Spread Of Non-indigenous Species Research Articles

Using biophysical modelling and marine connectivity to assess the risk of natural dispersal of non-indigenous species to comply with the Ballast Water Management Convention

AbstractThe introduction of Marine Non-Indigenous Species (NIS) poses a significant threat to global marine biodiversity and ecosystems. To mitigate this risk, the Ballast Water Management Convention (BWMC) was adopted by the UN International Maritime Organisation (IMO), setting strict criteria for discharges of ballast water. However, the BWMC permits exemptions for shipping routes operating within a geographical area, known as a Same-Risk-Area (SRA). An SRA can be established in areas where a risk assessment (RA) can conclude that the spread of NIS via ballast water is low relative to the predicted natural dispersal. Despite the BWMC's requirement for RAs to be based on modelling of the natural dispersal of NIS, no standard procedures have been established. This paper presents a methodology utilizing biophysical modelling and marine connectivity analyses to conduct SRA RA and delineation. Focusing on the Kattegat and Øresund connecting the North Sea and Baltic Sea, we examine two SRA candidates spanning Danish and Swedish waters. We provide an example on how to conduct an RA including an RA summary, and addressing findings, challenges, and prospects. Our study aims to advance the development and adoption of consistent, transparent, and scientifically robust SRA assessments for effective ballast water management.

Influence of habitat features on the colonisation of native and non-indigenous species

Marine artificial structures provide substrates on which organisms can settle and grow. These structures facilitate establishment and spread of non-indigenous species, in part due to their distinct physical features (substrate material, movement, orientation) compared to natural habitat analogues such as rocky shores, and because following construction, they have abundant resources (space) for species to colonise. Despite the perceived importance of these habitat features, few studies have directly compared distributions of native and non-indigenous species or considered how functional identity and associated environmental preferences drive associations. We undertook a meta-analysis to investigate whether colonisation of native and non-indigenous species varies between artificial structures with features most closely resembling natural habitats (natural substrates, fixed structures, surfaces oriented upwards) and those least resembling natural habitats (artificial materials, floating structures, downfacing or vertical surfaces), or whether functional identity is the primary driver of differences. Analyses were done at global and more local (SE Australia) scales to investigate if patterns held regardless of scale. Our results suggest that functional group (i.e., algae, ascidians. barnacles, bryozoans, polychaetes) rather than species classification (i.e., native or non-indigenous) are the main drivers of differences in communities between different types of artificial structures. Specifically, there were differences in the abundance of ascidians, barnacles, and polychaetes between (1) upfacing and downfacing/vertical surfaces, and (2) floating and fixed substrates. When differences were detected, taxa were most abundant on features least resembling natural habitats. Results varied between global and SE Australian analyses, potentially due to reduced variability across studies in the SE Australian dataset. Thus, the functional group and associated preferences of the highest threat NIS in the area should be considered in design strategies (e.g., ecological engineering) to limit their establishment on newly built infrastructure.

Recent invasion of Ponto-Caspian amphipods in the Masurian Lakeland associated with human leisure activities

Non-indigenous species (NIS) contribute to the decrease of native species’ diversity on a local and global scale. One of Europe’s most significant donors of freshwater invasions is the Ponto-Caspian Region. Following the construction of artificial canals connecting isolated waterbodies and the resulting heavy boat traffic, the Ponto-Caspian Amphipoda started to spread in Europe. Four amphipod species: Dikerogammarus haemobaphes, Dikerogammarus villosus, Pontogammarus robustoides and Chaetogammarus ischnus have invaded the Masurian Lakeland (North-eastern Poland). Based on literature and our data, we studied their distribution in 22 lakes in the region during the years 2001–2016. We analysed their distribution against several water quality parameters and levels of anthropogenic pressure. Our results also present the first records of two new invaders, D. villosus and C. ischnus, in the studied area. We show that the relative abundance and frequency of these two species rapidly increase and, simultaneously, the populations of the earlier invaders, i.e. D. haemobaphes and P. robustoides, decrease. The native species – Gammarus lacustris – seems to be negatively affected by NIS richness, as well as by the proximity of towns. The spread of NIS in the lakes appears to be facilitated by boating and the lower complexity of the shoreline. Our study shows how anthropogenic pressure, especially tourism, can facilitate bioinvasion, jeopardising native biodiversity unless appropriate regulations are implemented.

Non-indigenous seaweeds in the Northeast Atlantic Ocean, the Mediterranean Sea and Macaronesia: a critical synthesis of diversity, spatial and temporal patterns

ABSTRACT 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.

Validated Inventories of Non-Indigenous Species (NIS) for the Mediterranean Sea as Tools for Regional Policy and Patterns of NIS Spread

This work presents refined, updated subregional and regional non-indigenous species (NIS) inventories for the Mediterranean Sea, validated by national and taxonomic experts, with species records observed until December 2020. These datasets will be used as the baselines for the implementation of the Integrated Monitoring and Assessment Programme for the Mediterranean (IMAP) and the Mediterranean Quality Status Report 2023. In total, 1006 non-indigenous species have been found in Mediterranean marine and brackish waters. The highest numbers of NIS were observed in Israel, Türkiye, Lebanon and Italy. Approximately 45 species were categorized as data deficient, either due to lack of consensus on their alien status or the validity of their identification. Polychaeta, Foraminifera and macroalgae were the groups with the highest numbers of controversial species. There was a general increase in the yearly rate of new NIS introductions after the late 1990s, which appears to be slowing down in the last decade, but this may be confounded by reporting lags and differential research efforts. Between 1970 and 2020 there has been a steep increase in the proportion of shared species present throughout all four Mediterranean subregions, which are predominantly transported via shipping and recreational boating. While Lessepsian species are gradually spreading westwards and northwards, there is still a considerable invasion debt accumulating in the eastern and central Mediterranean.

The Effects of Non-Indigenous Macrophytes on Native Biodiversity: Case Studies from Sicily

Biological invasions are widely recognized as a major threat to native biodiversity, ecosystem functioning and services. Non-indigenous species (NIS) may in time become invasive (invasive alien species (IAS)), determining significant environmental, socioeconomic and human health impacts such as biodiversity loss and ecosystem service degradation. The Mediterranean islands, particularly Sicily and the circum-Sicilian islands (northwestern Mediterranean Sea), which are important hotspots of biodiversity, are notably vulnerable to anthropogenic pressures such as biological invasions. Therefore, monitoring NIS distribution as well as understanding their effects on native biodiversity is critical in these areas for planning effective conservation strategies. Here, we report four different case studies from Sicily that highlight how NIS may affect native biodiversity and habitats. The first three case studies were carried out within Marine Protected Areas (MPAs) and highlight (1) the ability of Caulerpa cylindracea to promote the establishment of other NIS, including biofouling worms belonging to the genus Branchiomma; (2) how the shift in habitat from the native Ericaria brachycarpa to the invasive Asparagopsis taxiformis may drastically erode the primary producer biomass and associated biodiversity; and (2) that the presence of Lophocladia lallemandii can affect the molluscan assemblage inhabiting the canopy-forming Gongolaria montagnei. The fourth case study, performed along the northwestern coast of Sicily, shows how Halophila stipulacea can affect the growth of the co-occurring native seagrass Cymodocea nodosa. Overall, these case studies demonstrate various ways in which NIS can interact with native biodiversity and habitats. Furthermore, they emphasize that MPAs are ineffective at preventing the introduction and spread of NIS.

Harnessing decay rates for coastal marine biosecurity applications: A review of environmental DNA and RNA fate

AbstractMarine nonindigenous species (NIS) are spreading at an alarming rate internationally through anthropogenic activities such as shipping and aquaculture, affecting local biodiversity and negatively impacting the ecosystem and human well‐being. Countries and international organizations have recognized this global threat and have begun implementing biosecurity management programs to ensure early detection, effective surveillance, and mitigation of marine NIS spread. Molecular techniques based on environmental DNA and RNA (eDNA/eRNA), collectively referred to as environmental nucleic acids (eNAs), have become a popular noninvasive tool for detecting NIS and monitoring biodiversity locally and globally. However, uncertainties about eNAs detection probabilities and the location of the source population impede the broad uptake of this tool in marine biosecurity programs. It's been hypothesized that most of these uncertainties can be explained by studying the molecules' dynamics within a marine environment and implementing eNAs distribution models. To contribute to further knowledge development in this area, our study reviews data from 20 recent reports on the degradation mechanisms and fate of eNAs in the marine environment. We classified the critical factors influencing eNAs' persistence that should be considered by biosecurity practitioners, outlining the complex interaction between the molecules' degradation processes and particular environmental conditions. To help guide the parameterization of eNAs distribution models, this review also summarizes and standardizes the marine decay rates of eDNA/eRNA from the literature. Finally, this manuscript outlines guidelines to help calculate accurate decay rates to build appropriate “fit‐for‐purpose” marine biosecurity tools for improved target detectability and greater resolution in assessing biodiversity.

Environment and shipping drive environmental DNA beta-diversity among commercial ports.

The spread of nonindigenous species by shipping is a large and growing global problem that harms coastal ecosystems and economies and may blur coastal biogeographical patterns. This study coupled eukaryotic environmental DNA (eDNA) metabarcoding with dissimilarity regression to test the hypothesis that ship-borne species spread homogenizes port communities. We first collected and metabarcoded water samples from ports in Europe, Asia, Australia and the Americas. We then calculated community dissimilarities between port pairs and tested for effects of environmental dissimilarity, biogeographical region and four alternative measures of ship-borne species transport risk. We predicted that higher shipping between ports would decrease community dissimilarity, that the effect of shipping would be small compared to that of environment dissimilarity and shared biogeography, and that more complex shipping risk metrics (which account for ballast water and stepping-stone spread) would perform better. Consistent with our hypotheses, community dissimilarities increased significantly with environmental dissimilarity and, to a lesser extent, decreased with ship-borne species transport risks, particularly if the ports had similar environments and stepping-stone risks were considered. Unexpectedly, we found no clear effect of shared biogeography, and that risk metrics incorporating estimates of ballast discharge did not offer more explanatory power than simpler traffic-based risks. Overall, we found that shipping homogenizes eukaryotic communities between ports in predictable ways, which could inform improvements in invasive species policy and management. We demonstrated the usefulness of eDNA metabarcoding and dissimilarity regression for disentangling the drivers of large-scale biodiversity patterns. We conclude by outlining logistical considerations and recommendations for future studies using this approach.

Global Impacts of a Bilateral Trade Policy on Ballast Water-Mediated Species Spread Risk: A Case Study of Sino-US Trade.

A trade policy could generate both economic and environmental impacts. This work is focused on the impacts of a bilateral trade policy on ballast water-mediated nonindigenous species (NIS) spread risk. Taking the hypothetical Sino-US trade restriction as an example, we integrate a computable general equilibrium model and a higher-order NIS spread risk assessment model to examine the impacts of bilateral trade policy on both the economy and NIS spread risks. We have two important findings. First, the Sino-US trade restriction would cause decreases in NIS spread risks to China and the US, as well as to three quarters of worldwide countries/regions. However, the rest one fourth would experience increased NIS spread risks. Second, the relationship between changes in exports and changes in NIS spread risks might not be directly proportional. This is observed with 46% of countries and regions that would see their exports increase but their NIS spread risks drop, with positive impacts on both their economies and environment under the Sino-US trade restriction. These results reveal both broader global impacts as well as the decoupled economic and ecological impacts of a bilateral trade policy. These broader impacts demonstrate the necessity for national governments, which are parties to bilateral agreements to give due consideration to the economic and environmental impacts on countries and regions outside of the agreement.

Location and building material determine fouling assemblages within marinas: A case study in Madeira Island (NE Atlantic, Portugal)

Marinas are hubs for non-indigenous species (NIS) and constitute the nodes of a network of highly modified water bodies (HMWB) connected by recreational maritime traffic. Floating structures, such as pontoons, are often the surfaces with higher NIS abundance inside marinas and lead the risk for NIS introduction, establishment and spread. However, there is still little information on how the location within the marina and the substratum type can influence the recruitment of fouling assemblages depending on water parameters and substratum chemical composition. In this study, fouling recruitment was studied using an experimental approach with three materials (basalt, concrete and HDPE plastic) in two sites (close and far to the entrance) in two marinas of Madeira Island (NE Atlantic, Portugal). The structure of benthic assemblages after 6- and 12-months colonization, as well as biotic abundance, NIS abundance, richness, diversity, assemblages' volume, biomass and assemblages' morphology were explored. Differences between marinas were the main source of variation for both 6- and 12-month assemblages, with both marinas having different species composition and biomass. The inner and outer sites of both marinas varied in terms of structure and heterogeneity of assemblages and heterogeneity of morphological traits, but assemblages did not differ among substrata. However, basalt had a higher species richness and diversity while concrete showed a higher bioreceptivity in terms of total biotic coverage than the rest of materials. Overall, differences between and within marinas could be related to their structural morphology. This study can be valuable for management of urban ecosystems, towards an increase in the environmental and ecological status of existing marinas and their HMWB and mitigation coastal ecosystems degradation.

Fouling bryozoans in Argentine harbours (Southwest Atlantic): new records and the description of a new species

Non-indigenous bryozoans are frequent components of biofouling assemblages in harbour environments worldwide. We performed a survey of artificial hard substrates in six harbours spanning 16 degrees of latitude along the coast of Argentina, from Ingeniero White (38º47' S) to Ushuaia (54º48' S). Microeciella argentina n. sp., distributed in warm-temperate waters of northern Patagonia and Buenos Aires Province, is described. The non-indigenous species (NIS) Callopora dumerilii, Smittoidea spinigera and Stephanollona boreopacifica are recorded here for the first time in the Southwest Atlantic. Their occurrence in fouling assemblages of warm-temperate harbours and their previous absence in these areas suggest that they probably arrived in Argentina by international shipping traffic. Callopora dumerilii is native to Europe and the northeast Atlantic. Smittoidea spinigera and Stephanollona boreopacifica are native to China and Korea, respectively. The morphological differences between S. spinigera and the Californian species S. prolifera, which is invading European harbours in the North Sea, are discussed. Bugula neritina, Bugulina flabellata, Cryptosula pallasiana and Fenestrulina delicia, common in harbours of Buenos Aires Province, are here recorded in Patagonia, highlighting the importance of regional shipping traffic to secondary spread of NIS. Arachnidium fibrosum, Buskia socialis, Anguinella palmata, Aetea cultrata, Bicellariella edentata and Exochella moyanoi, previously known from Brazil, and Hippothoa divaricata, are here recorded in Argentina. This study shows that warm-temperate harbours in Buenos Aires Province and northern Patagonia are particularly prone to the introduction of non-indigenous bryozoans.

Short-term colonization of fouling communities within the port of Livorno (Northern Tyrrhenian Sea, Western Mediterranean): Influence of substrate three-dimensional complexity on non-indigenous species establishment

The influence of substrate morphology on early stages of fouling development was assessed through submerged experimental substrates with different morphological complexity. The experiment was carried out within commercial and touristic harbours of the port of Livorno (Italy), analysing the communities at three steps of colonization (14, 28, 42 days). We assessed the effect of substrate complexity on recruitment of non-indigenous species (NIS), combined with the influence of port use destinations. NIS were recorded in both use destination areas since the first step of colonization. Substrate morphological complexity significantly affected fouling colonization and particularly NIS assemblages. We found that high-complexity substrates are particularly suitable for NIS establishment in comparison with less complex ones. The touristic harbour exhibited a potential for fouling colonization higher than the commercial harbour. These results contributed to the understanding of factors involved in NIS establishment and spread, as well as in their spatial-temporal dynamics within port environments.

The First Record of Non-Indigenous Cladoceran Evadne nordmanni Lovén, 1836 (Cladocera, Podonidae) in the Middle Part of the Caspian Sea

The introduction and spread of non-indigenous species may have ecological, environmental and economic impacts where they invade. This work aims to study the morphological characteristics, the quantitative variables, the possibility of coexistence with other native species and the pathways of introduction of non-indigenous cladoceran Evadne nordmanni (Lovén, 1836) in the middle part of the Caspian Sea. Ballast water is a possible vector for the introduction of cladoceran Evadne nordmanni into the Caspian Sea. The abundance of Evadne nordmanni in all surveyed areas reached an average of 799 individuals/m3. Its biomass was 257.58 mg/m3. Evadne nordmanni significantly contributes to the abundance and biomass of zooplankton in the Middle Caspian Sea. The proportion of the dominant calanoida Acartia tonsa decreased from 71–90% to 40% with the appearance of Evadne nordmanni. Further investigations are needed to analyze the responsible route of Evadne nordmanni introduction to the Caspian Sea and its consequences on biodiversity; since this species is a predator and could have consequences on the feeding conditions of planktivorous fish in the Caspian Sea.

Marine species introduction via reproduction and its response to ship transit routes

AbstractThe introduction of nonindigenous species (NIS) threatens global ecosystems and results primarily from human transportation and trade activities. Although some NIS can disperse immediately upon arrival (for example, mobile species), actual inoculation for other (sessile) species can require a reproductive event to produce propagules that disperse and establish. NIS reproductive potential, however, can vary with environmental conditions experienced during transit and upon arrival that differ substantially by route. We propose that variation in reproductive responses, both across species and transit routes, is a critical but overlooked driver of species invasions. We illustrate these concepts using vessel biofouling organisms, which are exposed to vastly different conditions during transport across the world’s oceans. Current knowledge gaps prevent precise predictions of the potential for species to be introduced via reproduction. Integrating reproductive potential into management strategies is key to limiting NIS spread, particularly as climate change and novel events continue to alter global transportation networks.Front Ecol Environ 2022;

From Plates to Baits: Using a Remote Video Foraging System to Study the Impact of Foraging on Fouling Non-Indigenous Species

Marinas are a gateway for the introduction and establishment of non-indigenous species (NIS). In these habitats, competition and predation are crucial determinants for NIS establishment and invasiveness. However, fish trophic preferences and biotic effects inside marinas are poorly known. This study proposes a novel method that combines the deployment of settlement plates to recruit different assemblages, followed by their use as bait in remote underwater video systems. This combined approach, addressed as a remote video foraging system (RVFS), can record fish foraging behaviour, including feeding choices and their impacts on fouling assemblage composition. An experimental RVFS trial carried out in a marina of Madeira Island, Portugal (NE Atlantic), identified the Mediterranean parrotfish, Sparisoma cretense, as the most important fouling grazer in the area. S. cretense behaved as a generalist and increased the heterogeneity of fouling assemblages, which can hamper NIS dominance of the fouling and reduce the pressure of propagules from the marina to the natural environment. The RVFS tool was useful to understand the trophic links between foragers and fouling and has the potential to provide relevant information for the management of NIS introductions, establishment and spread.

The invasive species Rangia cuneata: A new food source for herring gull (Larus argentatus)?

AbstractContinued human population growth and the associated development of coasts lead to dramatic effects on marine coastal ecosystems altering food resources and habitats for several species and resulting in novel species interactions. The Bay of the Seine, located in the eastern part of the English Channel, is one of the most anthropized sea in the world. Here, we report an observation of the European herring gulls (Larus argentatus) feeding on the nonindigenous species (NIS) Rangia cuneata in the Bay of the Seine. Observations of otter prints (Lutra lutra) and excrements were also found near the bivalves, suggesting that this species also feed on the NIS bivalve. Our study suggests that the spread of NIS in coastal marine ecosystem is expected to drive changes in the foraging behavior of top predators.

Rapid niche shifts as drivers for the spread of a non‐indigenous species under novel environmental conditions

AbstractAimIdentifying niche shifts is key for forecasting future species distributions. Non‐indigenous species (NIS) are one of the greatest threats to biodiversity, and understanding how niche shifts affect the spread of NIS is fundamental. Here, we modelled the native and introduced niches, as well as the potential geographical extent of a widely distributed NIS, the Pacific oyster Magallana gigas. We then tested for niche shifts in environmental space and predicted spread under contemporary climate change (CCC) conditions.LocationGlobal.MethodsWe used: (1) the two‐dimensional Centroid shift, Overlap, Unfilling and Expansion (COUE) framework and (2) the n‐dimensional hypervolume framework (NDH) to quantify the niches in both analogue and total environmental spaces. Niches were tested for equivalency by comparing the observed and randomized overlaps. Ensemble ecological niche models (ENMs) were then used to predict habitat suitability for the present‐day and two future CCC scenarios.ResultsThe NDH framework indicated that the introduced niche of M. gigas has shifted into new environmental conditions compared to the native niche. In contrast, COUE framework implied no niche shift, but the first two dimensions only accounted for a small proportion of the overall environmental variability. Ensemble ENMs revealed suitable areas where M. gigas has yet to be recorded and predicted both a poleward expansion and a tropical contraction of suitable habitat for M. gigas by 2100.Main conclusionsWe found that M. gigas has rapidly shifted its niche in both analogue and non‐analogue environmental spaces since it was first recorded as introduced species over 50 years ago. Our results suggested that niche shifts facilitate both present‐day and future spread of NIS. Additionally, our study demonstrated the importance of modelling niche dynamics in multidimensional space for predicting range shifts of NIS under CCC.

The role of marinas in the establishment and spread of non-indigenous species in Baltic Sea fouling communities

The study included the sampling of 12 marinas across six areas of the Baltic Sea with settlement plates and scraping of submerged structures to assess the role of marinas in the spread of non-indigenous species (NIS) via biofouling. 15 NIS were detected in the marinas and secondary spread of previously introduced NIS was detected in five out of six sea areas. Salinity and sea area significantly affected the composition of the fouling assemblages. Settlement plates appeared as the more efficient sampling method over scraping, while the seasonal analyses revealed that the monitoring effort should span over the summer and early autumn in the south-eastern, central, and northern Baltic Sea. The present findings indicate that marinas contribute to the spread of non-indigenous fouling organisms, and there is an increasing demand for the monitoring of marinas and stricter regulations regarding the biofouling management of leisure boats in the Baltic Sea.

Monitoring non-indigenous macroalgae in a Mediterranean MPA: Lessons from a short-temporal variability of pristine habitats invasion

Since there is no local management for Marine Protected Areas (MPAs) to prevent the establishment of macroalgae NIS, successful efforts to contrast their spread probably should concentrate in the conservation of resistant habitats. The study aimed to evaluate the role of depth and habitat in the spread of macroalgal non-indigenous species (NIS). A multifactorial sampling design was employed to compare the abundance of NIS macroalgae over a one-year period across different substrates and depths within a Mediterranean MPArea. Moreover, the ecological quality of macroalgal assemblages in relation to invasion was assessed through the ALien Biotic IndEX (ALEX). The NIS macroalgae found in the MPA, Caulerpa cylindracea, Acrothamnion preissii, Womersleyella setacea and Falkenbergia sp., were overall quite low in abundance and, accordingly, the ALEX index had generally high values. The substrate, depth and time significantly affected NIS abundance; however, the lack of significant interannual variability (December 2018–December 2019), both in pooled and separated NIS abundance, suggested that the occurrence of these four NISs will no further expand in the MPA at the scale of habitat. The highlighted patterns in NIS abundance suggest the importance of detailed sampling designs of monitoring taking into consideration different habitats and depths and using suitable sampling methods to assess NIS establishment and spread, such as those required by international directives.

Are they always bad? Assessing benefits of non-indigenous species in aquatic environment and their implications

Non-indigenous species (NIS), non-native, or alien species are any organisms living and spreading outside their natural habitat. Many of NIS spread to a new environment accidentally, while some other species are intentionally introduced by humans to a new habitat in many different pathways, as follows: 1) release; 2) escape; 3) contaminant; 4) stowaway; 5) corridor; and 6) unaided. Threaten native biodiversity may be the most problematic impact of NIS. They can also disrupt food-web organizations and affect the ecosystem structures. Additionally, the problem is exacerbated by disagreements regarding whether or not NIS should be permitted for aquaculture production. The likelihood of NIS escaping, being released from aquaculture, and establishing in its native habitat poses a significant threat to the ecosystem and biodiversity. NIS also have positive impacts as ecosystem engineers which may increase the biodiversity of native communities. Other benefits of NIS include providing an alternative food source and supporting fisheries and aquaculture sectors. Understanding the introduction process and the impacts of NIS should be supported by effective policy frameworks and management approaches, including risk assessment, prevention and control, pathway and vector management, early detection and rapid response, eradication, and mitigation and restoration. Furthermore, the crucial efforts would be raising public awareness, improving scientific research, and developing strategy regarding biosecurity issues as consequences of the emergence of interactions complexity among NIS and other global ecological change drivers.