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Fisheries-dependent data and information gathered through fisheries-related scientific surveys can significantly contribute to research on the patterns and processes underlying marine biological invasions and their interactions with fisheries. This study presents an overview of the presence of non-native fish species in the North Aegean Sea, offering insights into their distributions and impact on fisheries. The findings are based on a comprehensive compilation of commercial fisheries-dependent and scientific survey data collected in Greece from 2016 to 2023, along with a systematic review of the international scientific literature. The study resulted in the documentation of the presence of 37 nonnative fish species, including several recorded for the first time in the area. The results suggest that non-native fish species invasions in the North Aegean Sea are dynamic. Although most species were classified as casual, and the frequencies of occurrence as well as the quantities in commercial fisheries catches of established species are smaller than in the South Aegean Sea, species introductions and the extent of occurrence and area of occupancy of several species have been increasing since the 2000s. The significance of non-native fish species is becoming increasingly relevant to commercial fisheries in the study area. This is particularly evident in the Northeastern Aegean Sea, where catches of non-native species are on the rise, and new species with potential commercial value have emerged in recent years. [ABSTRACT FROM AUTHOR]

The brown seaweed Rugulopteryx okamurae (Dictyotales, Ochrophyta), native to the Pacific Ocean and widely distributed in Asia, has been recently recognized as an emblematic case of biological invasion by marine macroalgae in European waters. Since 2015 and from the Strait of Gibraltar, R. okamurae has rapidly spread towards Atlantic and Mediterranean coastal areas exhibiting an invasive behaviour with significant ecological and socio-economic impacts. Here, we report the first morphologically and genetically confirmed observation of this species in Italy, along the north-western coast of Sicily (Gulf of Palermo). Specimens were found as drifted material and as an established population on Posidonia oceanica, representing its new eastern distribution limit in the Mediterranean Sea, as the species was previously established in Marseilles (France). Furthermore, we performed a favorability distribution model with the current introduced distribution of the species for the Mediterranean, which shows most of the western Mediterranean, including the Balearic archipelago, Corsica and Sardinia, central Mediterranean, including Sicily, and the northern coast of Africa together with eastern Mediterranean basin, as highly favorable for R. okamurae. The most probable vectors for this introduction are sea currents and maritime traffic, including fishing activities. This hypothesis was supported by some of the ranked variables in the favorability model, i.e., current velocity, and the proximity of the introduced population to fishing ports. These results are a warning that the species can cover large sea distances via sea currents, thus also threatening the ecosystems and marine resources of the central and eastern Mediterranean Sea, as these areas are forecasted to be highly favorable regions for the species. We suggest coordinated actions at the European level with stakeholders in the fishing sector regarding prevention, both because it is a highly affected sector and because it potentially has a very important role in the dispersion of the species. [ABSTRACT FROM AUTHOR]

Three intertidal varunid crab species of the genus Hemigrapsus , viz. H. penicillatus , H. sanguineus , and H. takanoi , are widely distributed along the East Asian coastline. The first two became globally well-known after their introduction into Atlantic waters of North America and Europe. Since the first record in the late 1980s, they established breeding populations and now live in sympatry with native and other invasive crab species. The aim of this study was to determine the correct species identity and geographic origin of these invasive populations and, if possible, estimate the number of independent invasion events. For that purpose, specimens from the three species were obtained from native populations in Taiwan, Japan, Russia, Korea, and China, and genetically compared to invasive populations from Europe and the U.S.A. Sequences of the mitochondrial cytochrome c oxidase subunit I gene were generated and used for haplotype network and AMOVA analyses, thus providing insights into the potential invasion pathways, gene flow, and phylogeography of the two invasive species. Pronounced geographic structure for all three species is revealed in their native ranges, with a marked differentiation among northern and southern populations. We furthermore provide evidence that all invasions into North America and Europe originated from northern Asian populations, which is in line with similar climatic conditions in Europe, northeastern America and northern Asia. Our results also confirm the recent finding that all European populations previously thought to consist of H. penicillatus should be reclassified as H. takanoi. [ABSTRACT FROM AUTHOR]

The article offers information on a one-day consultative meeting held last year on collaborative strategies for managing aquatic biological invasions. It discusses the significance of studying biological invasions, especially in aquatic ecosystems, due to their threats to biodiversity and livelihoods. Topics include the participation of experts, policymakers, and stakeholders from various organizations, the objectives of the meeting, and the significance of understanding.

The risks imposed by biological invasions on marine ecosystems are increasing worldwide. The mud crab Rhithropanopeus harrisii has recently expanded its distribution to the northeastern Baltic Sea, where low predatory pressures and the absence of functionally similar competitors favored the establishment of the species. Few studies have addressed the effects of the mud crab on Baltic benthic communities and habitats. Even fewer have looked at the consequences of the invader on habitats dominated by Fucus vesiculosus, the main habitat-forming macrophyte in the Baltic Sea. The present study experimentally analyzed, under laboratory conditions, the effects of R. harrisii on Baltic F. vesiculosus habitats and associated communities under different temperatures simulating summer and winter regimes. Our results show that the effects of the mud crab are modulated by temperature, being more pronounced under summer conditions when the metabolic demands and food intake requirements are higher. The experiment provided new insights into the capacity of R. harrisii to disrupt recruitment in native snail populations, jeopardizing the persistence of healthy populations of key grazers in F. vesiculosus habitats. Moreover, our results conclusively demonstrated the capacity of the invader to decimate native blue mussel populations. The impacts on functionally relevant invertebrates can have far-reaching ecological consequences, altering the food web and disrupting entire coastal ecosystems in the Baltic Sea. [ABSTRACT FROM AUTHOR]

Biological invasions have become a defining feature of marine Mediterranean ecosystems with significant impacts on biodiversity, ecosystem services, and human health. We systematically reviewed the current knowledge on the impacts of marine biological invasions in the Mediterranean Sea. We screened relevant literature and applied a standardised framework that classifies mechanisms and magnitude of impacts and type of evidence. Overall, 103 alien and cryptogenic species were analysed, 59 of which were associated with both negative and positive impacts, 17 to only negative, and 13 to only positive; no impacts were found for 14 species. Evidence for most reported impacts (52%) was of medium strength, but for 32% of impact reports evidence was weak, based solely on expert judgement. Only 16% of the reported impacts were based on experimental studies. Our assessment allowed us to create an inventory of 88 alien and cryptogenic species from 16 different phyla with reported moderate to high impacts. The ten worst invasive species in terms of reported negative impacts on biodiversity include six algae, two fishes, and two molluscs, with the green alga Caulerpa cylindracea ranking first. Negative impacts on biodiversity prevailed over positive ones. Competition for resources, the creation of novel habitat through ecosystem engineering, and predation were the primary reported mechanisms of negative effects. Most cases of combined negative and positive impacts on biodiversity referred to community-level modifications. Overall, more positive than negative impacts were reported on ecosystem services, but this varied depending on the service. For human health, only negative impacts were recorded. Substantial variation was found among Mediterranean ecoregions in terms of mechanisms of impact and the taxonomic identity of impacting species. There was no evidence that the magnitude of impact increases with residence time. Holistic approaches and experimental research constitute the way forward to better understanding and managing biological invasions. [ABSTRACT FROM AUTHOR]

The invasive macroalga Caulerpa cylindracea has spread widely in the Mediterranean Sea, becoming a favorite food item for native fish for reasons yet unknown. By using a combination of behavioral, morphological, and molecular approaches, herein we provide evidence that the bisindole alkaloid caulerpin, a major secondary metabolite of C. cylindracea, significantly increases food intake in the model fish Danio rerio, influencing the regulation of genes involved in the orexigenic pathway. In addition, we found that the compound improves fish reproductive performance by affecting the hypothalamus–pituitary–gonadal axis. The obtained results pave the way for the possible valorization of C. cylindracea as a sustainable source of a functional feed additive of interest to face critical challenges both in aquaculture and in human nutrition. [ABSTRACT FROM AUTHOR]

Human-induced pressures have led to substantial changes in marine ecosystems worldwide, with the introduction of non-indigenous species (NIS) emerging as a significant threat to ecological, economic, and social aspects. The Macaronesian islands, comprising the Azores, Madeira, Canary Islands, and Cabo Verde archipelagos, are regions where the regional economy is dependent on marine resources (e.g., marine traffic, ecotourism and fisheries). Despite their importance, concerted efforts to manage marine biological invasions in Macaronesia have been scarce. In this context, the current study aims to contribute to the much-needed debate on biosecurity measures in this unique insular ecosystem to prevent and mitigate the impact of NIS. By adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria, this work validated and analyzed 260 documents providing insights into the management of NIS in Macaronesia until 2022. These documents revealed the presence of 29 Invasive Alien Species (IAS), most of which are misconceptions regarding this terminology. Most studies focused on the stages of early detection, rapid response, and eradication across the archipelagos. Cabo Verde had comparatively fewer studies. The most common techniques include monitoring/sampling, literature reviews, and taxonomic reviews. NIS introduction pathways were mainly attributed to transport (stowaway) and unaided migration, with ship fouling, ballast water, rafting, ocean currents, and tropicalization being also identified as significant contributors. This systematic review highlights the current efforts to establish robust biosecurity protocols in Macaronesia and emphasizes the urgent need to safeguard the region's ecological, economic, and social well-being. • First systematic review regarding management of non-indigenous species in Macaronesia. • 260 documents providing insights into the management of NIS in Macaronesia until 2022. • 29 Invasive Alien Species (IAS) were detected, most of which are misconceptions regarding this terminology. • NIS introduction pathways were mainly attributed to transport (stowaway) and unaided migration. • This study highlights the current efforts to establish robust biosecurity protocols in Macaronesia. [ABSTRACT FROM AUTHOR]

Aims: The present study is the first attempt to grasp the scale and richness of marine biological invasions in Macaronesia. We pioneered a comprehensive non‐native species (NNS), inventory in the region to determine their diversity patterns and native distribution origins. NNS were defined here as the result of both introductions and range expansions. We also used statistical modelling to examine relationships among NNS richness, anthropogenic activities, demographic and geographical variables across Macaronesia. Location: Macaronesia. Methods: A comprehensive literature search was conducted for marine NNS records in Macaronesia, registering the first record's location and year from 1884 to 2020. We used univariate and multivariate analyses to evaluate differences and similarities in community composition. By applying a Generalized Linear Model (GLM), we tested hypotheses regarding NNS richness as a function of anthropogenic activities, demographic and geographical variables. Results: A total of 144 marine non‐native species (NNS) were recorded for the whole of Macaronesia. The highest NNS richness was registered in the Canary Islands (76 NNS), followed by the Azores (66 NNS), Madeira (59 NNS) and finally Cabo Verde (18 NNS). Some differences amongst archipelagos were observed, such as the high number of non‐native macroalgae in the Azores, fishes in the Canary Islands and tunicates in Cabo Verde. Overall, macroalgae, tunicates and bryozoans were the predominant taxonomic groups in the Macaronesian archipelagos. Madeira and Canary Islands were the archipelagos with more similarity in marine NNS, and Cabo Verde the most divergent. Finally, GLM suggested that non‐native richness patterns across Macaronesia were dependent on the considered archipelago and strongly affected by (1) minimum distance to the mainland, (2) the total number of ports and marinas and (3) total marinas area (km2). Conclusions: The model results and NNS listing in the present study will likely raise the awareness and response regarding marine NNS in the whole Macaronesia region, serving as a baseline for future research as well as implementing and enforcing regulations related to the introduction of marine NNS in oceanic islands. [ABSTRACT FROM AUTHOR]

The invasive macroalga Caulerpa cylindracea has spread widely in the Mediterranean Sea, becoming a favorite food item for native fish for reasons yet unknown. By using a combination of behavioral, morphological, and molecular approaches, herein we provide evidence that the bisindole alkaloid caulerpin, a major secondary metabolite of C. cylindracea, significantly increases food intake in the model fish Danio rerio, influencing the regulation of genes involved in the orexigenic pathway. In addition, we found that the compound improves fish reproductive performance by affecting the hypothalamus–pituitary–gonadal axis. The obtained results pave the way for the possible valorization of C. cylindracea as a sustainable source of a functional feed additive of interest to face critical challenges both in aquaculture and in human nutrition.

The introduction of non-indigenous species (NIS) induces severe impacts on marine biodiversity and ecosystems. Macaronesia is an ecologically relevant region where several NIS were detected recently. For the first time, a standard experimental approach was designed to examine biofouling assemblages and investigate NIS across the region. In this context, sessile biofouling assemblages were examined in four recreational marinas in all the Macaronesian archipelagos from 2018 to 2020: the Azores, Madeira, Canary Islands, and Cabo Verde. We hypothesised that NIS numbers, abundance, and recruitment differed in each location due to abiotic and biotic features. From the Azores (higher latitudes) to Cabo Verde (lower latitudes), NIS recruitment and percentage cover decreased following a partial latitude gradient. The present study unveiled 25 NIS, with new records for the Azores (two cryptogenic species), Canary Islands (one NIS and two cryptogenic species), and Cabo Verde (three NIS and three cryptogenic species). The present research represents a pioneer and relevant step in advancing our current understanding of marine biological invasions in Macaronesia, employing a standard and low-cost approach. [Display omitted] • First experimental study on NIS in the Macaronesia • NIS recruitment and percentage cover decreased with latitude. • New records for the Azores, Canary Islands and Cabo Verde • Advancing our current understanding of marine biological invasions in Macaronesia [ABSTRACT FROM AUTHOR]

The introduction and transport of marine invasive species into new environments are a great threat to biodiversity and ecosystem services with potential economic repercussions. There are several routes and mechanisms by which alien species are transported and dispersed in the marine environment (shipping, waterways, and aquaculture). Each year, millions of tons of plastic enter the ocean. The presence of floating marine litter in marine environments provides a substrate for marine organisms and may increase the potential for the transport of alien species. Research on the role of marine litter in the introduction of alien marine species has grown exponentially in recent years. In this study, studies examining the transport and dispersal of alien species by marine litter are reviewed. In this review, we identified 67 alien species associated with marine litter. The most recurrent alien phyla found on marine litter are Arthropoda (29 %), Mollusca (23 %), Bryozoa (19 %), Annelida (7 %) and Cnidaria (5 %). Plastic appears to be more efficient in transporting alien species than by natural means. Their characteristics (buoyancy and persistence) allow them to be widely dispersed throughout all ocean compartments. Thus, plastics may act as a primary vector, carrying organisms to remote areas but can also facilitate the secondary spread of alien species between points of invasion. Despite the growing number of studies on this subject, much work remains to be done to understand the roles of plastics in the introduction of alien species and to develop solutions to mitigate the issue. • The role of marine litter in the biological invasion is poorly studied. • A total of 67 alien species were identified associated with marine litter. • Plastic litter are an important vectors for the spread of alien species. • The most alien phyla found on marine litter are Arthropoda, Mollusca and Bryozoa • Plastics can act as a primary vector, but also facilitate the secondary spread of alien species. [ABSTRACT FROM AUTHOR]

Identifying the areas of the world with suitable environmental conditions for the establishment of invasive species represents a fundamental basis for preventing their impacts. One of the most widely used tools for this is ecological niche modeling. Nonetheless, this approach may underestimate the specie's physiological tolerances (it's potential niche) since wildlife populations of species usually do not occupy their entire environmental tolerance. Recently, it has been suggested that incorporating occurrences of phylogenetically related species improves the prediction of biological invasions. However, the reproducibility of this technique remains unclear. Here, we evaluated the generality of this protocol by assessing whether the construction of modeling units above species level improves the capacity of niche models to predict the distribution of 26 target marine invasive species. For each, we constructed supraspecific modeling units based on published phylogenies by grouping the native occurrence records of each invasive species with the records of its phylogenetically closest relative. We also considered units at species level, including only the presence of records in the native areas of the target species. We generated ecological niche models for each unit with three modeling methods (minimum volume ellipsoids – MVE, machine learning algorithms – Maxent and a presence-absence method – GLM). In addition, we grouped the 26 target species based on whether or not the species are in environmental pseudo-equilibrium (i.e., it occupies all habitats where it can disperse) and have any geographical or biological constraints. Our results suggest that the construction of supraspecific units improves the predictive capacity of correlative models to estimate the invasion area of our target species. This modeling approach consistently generated models with a higher predictive ability for species in non-environmental pseudo-equilibrium and with geographical constraints. • Supraspecific units in ecological niche modeling could be useful for improving the model transferring. • The effectiveness of supraspecific units to improve models transferring is strongly influenced by BAM scenario. • Modeling above species level could enrich fundamental niche characterization specially in species with unfilled niches. [ABSTRACT FROM AUTHOR]

Coastal areas are environments of high diversity and severely threatened by hazards as marine litter and biological invasions. Citizens' knowledge and awareness are drivers of changes needed to improve environment conservation. Density both of litter and IAS Cortaderia selloana were measured from six beaches in southwest Bay of Biscay along with awareness of inhabitants of the zone using a social survey. Relationship between beach littering, alien invasion and perception and awareness of adults and students were assessed. Litter levels were associated with port presence and showed relationship between environmental degradation, IAS and litter accumulation. Adults were more aware about both issues and their perception of litter and plant invasion were positively correlated. Results suggest enhancing marine awareness, with more effort addressed specifically to students. There is a misperception of the real magnitude of IAS and litter impacts that should be approached improving awareness about this topics in the younger generations. [ABSTRACT FROM AUTHOR]