The biological traits of the sixty-eight most widespread multicellular non-indigenous species (MWNIS) in European Seas: Baltic Sea, Western European Margin of the Atlantic Ocean and the Mediterranean ...Sea were examined. Data for nine biological traits was analyzed, and a total of 41 separate categories were used to describe the biological and ecological functions of these NIS.
Our findings show that high dispersal ability, high reproductive rate and ecological generalization are the biological traits commonly associated with MWNIS. The functional groups that describe most of the 68 MWNIS are: photoautotrophic, zoobenthic (both sessile and motile) and nektonic predatory species. However, these ‘most widespread’ species comprise a wide range of taxa and biological trait profiles; thereby a clear ”identikit of a perfect invader” for marine and brackish environments is difficult to define. Some traits, for example: “life form”, “feeding method” and “mobility”, feature multiple behaviours and strategies. Even species introduced by a single pathway, e.g. vessels, feature diverse biological trait profiles.
MWNIS likely to impact community organization, structure and diversity are often associated with brackish environments. For many traits (“life form”, “sociability”, “reproductive type”, “reproductive frequency”, “haploid and diploid dispersal” and “mobility”), the categories mostly expressed by the impact-causing MWNIS do not differ substantially from the whole set of MWNIS.
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•We analysed nine biological traits of the most widespread NIS in European seas.•We looked for similar biological trait profiles amongst the 68 most widespread NIS.•Three major profiles emerged: photoautotrophic, zoobenthic and nektonic species.•Many widespread NIS are benthic iteroparous invertebrates with pelagic larva.•Several widespread NIS feature multiple categories of feeding and mobility.
The introduction of non-indigenous species (NIS) is a major driver for global change in species biogeography, often associated with significant consequences for recipient ecosystems and services they ...provide for humans. Despite mandated by several high-level international legislative instruments, comprehensive quantitative evaluation on ecosystem impacts of marine NIS is scarce and lack a robust and data-driven assessment framework. The current study is aiming at fulfilling this gap, through quantitative assessment on the effects of the widespread NIS of the Baltic Sea on multiple ecosystem features and components including direct food-web effects. The outcomes of this study allowed identifying the most impacting widespread NIS, together with defining the processes underlying the most significant changes and outlined major sources of uncertainty. Lack and/or bias in the availability of evidence of impacts was recorded for several (both recent and early) introductions. Realizing a sophisticated, data and information-hungry framework for the evaluation of ecosystem impacts of NIS is not pragmatic for management purposes in the foreseeable future. Instead, simple approaches, such as application of common statistical parameters like absolute effect size, are more likely to result in tangible outcomes. As bearing no unit, effect sizes can be later easily aggregated across taxa, affected ecosystem features or spatial scales. The proposed approach enables performing systematic comparisons on the severity of impacts of different NIS along different study disciplines and ecosystems.
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•Effects of widespread NIS on ecosystem features and properties were quantified.•Most impactful NIS, processes underlying the changes and sources of uncertainty were identified.•Among communities, fish have been impacted the most while the pelagic realm is more affected than the benthic.•Significant effects were evident on the entire food web.•The effect size method offers a robust approach for general applications on quantification of the effects of NIS.
Several decades of research on invasive marine species have yielded a broad understanding of the nature of species invasion mechanisms and associated threats globally. However, this is not true of ...the Arctic, a region where ongoing climatic changes may promote species invasion. Here, we evaluated risks associated with non‐indigenous propagule loads discharged with ships' ballast water to the high‐Arctic archipelago, Svalbard, as a case study for the wider Arctic. We sampled and identified transferred propagules using traditional and DNA barcoding techniques. We then assessed the suitability of the Svalbard coast for non‐indigenous species under contemporary and future climate scenarios using ecophysiological models based on critical temperature and salinity reproductive thresholds. Ships discharging ballast water in Svalbard carried high densities of zooplankton (mean 1522 ± 335 SE individuals m⁻³), predominately comprised of indigenous species. Ballast water exchange did not prevent non‐indigenous species introduction. Non‐indigenous coastal species were present in all except one of 16 ballast water samples (mean 144 ± 67 SE individuals m⁻³), despite five of the eight ships exchanging ballast water en route. Of a total of 73 taxa, 36 species including 23 non‐indigenous species were identified. Of those 23, sufficient data permitted evaluation of the current and future colonization potential for eight widely known invaders. With the exception of one of these species, modelled suitability indicated that the coast of Svalbard is unsuitable presently; under the 2100 Representative Concentration Pathway (RCP) 8·5 climate scenario, however, modelled suitability will favour colonization for six species. Synthesis and applications. We show that current ballast water management practices do not prevent non‐indigenous species from being transferred to the Arctic. Consequences of these shortcomings will be shipping‐route dependent, but will likely magnify over time: our models indicate future conditions will favour the colonization of non‐indigenous species Arctic‐wide. Invasion threats will be greatest where shipping transfers organisms across biogeographic realms, and for these shipping routes ballast water treatment technologies may be required to prevent impacts. Our results also highlight critical gaps in our understanding of ballast water management efficacy and prioritization. Thereby, our study provides an agenda for research and policy development.
Many communities are shifting composition, with losses of native species and increases of non‐indigenous species (NIS). At its extreme, such alteration of ecological guilds can result in ...simplification with a single NIS performing an ecological role once carried out by a suite of natives. This alteration has occurred in many rivers of the south‐eastern U.S.A., where the invasive filter‐feeding freshwater clam Corbicula fluminea has proliferated following the nearly complete extirpation of native mussels.
We investigated the factors controlling the distribution and abundance of Corbicula, as well as estimated the ecological service it provides via water filtration. With a nested design, we surveyed multiple transects within four to six sites within each of four rivers that spanned three large catchments in the Georgia piedmont, collecting data on Corbicula density and physical habitat characteristics associated with its presence.
We found Corbicula present in over half of the 1,536 sampled 0.044 m2 sampled plots, 90 of the 93 transects that spanned the width of the river, and all 1–2 km sample sites, underscoring the clam's ubiquity in the study region. At the river scale, Corbicula densities ranged from 50–212 Corbicula m−2, although individual sites ranged from 7–483 Corbicula m−2. Corbicula was more abundant in areas with higher proportions of gravel, and less abundant with higher proportions of bedrock. A hierarchical model with river, site, and these two substrate variables explained 32% of the variation in Corbicula density.
Using observed densities and published per capita feeding rates, we calculated system‐wide collective filtration rates provided by Corbicula. In the four rivers surveyed and based on estimated residence times for median flows for the summer of 2012, Corbicula is estimated to filter water as many as seven times during median flows and 18 times during minimum flows before water flows out of a 10‐km reach. Due to high abundances and per biomass filtration rates, Corbicula plays an important role in these rivers.
Invasive species, biotic homogenisation, and the loss of functional redundancy may mean that many more rivers are similar to our studied rivers, with a single, often invasive, species dominating ecosystem function. Understanding the influence of biotic homogenisation on ecosystem function is of foremost importance to evaluate the resilience of natural systems.
Based on a search of publications in the scientific literature as well as international reports available online, I draw up a list of 25 documents which include cross-references to the terms offshore ...wind farms (OFW), and non-indigenous species (NIS). This review shows that no relationship has yet been clearly established between the implementation of OFWs and the colonization of NIS on turbine foundations and scour protections. Evidence for such an effect needs to be documented and confirmed in the future.
•Do the offshore wind farms (OWF) play a role in the spread of non-indigenous species (NIS)?•25 papers include the terms OWF and NIS has been analyzed.•No relationship has been established between OFWs and their colonization by NIS.•Evidence for such an effect needs to be documented and verified in the future.
Aim
Global biodiversity and ecosystems are highly impacted by anthropogenic activities, such as climate change and introduction of non‐indigenous species. As numerous species from the Ponto‐Caspian ...region have established in the North and Baltic Seas, as well as in the Laurentian Great Lakes, there have been large number of studies examining environmental tolerance of these species to determine their future potential to spread. However, many of those studies were conducted only on adult stages, while neglecting the possibility that early life history stages might not be equally resilient.
Location
Northern European, Ponto‐Caspian and North American regions.
Methods
To determine whether juveniles would demonstrate the same environmental tolerance as their parents, we examined the salinity tolerance of adults and juveniles of one Northern European (Gammarus salinus), one Ponto‐Caspian (Pontogammarus maeoticus) and one North American species (Gammarus tigrinus). Additionally, we compared our study to that of Paiva et al. (Global Change Biology, 24, 2018, 2708), who tested the salinity tolerance of the same species using only adults.
Results
Our study determined that both adults and juveniles of all three species tolerated wide ranges of salinity, with juveniles of G. salinus tolerating only slightly narrower salinity range than their parents, while those of P. maeoticus and G. tigrinus much narrower range. Additionally, we determined better survival and higher growth rates of juveniles of G. salinus in higher salinities and better survival of P. maeoticus in lower salinities.
Main conclusions
Based on juvenile salinity tolerance, our study further supported findings of Paiva et al. (2018), where Northern European species may be adapted to marine, while Ponto‐Caspian to lower saline and freshwater environments. The North American species is probably adapted to intermediate salinities. As juveniles do not tolerate the same salinity stress as adults, we emphasize the importance of testing all life history stages when predicting species resilience to environmental stressors.
Anthropogenic disturbance is considered a risk factor in the establishment of non-indigenous species (NIS); however, few studies have investigated the role of anthropogenic disturbance in ...facilitating the establishment and spread of NIS in marine environments. A baseline survey of native and NIS was undertaken in conjunction with a manipulative experiment to determine the effect that heavy metal pollution had on the diversity and invasibility of marine hard-substrate assemblages. The study was repeated at two sites in each of two harbours in New South Wales, Australia. The survey sampled a total of 47 sessile invertebrate taxa, of which 15 (32%) were identified as native, 19 (40%) as NIS, and 13 (28%) as cryptogenic. Increasing pollution exposure decreased native species diversity at all study sites by between 33% and 50%. In contrast, there was no significant change in the numbers of NIS. Percentage cover was used as a measure of spatial dominance, with increased pollution exposure leading to increased NIS dominance across all sites. At three of the four study sites, assemblages that had previously been dominated by natives changed to become either extensively dominated by NIS or equally occupied by native and NIS alike. No single native or NIS was repeatedly responsible for the observed changes in native species diversity or NIS dominance at all sites. Rather, the observed effects of pollution were driven by a diverse range of taxa and species. These findings have important implications for both the way we assess pollution impacts, and for the management of NIS. When monitoring the response of assemblages to pollution, it is not sufficient to simply assess changes in community diversity. Rather, it is important to distinguish native from NIS components since both are expected to respond differently. In order to successfully manage current NIS, we first need to address levels of pollution within recipient systems in an effort to bolster the resilience of native communities to invasion.
Plastic debris constitutes up to 87% of marine litter and represents one of the most frequently studied vectors for marine alien species with invasive potential in the last 15 years. This review ...addresses an integrated analysis of the different factors involved in the impact of plastic as a vector for the dispersal of marine species. The sources of entry of plastic materials into the ocean are identified as well as how they move between different habitats affecting each trophic level and producing hot spots of plastic accumulation in the ocean. The characterization of plastic as a dispersal vector for marine species has provided information about the inherent properties of plastics which have led to its impact on the ocean: persistence, buoyancy, and variety in terms of chemical composition, all of which facilitate colonization by macro and microscopic species along with its dispersion throughout different oceans and ecosystems. The study of the differences in the biocolonization of plastic debris according to its chemical composition provided fundamental information regarding the invasion process mediated by plastic, and highlighted gaps of knowledge about this process. A wide range of species attached to plastic materials has been documented and the most recurrent phyla found on plastic have been identified from potentially invasive macrofauna to toxic microorganisms, which are capable of causing great damage in places far away from their origin. Plastic seems to be more efficient than the natural oceanic rafts carrying taxa such as Arthropoda, Annelida, and Mollusca. Although the differential colonization of different plastic polymers is not clear, the chemical composition might determine the community of microorganisms, where we can find both pathogens and virulent and antibiotic resistance genes. The properties of plastic allow it to be widely dispersed in practically all ocean compartments, making this material an effective means of transport for many species that could become invasive.
The invasive species Melanoides tuberculata (O. F. Müller, 1774) is reported from the open environment from the Czech Republic for the first time. An abundant population was found in the artificially ...heated Skryjský potok, a stream which flows from the cooling reservoir below the Dukovany nuclear power plant. The species is unlikely to occur outside the heated water due to its affinity for warm water.
Prioritization is indispensable for the management of biological invasions, as recognized by the Convention on Biological Diversity, its current strategic plan, and specifically Aichi Target 9 that ...concerns invasive alien species. Here we provide an overview of the process, approaches and the data needs for prioritization for invasion policy and management, with the intention of informing and guiding efforts to address this target. Many prioritization schemes quantify impact and risk, from the pragmatic and action-focused to the data-demanding and science-based. Effective prioritization must consider not only invasive species and pathways (as mentioned in Aichi Target 9), but also which sites are most sensitive and susceptible to invasion (not made explicit in Aichi Target 9). Integrated prioritization across these foci may lead to future efficiencies in resource allocation for invasion management. Many countries face the challenge of prioritizing with little capacity and poor baseline data. We recommend a consultative, science-based process for prioritizing impacts based on species, pathways and sites, and outline the information needed by countries to achieve this. This should be integrated into a national process that incorporates a broad suite of social and economic criteria. Such a process is likely to be feasible for most countries.
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