Non-indigenous Invasive Species Research Articles

Assessing Diet & Trophic Position of Fish in Chenderoh Reservoir, Malaysia: SCA & SIA Approach

The present study assessed and compared the diet and trophic positions (TP) of two carnivorous fish H. macrolepidota and C. ocellaris from Chenderoh Reservoir, Malaysia. The focal goal of the study was to understand the effects of invasive non-indigenous species (NIS), C. ocellaris, on the native indigenous (IS) fish species, H. macrolepidota. Data were acquired from September 2014 to February 2015 within the study area. The assessment was grounded in stomach content analysis (SCA) and stable isotope analysis (SIA), which collectively clarified the feeding habits and trophic positions (TP) of these selected fish. In total, 184 fish samples (comprising 64 individuals of H. macrolepidota and 120 individuals of C. ocellaris) underwent stomach content analysis (SCA). Additionally, 24 individuals (12 of H. macrolepidota and 12 of C. ocellaris), sampled from December 2014 to February 2015, were selected for stable isotope analysis (SIA). The mean RGL values for H. macrolepidota and C ocellaris were 0.98 ± 0.18 and 1.10 ± 0.15 (Mean ± SD), respectively, aligning with known ranges for carnivorous fish. These values also clarified that both species occupy higher TP in the food web as tertiary or quaternary consumers. SCA findings also revealed that fish and crustaceans were the predominant food categories for H. macrolepidota, while C. ocellaris predominantly fed on fish. The mean stomach fullness index (MSF) and the gastrosomatic index (GSI) corroborated the differences in the foraging performance of the fishes, with C. ocellaris having a higher MSF (2.03) compared to H. macrolepidota (0.65). These implied that C. ocellaris had plentiful of food and encountered fewer diet-related challenges in the ecosystem. From SIA, δ13C values indicated that the primary carbon sources for both species are C3 plants, particularly aquatic vegetation. Further, δ15N values further ensured that both H. macrolepidota and C. ocellaris are carnivorous in nature and occupy higher TP in the ecosystem.

Transient population dynamics drive the spread of invasive wild pigs and reveal impacts of management in North America

Invasion of nonindigenous species is considered one of the most urgent problems affecting native ecosystems and agricultural systems. Mechanistic models that account for short-term population dynamics can improve prediction because they incorporate differing demographic processes that link the environmental conditions of a spatial location explicitly with the invasion process. Yet short-term population dynamics are rarely accounted for in spatial models of invasive species spread.Accounting for transient (short-term) population dynamics that arise from the interaction of age structure and vital rates, we predict the stochastic population growth rate and establishment probability of wild pigs following introduction into any location in North America. Established ecological theory suggests that the rate of spatial spread is proportional to population growth rate. Using observed geographic distribution data for wild pigs we calculated geographic spread rates (watersheds/year) from 1982 to 2021. We investigated if observed spread rates increased in watersheds with higher stochastic population growth rates. Stochastic population growth rate and establishment probability of wild pigs increased with increasing initial population (propagule) size and length of establishment time. Areas along the Mississippi, Ohio, and lower portions of the Missouri river drainages had the highest probability of wild pig establishment with many regions having probabilities close to 1. Spread rates demonstrated strong spatial heterogeneity with the greatest rates of spread (5.8 watersheds/year) occurring from 2008 to 2013 prior to the establishment of a National wild pig control program in 2013. Spread rates declined 82% (0.57 watersheds/year) in the period from 2013 to 2021 compared to the period from 1982 to 2013. We found significant positive associations among stochastic population growth rate and observed geographic rates of spread. Stochastic population growth rate explained a large amount of variation (79.3–92.1%) in annual rate of watershed spread of wild pigs. Our predicted probabilities of establishment and population growth can be used to inform surveillance and control efforts to reduce the potential for establishment and spread of wild pigs.

Temporal development of fish communities in brackish lagoons of the Baltic Sea considering the invasion of the non-indigenous round goby (Neogobius melanostomus)

Globally, successful invasions of non-indigenous species affect biodiversity and can push ecosystems beyond tipping points. This study aimed to identify factors that influence round goby (Neogobius melanostomus) abundances and distribution pathways along the eastern German coast of the Baltic Sea over a 12year period. The study further explored how the invasion of round goby affected the local fish and benthos assemblages in terms of species numbers and diversity. Round goby invaded various areas and estuaries and has established self-sustaining populations at low densities with further westward spread along the coast appearing to be ongoing. Salinity emerged as the most important predictor for overall round goby abundance, while the influence of macrozoobenthos abundance, vegetation cover, oxygen concentration, and water temperature were comparably low, indicating that round goby have a high tolerance in this regard. Negative impacts of round goby on benthic organisms and indigenous fish species, such as native gobiids, flounder (Platichthys flesus), ruffe (Gymnocephalus cernua), perch (Perca fluviatilis), pikeperch (Sander lucioperca), and cod (Gadus morhua), were not observed. This could be attributed to the comparably low densities of round goby at the sampling areas (0.0001 to 0.2 fish per m2) in combination with a potential surplus of benthic resources counteracting negative effects of predation and competition. The results suggest that its broad environmental adaptability could have enabled round goby to occupy a vacant ecological niche in coastal areas of the south-western Baltic Sea, which is generally considered to be species-poor due to strong environmental gradients. However, it cannot be excluded that certain effects of the round goby invasion may be too subtle to be detected. Thus, the results of our study underline the need for a specific long-term monitoring of the round goby invasion across taxa and habitats.

Non-indigenous aquatic fauna in transitional waters from the Spanish Mediterranean coast: A comprehensive assessment

Understanding drivers of spatial variation in non-indigenous species (NIS) is a key goal in invasion biology, but comprehensive assessments providing high-resolution data are extremely scarce. Anthropogenic modifications to transitional waters facilitate the invasion of NIS where they cause both ecological and economic important damage. By screening validated data sources, we conducted a comprehensive assessment of non-indigenous aquatic fauna in Spanish Mediterranean transitional waters (30 sites), as well as assessed introduction pathways, native regions, NIS assemblage patterns and temporal introduction rate. One hundred and twenty-nine NIS were inventoried, with 72 % established and more than half listed before 1980. Two intentional (release, escape) and two unintentional (contaminant, stowaway) introduction pathways were dominant. Recorded NIS originated mostly from North America and Asia. A clear nested pattern in NIS assemblages was observed across sites, suggesting secondary spread from the most invaded waters placed in the northern regions. Our updated inventory should be pivotal for designing prevention protocols and informing specific management plans on non-indigenous fauna in transitional waters.

Distribution of Non-Indigenous Crayfish Species in Estonia and Their Impacts on Noble Crayfish (Astacus astacus L.) Populations

Invasive non-indigenous crayfish species (NICS) are a major threat to the existence of native crayfish populations in European freshwater ecosystems. The discovery of signal crayfish Pacifastacus leniusculus, marbled crayfish Procambarus virginalis, and spiny-cheek crayfish Faxonius limosus in Estonia has increased the risk of extinction of Estonia’s only native crayfish species, the noble crayfish Astacus astacus. The aim of this study was to give an overview of the status, distribution, and impacts of P. leniusculus, F. limosus, and Procambarus virginalis on A. astacus populations and assess the effect of trapping on NICS abundance. Annual monitoring of crayfish has been carried out since 2008 as part of A. astacus conservation and the NICS eradication plan. In this study, we present data from nine sampling locations monitored from 2010 to 2022. The spread of NICS continues to increase beyond their distribution areas, and in two sampling locations P. leniusculus and A. astacus live in sympatry. Our results suggest that trapping has a limited effect on population abundance, as NICS have already caused the extinction of two A. astacus populations. However, intensive trapping should continue simultaneously with sensitive molecular techniques to monitor the spread of NICS.

Predation facilitates the abundance of biofouling non-indigenous species in estuarine marinas in NE Atlantic Portugal

Harbours are highly modified habitats that differ from natural areas. They are hotspots of non-indigenous species (NIS) and act as stepping-stones in invasive processes. However, local communities can exert biotic resistance against biological invasions through trophic interactions and competition. This study assesses the biotic effects of predation on the recruitment of fouling assemblages in three marinas of NE Atlantic Portugal (Cascais, Setúbal and Sines), with particular emphasis on NIS, using predator exclusion experiments. Predation increased the relative abundance of NIS, mainly Watersipora subatra, in the estuarine marinas of Cascais and Setúbal, while no predation effects were registered in the coastal marina of Sines. Therefore, predation can increase the risk of NIS invasion (biotic facilitation). Furthermore, local ecosystems may have different effects and differ in vulnerability against NIS invasions. Finally, a better understanding of coastal invasive ecology and biotic effects in coastal artificial habitats will improve our capacity for NIS management.

High throughput SNP chip as cost effective new monitoring tool for assessing invasion dynamics in the comb jelly Mnemiopsis leidyi

High throughput low-density SNP arrays provide a cost-effective solution for population genetic studies and monitoring of genetic diversity as well as population structure commonly implemented in real time stock assessment of commercially important fish species. However, the application of high throughput SNP arrays for monitoring of invasive species has so far not been implemented. We developed a species-specific SNP array for the invasive comb jelly Mnemiopsis leidyi based on whole genome re-sequencing data. Initially, a total of 1,395 high quality SNPs were identified using stringent filtering criteria. From those, 192 assays were designed and validated, resulting in the final panel of 116 SNPs. Markers were diagnostic between the northern and southern M. leidyi lineages and highly polymorphic to distinguish populations. Despite using a reduced representation of the genome, our SNP panel yielded comparable results to using a whole genome re-sequencing approach (832,323 SNPs), recovering similar values of genetic differentiation between samples and detecting the same clustering groups when performing Structure analyses. The resource presented here provides a cost-effective, high throughput solution for population genetic studies, allowing to routinely genotype large number of individuals. Monitoring of genetic diversity and effective population size estimations in this highly invasive species will allow for the early detection of new introductions from distant source regions or hybridization events. Thereby, this SNP chip represents an important management tool in order to understand invasion dynamics and opens the door for implementing such methods for a wider range of non-indigenous invasive species.

Predicting ecological impacts of the invasive brush-clawed shore crab under environmental change

Globally, the number of invasive non-indigenous species is continually rising, representing a major driver of biodiversity declines and a growing socio-economic burden. Hemigrapsus takanoi, the Japanese brush-clawed shore crab, is a highly successful invader in European seas. However, the ecological consequences of this invasion have remained unexamined under environmental changes—such as climatic warming and desalination, which are projected in the Baltic Sea—impeding impact prediction and management. Recently, the comparative functional response (resource use across resource densities) has been pioneered as a reliable approach to quantify and predict the ecological impacts of invasive non-indigenous species under environmental contexts. This study investigated the functional response of H. takanoi factorially between different crab sexes and under environmental conditions predicted for the Baltic Sea in the contexts of climate warming (16 and 22 °C) and desalination (15 and 10), towards blue mussel Mytilus edulis prey provided at different densities. Hemigrapsus takanoi displayed a potentially population-destabilising Type II functional response (i.e. inversely-density dependent) towards mussel prey under all environmental conditions, characterised by high feeding rates at low prey densities that could extirpate prey populations—notwithstanding high in-field abundances of M. edulis. Males exhibited higher feeding rates than females under all environmental conditions. Higher temperatures reduced the feeding rate of male H. takanoi, but did not affect the feeding rate of females. Salinity did not have a clear effect on feeding rates for either sex. These results provide insights into interactions between biological invasions and climate change, with future warming potentially lessening the impacts of this rapidly spreading marine invader, depending on the underlying population demographics and abundances.

Relevance of feeding ecology in the management of invasive species: Prey variability in a novel invasive crab

The diet composition of non-indigenous species (NIS) provides essential information to recognise potential impacts on ecosystems. This study examined the feeding ecology of the novel invasive crab Cronius ruber from demographic and seasonal perspectives. It identified 52 prey items in crab gut contents (n = 278), and more than 18% of the studied specimens had empty guts. The high-frequency prey belonged to Brachyuran (51.54%) and Polychaete (34.36%), followed by Echinidea (22.47%), Gastropoda (21.15%) and Perciformes (20.70%). Additionally, the night sampling showed prey that were not observed in the examined stomach contents. The daily ingestion rates based on polychaeta indicated more prey consumption by juveniles (<55 mm carapace width (CW)) and adults crabs (55 mm–75 mm CW) than the old adults (>75 mm CW). This falls in line with the number of prey items retained in individuals’ guts, which changed seasonally and in ontogenic groups. Moreover, the visual night observations showed that native predators foraged on the invasive crab. These predators were groupers, octopus and elasmobranchs. The seasonal and ontogenic differences observed in diet through the stomach content analysis and daily ingestion rates suggest that C. ruber eats a generalist diet. The dissimilarity analysis suggested possible resource partitioning in ontogenic groups. Our results could represent the baseline for future studies into the possible impacts of this invasive NIS, as well as some arguments to include C. ruber on the list of invasive alien species of European Union concern.

The potential for proliferation of an invasive fanworm due to harvesting in mussel aquaculture

Biofouling, including the accumulation of invasive non-indigenous species, significantly increases production and processing costs in shellfish aquaculture. Harvesting operations have the potential to exacerbate this problem through the fragmentation and discharge of biofouling species and by triggering the release of propagules that can subsequently re-establish in the vicinity. In this study, the potential for the proliferation of the invasive Mediterranean fanworm, Sabella spallanzanii, from harvesting operations in the aquaculture of green-lipped mussels, Perna canaliculus, was examined in New Zealand. The Mediterranean fanworm were experimentally fragmented and held on a mussel farm and in laboratory conditions. Wound closure in most fragments was observed within three days after fragmentation and most fragments had started regeneration of new body structures (new branchial crown or tail segment) within 14 days after fragmentation. Survival was higher for posterior fragments compared to anterior fragments, both in the laboratory and field conditions. Although, posterior fragment survival in the field was lower compared to the laboratory. The size of the fanworm fragment had no effect on regeneration or survival. A large number of fanworms stayed attached to the recovered grow-out rope after passing through the machinery to strip the mussels from the rope. Consequently, the rope and attached fanworms were retained on board the harvesting vessel for return to shore facilities for cleaning prior to reuse, precluding their release back into the sea. Only a small proportion of fanworms were processed through the mussel harvesting machinery with the majority sustaining several wounds, and were often bleeding heavily or were dead. Such injuries are known to result in the release of gametes from fanworm, however, only ripe fanworm sperm are known to be viable when released into seawater. Overall, the results of this study indicate that the potential for proliferation of fanworm from harvesting activities in mussel aquaculture is limited, and could be eliminated by the physical removal of waste material prior to discharge at sea.

Insight into the noble crayfish morphological diversity: a geometric morphometric approach

The noble crayfish (Astacus astacus), a keystone species of high ecological, economic, and cultural importance in Europe, is threatened due to a long-term population decline caused by anthropogenic pressure on its habitats, the presence of non-indigenous invasive crayfish species and climate change. Since the effective protection of the remaining populations requires conservation measures based on the comprehensive knowledge of the species, including good understanding of its genetic and morphological variability, our aim was to study morphological features of the noble crayfish in Croatia using geometric morphometrics for the first time. We applied two-dimensional geometric morphometrics to find morphological differences among 15 populations of the noble crayfish from Croatian freshwater habitats, grouped according to previously established (a) mitochondrial (genetic) lineages, (b) genetic clusters inferred from nuclear microsatellites, as well as (c) river basins and (d) habitat types (lotic, lentic). Overall, the results indicated the existence of morphological diversity among the studied populations of the noble crayfish in Croatia. Shape analysis showed differences in cephalon based on crayfish affiliation to different genetic lineages, genetic clusters, river basins and habitat types. Our study provided novel insights into morphological diversity of the endangered noble crayfish in the area of its high genetic diversity.

Invasion risk to Yangtze River Estuary posed by resting eggs in ballast sediments from transoceanic ships

Biological invasions and loss of biodiversity are serious problems of increasing globalization. The hypothesis that resting eggs in ballast sediments from transoceanic ships provide an invasion of nonindigenous species was tested by directly comparing egg communities between ballast and natural sediment. The richness, abundance and taxonomic composition of resting eggs were quantified for sediments collected from transoceanic ships arriving at Shanghai Port and natural seafloor of the Yangtze River Estuary. Twelve species were identified in ballast sediments with an average abundance of 19.0 ind. kg−1, while eleven species were identified in natural sediments with an average abundance of 55.3 ind. kg−1. Seven of twelve ballast species were potential invaders compared with natural sediments. The invertebrate communities of resting eggs in ballast sediments differed from those in natural sediments, based on non-metric multidimensional scaling and analysis of similarity. Hatching experiments on resting eggs from ballast sediments showed that there were 1.4 ind. kg−1 copepod nauplii hatched within the first 24 h, suggesting the invasive risk would be present during the first day of de-ballasting. These results indicate that sediments within ballast tanks posed a potential risk for estuarine communities.

Does Sand Beach Nourishment Enhance the Dispersion of Non-Indigenous Species?—The Case of the Common Moon Crab, Matuta victor (Fabricius, 1781), in the Southeastern Mediterranean

Sand beach nourishment (BN) is one of the commonest “soft solutions” for shore protection and restoration. Yet it may have ecological consequences. Can this practice enhance the introduction and dispersal of non-indigenous species (NIS)? There has been little research on the impacts of nourishment on NIS, especially in the southeastern Mediterranean, a region considered most affected by invading biota. However, so far only one study referred to the possible interaction between BN and the success of invading species. It reports increasing numbers and densities of the aggressive, omnivorous Indo-Pacific moon crab, Matuta victor (Fabricius, 1781) in Haifa Bay (northern Israel) between 2011 and 2017. This research suggests a possible role of anthropogenic disturbance in the outbreak of M. victor and blames the Israel Ministry of Environmental Protection for authorizing a (rather small scale) BN in Haifa Bay in 2011 as an alleged cause for this outbreak. Circumstantial indirect evidence is not sufficient to establish the role of nourishment in promoting the establishment and dispersal of NIS. There are plenty of examples of successful settlement and rapid and large-scale distribution of NIS (including another member of the genus Matuta), especially in the eastern Mediterranean, without any BN in the region. Furthermore, the location where the M. victor specimens were sampled was exposed to more prevailing and frequent anthropogenic marine stressors than BN, such as eutrophication, pollution, fishing activities and particularly port construction. To firmly establish an assumed role of nourishment in the invasion of NIS, assessments must be based on solid and orderly planned scientific research to be designed well before the beginning of any BN. It is suggested that direct communication between environmental regulators and scientists is crucial for improving both scientific research and environmental management policies.

Use of Invasive Water Hyacinth for Composting of Ordinary Leaf Litter

Many lakes, canals and wetlands in Sri Lanka are infested by water hyacinth (Eichhornia crassipes (Mart.) Solms), which is a non-indigenous invasive aquatic weed species. It causes a complete blockage of water resources that makes irrigation and fishing very difficult. Among various eradication methods of water hyacinth, composting has been extensively used in many countries. However, the degree of toxicity and the quality of compost are important for field applications. Therefore, the present study was aimed at transforming ordinary leaf litter into quality compost using water hyacinth and various other amendments, and comparing the compost quality in terms of heavy metals, pH, electrical conductivity (EC) and C: N ratio. The weeds were collected from the Moragoda canal, Galle, Sri Lanka. The compost trials were prepared using water hyacinth and different other raw materials and one compost trial was prepared using water hyacinth alone. The mixtures were decomposed aerobically for 12 weeks by windrow method and prepared composts were analysed for pH, EC, organic C %, total N %, Cu, Cd, Pb, Zn, Ni, and As. Finally, the obtained results were compared with the indices given for compost by the Sri Lankan standards. Considering the C: N ratio, pH, EC which obtained 17.84, 7.5, 1.95 dSm-1, respectively and heavy metal content less than permissible limit, it revealed that compost mixture with a composition of water hyacinth and dry leaf litter was the most suitable mixture to recommend for field application.

Macroalgae niche modelling: a two-step approach using remote sensing and in situ observations of a native and an invasive Asparagopsis

We are facing a global loss of biodiversity due to climate change. This will lead to unpredictable changes in ecosystems, affecting the goods and services they provide introduction of non-indigenous marine species. This represents one of the major threats to marine biodiversity and therefore, there is a strong need to assess, map and monitor these alien species. The appearance of non-indigenous species is especially dangerous in fragile ecosystems and it is of great importance to better understand the invasion mechanisms of these invasive species. This is the case for invasive alga Asparagopsis armata, present in the Azores Archipelago. In this study we propose a methodology to define the realized ecological niche of this invasive alga, alongside the native Asparagopsis taxiformis, to understand better its distribution and potential impact on native communities and ecosystem services. These objectives comply with the EU Biodiversity strategy for 2020 goals and the need to map and assess ecosystems and their services. The lack of reliable high-resolution data makes this a challenging task. Within this scope, we propose a combination of Remote Sensing, Unmanned Aerial Vehicle based imagery together with in-situ field data to build ecological niche modelling approaches as a cost-effective methodology to identify and characterize vulnerable marine ecosystems. Our results show that this combination can help achieve monitoring, leading to a better understanding of ecological niches and the consequences of non-indigenous species invasion in fragile ecosystems, like small islands, when faced with limited data.

The Introduction of the Asian Red Algae Melanothamnus japonicus (Harvey) Díaz-Tapia &amp; Maggs in Peru as a Means to Adopt Management Strategies to Reduce Invasive Non-Indigenous Species

Early detection of non-indigenous species is crucial to reduce, mitigate, and manage their impacts on the ecosystems into which they were introduced. However, assessment frameworks for identifying introduced species on the Pacific Coast of South America are scarce and even non-existent for certain countries. In order to identify species’ boundaries and to determine the presence of non-native species, through morphological examinations and the analysis of the plastid ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL-5P) gene, we investigated the phylogenetic relationships among species of the class Florideophyceae from the coast of Ancash, Peru. The rbcL-5P dataset revealed 10 Florideophyceae species distributed in the following four orders: Gigartinales, Ceramiales, Halymeniales, and Corallinales, among which the Asian species, Melanothamnus japonicus (Harvey) Díaz-Tapia &amp; Maggs was identified. M. japonicus showed a pairwise divergence of 0% with sequences of M. japonicus from South Korea, the USA, and Italy, the latter two being countries where M. japonicus has been reported as introduced species. Our data indicate a recent introduction event of M. japonicus in Peru, and consequently, the extension of its distribution into South America. These findings could help to adopt management strategies for reducing the spread and impact of M. japonicus on the Pacific Coast of South America.

The non-indigenous Oithona davisae in a Mediterranean transitional environment: coexistence patterns with competing species

The Venice lagoon (VL) has been recognized as a hot spot of introduction of non-indigenous species (NIS), due to several anthropogenic factors and environmental stressors that combined may facilitate NIS invasions. In the last decades an increasing number of zooplankton NIS have been observed in the VL. This work aims to provide a picture of the annual cycle and distribution of the recently recorded non-indigenous copepod Oithona davisae, considering the coexistence patterns with the congeneric resident Oithona nana. Therefore, zooplankton samplings were carried out monthly from August 2016 to July 2017 at five Long-Term Ecological Research LTER stations in the VL. Oithona davisae showed a persistent occurrence throughout the year with the highest abundances in the warm season and in the inner areas, while the congeneric O. nana, showing a different distribution pattern, resulted more abundant near the inlets of the Lagoon, where O. davisae reached the minimum density. Oithona davisae seems to find local conditions that promote its settlement and distribution, especially in the inner and more trophic lagoon sites. In other European coastal embayments or transitional waters, O. davisae occupied the niche left by the indigenous O. nana or can replace this congeneric species through competitive exclusion mechanisms. Our data indicate that, for now, such species replacement has not occurred in the VL. One of the causes is the extreme variety of habitats and niches offered by this environment allowing a balanced coexistence with O. nana and in general with the resident copepod community.

“If You Know the Enemy and Know Yourself”: Addressing the Problem of Biological Invasions in Ports Through a New NIS Invasion Threat Score, Routine Monitoring, and Preventive Action Plans

Invasive alien species (IAS) are currently considered one of the greatest threats to global marine ecosystems. Thus, ships and maritime activity have been identified as the main factors responsible for the vast majority of accidental species translocations around the world, implying that prevention should be the core of environmental port policies. Preventive port strategies should include analyzing risks based on traffic origins and volumes, revising port policies for inspections, estimating probabilities of non-indigenous species (NIS) appearance, monitoring routine species within ports, and finally implementing management plans and focused actions. Here, we conducted a comprehensive NIS prediction analysis for the port of Gijon (northern Spain), one of the largest ports in the south Bay of Biscay, as a case study that can be extrapolated to other international seaports. An extensive bibliographic search (1953–2020) was conducted and we identified 380 species that have been transported through hull fouling and ballast water around the world. We evaluated their likelihood of arriving (from 14 years of traffic data) and becoming established (from habitat suitability and demonstrated impacts and invasion ability) within the Gijon port, creating a new NIS Invasion Threat Score (NIS-ITS). This new index could help to identify target species that are likely invaders for early detection and prevention policies within the port. The results showed that 15 NIS had &amp;gt;90% likelihood of becoming a biological invasion problem in Gijon Port. At the same time, we reported morphological and genetic analysis of biota found in two successive annual monitoring surveys of Gijon port and ships (n = 612 individuals) revealing 18 NIS, including 6 of the NIS predicted from high NIS-ITS. Actually, 80% (12 NIS) of those potentially most dangerous species (NIS-ITS &amp;gt; 90%) have already been detected in the Bay of Biscay area. We propose the use of this new tool for a risk-reduction strategy in ports, based on accurate predictions that help in promoting specific early detection tests and specific monitoring for NIS that have a high chance of establishment. All international seaports can adopt this strategy to address the problem of biological invasions and become “blueports” in line with EU policy.

Identifying hotspots of non-indigenous species' high impact in the Maltese islands (Central Mediterranean Sea)

Several invasive non-indigenous species (NIS) cause ecological and socio-economic impacts. A good understanding of the impacts of invasive NIS in Mediterranean habitats is important for managing and prioritising measures in the marine environment. We applied a conservative additive model to sum up the Cumulative IMPacts of invasive Alien (CIMPAL) species of 19 invasive marine NIS on 13 habitats in Maltese waters. This analysis identified three hotspot areas of NIS' high impact and five top-priority together with four high-priority invasive NIS for management. By using CIMPAL, it was also possible to differentiate between areas within the same Marine Protected Area. CIMPAL is thus recommended as a good tool for managers and policy makers for prioritising measures as well as funds. Finally, recommendations are made with respect to future steps that are needed for the CIMPAL applicability, aiming to a more appropriate decision-making on prioritisation of hotspot areas and invasive marine NIS.

Fishery reforms for the management of non-indigenous species

Marine ecosystems are undergoing major transformations due to the establishment and spread of Non-Indigenous Species (NIS). Some of these organisms have adverse effects, for example by reducing biodiversity and causing ecosystem shifts. Others have upsides, such as benefits to fisheries or replacing lost ecological functions and strengthening biogenic complexity. Stopping the spread of NIS is virtually impossible and so the societal challenge is how to limit the socioeconomic, health, and ecological risks, and sustainably exploit the benefits provided by these organisms. We propose a move away from the notion that NIS have only negative effects, and suggest a turn towards an Ecosystem-Based Fishery Management approach for NIS (EBFM-NIS) in the Mediterranean Sea, the world's most invaded marine region. A structured, iterative, and adaptive framework that considers the range of costs and benefits to ecosystems, ecosystem services, and fisheries is set out to determine whether NIS stocks should be managed using sustainable or unsustainable exploitation. We propose fishery reforms such as multiannual plans, annual catch limits, technical measures for sustainable exploitation, and legitimization of unlimited fishing of selected NIS and introduction of a radical new license for NIS fishing for unsustainable exploitation. Depending on local conditions, investment strategies can be included within the EBFM-NIS framework to protect/enhance natural assets to improve ecosystem resilience against NIS, as well as fishery assets to improve the performance of NIS fisheries. Examples of the former include the enhancement of Marine Protected Areas, harvesting of invasive NIS within MPAs, and protection of overfished predators and key species. Examples of the latter include market promotion and valorisation of NIS products, development of novel NIS products, and innovative/alternative NIS fishing such as fishery-related tourism (‘pescatourism’). The application of the suggested EBFM-NIS would create jobs, protect and enhance ecosystem services, and help to meet the United Nations Sustainable Development Goal 14: Conserve and sustainably use the oceans, seas, and marine resources for sustainable development.