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This study aims at assessing the reserve effect on fish assemblage in a small urban fully protected and highly enforced Marine Protected Area (MPA), Larvotto MPA (Monaco, Mediterranean Sea). The data about fish density, size, and biomass was collected by underwater visual census in the MPA and unprotected areas in two habitats, artificial rocky substrates and Posidonia oceanica meadows. On artificial rocky substrates, we recorded significantly higher fish biomass within the MPA compared to unprotected areas, while no significant difference was detected on Posidonia , with this suggesting the habitat-specific responses of fish assemblages to protection. Here we highlight the potential effectiveness of highly enforced small-sized urban MPAs, such as the Larvotto MPA, in generating ecological benefits, and speculate about their potential role in supporting networks of MPAs. This study supports increased attention to urban MPAs in conservation efforts, emphasizing the need for efficient management strategies in the face of ongoing coastal expansion. [ABSTRACT FROM AUTHOR]

We report for the first time in Italian waters a periodic and frequent presence of a summer aggregation of common eagle ray Myliobatis aquila in the island of Marettimo (southwestern Tyrrhenian Sea), which is part of the Marine Protected Area of the Egadi Islands. These aggregation could be related to different phenomena such as reproduction, feeding or simply as a transit zone.

In Mediterranean, the exploitation and exportation of holothurians as food is increasing during the last 25 years, with Turkey and Greece as leading countries. In Greece, the fishery is expanding by the development of two métiers; however, official monitoring is missing, creating concerns on the future viability of the industry. To evaluate the status and future perspectives of holothurian fisheries, an extensive field survey has been completed (May 2019–July 2021) covering 162 sites dispersed in the Hellenic Seas. Field data included the assessment of the abundance of holothurians (via 100 m transect replicates), and catch per unit of effort (CNPUE and CBPUE, based on 10-min commercial fishing practices). H. tubulosa, H. poli, H. mammata and H. sanctori were fished in 41.35% of the surveyed stations. H. poli (CNPUE 168 specimens, CBPUE 22.24 kg) and H. tubulosa (CNPUE 127 specimens, CBPUE14.51 kg) were the most common species, forming locally dense populations. Mean annual catch was 275 metric tons (2016–2021) according to the processing of the units' data; 62% of the production was made by H. tubulosa and 38% by H. poli. Our results suggest the existence of exploitable grounds in the north Aegean, the central Cyclades, and the north Dodecanese, according to the prevalent environmental conditions (organic load) and fishing pressure. [ABSTRACT FROM AUTHOR]

Simple Summary: The presence of batoids in Gran Canaria, Canary Islands, Spain, in the Mid-Eastern Atlantic Ocean, is quite common depending on the species and time of year. For that reason, we examined the behaviour of spiny butterfly rays (Gymnura altavela) in the shallow waters of Gran Canaria, where the species' affinity to certain beaches was analysed according to the time of year and preference for the type of ocean environment. Such knowledge is important given the lack of information available on the species that is nevertheless vital for its sufficient management and conservation. 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. [ABSTRACT FROM AUTHOR]

Fish aggregating devices (FADs) are used worldwide to attract fish. Previous studies revealed that FADs affect the distribution and dispersal patterns of juvenile fish species during their life stage under floating objects. In this study, we hypothesised that a system of FADs arranged along an inshore–offshore gradient could favour the approach of young fish associated with FADs towards coastal habitats, using individual FADs as stepping stones. Our findings suggest that FAD systems might exert two different effects on juvenile fish distribution: (a) offshore FADs tend to retain associated fish for longer periods of time compared with coastal FADs, (b) coastal FADs favour the transition of fishes from the pelagic to the benthic domain. Furthermore, in order to obtain more information on the dynamic and movement patterns of the young-of-the-year (YOY) Seriola dumerili and Caranx crysos associated with FADs, tagging experiments and underwater visual censuses were conducted. The two juvenile species tagged and released under FADs placed at different distances from the coast showed different movement patterns. S. dumerili exhibited low FAD fidelity and large movements, while C. crysos showed high fidelity to the site. The results of the two research approaches confirm that FADs affect the dispersal of species toward the coast and their correct use could help to improve the sustainable management of these coastal fish resources. [ABSTRACT FROM AUTHOR]

The study compares two methods (i.e., quadrants and distances) for estimation of population density in O. gaudichaudii. On the beach "Los Ranchos", 13 transects were established and eight in "Las Bocas"; in addition, a visual census was carried out on each beach. In the analyses Los Ranchos was considered as an area and as two subdivisions (Los Ranchos-1, 2). The results showed that, the sampling by quadrants was more precise in Los Ranchos- 2 (6% of bias) and Las Bocas (4% of bias) while, the distance sampling was more accurate in Los Ranchos beach (32% of bias) and Los Ranchos-1 (29% of bias). In beaches with high densities (> 0,5 ind./m2) the method by quadrants should be selected and on beaches with low densities (< 0,5 ind./m2) the method by distances is recommended. [ABSTRACT FROM AUTHOR]

The genus Smeagol consists of five named species of air-breathing marine slugs (restricted to southern Australia and New Zealand) and three undescribed taxa from southern Japan. Only one species, S. hilaris, is known to be from New South Wales (NSW), and it previously had a known distribution limited to one site, Merry Beach on the south coast. This diminutive invertebrate is classified as critically endangered in NSW due to its extremely restricted distribution and concern about its historically declining numbers. Accordingly, the aims of this study were to survey the known population of S. hilaris at Merry Beach and to explore other potentially suitable sites, using a visual census method, to determine if further populations or species exist in NSW. The resulting quantitative surveys of the known population and a new population at Storm Bay, Kiama, NSW, are reported here. DNA barcoding of a ~650 bp segment of the mitochondrial cytochrome c oxidase I (COI) gene for several individuals from each population confirmed the conspecificity among the two populations. The population at Merry Beach was found to remain viable, while the discovery of the new population of S. hilaris represents a doubling of the known global populations of this species. Details of the highly-specialised niche habitat occupied by Smeagol in New South Wales and recommendations for ongoing management are documented. [ABSTRACT FROM AUTHOR]

The abundance and movement patterns of lemon sharks (Negaprion brevirostris) at Lama Bay, Biological Reserve Rocas Atoll, were reassessed by visual census. We considered tides and daylight periods to plan our observations during two expeditions in 2015. Using daily visual counts, the mean abundance of individuals was 29 in austral summer (maximum 35) and 31 in winter (maximum 41). The results indicated that the local lemon shark population might have recovered after 18 years of a substantial drop in mean abundance. In addition, the movement pattern of the species corroborated previous studies related to their fidelity to the birthplace. These results justify the need of continuous monitoring of lemon sharks over the course of time at Rocas Atoll using non-lethal and non-invasive techniques. [ABSTRACT FROM AUTHOR]

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]

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. [ABSTRACT FROM AUTHOR]

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.

Although more than 600 marine caves have been recorded so far along the Greek coasts of the Aegean Sea (Eastern Mediterranean), only a few have been systematically studied for their biodiversity. In this study, the benthic communities of six marine caves within a Protected Area of South-Eastern Aegean were studied for the first time, both qualitatively and quantitatively. The association of different geomorphological and topographical factors of the caves with the benthic community structure was investigated. A total of 120 photographic quadrats covering the entrance and semi-dark cave zones were analysed, with regard to coverage and taxon abundance, while motile taxa were qualitatively recorded by visual census. The ecological quality status of the caves was also assessed under an ecosystem-based approach. In total, 81 sessile and 45 motile taxa were recorded, including 12 protected and 10 non-indigenous species. Multivariate community analysis demonstrated that the geomorphological and topographical variables of the caves are significantly associated with the observed biotic patterns. The ecological quality of the caves was assessed as poor or moderate according to the CavEBQI index, highlighting the necessity for systematic monitoring. This study paves the way for similar studies in marine cave habitats aiming at the development of management and conservation actions. [ABSTRACT FROM AUTHOR]

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, spanning 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Fish aggregating devices (FADs) are used worldwide to attract fish. Previous studies revealed that FADs affect the distribution and dispersal patterns of juvenile fish species during their life stage under floating objects. In this study, we hypothesised that a system of FADs arranged along an inshore–offshore gradient could favour the approach of young fish associated with FADs towards coastal habitats, using individual FADs as stepping stones. Our findings suggest that FAD systems might exert two different effects on juvenile fish distribution: (a) offshore FADs tend to retain associated fish for longer periods of time compared with coastal FADs, (b) coastal FADs favour the transition of fishes from the pelagic to the benthic domain. Furthermore, in order to obtain more information on the dynamic and movement patterns of the young-of-the-year (YOY) Seriola dumerili and Caranx crysos associated with FADs, tagging experiments and underwater visual censuses were conducted. The two juvenile species tagged and released under FADs placed at different distances from the coast showed different movement patterns. S. dumerili exhibited low FAD fidelity and large movements, while C. crysos showed high fidelity to the site. The results of the two research approaches confirm that FADs affect the dispersal of species toward the coast and their correct use could help to improve the sustainable management of these coastal fish resources.

The genus Smeagol consists of five named species of air-breathing marine slugs (restricted to southern Australia and New Zealand) and three undescribed taxa from southern Japan. Only one species, S. hilaris, is known to be from New South Wales (NSW), and it previously had a known distribution limited to one site, Merry Beach on the south coast. This diminutive invertebrate is classified as critically endangered in NSW due to its extremely restricted distribution and concern about its historically declining numbers. Accordingly, the aims of this study were to survey the known population of S. hilaris at Merry Beach and to explore other potentially suitable sites, using a visual census method, to determine if further populations or species exist in NSW. The resulting quantitative surveys of the known population and a new population at Storm Bay, Kiama, NSW, are reported here. DNA barcoding of a ~650 bp segment of the mitochondrial cytochrome c oxidase I (COI) gene for several individuals from each population confirmed the conspecificity among the two populations. The population at Merry Beach was found to remain viable, while the discovery of the new population of S. hilaris represents a doubling of the known global populations of this species. Details of the highly-specialised niche habitat occupied by Smeagol in New South Wales and recommendations for ongoing management are documented.

In this study, loggerhead sea turtle Caretta caretta (Linnaeus 1758) was observed for the first time around the shipwreck of coast guard boat in Ördek Yalağı located at Gökceada Island, North Aegean Sea. The shipwreck is at a depth of 24.8 m. The loggerhead sea turtle Caretta caretta was recorded exactly on the ground and 2 m away from the ship on the shore side of the ship. In this study, Caretta caretta was recorded for the first time in this water depth and around a shipwreck that was used as an artificial reef for Turkish waters.

Although more than 600 marine caves have been recorded so far along the Greek coasts of the Aegean Sea (Eastern Mediterranean), only a few have been systematically studied for their biodiversity. In this study, the benthic communities of six marine caves within a Protected Area of South-Eastern Aegean were studied for the first time, both qualitatively and quantitatively. The association of different geomorphological and topographical factors of the caves with the benthic community structure was investigated. A total of 120 photographic quadrats covering the entrance and semi-dark cave zones were analysed, with regard to coverage and taxon abundance, while motile taxa were qualitatively recorded by visual census. The ecological quality status of the caves was also assessed under an ecosystem-based approach. In total, 81 sessile and 45 motile taxa were recorded, including 12 protected and 10 non-indigenous species. Multivariate community analysis demonstrated that the geomorphological and topographical variables of the caves are significantly associated with the observed biotic patterns. The ecological quality of the caves was assessed as poor or moderate according to the CavEBQI index, highlighting the necessity for systematic monitoring. This study paves the way for similar studies in marine cave habitats aiming at the development of management and conservation actions.

It is widely documented that reef fish populations are declining on a global scale as a result of habitat loss and degradation, pollution, over fishing, and lack of management and enforcement. Efforts to document fish assemblages are being conducted around the globe to determine the current state of reefs and identify the anthropogenic factors that affect reef health. Numerous academic, government, and non-government institutions incorporate a variety of visual census methods into their monitoring programs. Methods vary depending on multiple factors including the research question being asked, the species’ ecology, spatial distribution of species of interest, environment being studied, and the suitability of the method to the research program. As such, the results obtained from each method are oftentimes incomparable due to the spatial and temporal scales adopted by each method. Though a wide variety of methods are currently being used, three methods seem to be the most prevalent within the research community to survey reef fishes: the belt transect, stationary point count, and timed visual assessment methods. The purpose of this project was to provide the research community with a holistic view of the work that was being done around the world, and to gather their opinions on the topic of standardizing methodologies. The project was also aimed to act as a catalyst to build momentum and generate discussion among the research community towards a solution to this issue

We determined the composition of ichthyofauna of the bays of Huatulco National Park using the the visual census technique for 351 ten-meter-long transects between January 2009 and December 2010. Eighty-nine species belonging to 69 genera and 42 families were identified. The most frequently represented families, according to numbers of species, were Pomacentridae, Labridae and Carangidae, and the most numerous genera were Haemulon, Halichoeres and Scarus. Acanthurus triostegus, Bothus constellathus, Chaetodipterus zonatus, Hemicaranx leucurus, Microlepidotus brevipinnis and Xenichthys xanti were recently recorded for the first time in the study area. The presence of Chaenomugil proboscideus, Narcine entemedor and Pseudobatos leucorhynchus in the Huatulco Bays is confirmed. The fish community in the Huatulco Bays was most similar to those in Panama and Costa Rica. Data published through GBIF (doi:10.15470/eb4hrm).

In this work, we present first data on biological and ecological aspects of Gobius incognitus from specimens from the Ionian Sea (central Mediterranean Sea). In particular, we provided first data on habitat preference, diet and length-weight relationship of G. incognitus on material with confirmed species identity. The species preferred "mixed bottom" (sand and rocks), where it reached relatively high abundances. The diet analysis showed that G. incognitus is a generalist and opportunistic feeder. However, small benthic crustaceans were the most important prey group. The mean total length of specimens was 6.72 ± 1.85 cm and the growth was positive allometric. [ABSTRACT FROM AUTHOR]

Coastal fishes are not only valuable elements of marine biodiversity, but they also play an important ecological role in the functioning of coastal ecosystems: food resource, transfer of nutrients, predators. Therefore, data on the compositions of fish assemblages are of great importance. The objectives of the present study were to (i) define the faunistic characteristics of a typical fish community on the Mediterranean coast; (ii) investigate spatiotemporal changes in fish assemblages. Based on a set of indices (Fast protocol) and a long-term data set (6 years, 612 visual counts, 154 h of diving), changes in coastal fish communities were analyzed. Our results indicated that there was a significant shift in fish community structure, with a general decline of the calculated indices. In our study, part of the observed variability in fish assemblage structure could be due to different factors as site location and sampled year. The changes in the fish assemblages associated with inter-annual fluctuations observed in this study also provide important insights into how fish communities may change under environmental and anthropogenic influences.

Coralligenous habitat is considered as one of the most important special habitat types in the Mediterranean; however, due to its inaccessibility, little is known about it, although it is considered as one of the Mediterranean’s richest habitats in terms of species. Due to a low number of studies, it was presumed that the richness of coralligenous fish assemblages is underestimated using traditional visual census methods which are not applicable to the deep, steep, and vertical slopes of coralligenous cliffs and do not capture exhaustively cryptobenthic species commonly found in this habitat. This paper aims at producing a more complete assessment of fish assemblages on a coralligenous cliff by combining different methods, particularly the deep vertical transect visual census and square with anesthetics method. A total of 76 fish species were recorded on a single coralligenous cliff, supporting the opinion that coralligenous cliffs are important Mediterranean biodiversity hotspots. The analysis of species traits between species recorded by the different methods showed how complementary they are to better describe species compositions. Hence, the result of this study demonstrates that the combined use of methods is essential for a more exhaustive description of the whole fish community structure and for accurate estimates of the abundance and diversity patterns, particularly in complex habitats such as coralligenous cliffs.

Data on the distribution and ecology of cryptobenthic fish of marine caves in the Mediterranean Sea are extremely scarce but necessary for scientists and marine managers alike in order to understand these fish’s ecological role and assess their conservation status. Broadscale surveys by implementing underwater visual census and photographic sampling in marine caves of the northeastern Mediterranean Sea, within different expeditions during the last 5 years, brought to light new records of eight rarely reported cryptobenthic fish species. To a smaller extent, complementary citizen science data from diving professionals of Crete were used to fill distribution gaps. A total of 36 new records (66 individuals) from 18 marine caves and caverns of the Aegean and northeastern Levantine Seas were assembled, belonging to the gobies Corcyrogobius liechtensteini, Didogobius splechtnai, Gammogobius steinitzi, and Thorogobius ephippiatus, the blenny Microlipophrys nigriceps, the tripterygiid Tripterygion melanurum, the speleophilic bythitid Grammonus ater, and the gobiesocid Lepadogaster cf. lepadogaster. The above species have been rarely reported from the Eastern Mediterranean Sea, with D. splechtnai and G. steinitzi being recorded for the first and second time from Greek waters, respectively, while L. cf. lepadogaster constitutes the second record of a clingfish species in a marine cave of the Aegean Sea. Interesting behavioral and ecological habits were also noted for some species, based on in situ observations and photographic evidence. Our study contributes to filling gaps in the knowledge of cave fish diversity and demonstrates that cryptobenthic mobile species in understudied cryptic habitats are more common than previously thought in the Mediterranean Sea.

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]

The efficacy of a Mediterranean Marine Protected Area (National Marine Park of Zakynthos – NMPZ, Ionian Sea, Greece) that implements a seasonal no-take zone as part of its management scheme was assessed using fish data collected in situ with underwater visual census. Sampling was conducted at two habitat types ( Posidonia oceanica meadows and rocky reefs) that occur at sites of different protection level with respect to fisheries (high protection: seasonal no-take zone within the MPA; intermediate: zones within the MPA where small-scale fishing is allowed; none: areas outside the MPA, where all types of fishing are allowed, including trawlers, purse seiners, and recreational fishing). The data were used to examine the effects of protection level and habitat type on community parameters, trophic structure and functional diversity of fish populations that occupy the upper sublittoral zone. Overall, habitat type had a more pronounced effect than protection level on all investigated parameters. Biomass, density and number of fish species with low commercial value were higher in sites of intermediate protection, but no substantial fisheries-related ecological benefits were detected for targeted fish in the seasonal no-take zone. Conducted 8 years after the initial implementation of the seasonal no-take management scheme, our study suggests that existing fishing regulations in the NMPZ provide some measurable effects, but fall short of maintaining sufficient protection for the recovery of apex predators or other commercially important fish species. A revision of the existing zoning system to include permanent no-take zones, alongside the regulation of professional fishing and all extractive activities in the rest of the MPA, are strongly encouraged in order to enhance the effectiveness of fisheries management. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Four visual censuses targeting Octopus vulgaris living in dens on sandy bottoms were carried out from June to October 2013 in the National Park of the Atlantic Galician Islands (NW Spain). Censuses were undertaken by scuba diving between 5 and 21 m depth in daytime. The total area swept was 13.75 ha. There were no significant differences between octopus presence in dens during open and closed fishing seasons. Depth had a significant negative relationship with occupancy. The average number of dens per 1000 m2 was 3.84±0.84 in June and 3.89 in October. The area per den was 260 m2. Den number estimations varied between 1586 and 2057. The largest number of dens (76.5%) was found between 5 and 10 m depth. Den distribution was clumped. No significant differences were found between octopus size classes (small, medium and large) and den diameter. Associate dens were observed. There were no significant differences in den diameter and shell types found around the middens. Many dens could be “permanent”. Drilling bivalve shell behaviour is discussed. The surveyed area had around 1100 individuals, mainly small specimens. No significant differences were found between octopus size and depth. Substrate, den type and food abundance and availability (especially razors Ensis arcuatus) seem to be the main factors influencing dens and octopus density and distribution. Den availability does not appear to be a limiting factor in this case. Temperature, den availability, predators and fishing pressure influencing density and distribution are discussed. Rodas inlet may be a preferential habitat for O. vulgaris individuals ranging from 200 to 2000 g, but especially small specimens ( ≤ 1000 g).

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]

Opportunistic encounters with an elusive large-bodied sicydiine goby in a single plunge pool led us to photograph and deploy three video cameras to detect individuals in that pool. Subsequently, a catchment-wide search indicated that the species, eventually identified as Sicyopterus cynocephalus, was confined to the single pool where it was originally detected. A network of ten video cameras was then deployed to estimate the number of individuals of that species and of a congener, S. lagocephalus, by non-destructive means. This study provides the first record of S. cynocephalus in Australia, and showcases the synergy of active snorkel searches and a remote camera network in counting individuals of two sympatric species of Sicyopterus. [ABSTRACT FROM AUTHOR]

The seaweed Kappaphycus alvarezii (Doty) Doty ex P. C. Silva, a red algal species, is the main global source of Kappa carrageenan. The introduction of such exotic species in regions outside their original locale can change the community structure of the areas into which they are introduced. The possible influence of seaweed farming on the rocky reef fish assemblage was assessed in Paraty, Brazil. The reef fish assemblage in the seaweed farming area was compared before and after the commencement of farming with two undisturbed control areas. Among the ten species ranked as the most frequently occurring in each area, eight were the same. The fish community structure close to the seaweed farming area did not change from that of the control areas, over the months of the study. Neither the fish diversity and richness indices, nor the total average abundance among areas was significantly altered. The average abundance of the different trophic groups varied over time in both the farm and control areas, revealing similar patterns. These results suggest that K. alvarezii can be cultivated up to at least 50 m from a rocky coast without altering the fish community structure of the surrounding waters. [ABSTRACT FROM AUTHOR]

Fish assemblages associated with 16 marine caves were investigated along the coasts of Spain, France and Italy. Sampling was done in caves that encompassed blind caves (one entrance) and caves with several openings, remarkably variable in morphology, overall extension, presence/absence of ceiling, and characteristics of the bottom. On the whole, 33 fish species were recorded. The distribution patterns of fish assemblages (both in terms of density and biomass) showed a significant variability at the regional (hundreds of kms) and local scale (kms/hundreds of meters), which confirms the great heterogeneity of the cave-associated communities. In terms of occurrence, only the cardinal fish Apogon imberbis and the gobid Corcyrogobius liechtensteini were found in all 16 caves, followed by Scorpaena notata and Serranus cabrilla (n = 15) and Diplodus vulgaris and Didogobius splechtnai (n = 11). A significant number of species were occasionally found, like Sarpa salpa and Diplodus annularis. They usually occur outside caves and could be considered as "sporadic cave visitors". The high densities of A. imberbis and its frequency of occurrence shows that this species is by far the most represented fish within caves in the western Mediterranean. In spite of the conspicuous variation from cave to cave (from 10 to 70% of the whole fish biomass), a general pattern emerges showing that A. imberbis accounts for a significant proportion of the fish biomass. Average density and biomass of A. imberbis are significantly variable at regional scale (hundreds of kms), but not at local scale (kms/hundred meters). A similar pattern could be explained by multiple processes acting concurrently. Although further studies are needed (e.g. to prove nychthemeral movements inside-outside caves for feeding), this study shows that, based on its density and biomass, A. imberbis has the potential to fulfill a crucial trophic role within Mediterranean marine caves as a vector of organic matter. [ABSTRACT FROM AUTHOR]

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.