region, which has unique features such as being heavily influenced by industrialization and having different types of marine habitats was preferred as a monitoring point. By determining the current status of fish density and diversity, the focus was on obtaining data that could allow future comparisons. Without the seasonal variability, 39 fish species representing 14 families were identified, with two abundant families: ten species in both Sparidae and Labridae. The greatest fish diversity was recorded respectively in the spring, summer and autumn. Abundant species were Boops boops with 19.3%, Chromis chromis (17.4%), Spicara smaris (15.0%) and Atherina boyeri (12.5%) in total abundance. A total of 1.89 individuals/m2 that weighed 20.43 g/m2 were identified in the study period.

Management and conservation actions in marine-protected areas require baselines for monitoring threatened marine fauna such as elasmobranchs. This article provides evidence of the occurrence of 34 species of elasmobranchs (21 sharks and 13 batoids) in the Malpelo Flora and Fauna Sanctuary, Colombia, including five new records of sharks and three of rays. From 1987 to 2021, new records were obtained by underwater visual census using SCUBA, manned submersibles and deep-ocean cameras to depths of up to 2211 m. Of the recorded species, 21 are considered as threatened taxa (64%) by the IUCN, making the Malpelo Flora and Fauna Sanctuary an essential conservation area for this highly threatened group of species.

The presence of spiny butterfly rays, Gymnura altavela, in waters less than 20 m deep off the Canary Islands shows marked seasonality, with relatively high abundances in the summer and autumn. Large aggregations of sometimes hundreds of individuals, primarily females, appear in specific shallow areas of the archipelago and seem to be associated with the seasonal variation in water temperature. This seasonal pattern of presence or absence in shallow areas suggests that spiny butterfly rays migrate into deeper waters or other unknown areas during the rest of the year. G. altavela shows sexual dimorphism; in our study, females were larger and more abundant than males, with a sex ratio of 1:18.9. The species’ estimated asymptotic length, L∞, was 183.75 cm and thus close to the common length reported for the species (200 cm). The von Bertalanffy growth constant (k) oscillated between 0.210 and 0.310 year−1, as similarly described for the species in the Western North Atlantic off the U.S. coast. From June to November, the seawater temperature oscillated between 19 and 24 °C, and massive aggregations of females occurred at 22–24 °C and in a few specific sandy beaches on the islands. Spiny butterfly rays, mostly females, show a preference for aggregating in shallow waters during summertime, probably conditionate to mating or breeding behaviour.

Increasing speed and magnitude of global change threaten the world's biodiversity and particularly coral reef fishes. A better understanding of large-scale patterns and processes on coral reefs is essential to prevent fish biodiversity decline but it requires new monitoring approaches. Here, we use environmental DNA metabarcoding to reconstruct well-known patterns of fish biodiversity on coral reefs and uncover hidden patterns on these highly diverse and threatened ecosystems. We analysed 226 environmental DNA (eDNA) seawater samples from 100 stations in five tropical regions (Caribbean, Central and Southwest Pacific, Coral Triangle and Western Indian Ocean) and compared those to 2047 underwater visual censuses from the Reef Life Survey in 1224 stations. Environmental DNA reveals a higher (16%) fish biodiversity, with 2650 taxa, and 25% more families than underwater visual surveys. By identifying more pelagic, reef-associated and crypto-benthic species, eDNA offers a fresh view on assembly rules across spatial scales. Nevertheless, the reef life survey identified more species than eDNA in 47 shared families, which can be due to incomplete sequence assignment, possibly combined with incomplete detection in the environment, for some species. Combining eDNA metabarcoding and extensive visual census offers novel insights on the spatial organization of the richest marine ecosystems.

Different techniques have been employed for fish surveys in freshwater impoundments, however, despite the increasing applicability of underwater video systems for fish sampling in different aquatic ecosystems, such technology has not been tested in reservoirs. This study compares estimates of fish species richness, community composition, and size structure derived from visual census (VC) and underwater video (UWV) in two Neotropical reservoirs. The total number of species recorded by both sampling methods was similar, even though UWV recorded higher mean number of species than VC, in both reservoirs. In general, VC was more efficient in recording cryptic and resident species, while UWV, was better for highly mobile species. Considering size classes, VC was more efficient than UWV in detecting smaller individuals (i.e., 31–79 mm total length). Although observational sampling methods depend on water transparency, UWV can be considered a complementary and promising technique for fish surveys in shallow areas of clear reservoirs.

Kawasan konservasi perairan (KKP) berfungsi untuk mengelola sumber daya perikanan dan keanekaragaman hayati laut agar dapat dimanfaatkan secara berkelanjutan. Kondisi ikan karang merupakan salah satu bioindikator untuk mengukur dampak pengelolaan KKP. Tujuan dari penelitian ini adalah untuk melihat dampak pembentukan KKP Daerah (KKPD) Pulau Ay dan Pulau Rhun terhadap sumber daya perikanan karang di Kepulauan Banda, Maluku, Indonesia. Metode yang digunakan untuk pengumpulan data yaitu Underwater Visual Census (UVC) dan Fish Length Estimation dengan bantuan peralatan SCUBA. Analisis data dilakukan dengan membandingkan data sekunder dan data primer yang meliputi kelimpahan, biomassa, status tropik dan komposisi ukuran ikan besar dan ikan kecil dari 10 famili ikan target dan ekonomis penting sebelum dan sesudah Pulau Ay dan Pulau Rhun dicadangkan sebagai KKP. Hasil penelitian menunjukan bahwa kelimpahan dan biomassa ikan karang secara temporal berfluktuasi sebelum dan sesudah Pulau Ay dan Pulau Rhun dicadangkan sebagai KKP, namun masih dalam kondisi melimpah dan tinggi. Status tropik dan komposisi ukuran ikan karang berubah-ubah sebelum dan sesudah pencadangan KKP, namun masih dalam kondisi seimbang antar kelompok tropik, ikan besar dan ikan kecil. Kesimpulan penelitian ini adalah pencadangan KKPD memberikan dampak positif terhadap sumber daya ikan karang di Pulau Ay dan Pulau Rhun.

The visual census of band transect (CVB) is one of the most used monitoring protocol on reefs, however this study confirms that its application fail in the detection and estimation of abundance of invasive lionfish. CVB vs Lionfish Search Census (CBP) was compared on Mexican Caribbean reefs. Differences in abundance of lionfish were found between CVB and CBP. Bias among both methods was significantly correlated to the cryptic behavior of inactivity and depth of the site. Finally, the use of different lionfish sampling methods and the application of CBP for monitoring reefs in the region are discussed.

Fish Aggregating Devices (FADs) are used world-wide to attract fish. A previous study revealed that FADs affect the distribution and dispersal patterns of juveniles of the greater amberjack Seriola dumerili. This occurs because FADs placed off-shore prevent juveniles from approaching the coast while those placed in-shore facilitate their recruitment in coastal areas. In order to obtain more information on the dynamic and movement patterns of the YOY S. dumerili associated with FADs, a tagging experiment was conducted in the Gulf of Castellammare. The 96 juveniles tagged and released under FADs placed at different distances from the coast showed a different movement patterns. The highest sighting rate and shortest distance traveled by fishes were recorded at the off shore FADs. These results reinforce those of previous studies on the same species.

Perairan pesisir Desa Kerobokanmemiliki wilayah terumbu karang yang penting karena terdapat spot rekrutmen sebagai wilayah terumbu buatan alami. Penelitian ini bertujuan untuk mengetahui nilai indeks keanekaragaman, keseragamandan dominansi karang pada terumbu buatan alami “Bioreeftek” di salah satu spot perairan pesisir Desa Kerobokan, Kecamatan Sawan, Kabupaten Buleleng, Provinsi Bali.Metode penelitian yang diaplikasikan adalah observasi dengan sensus visual dengan kamera bawah air dan peralatan selam SCUBA pada enam unit terumbu buatan. Pengambilan data observasi dilakukan pada September 2020. Total rekrutmen karang yang ditemukan sebanyaksembilan jenis biota pada terumbu buatan B1-B6 (B=Bioreeftek), yaitu Podobacia sp, Sponge, Atriolum robustum, Favites sp, Gorgonia sp, Porites sp, Diploastrea sp, Coralline algae dan Pocillopora damicornis . IndeksKeanekaragaman tertinggi B3 = 3,4; Indeks Keseragaman tertinggi B3 = 2, 48; Indeks Dominansi tertinggi B5 = 0,68. Biota yang paling banyak ditemukan pada terumbu buatan B1-B6 adalah Coralline algae dan karang Scleractinia dari jenis Favites sp . Kondisi kualitas air di perairan Buleleng menunjukan kondisi normaldan masih berada pada standar baku yang ditetapkan oleh Keputusan Menteri Lingkungan Hidup No. 51 Tahun 2004, kecuali konsentrasi nutrien. This study aims to determine the diversity index value, uniformity, and dominance of corals on natural artificial reefs "Bioreeftek" in Kerobokan Village coastal waters, Sawan District, Buleleng Regency, Bali Province. Data collection was carried out on September 2020. Observations with visual census using underwater cameras and SCUBA diving equipment was applied to observe coral recruitment insix artificial reef units. The results showed that there werenine types of biota found on artificial reefs B1-B6 (B = bioreeftek), that were Podobacia sp, Sponge, Atriollum robustum, Favites sp, Gorgonia sp, Porites sp, Diploastrea sp, Coralline algae and Pocillopora damicornis . The highest diversity index found in B3 = 3,4; The highest uniformity index found B3 = 2,48; and the highest dominance index was in B5 = 0,68. Coralline algae and Scleractinian corals ( Favites sp )were abundantly found in artificial reefs B1-B6.Water quality condition in Buleleng water generally showed a normal condition for supporting marine lifes, with exception of nutrient

This manuscript reports the first sightings and collection of the swimming crab Cronius ruber (Lamarck, 1818) on the coast of Madeira Island, Portugal. After the recent record in the Canary Islands, this represents a further step northward on this species’ expansion in distribution in the eastern Atlantic. The crab was first spotted during underwater visual census surveys done by scuba diving in July 2018 and was repeatedly observed during the following months, in different locations on the south coast of Madeira. Analysis of temperature data from several geographic locations where C. ruber is present was performed to assess how thermal regimes and ongoing changes may influence this recent distribution shift. Current temperature trends in Madeira suggest that the arrival and establishment of C. ruber to Madeira might have been facilitated this thermophilic species, adding evidence for the ongoing tropicalization of this area. Finally, the current spread of C. ruber in both Canaries and Madeira island systems highlights the need for a long-term monitoring program targeting this and other non-indigenous species (NIS).

In this study, fish assemblages on deployed artificial fish habitats and natural rocky habitats were compared 1 year post-deployment in Zuari estuary, southwest coast of India employing underwater visual census. Comparisons demonstrated significant differences in fish species composition between artificial fish habitats and natural rocky habitats. Within the artificial fish habitats, the habitats located at deeper regions indicated high richness, diversity and species abundance. The rich and diverse fish assemblages on deeper artificial fish habitats might be a result of isolated location, species behavioral preferences on feeding and shelter and complexity of the habitat.

The colonization of artificial structures by benthic organisms in the marine realm is known to be affected by the general trophic patterns of the biogeographical zone and the prevailing environmental traits at the local scale. The present work aims to present quantitative data on the early settlement progress of macrofaunal benthic assemblages developing on artificial reefs (ARs) deployed at the Underwater Biotechnological Park of Crete (UBPC) in the oligotrophic Eastern Mediterranean. Visual census and subsequent image analysis combined with scraped quadrats were used to describe the establishment of the communities and their development over three consecutive campaigns, span-ning 5 years post-deployment. Macroalgae consistently dominated in terms of coverage, while sessile invertebrates displayed different patterns over the years. Polychaeta and Bryozoa were gradually replaced by Cnidaria, while Porifera and Mollusca displayed an increasing trend over the years. Motile benthos was mainly represented by Mollusca, while the abundance of Polychaeta increased in contrast to that of Crustacea. For both sessile and motile assemblages, significant differences were observed among the years. The results of this study indicate that ecological succession is still ongoing, and further improvement in the monitoring methodology can assist towards a more accurate assessment of the community composition in complex AR structures. European Union MIS 5002670, MIS 5027402

Marine fish community is very sensitive to environmental changes. So the number of species, abundance, and biodiversity index can be used as a reference to assess the quality of the aquatic environment. The aim of this study was to describe fish biodiversity in Belitung Timur, Bangka Belitung Islands, Indonesia. Three islands were visited i.e. Pekandis Island, and Keran Island, Gosong Semut (Gosong refers to sandbar) for reef fish survey and for the economical fish study we also visited fisheries landing sites (i.e. Teluk Pering, Tanjung Batu Pulas, and Pantai Burung Mandi). The underwater visual census was used for in situ surveys of reef fish, and the fish species landed in fisheries landing site also been checked. Forty-two families of economical fish that had been landed by local fishermen were identified, and ten families of reef fish were found in reef systems of research location. A total of 10 families were recorded from three islands in Belitung Timur Regency. In addition, 42 families of commercial fish were also observed in fish landing sites from the coastline of Belitung Timur Regency, Bangka Belitung Islands.

Este artículo contiene 10 páginas, 5 figuras, 3 tablas, Ocean sprawl is replacing natural substrates with artificial alternatives. We hypothesized that, after submersion, high occupancy, high mobility species colonize artificial substrates faster than low occupancy, low mobility species, a biodiversity divergence that will slowly fade out with time. Using quantitative visual census of species in 10 artificial and their adjacent natural substrates, we tested for the existence and temporal evolution of this divergence. Assigning species to one of three occupancy and one of three mobility categories, we found that artificial substrates increased the performance of high mobility, high occupancy species while decreased the performance of low occupancy species with medium and low mobility. This biodiversity divergence remained unchanged over the 50-year underwater timespan of the artificial substrates investigated. Our results suggest that proliferation of artificial substrates is building up a biodiversity loss driven by the least conspicuous and uncommon benthic and sessile species that is undermining coastal marine biodiversity., This work was supported by the Spanish Ministry of Economy grant MARINERES [grant number CGL2013-49122-C3-1-R].

Current literature considers that Nasolamia velox has a limited distribution along the coastline of the Eastern Pacific with sporadic sightings in the Galapagos Archipelago. This study provides evidence of the occurrence of this species at the Revillagigedo Archipelago (18°99′186″N 112°08′44″W), Mexico, using acoustic telemetry and videos taken from 2014 to 2016. We report here movements from a coastal location (National Park Cabo Pulmo) to a group of oceanic islands (Revillagigedo Archipelago) by one single individual, supporting the idea of the potential connectivity of sharks between the Gulf of California and the Revillagigedo Archipelago. This report extends the known distribution of N. velox to 400 km off the mainland coast of the Americas, thereby increasing the knowledge of the distribution of a species commonly reported in fishery landings of the Eastern Pacific.

The visual survey is the most common method to quantify and characterize beach litter. However, it is very labor intensive and difficult to carry out on beaches which are remote or difficult to access. We suggest an alternative approach for assessing beach litter using an unmanned aerial vehicle (UAV), or aerial drone, with automated image requisition and processing. Litter of different sizes, colours, and materials were placed randomly on two beaches. Images of beaches with different substrates were obtained by the drone at different operating heights and light conditions and litter on the beaches was identified from the photos by untrained personnel. The quantification of beach litter using the drone was three times faster than that by visual census. This study has demonstrated the potential of using the drone as a cost-effective and an efficient sampling method in routine beach litter monitoring programs.

ARPA Puglia (Italy), the Regional Agency for the Environmental Prevention and Protection, has chosen to use the Scientific Diving Operator figure (ESD) in order to meet some of the environmental monitoring activities foreseen by European Directives, such as WFD-Water Framework Directive 2000/60/EC and the MSFD-Marine Strategy Framework Directive 2008/56/EC. Regarding the environmental monitoring obligations of the aforementioned Directives, many of them involve underwater operations. For example, both Directives (MSFD and WFD) require Posidonia oceanica monitoring in situ, by collecting data on shoot density and other eco-biometric parameters, also describing the main ecological aspect of seagrass meadows; about Pinna nobilis, the visual census of its distribution and abundance is carried out underwater; the non-indigenous species census provided by MSFD requires the qualitative and quantitative sampling of the benthic communities of hard bottoms in harbors performed by a scratching technique. All the described activities need operations by ESDs, so ARPA Puglia developed a path for the implementation of good practices on the subject: adopting the national Guide Lines "Good practices for the safe performance of the underwater activities” (ISPRA manual n. 94/2013; D.D.G. n.229/2016); identifying the diving equipment as Personal Protective Equipment (PPE); allowing the acquisition or renewal of ESD scientific license for the operational staff; allowing the annual medical check-up for the ESD operational staff; opening of a national call in order to acquire specialized figures, selected according to ESD Panel standards. Details of environmental monitoring activities carried out by ARPA Puglia ESDs are described in this document.

ResumenEl pepino café Isostichopus fuscus es una especie de alto valor comercial y en México está bajo protección federal. La pesquería se desarrolla en la península de Baja California, siguiendo reglas de manejo determinadas en Mesas Técnicas mediante acuerdos entre agencias de gobierno, científicos y pescadores organizados. Uno de ellos es que las evaluaciones de abundancia deben hacerse durante el día, cuando el pepino se oculta en oquedades, arrojando un valor inferior, pero no se ha comprobado. El objetivo del presente trabajo fue comparar la abundancia del pepino café en censos conducidos en transectos de 100×2 m, fijos al fondo y realizados durante el día y la noche del mismo día. Los resultados indican que hubo significativamente más pepinos observados en horas de oscuridad (promedio±error típico=3.714±0.075) que de luz (1.943±0.045), y que además es posible corregir la abundancia por transecto en el día con una ecuación lineal (pendiente=1.43; ordenada=1.18). La diferencia de cuota potencial calculada con los censos de día es aproximadamente un 15% menor a la que se obtendría en conteos nocturnos. Se concluye que la medida actual debe ser exitosa para un manejo precautorio del recurso.AbstractThe brown sea cucumber Isostichopus fuscus, is a holothurid with high commercial value. In Mexico it is federally protected, and the fishery in the Baja California Peninsula follows management actions established by technical committees, on the basis of agreements among government agencies, scientists and organized fishermen. One of these agreements is that evaluations of its abundance must be done during the day, as it has been suggested that during daylight hours the organisms hide inside holes, resulting on lower values, but this has not been demonstrated yet. Thus the objective of this study was to compare the abundance in census conducted inside fixed transects of 100 x 2 m, and surveyed at day and night of the same day. The results show that there were significantly more sea cucumbers seen during dark hours (mean±standard error 3.714±0.075) than during light time (1.943±0.045 per census); daylight estimated abundance can be corrected by a linear equation (slope=1.43; ordinate=1.18). Therefore, the quota estimated from censuses conducted during daylight is 15% lower than those that would be obtained at night. In conclusion, daylight censuses work as a precautionary management strategy of this species.

International audience; The multidisciplinary programme BioReCIE (Biodiversity, Resources and Conservation of coral reefs at Eparses Is.) inventoried multiple marine animal groups in order to provide information on the coral reef health of the Iles Eparses. All five classes of echinoderms were observed by visual census, photographed and later identified. About 100 species are reported, including a few unidentified ones which require further studies. The Holothuroidea and Ophiuroidea are the most diverse. One new species, the asterinid Aquilonastra chantalae O'Loughlin and McKenzie (2013), was discovered in addition to several new records of echinoderms. The illegal fishery targeting holothurians, which are presently highly valuable resources in this zone, is discussed.

Although underwater visual census (UVC) is the most frequently used technique for quantifying reef fish assemblages, remote video analysis has been gaining attention as a potential alternative. In the South Atlantic Ocean, Millepora spp. (class Hydrozoa) are the only branching coral species; however, little is known about the ecological role that they play for reef fish communities. We compared these two observation methods (remote video and UVC) to estimate reef fish abundance and species richness associated with colonies of the fire-coral Millepora alcicornis at Tamandare Reefs, Northeast Brazil. Additionally, the two different techniques were used to compare species behaviour in association with fire-corals in order to examine the biases associated with each technique and provide useful information for behavioural ecologists studying fish-coral associations. There were no differences in reef fish abundance or species richness sampled by remote video or UVC. However, a significant difference in the behaviour of associated fish was recorded between the two methods. In the presence of a diver carrying out a UVC, fish were observed spending more time sheltered amongst the coral branches compared with passively swimming on coral colonies with the remote video technique. Specifically, on the remote video recordings agonistic interactions between fish and passive swimming accounted for 33.3% and 22.2% of the census time, respectively. By comparison, when observed by a diver fish spent 34.8% of their time sheltering amongst the coral branches. We demonstrate that both techniques are similarly effective for recording fish abundance and species richness associated with fire-corals. However, differences were observed in the ability of each method to detect the behaviour of coral-associated fishes. Our findings show that behavioural ecologists studying complex fish-coral associations need to ensure that their aims are clearly defined and that they choose the most appropriate technique for their study in order to minimize methodological biases.

Los arrecifes rocosos proveen una alta diversidad de organismos. Se presentaron cambios en la estructura de la comunidad íctica a lo largo de la estación climática y la acción del oleaje. Este estudio evaluó la diversidad y la abundancia de los peces del arrecife rocoso La Viuda, Golfo Dulce, Costa Rica (8°37’33” N - 83°14’08” W). Los peces fueron estudiados con el método de Bohnsack y Bannerot comparando las estaciones seca y lluviosa, las zonas protegidas y expuestas al oleaje usando índices ecológicos. El total de especies fue 28, las familias más abundantes fueron Pomacentridae y Labridae. La diversidad de Shannon-Wiener resultó entre 1,1 y 1,73 nits/ind. El índice de Pielou en La Viuda fue 0.43. Se encontró mayor diversidad de especies en la época seca y en la zona protegida al oleaje.

The occurrence of the alien goby Vanderhorstia mertensi, off Akbük Cove, Anatolian coasts of Aegean Sea, is here well proven for the first time. On 12 Au- gust 2014, a single specimen was observed by visual census. This finding substantiate that its presence and also distribution is expanding northwards, along the Anatolian coasts of the Aegean Sea.

Reef fish utilize coral reef ecosystems as a place to live, foraging, spawning and nurturing. This study aims to determine the abundance of species, diversity and biomass of reef fish found in the waters of Ujong Pancu, Aceh Besar district. This research was conducted in October 2017, there were 5 research location. Data was collected using the Underwater Visual Census (UVC) method. The result show that the highest abundance of reef fish was found in waters of Lhok Mata Ie with a value of 5311.71 Ind/ ha. While the lowest abundance of reef fish was found in Tuan Island waters with a value of 896.67 Ind/ ha. Overall diversity of Ujong Pancu waters reefs is included in the medium-high category. The highest average biomass of reef fish is found in the water of East Batee Island with a value of 100.69 Kg/ ha. While the lowest average biomass of reef fish is found in the waters of West Batee Island with a biomass value 23.87 Kg/ ha. Keywords : Abundance, biomass, diversity, reef fish, Ujong Pancu

A spawning area of Lutjanus bohar, a marine fish of high economic value, is one of the eight important resources of Wakatobi and also a critical habitat in the waters of Hoga Island. For protecting the area, Wakatobi National Park has stated the area as a tourism zone (no-take zone). This research was conducted to evaluate progress toward spawning-area protection by examine number of individuals, length size of fish, and trespassing cases that occurred in the spawning area. Research was carried out in 2018-2019. Number of individuals and size of fish were collected by referring to the monitoring guidelines for the Spawning Aggregation Site (SPAGs), and observations with an Underwater Visual Census. Trespassing case data were collected by interview key persons. Descriptive analysis was used to describe progress toward spawning-area protection. The results indicate that the protection effort of spawning area has a positive impact in increasing number of individuals and length of Lutjanus bohar. However, number of trespassing cases in the waters of Hoga Island still shows an increase. Fishing activities are the most trespassing cases occurred in the spawning area. This approach should be implemented to evaluate the progress towards protection efforts, besides increasing the number of patrols and socialization with fishermen to increase their awareness.

Reef fishes is an important part in maintaining the balance of various components in the coral reef ecosystem. The existence of reef fish on coral reef ecosystems is a marker of the ecosystem in good condition. Furthermore, it is important to observe the condition of reef fish in a coral reef ecosystem to determine the population and diversity of reef fish in the ecosystem. Observation of reef fish generally by performing a manual visual census by scuba diver. In entering the industrial revolution 4.0 era there is a need to develop technology that is used to monitor the condition of reef fish in a coral reef ecosystem. The development of technology will certainly help researchers, and later on ecosystem manager, in observing the condition of reef fish with automatic identification. The technological development that can be done to observe reef fish is by applying deep learning. In this research we used YOLO deep learning algorithm for automatic identification. YOLO has the advantage of faster object detection. Application of deep learning to identify fish automatically is illustrated using underwater video recording of reef fish.

International audience; The present study highlights the importance of intertidal seagrass beds as nursery areas for coral reef fish juveniles along four sites (Mtsoubatsou, Sohoa, Boueni, Ngouja) on the western coast of Mayotte Island. The results collected by underwater visual census from November 2012 to January 2013 showed that mean total fish density between adults and juveniles varied significantly at each site, with juveniles always being more abundant in seagrass beds than adults. Of the total fish assemblages sampled in seagrass beds, 73% were juveniles and few adults of large species were observed. Overall, our study highlights the important functional role of intertidal seagrass beds for fish assemblages, as they are the primary habitat for the juveniles of many fish species on Mayotte reefs. Seagrass beds, however, are very vulnerable ecosystems and are decreasing worldwide. Therefore it is of primary importance to protect seagrass beds within the Indo-Pacific.

In this study gobiid fish species were investigated at 31 stations from the northeastern Aegean Sea. Different habitat types between 0 and 50 m depth were studied by scuba diving with newly modified underwater visual census with ranked prevalence using time-transect. Thirty-three species were determined as belonging to family Gobiidae. Distribution, abundance, and some ecological properties of the species were examined. Considering this, four of the observed species determined as very common, seven as common, ten as locally common, six as rare, and six as very rare in the area. Pseudaphya ferreri, Gammogobius steinitzi, and Corcyrogobius liechtensteini were determined for the first time for the area. Detailed morphological characters of some species are also given.

The use of natural areas for underwater coastal marine activities such as snorkelling is growing, but the amount of ecological and socioeconomic data on these activities is scarce and relates mainly to coral reef areas. Three underwater self-guided routes were designed at Marinha Beach (Algarve, Portugal), based on scientific information, with in situ interpretation and guidance, as a way to enhance biodiversity awareness and, hence, reduce the probability of human impacts. The routes were implemented in two consecutive summer seasons and after each season, visual census techniques were used to describe flora composition and cover area (seaweeds and seagrasses) in order to understand patterns and evaluate human impacts. Snorkelers' opinions and perceptions about several issues related to the routes' environmental education role (e.g. role in enhancing biocliversity awareness) were investigated by questionnaire after the snorkelling activity. An inter-annual difference inflora assemblages was found, probably associated to natural variability, rather than snorkelers' impacts. Results indicate that, in fact, in situ education and interpretation can raise environmental awareness if properly addressed, resulting in a satisfactory way of engaging snorkelers in the protection and in the conservation of the visited environments, thereby preventing negative ecological impacts. (C) 2015 Elsevier Ltd. All rights reserved.

Counting animals, from direct observation or from video or photo records, is one of the most common methods to estimate population density, used for aquatic, terrestrial and flying animals. However, numerous studies caution that the counts derived from visual census may be biased to different degrees depending on animal mobility and survey procedure. This methodological inconsistency hampers the comparison of counts of animals with different mobility or obtained by static and moving observers. In the present work, we provide a generic equation describing the visual census process in relation to animal mobility and survey procedure. Counts are converted into absolute density estimates (as individuals per area) depending on sampling area, animal speed, observer speed, visual sampling field and observation time. The equation offers a mechanistic basis for facilitating the standardization of counts of animals with different levels of mobility or resulting from divergent visual census techniques.

Summary Accuracy and precision are of great importance in the assessment of reef fish biomass when conducting an underwater visual census (UVC). Quantification and subsequent correction of the bias is required in order to standardize the estimates and correct for underwater distortion. To optimize the UVC, the observer should receive length-measurement training in order to obtain in situ-measurements that are as accurate and precise as possible. The objective of this study was to quantify the bias of fish length measurements made by divers with and without training in order to enhance reef fish biomass estimates. Adaptation of the diver to estimate fish lengths was analysed as a part of reef fish biomass monitoring in the Karimunjawa National Park, a national marine sanctuary in the Java Sea, Indonesia. Two divers practiced estimating a variety of fish in a natural environment by using styrofoam models attached to strings and sinkers. Analyses showed that by training the diver, his/her accuracy and precision improved substantially. Proving its reliability, an underwater visual census (UVC) becomes a useful and reliable method to assess the biomass of reef fishes.

12 pages, 5 figures, 5 tables, 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

ResumenEn este estudio se describe la composición y estructura de las comunidades de peces de las bahías Maguey y Cacaluta. La caracterización de la ictiofauna se realizó a través de censos visuales por transectos, los cuales se efectuaron en febrero, abril y julio de 2004. En ambas localidades se censaron 2 874 individuos, pertenecientes a 42 especies. Las familias mejor representadas fueron Pomacentridae y Labridae. Thalassoma lucasanum, Chromis atrilobata, Stegastes acapulcoensis y Microspathodon dorsalis fueron las especies dominantes. La composición, riqueza de especies, abundancia, diversidad y dominancia presentó una marcada diferenciación espacial, lo que permitió distinguir 3 componentes ícticos en cada localidad: el componente arenoso, rocoso y coralino. El componente coralino se caracterizó por registrar la mayor riqueza de especies, abundancia y diversidad, lo cual es resultado de la alta complejidad estructural de los ambientes que lo integraron. El componente arenoso se caracterizó por presentar la mayor dominancia. La mayor abundancia se registró en la época de secas, determinada principalmente por el incremento en la abundancia de C. atrilobata y T. lucasanum. La mayor riqueza de especies y diversidad se presentaron en la época de lluvias, probablemente como resultado de las altas temperaturas y alta producción de los procesos costeros regionales.AbstractThis study describes the composition and structure of the fish communities in Maguey and Cacaluta Bays. Ichthyofauna was characterized using transect visual census in February, April and July of 2004. A census was taken in both localities of 2 874 individuals belonging to 42 species. Pomacentridae and Labridae were the families that were most represented. Thalassoma lucasanum, Chromis atrilobata, Stegastes acapulcoensis and Microspathodon dorsalis were the dominant species. Composition, species richness, abundance, diversity and dominance presented notable spatial differentiation, making it possible to distinguish 3 ictic components in each locality: sandy, rocky and coralline. The coralline component registered the greatest species richness, abundance and diversity due to the high structural complexity of its environment. The sandy component presented the greatest dominance. The dry seasons presented the greatest abundance, primarily determined by the increase in the abundance of C. atrilobata and T. lucasanum. The greatest species richness and diversity was present during rainy seasons, likely due to high temperatures and high production associated with regional coastal processes.

Spatiotemporal patterns of distribution of sea bass, Dicentrarchus labrax, and sea bream, Sparus aurata, and their influence on artisanal fisheries are explored before and after an escape event that released 1.5 million fish into the wild off La Palma (Canary Islands). Data were collected by in situ visual census and first sale data as a proxy of artisanal fisheries landings. Permutational anova of escapee abundances in shallow coastal habitats revealed consistent spatial patterns that linked densities of these fish to distance from escape point, whereas temporal patterns were related to a higher biomass released during winter. A nearby marine protected area did not show different densities of escaped fish. Local artisanal fleet catches accurately reflected the massive escape event and offer the main contingency force to mitigate the potential negative effects of massive escape events over shallow coastal habitats. KT was funded by a PhD fellowship from the Canary Island Government, cofinanced by the European Union (FEDER).

From April to June Atlantic bluefin tuna, Thunnus thynnus, migrate along the western Sardinian coastline in a southward direction, where they are intercepted by the trap fishery. Fishermen claim that Mistral episodes facilitate the entry of tuna schools towards the traps, thus increasing capture rates. To test the fishermen’s hypothesis we conducted underwater visual counts of tuna in the trap chambers and analysed these data under the effect of wind. The results indicate a “stair-step” pattern in the abundance of tuna, demonstrating that major increases in abundance are associated with the Mistral. The second analytical approach involved a longer time scale to test whether higher Mistral occurrences corresponded to periods when higher captures were recorded. Using a linear regression model we found a significant correlation (p < 0.01) between catches and the wind speed class ≤ 15 knots. We hypothesize that the wind-driven current may produce favourable conditions for tuna migration and could play a significant role in enabling fish to save energy. It was also noted that the wind speed class > 15 knots seemed to have a negative effect on captures. This pattern may be caused by wind-induced advection of coastal waters generating a physical boundary that may have had a deterrent effect on tuna schools. Entre abril y junio, el atún rojo (Thunnus thynnus) emigra a lo largo de la costa oeste de Cerdeña en dirección suroeste, donde es interceptado por las almadrabas locales. Los pescadores afirman que los fuertes vientos del Noroeste (Mistral) facilitan la entrada de los bancos hacia las almadrabas incrementando las capturas. Para verificar la hipótesis de los pescadores se han contado los ejemplares de atún mediante observaciones subacuáticas y se han puesto en relación a los datos de viento recogidos en la zona. Los resultados muestran un modelo de incremento “escalonado” de abundancia en la almadraba, cuyos valores más altos corresponden a los vientos más fuertes. Para probar si los años con mayor número de días con vientos del NO se corresponden con mayor número de capturas, hemos hecho un segundo enfoque del análisis que utiliza una escala de tiempo más amplia. Mediante un modelo de regresión lineal encontramos una correlación positiva significativa (p < 0.01) entre las capturas y la clase de vientos ≤15 nudos. Sin embargo, la clase de vientos > 15 nudos parece tener un efecto negativo en las capturas. Una posible explicación que encontramos es que la advección de aguas costeras, provocada por el viento, genera una barrera física en el área de la almadraba, manteniendo los bancos alejados.

International audience; Movement patterns of some coral reef fishes change with natural cycles (e.g., tidal, lunar and seasonal), resulting in short-term shifts in fish assemblages. We reviewed the literature on temporal changes in coral reef fish assemblages derived from underwater visual census (UVC) and found that movement was rarely considered in experimental design and analysis or as cause of change in interpretation of the results. Studies of vagile species, large individuals, species forming transient spawning aggregations and studies of fishes in contiguous habitats are most likely to be affected by such movements. Ignoring predictable patterns of movement associated with such natural cycles in survey design and analysis increases “unexplained” variation, making it more difficult to detect longer-term changes in fish assemblages and reducing the effectiveness of UVC as a monitoring tool.

WOS: 000323076900003, Fish farm structures attract a variety of fish species by providing solid structure, and 'free meals' in the form of uneaten feed and feces that fall from the cages. In this study, we compared the composition and abundances of wild fish populations around 2 fish farms in the Red Sea and at nearby reference locations. Fish assemblages were evaluated by SCUBA divers carrying out rapid visual censuses in August, September and October 2007. A total of 87 238 fishes, representing 39 species and 25 families and a number of trophic levels, were observed. Overall, the abundance, biomass, and diversity of wild fish were much greater at the sea cages than at the open-water reference sites, at both fish farms. It is noteworthy that 35 out of the 39 species observed at the farms were juveniles and adults of coral-reef fish species. This finding is especially interesting, considering that the nearest coral reefs were >4 km away and reef fishes generally have small home ranges, typically, TUBITAK_BIDEB programTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK), We are grateful to Steve Breitstein, Amir Yurman, Omer Polak, Nadav Shashar, Dan Tchernov, and other colleagues and students of the Inter University Institute (IUI) in Eilat for providing access to their laboratories. We also thank the staff of Ardag and Dagsuf farms for their assistance both underwater and above. This study was supported by the TUBITAK_BIDEB program.

Exploratory field surveys were carried out in 2009 to estimate the population size of three troglobitic (Aegla microphthalma from Santana Cave, A. cavernicola from Areias de Baixo Cave and A. leptochela from Paiva Cave) and one troglophile aeglid species (A. marginata from Paiva Cave and Barra Bonita Cave) from the karst region of the Alto Ribeira by means of visual census (all caves) and markrecapture technique (Paiva Cave only). Results were compared with previous population size data obtained in 1994 for the same species and respective localities. A. marginata was no longer found at the Barra Bonita Cave and no A. microphthalma specimens were eye-spotted at the Santana Cave. Thirteen specimens of A. cavernicola were found at the Areias de Baixo Cave. Only Paiva Cave provided enough number of individuals of the co-existing aeglids A. leptochela and A. marginata produced significant population size estimates, which indicated a sharp decline of the cave dwelling population size of both species as compared to previous data

Underwater visual census (UVC) is one of the more frequently used methods for monitoring of subtidal fish communities. However, population estimates from UVC are plagued by numerous biases that ultimately reduce the diagnostic power of the data. Adaptations to methods that account for detection errors by employing multiple observers can reduce many of these biases, but have received little consideration in past marine research. In the terrestrial environment the double-observer method has been successfully applied to estimate visibility bias, observer bias and detection probabilities. We used an independent double-observer method to measure the influence of observer type (volunteers and researchers) and fish community structure on the detection probability and count dissimilarity between two observers simultaneously surveying the same transect. Community data collected by volunteers were of a consistently lower quality than that collected by researchers. However, this was not the case for the dominant species for which researchers and volunteers produced similar data. The analysis further suggested that rare species contributed disproportionately to the bias in UVC data because the abundance of a species within a survey area determined its detection probability. Our results highlight the need to account for detection probability during UVC and it is recommended that future research based on UVC integrates an independent double-observer approach. Furthermore, the results indicate that care needs to be taken when designing monitoring programmes as allowing inexperienced volunteers to participate can undermine the integrity of the data.

The shoemaker spinefoot Siganus sutor is a fast-growing, short-lived, gonochorist and herbivorous reef fish that forms transient fish spawning aggregations (FSAs). In the Seychelles, FSAs of this species occur monthly between September and June around the full moon. To study the spawning aggregation dynamics of S. sutor, 39 reproductively active individuals were acoustically tagged and monitored at 3 known FSA sites (Pate Polite, Pate Desire and Pate Dividi) off the west coast of Praslin island (Seychelles) between October 2010 and April 2011. The presence and absence of tagged fish at the 3 sites were monitored using moored arrays of passive acoustic receivers, while the density of fish at the FSAs was quantified using underwater visual census (UVC). Most tagged fish (87.0%) detected in more than 1 spawning period showed fidelity to single spawning sites. Predominantly, tagged individuals arrived at FSA sites at dawn and departed at dusk. Spawning residency times at FSA sites ranged from 0.02 to 16.1 d. At Pate Polite, residency times were higher in the first half of the spawning season. Residency times were often several-fold shorter than aggregation duration which, when combined with patterns in arrival and departure times, indicates high turnover of fish within aggregations. The findings of this study provide information needed for emerging co-management schemes that aim to sustain this socio-economically important fishery.

Sagori island waters is rich of coral reef and reef fish with high economic value. It’s has also been designated as a general use zone by the government. In the other side, the needs of consumption is increasing by the growth of people in the Island and neighbours as well. Those condition, presumed as the main factor for fisherman to increase their effort in catching the reef fishes, in any possible way. However, Visual Census technique (VCT) shows that that the number of reef fish was spread evenly on a coral reef condition is still good enough, but are not in a reverse condition. That is then presumed as the static production value of coral reef ecosystem (SPV). The economic value of coral reefs per hectare in Sagori Islands is shown based on Present Value Generated per Hectare (PV) which state that people in Sagori Island has just use about 56.99% of the resources. By cash flow analysis within projected to 10 years ahead, this fisheries business unit shows that it is still good to be performed.

Methods for monitoring the status of marine communities are increasingly adopting the use of images captured in the field. However, it is not always clear how data collected from photographic images relate to historic data collected using traditional underwater visual census methods. Here, we compare coral health and disease data collected in situ by scuba divers with photographic images collected simultaneously at 12 coral reef sites. Five globally relevant coral diseases were detected on 194 colonies from in situ surveys and 79 colonies from photos, whilst 698 colonies from in situ surveys and 535 colonies from photos exhibited signs of compromised health other than disease. Comparisons of in situ surveys with photographic analyses indicated that the number of disease cases occurring in the examined coral populations (prevalence) was six times higher (4.5 vs. 0.8% of colonies), whilst compromised health was three times higher (14 vs. 4% of colonies) from in situ surveys. Skeletal eroding band disease, sponge overgrowth and presence of Waminoa flatworms were not detected in photographs, though they were identified in situ. Estimates of black band disease and abnormally pigmented coral tissues were similar between the two methods. Estimates of the bleached and healthy colonies were also similar between methods and photographic analyses were a strong predictor of bleached (r 2 = 0.8) and healthy (r 2 = 0.5) colony prevalence from in situ surveys. Moreover, when data on disease and compromised health states resulting in white or pale coral colony appearance were pooled, the prevalence of ‘white’ colonies from in situ (14%) and photographic analyses (11%) were statistically similar. Our results indicate that information on coral disease and health collected by in situ surveys and photographic analyses are not directly comparable, with in situ surveys generally providing higher estimates of prevalence and greater ability to identify some diseases and compromised states. Careful sampling of photographs can however identify signs of coral stress, including some coral diseases, which may be used to trigger early-warning management interventions.

Floating litter in the estuarine system of Santos-Sao 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.

An advanced and accurate census methodology that fuses acoustic and visual census of the freshwater dolphins has been successfully introduced for the Ganges river dolphins that inhabit and migrate in a long tract of the Ganges river system. In order to conduct an accurate census of the dolphins, an acoustic array system with provision to display the dolphin's real-time direction data on a GUI (Graphical User Interface), i.e. the RAPID-Array (Real-time Acoustic Passive In-situ Dolphin tracking Array) was developed in 2014. Targeting 10–13 Ganges river dolphins (adults, juveniles and calves) that were estimated to inhabit a 7-km stretch, i.e. a part of the entire 200km riverstretch from Bhitora to Allahabad in India, using the array, the initial census using fusion of acoustic and visual census was conducted for one day on 24 November 2015. Based on the data acquired during the census, an estimate of the number of the dolphins was quickly made at the site. The effectiveness of the proposed method was demonstrated for carrying out the census in a long tract of the entire habitat.

Fishes and macroinvertebrates associated to two types of articial habitats deployed in Taganga Bay were assessed by stationary visual census to compare these assemblages. Forty-one species of shes and nine macroinvertebrates were observed in eleven visual censuses. The distribution patterns depicted in abundance and richness between the two types of habitats used (concrete blocks vs. articial shelters), were a possible response to dissimilarities in their location and number of visual census. A relative high sh richness and diversity were found in these articial habitats, in comparison to other articial structures in Colombia, probably owing to their proximity with heterogeneous natural habitats. The use of complex articial habitats could have potential useful to conserve, restore and manage some marine resources supported in planned researches in this area.

The fish species endemic to Malpelo Island have been scarcely studied, resulting in a lack of information on their densities and habitat preferences. The distribution and abundance of the endemic reef fish species of Malpelo were estimated using underwater visual census techniques. The most abundant species were Axoclinus rubinoffi (0.18 fish/m²) and Lepidonectes bimaculatus (0.08 fish/m²). The highest abundance was found in rocks covered by coralline algae in the Bajo de Junior site. Las especies de peces endémicos de la isla Malpelo han sido poco estudiadas, al punto que no se cuenta con información sobre sus densidades y preferencias de hábitat. Mediante censos visuales se estudió la distribución y abundancia de las especies de peces arrecifales endémicos de Malpelo. Las especies más abundantes fueron Axoclinus rubinoffi (0.18 peces/m²) y Lepidonectes bimaculatus (0.08 peces/m²). La mayor abundancia se encontró en el Bajo de Junior y en relación con sustrato rocoso cubierto con algas coralináceas incrustantes.

Annual spawning aggregations of red hind Epinephelus guttatus form at predictable times and locations and have historically succumbed to overfishing. Monitoring the status and res- toration of aggregations is essential for evaluating the effectiveness of fishery management meas- ures. Passive acoustic and diver-based underwater visual census (UVC) techniques were used to develop an efficient method for estimating red hind density from sound production at spawning aggregations. Red hind sound production was recorded from November 2010 to April 2011 at Abrir la Sierra, Puerto Rico. UVC surveys were conducted during the spawning season to assess changes in red hind density over a fixed time and area. Sound recorded from 18:00 to 19:00 h Atlantic Standard Time (UTC � 4) was representative of total daily changes in red hind sound pro- duction and was selected for the development of an efficient density estimation model. Pro- nounced daily changes in sound production and density were observed after the December 2010 and January 2011 full moons. Two hourly sound level measurements were compared to densities estimated by UVC surveys, yielding significant linear regressions, which were used to predict changes in fish density as measured at the aggregation site. Passive acoustic methods allowed to predict changes in red hind density and habitat use at a higher temporal resolution than previ- ously possible with traditional methods. Red hind sound production and inferred densities can be monitored and analyzed efficiently for multiple aggregation sites simultaneously, documenting short-term and long-term changes in red hind densities at spawning aggregation sites and provid- ing important information for the support or development of management strategies.