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\"Here begins Arthur Curry's recollection of the epic journey that led him to become the mythical superhero we know as Aquaman. Since his dramatic debut in the 1940s, Aquaman has gone from admired hero to legendary icon. Able to breathe in both air and water, the King of the Seven Seas has fought villainy from the deepest depths of the oceans to the outer limits of the galaxy. He is unquestionably one of the greatest heroes the world has ever seen, but his rise to power was not easy.\"-- Provided by publisher.

Background Identification of ancient evolutionary lineages and areas of natural admixture can have important implications for conservation policies aimed at preserving biodiversity in the face of existential threats. The island gecko Tarentola boettgeri is potentially threatened by the introduced California kingsnake ( Lampropeltis californiae ) within the relatively small oceanic island (1532 km 2 ) of Gran Canaria, Canary Islands, Spain. Results A 1.9-Gb T. boettgeri genome was assembled de novo from PacBio HiFi reads. Sequences obtained by genotyping-by-sequencing (GBS) were aligned to this reference and provided over 440,000 SNPs from 134 geckos obtained from 40 sample sites (Fig. 1). Analyses of ancestry coefficients supported five genomic groups within Gran Canaria plus two additional groups from the other parts of its range, namely the Canary Island of El Hierro and the Selvagens archipelago. Phylogenomic and divergence time analyses of both GBS sequences and SNPs revealed lineage divergence within Gran Canaria, starting 1.5–2.9 Ma, and also between-island divergence due to subsequent colonization of both the Selvagens and El Hierro around 1 Ma. The latter two colonization events occurred from distinct lineages that had originated in the NW and the W of Gran Canaria, respectively. Lineage divergence within Gran Canaria appears to have been followed by secondary contact and admixture, likely starting in the Late Pleistocene around 20–110 Ka ago. Individuals with significant mixed ancestry appear to be limited to as little as 5 km either side of contact zones. This facilitates identification of sites containing individuals with negligible mixed ancestry for each of the five ancient lineages. Conclusions The ability to genomically identify five ancient Gran Canarian lineages and geographical areas with ostensibly low mixed ancestry provides a foundation for practical conservation actions—such as selecting sites for creation of snake exclusion areas and/or the acquisition of individuals for ex situ captive breeding. These actions will help conserve the extensive within-island diversity in this species.

Marine biodiversity monitoring in the Mediterranean’s increasingly threatened ecosystems is crucial for effective ecosystem conservation and management. Here, we leveraged the Mediterranean International Trawl Survey program (MEDITS) to implement eDNA sampling through the recently tested ‘metaprobe’ procedure and characterize fish assemblages in three separate areas off the Italian coasts: Northern Adriatic Sea (NoAS), Ligurian and Northern Tyrrhenian Sea (LNTS), and Sardinian Sea (SaS). By combining the information from two homologous mitochondrial 12S metabarcodes––i.e., Elas02 and Tele02 targeting elasmobranchs and teleosts, respectively––we identified 108 species, over 60% of which overlapped with those caught by the trawl net. We produced an accurate reconstruction of fish community composition of the examined sites, reflecting differences in species assemblages linked with both geographic area and depth range. Metaprobe eDNA data consistently returned a biodiversity ‘bonus’ mostly consisting of pelagic taxa not captured through bottom trawl surveys, including rare and endangered taxa (e.g., elasmobranchs). Overall, the spatial characterisation of the assemblages across the surveyed areas was better delineated and more robust using eDNA metabarcoding than trawl data. Our results support the operationalisation of the metaprobe as a simple, inexpensive, versatile sampling tool, in association with pre-existing ship surveys, to overcome many of the limitations of marine data collection and strengthen marine management.

Norwegian lobster, Nephrops norvegicus , are a generalist scavenger and predator capable of short foraging excursions but can also suspension feed. Existing knowledge about their diet relies on a combination of methods including morphology-based stomach content analysis and stable isotopes, which often lack the resolution to distinguish prey items to species level particularly in species that thoroughly masticate their prey. DNA metabarcoding overcomes many of the challenges associated with traditional methods and it is an attractive approach to study the dietary profiles of animals. Here, we present the diet of the commercially valuable Nephrops norvegicus using DNA metabarcoding of gut contents. Despite difficulties associated with host amplification, our cytochrome oxidase I (COI) molecular assay successfully achieves higher resolution information than traditional approaches. We detected taxa that were likely consumed during different feeding strategies. Dinoflagellata, Chlorophyta and Bacillariophyta accounted for almost 50% of the prey items consumed, and are associated with suspension feeding, while fish with high fisheries discard rates were detected which are linked to active foraging. In addition, we were able to characterise biodiversity patterns by considering Nephrops as natural samplers, as well as detecting parasitic dinoflagellates (e.g., Hematodinium sp.), which are known to influence burrow related behaviour in infected individuals in over 50% of the samples. The metabarcoding data presented here greatly enhances a better understanding of a species’ ecological role and could be applied as a routine procedure in future studies for proper consideration in the management and decision-making of fisheries.

Urban coastal habitats experience substantial disturbances due to their proximity to human settlements and activities. Yet, despite the negative impact of urbanization on coastal environments, industrial structures can also provide artificial habitats. These are often easily accessible to regular surveys, including water sampling for environmental DNA (eDNA) analysis, an emerging and powerful tool for monitoring biodiversity in aquatic ecosystems. In this study, we utilized eDNA metabarcoding to investigate temporal and spatial trends in fish assemblages within urban coastal habitats between the Dee and Mersey estuaries (United Kingdom), historically one of the most anthropogenically impacted postindustrial coasts in the world. Over a 12‐month period, we conducted nine water sampling trips at two locations: the Albert Docks in central Liverpool, and the Marine Lake in West Kirby. Illumina sequencing was used to analyze PCR amplicons generated using the fish‐targeted Tele02‐12S metabarcoding region. We found significant changes in fish community composition across the different months. Fish communities also significantly differed between the two sites, with the patterns of temporal changes varying substantially between them. Seasonal appearances/disappearances of specific taxa (e.g., European eel, sand smelt, flounder, and herring) shed light on important ecological and behavioral processes that may have management implications. Results also corroborate previous findings on the importance of “molecular bycatch” (nontarget sequences) in expanding our understanding of the anthropogenic influences on the natural environment. Overall, our findings emphasize the value of eDNA monitoring as a noninvasive, affordable, and sensitive approach for routine monitoring of temporal trends in fish assemblages, facilitating the stewardship of resilient urban coastal zones, and recognizing interventions that could increase biodiversity.

Marine biodiversity stewardship requires costly and time‐consuming capture‐based monitoring techniques, which limit our understanding of the distribution and status of marine populations. Here, we reconstruct catch and demersal community composition in a set of 24 fishing sites in the central Tyrrhenian Sea by gathering environmental DNA (eDNA) aboard commercial bottom‐trawl fishing vessels. We collected genetic material from two sources: the water draining from the net after the end of hauling operations (“slush”), and custom‐made rolls of gauze tied to a hollow perforated sphere placed inside the fishing net (“metaprobe”). Species inventories were generated using a combination of fish‐specific (Tele02 12S) and universal metazoan (COI) molecular markers. DNA metabarcoding data recovered over 90% of the caught taxa and accurately reconstructed the overall structure of the assemblages of the examined sites, reflecting expected differences linked to major drivers of community structure in Mediterranean demersal ecosystems, such as depth, distance from the coast, and fishing effort. eDNA also returned a “biodiversity bonus” mostly consisting of pelagic species not catchable by bottom trawl but present in the surrounding environment. Overall, the “metaprobe” gauzes showed a greater biodiversity detection power as compared to “slush” water, both qualitatively and quantitatively, strengthening the idea that these low‐cost sampling devices can play a major role in upscaling the gathering of data on both catch composition and the broader ecological characteristics of marine communities sustaining trawling activities. This approach has the potential to drastically expand the reach of ecological monitoring, whereby fishing vessels operating across the oceans may serve as opportunistic scientific platforms to increase the strength and granularity of marine biodiversity data. We reconstruct catch and demersal community composition by collecting environmental DNA aboard commercial bottom‐trawl fishing vessels. DNA metabarcoding data recovered over 90% of the caught taxa and returned a “biodiversity bonus” of mainly pelagic species not catchable by bottom trawl but present in the surrounding environment. This approach has the potential to drastically expand the reach of ecological monitoring, whereby fishing vessels operating across the oceans may serve as opportunistic scientific platforms to increase the strength and granularity of marine biodiversity data.

Volunteer‐based biodiversity recording is a powerful source of scalable data yet to be used to its full potential by the scientific community. Coastal ecosystems are varied and diverse, making it difficult for managers to identify flexible methods for monitoring biological components. Emerging technologies such as environmental DNA (eDNA) analysis are promising for measuring aquatic biodiversity, yet most management organizations lack personnel and capacity to collect molecular data. Here we investigate, together as professional and non‐professional (citizen) scientists, the efficacy of a quasi‐passive eDNA capture technique. Volunteer SCUBA divers and snorkelers used low‐cost materials, namely cotton medical gauze, to capture eDNA via swimming. We compared this method to conventional eDNA capture techniques in an aquarium and nature, collectively iterating the field and laboratory procedures to improve feasibility. With a small (<30) network of volunteers, we detected 275 unique teleost and elasmobranch taxa, 180 of which could be identified to species level. These detections were from varied marine habitats spanning 90° of latitude, including Atlantic, Pacific and Indian Ocean waters off European, North American, African and Asiatic coasts. The swimming motion of divers was more effective than stationary soaking and the fish communities sampled by divers were comparable to that of conventional eDNA samples. The ease of this technique, matched by the eagerness and generosity of volunteers, presents an untapped, viable approach for scaling multi‐species marine eDNA monitoring as well as an avenue for improving science literacy.

The common octopus (Octopus vulgaris) is a highly valued cephalopod species which is marketed with different grades of processing, such as frozen, cooked or even canned, and is likely to be mislabeled. Some molecular methods have been developed for the authentication of these products, but they are either labor-intensive and/or require specialized equipment and personnel. This work describes a newly designed rapid, sensitive and easy-to-use method for the detection of Octopus vulgaris in food products, based on Recombinase Polymerase Amplification (RPA) and a detection using a Lateral Flow assay (LFA). After studying several gene markers, a system of primers and nfo-probe was designed in the COI (Cytochrome Oxidase I) region and was successfully tested in 32 reference samples (covering 14 species) and 32 commercial products, after optimization. The method was also validated in a ring trial with eight European laboratories and represents a useful tool for food authenticity control at all levels of the value chain.

Despite the striking physical and environmental gradients associated with depth variation in the oceans, relatively little is known about their impact on population diversification, adaptation and speciation. Changes in light associated with increasing depth are likely to alter the visual environment of organisms, and adaptive changes in visual systems may be expected. The pelagic beaked redfish, Sebastes mentella, exhibits depth-associated patterns of substructure in the central North Atlantic, with a widely distributed shallow-pelagic population inhabiting waters between 250 and 550 m depth and a deep-pelagic population dwelling between 550 and 800 m. Here we performed a molecular genetic investigation of samples from fish collected from 'shallow' and 'deep' populations, using the mitochondrial control region and the gene coding for the visual-pigment rhodopsin. We identify patterns suggestive of potential adaptation to different depths, by detecting a specific amino acid replacement at the rhodopsin gene. Mitochondrial DNA results reflect a scenario of long-term demographic independence between the two S. mentella groups, and raise the possibility that these 'stocks' may in fact be two incipient species.

Morphology-based identification of North Atlantic Sebastes has long been controversial and misidentification may produce misleading data, with cascading consequences that negatively affect fisheries management and seafood labelling. North Atlantic Sebastes comprises of four species, commonly known as ‘redfish’, but little is known about the number, identity and labelling accuracy of redfish species sold across Europe. We used a molecular approach to identify redfish species from ‘blind’ specimens to evaluate the performance of the Barcode of Life (BOLD) and Genbank databases, as well as carrying out a market product accuracy survey from retailers across Europe. The conventional BOLD approach proved ambiguous, and phylogenetic analysis based on mtDNA control region sequences provided a higher resolution for species identification. By sampling market products from four countries, we found the presence of two species of redfish ( S. norvegicus and S. mentella ) and one unidentified Pacific rockfish marketed in Europe. Furthermore, public databases revealed the existence of inaccurate reference sequences, likely stemming from species misidentification from previous studies, which currently hinders the efficacy of DNA methods for the identification of Sebastes market samples.