Who, why and how: stakeholder attitudes toward marine non-indigenous species management in Portuguese Atlantic Islands

The role of constructed reefs in non-indigenous species introductions and range expansions

This paper evaluates the potential effects of future commercial shipping through the Northern Sea Route and Northwest Passage on the spread of nonindigenous species (NIS) between Europe, the United States, and the Asia-Pacific region. We modeled NIS spread risk as a function of two factors: NIS introduction and NIS establishment. The change in risk of NIS introduction from one region to another is based on the expected commodity trade flow between the two regions given Arctic shipping routes. The risk of NIS establishment is based on current marine climate similarities between regions and projected 2030 terrestrial climate similarities. Results indicate that the United States, China, and Japan are at greatest risk for increased terrestrial and marine NIS spread to and from one another given their relatively high levels of trading activity and terrestrial and marine climate similarities. While increased trade between European and Asia-Pacific countries is expected in the future, only Japan has terrestrial climate similar enough to that of European countries to be considered a substantial terrestrial NIS spread risk, while China has the potential to increase the risk of marine NIS species spread in Europe.

East is east and West is west? Management of marine bioinvasions in the Mediterranean Sea

This study assessed the influence of summer seawater temperature and shipping on the introduction, establishment, and spread of nonindigenous fouling species on both local and regional scales in coastal regions of the USA. Using photographic surveys of 80 marinas on the east and west coasts of the USA, we defined thermal niches and ranges of summer sea surface temperature (SSST) for 27 abundant fouling species. We calculated percent cover of all abundant tunicates and bryozoans across sites and correlated species richness with water temperature and cargo shipping volume in each region. We quantified the relative importance of cargo shipping, seawater temperature, and distance between sites using Jaccard similarity between paired sites. Native species richness was positively correlated with SSST, while nonindigenous species (NIS) richness displayed a parabolic relationship with a peak at 20 °C. Temperature and cargo shipping traffic explained 53 % of variability in NIS richness, and only temperature was correlated with similarity between sites. We also found no link between similarity and distance between sites, and site–site comparisons showed no effect of NIS on native species richness on the scale of this study. It appears that cargo shipping may play a regional role in introduction of new species, but on local scales NIS distributions are more haphazard, possibly driven by local recreational boat traffic and associated larval dispersal or by other vectors affecting the local spread of these species. Our study demonstrates the importance of seawater temperature in allowing spread of NIS and influencing similarity between sites and regions.

Many coastal regions are encountering issues with the spread of nonindigenous species (NIS). In this study, we conducted a regional risk assessment using a Bayesian network relative risk model (BN-RRM) to analyze multiple vectors of NIS introductions to Padilla Bay, Washington, a National Estuarine Research Reserve. We had 3 objectives in this study. The 1st objective was to determine whether the BN-RRM could be used to calculate risk from NIS introductions for Padilla Bay. Our 2nd objective was to determine which regions and endpoints were at greatest risk from NIS introductions. Our 3rd objective was to incorporate a management option into the model and predict endpoint risk if it were to be implemented. Eradication can occur at different stages of NIS invasions, such as the elimination of these species before being introduced to the habitat or removal of the species after settlement. We incorporated the ballast water treatment management scenario into the model, observed the risk to the endpoints, and compared this risk with the initial risk estimates. The model results indicated that the southern portion of the bay was at greatest risk because of NIS. Changes in community composition, Dungeness crab, and eelgrass were the endpoints most at risk from NIS introductions. The currents node, which controls the exposure of NIS to the bay from the surrounding marine environment, was the parameter that had the greatest influence on risk. The ballast water management scenario displayed an approximate 1% reduction in risk in this Padilla Bay case study. The models we developed provide an adaptable template for decision makers interested in managing NIS in other coastal regions and large bodies of water.

Globalization has significantly accelerated maritime transportation, which serves as one of the primary pathways for the introduction of non-indigenous species (NIS) into new marine environments. Once established, these species can become invasive, threatening biodiversity, ecosystem services, and local economies. Effective management of NIS requires a comprehensive understanding of species distributions, environmental factors, and potential introduction pathways. This study, conducted in 2023-2024 by the National Center for Wildlife (NCW) in collaboration with the King Abdullah University of Science and Technology (KAUST), provides the first comprehensive assessment of non-indigenous marine species in the Red Sea and the Arabian Gulf. The study aimed to establish baseline data to guide biosecurity management strategies and inform the development of a region-specific biosecurity framework/program.A multi-method approach was employed, including a literature review, maritime traffic risk assessment, and field sampling. PVC settlement panels were deployed for three months at 34 locations in the Red Sea and Arabian Gulf between 1-2 meters depth to assess biofouling communities. Data collected from each location included environmental parameters such as salinity, temperature, dissolved oxygen, pH, and weather conditions. Water samples were analyzed for nutrient concentrations, chlorophyll-a, and eDNA to further characterize local biodiversity. Specimens were identified by taxonomic experts and subjected to DNA barcoding to create a reference library. The study also assessed maritime traffic patterns to determine potential NIS introduction risks.The literature review identified 181 potential NIS species in the Red Sea and 168 in the Arabian Gulf. Based on maritime traffic data and modeling techniques, our findings showed that regions with high maritime traffic and environmental similarity, such as the Sunda Shelf, East China Sea, and Mediterranean, posed the greatest NIS introduction risks to both seas. Key hotspot ports for NIS introductions in the Arabian Gulf include Fujairah, Jebel Ali, and Ras Laffan, while ports in the Red Sea include Jeddah, Sokhna, and Port Sudan.The findings underscore the urgency for a biosecurity framework to mitigate the risks associated with the introduction of NIS in these regions. In response, the NCW is leading efforts to develop and implement a tailored biosecurity framework aligning with the Cartagena Protocol on Biosafety to the Convention on Biological Diversity and Nagoya Protocol to safeguard marine ecosystems and biodiversity in the Arabian Gulf and Red Sea. This study provides essential data that will inform future regional biosecurity strategies in the Red Sea and Arabian Gulf, supporting the protection of the associated critical marine ecosystems from invasive species.

The European Union lacks a comprehensive framework to address the threats posed by the introduction and spread of marine non-indigenous species (NIS). Current efforts are fragmented and suffer substantial gaps in coverage. In this paper we identify and discuss issues relating to the assessment of spatial and temporal patterns of introductions in European Seas (ES), based on a scientifically validated information system of aquatic non-indigenous and cryptogenic species, AquaNIS. While recognizing the limitations of the existing data, we extract information that can be used to assess the relative risk of introductions for different taxonomic groups, geographic regions and likely vectors. The dataset comprises 879 multicellular NIS. We applied a country-based approach to assess patterns of NIS richness in ES, and identify the principal introduction routes and vectors, the most widespread NIS and their spatial and temporal spread patterns. Between 1970 and 2013, the number of recorded NIS has grown by 86, 173 and 204% in the Baltic, Western European margin and the Mediterranean, respectively; 52 of the 879 NIS were recorded in 10 or more countries, and 25 NIS first recorded in European seas since 1990 have since been reported in five or more countries. Our results highlight the ever-rising role of shipping (commercial and recreational) as a vector for the widespread and recently spread NIS. The Suez Canal, a corridor unique to the Mediterranean, is responsible for the increased introduction of new thermophilic NIS into this warming sea. The 2020 goal of the EU Biodiversity Strategy concerning marine Invasive Alien Species may not be fully attainable. The setting of a new target date should be accompanied by scientifically robust, sensible and pragmatic plans to minimize introductions of marine NIS and to study those present.

The influence of recreational boat traffic in the introduction of non-indigenous fouling species in three Ligurian marinas (Mediterranean Sea, Italy)

Bryozoans are major components in fouling communities, showing characteristics that facilitate their introduction into new areas mainly through hull fouling. Artificial structures in marinas are key for the introduction of bryozoan non-indigenous species (NIS), acting as a reservoir for their further spread to other areas. Considering that NIS management should be preventative, a comprehensive understanding of bryozoan diversity in marinas is mandatory. This is especially relevant in areas that rely heavily on shipping, such as the Canary Islands, where this information is still lacking. Here, we assessed bryozoan diversity in recreational marinas of Tenerife, Gran Canaria, Fuerteventura and Lanzarote. We found 24 taxa: 12 NIS, eight cryptogenic species and four unassigned. Seven of these species constituted new records for Canary Islands, including three for Spain, four for Macaronesia and two for the North-Eastern Atlantic. Primary taxonomical, faunistic and ecological studies are crucial to properly conduct adequate management programmes for NIS.

Exploring marine invasions connectivity in a NE Atlantic Island through the lens of historical maritime traffic patterns

Non-indigenous Species (NIS) pose significant threats to marine biodiversity globally, especially in ecologically sensitive habitats such as Marine Protected Areas (MPAs). This study uses data collected in the Autonomous Region of Madeira (North Atlantic), Portugal, to create a spatial model aiming to (1) develop a spatially explicit index of NIS dispersal from known hotspots such as ports, harbours, marinas, and anchoring areas; (2) assess the relative vulnerability of Madeira's MPAs to local NIS dispersion and establishment; and (3) provide insights for a scalable NIS monitoring framework and evaluating invasion risks. The spatial model integrates maritime traffic intensity and proximity to NIS hotspots, using a straightforward approach that can be applied in data-limited contexts. While designed to address Madeira's regional challenges, the model is adaptable to other biogeographic contexts and can incorporate additional complexity, such as species-specific traits or ecological layers, to suit different settings. Our findings underscore the role of maritime infrastructure and vessel traffic in NIS spread, revealing the vulnerability of Madeira's MPAs due to insufficient ecological monitoring and the absence of NIS monitoring and early detection programs. This study provides practical recommendations for improving MPA management and mitigating NIS risks, contributing to regional conservation efforts. Additionally, it establishes a baseline risk assessment approach that can be customised and expanded to guide NIS management and biodiversity conservation in other regions, particularly those with similar challenges.

Effective monitoring of non-indigenous seaweeds and combatting their effects relies on a solid confirmation of the non-indigenous status of the respective species. We critically analysed the status of presumed non-indigenous seaweed species reported from the Mediterranean Sea, the Northeast Atlantic Ocean and Macaronesia, resulting in a list of 140 species whose non-indigenous nature is undisputed. For an additional 87 species it is unclear if they are native or non-indigenous (cryptogenic species) or their identity requires confirmation (data deficient species). We discuss the factors underlying both taxonomic and biogeographic uncertainties and outline recommendations to reduce uncertainty about the non-indigenous status of seaweeds. Our dataset consisted of over 19,000 distribution records, half of which can be attributed to only five species (Sargassum muticum, Bonnemaisonia hamifera, Asparagopsis armata, Caulerpa cylindracea and Colpomenia peregrina), while 56 species (40%) are recorded no more than once or twice. In addition, our analyses revealed considerable variation in the diversity of non-indigenous species between the geographic regions. The Eastern Mediterranean Sea is home to the largest fraction of non-indigenous seaweed species, the majority of which have a Red Sea or Indo-Pacific origin and have entered the Mediterranean Sea mostly via the Suez Canal. Non-indigenous seaweeds with native ranges situated in the Northwest Pacific make up a large fraction of the total in the Western Mediterranean Sea, Lusitania and Northern Europe, followed by non-indigenous species with a presumed Australasian origin. Uncertainty remains, however, regarding the native range of a substantial fraction of non-indigenous seaweeds in the study area. In so far as analyses of first detections can serve as a proxy for the introduction rate of non-indigenous seaweeds, these do not reveal a decrease in the introduction rate, indicating that the current measures and policies are insufficient to battle the introduction and spread of non-indigenous species in the study area.

Marine biological invasions threaten biodiversity worldwide. Here we explore how Marine Protected areas, by reducing human use of the coast, confer resilience against the introduction of non-indigenous species (NIS), using two very different Pacific islands as case studies for developing and testing mathematical models. We quantified NIS vectors and promoters on Vancouver (Canada) and Moorea (French Polynesia) islands, sampled and barcoded NIS, and tested models at different spatial scales with different types of interaction among vectors and between marine protection and NIS frequency. In our results NIS were negatively correlated with the dimension of the protected areas and the intensity of the protection. Small to medium geographical scale protection seemed to be efficient against NIS introductions. The likely benefit of MPAs was by exclusion of aquaculture, principally in Canada. These results emphasize the importance of marine protected areas for biodiversity conservation, and suggest that small or medium protected zones would confer efficient protection against NIS introduction.

Comprehensive bioeconomic modelling of multiple harmful non-indigenous species

Marine debris (MD) can be a transport vector for diverse marine communities, including non-indigenous species (NIS). This study assessed MD potential role as a substrate for colonization and dispersal vector for NIS in the Madeira Archipelago (NE Atlantic) by examining three MD categories: floating (FMD), seafloor (SMD), and beached (BMD). Opportunistic sampling, conducted in collaboration with local maritime stakeholders, documented MD sightings with photographs and GPS coordinates. A total of 92 MD items were inspected, revealing 108 fouling species across 11 phyla, with 13% identified as NIS. SMD exhibited the highest proportion of NIS (9.6%), followed by BMD (4.4%) and FMD (3.9%). Notably, the study provides evidence that FMD functions as both a substrate and a dispersal vector for NIS in Madeira waters. Combining biogeographic analyses, oceanographic modelling, and MD identification marks, this study highlighted the North Atlantic Subtropical Gyre's currents as key pathways, transporting MD items from the Wider Caribbean, the North American east coast, and the Iberian Peninsula to Madeira within 2-3years. These findings emphasize Madeira's dual role as both a recipient and exporter of MD, with implications for NIS introductions and secondary spread. This study underscores the urgent need for standardized monitoring, stakeholder engagement, and proactive MD management strategies to mitigate NIS introductions and protect sensitive marine ecosystems like Macaronesia from the ecological risks of biological invasions.