Introduction

The introduction of non-native species (NNS) is widely recognized as one of the main threats to aquatic biodiversity (Katsanevakis et al. 2014, Roy et al. 2019), and it also impacts human wellbeing (Bacher et al. 2018). The Balkan Peninsula (hereafter Balkans) is considered one of the world biodiversity hotspots (Mittermeier et al. 2011) and, alongside the Iberian and Apennine Peninsulas, harbours vast genetic and species diversity (Hewitt 2011). Many aquatic animals are long-established in the Balkans, though there are numerous recently introduced species, even in isolated lakes (Bănărescu 2004, Piria et al. 2018). The Mediterranean Sea is also a hotspot of biodiversity (Coll et al. 2010), and NNS introduction, as one of the main threats, may disrupt its ecosystem structure and function (Sabelli & Taviani 2014, Slišković et al. 2021). In recent decades, increasing reports of NNS in the Mediterranean and Adriatic Sea have been made, suggesting this could soon be a serious threat to native biodiversity and the natural environment (Zenetos et al. 2012, Katsanevakis et al. 2013, Slišković et al. 2021).

Across Europe, a wide range of policies, legislation, and management approaches (including public awareness initiatives) have been developed to address the issue of NNS and invasive alien species (IAS) (see Copp et al. 2005 for definition). Regulation (EU) no. 1143/2014 of the European Parliament and of the Council on the prevention and management of the introduction and spread of invasive alien species (hereinafter the Regulation) came into force from 2015 (January 1^st) with the aim of laying down rules to prevent, minimize and mitigate adverse impacts on biodiversity from the introduction and spread of invasive alien species within the Union, both intentional and unintentional (EC 2014). The Regulation also includes an initial list of Invasive Alien Species of Union concern (2016) with two updates (2017 and 2019; EC 2014, 2016, 2017, 2019). Member States (MS) are required to take action on pathways of unintentional introduction, to take measures for the early detection and rapid eradication of these species, and to manage species that are already widely spread in their territory ( https://ec.europa.eu/environment/nature/invasivealien/list/index_en.htm) (Piria et al. 2017). In several European countries, lists of alien species have been compiled (e.g. Belgium, Portugal, UK (Boon et al. 2020)), and an inventory of alien species present in Europe has been established by the European Alien Species Information Network (EASIN) (Katsanevakis et al. 2012).

However, it is still not known whether this Regulation has prompted further actions in non-EU Balkan countries. Non-EU bordering countries are not obliged to enforce EU laws concerning NNS, potentially leaving open invasion corridors (Hulme 2015, Piria et al. 2017). In most non-EU Balkan countries, a lack of effective measures to control the introduction or translocation of NNS has been identified (Piria et al. 2017). Issues associated with IAS are cross-border and cannot be managed exclusively at the intra-EU level, as Member States along the EU borders may potentially be at greater risk of new bio-invasions via their non-EU neighbours (EC 2008). Common ground in the implementation of legislation between the EU and its neighbouring countries has been proposed (Piria et al. 2017), but as yet not developed. NNS and biodiversity are generally of low priority on the political agendas of many countries, and this hampers the implementation of EC directives and/or regulations (Piria et al. 2017). In addition, cross-border management of IAS between EU and non-EU countries is poorly funded and fragmented in nature, which limits the extent or impedes the existence of NNS monitoring projects for early warning and rapid response systems at a pan-European level. Finally, the lack of coordination of scientific effort and dialogue between public institutions on IAS between EU and non-EU countries has been identified as a major drawback in the implementation of cross-border legislative action (Piria et al. 2017, Rak et al. 2019).

The topic of biological invasions is relatively new in education, and has only recently come to the attention of environmental educators (Verbrugge et al. 2021). There is still a general lack of environmental science programmes at primary and secondary school levels and in some university curricula, especially concerning invasion biology and native biodiversity (Piria et al. 2017). However, environmental education can play an important role by providing relevant learning outcomes and experiences for students and professionals in different sectors associated with introduction pathways or those involved in the mitigation and eradication of IAS (Verbrugge et al. 2021).

Many non-native taxa are known to have socioeconomic impacts, affecting different aspects of human wellbeing (security; material and non-material assets; health; social, spiritual, and cultural relations; freedom of choice and action; Bacher et al. 2018), and to generate considerable environmental and economic losses (dos Santos et al. 2019, Cuthbert et al. 2021). Understanding public perceptions of IAS is crucial for understanding behaviour and developing effective management strategies to maintain, preserve and improve biodiversity, ecosystem services and human wellbeing (Shackleton et al. 2019a). Socio-economic perception of IAS and NNS in the Balkan countries that are EU member candidates is still unknown and needs to be addressed as soon as possible.

The main aim of this paper was to survey the policy-level documents and principles addressing NNS in the Balkans. Also, education and socio-economic perceptions regarding NNS in the Balkans were assessed and opportunities for policy development and implementation of risk management for NNS in the Balkans are discussed.

Material and Methods

The questionnaire was prepared under Work Package 1 of the ERASMUS+ project ‘’Educational capacity strengthening for risk management of non-native aquatic species in the Western Balkans (Albania, Bosnia and Herzegovina, and Montenegro) (see Acknowledgements) and comprised 21 questions addressing four areas (Table 1): A) policy, B) general environmental perception, C) educational issues, and D) socioeconomic perception. Specific questions related to environmental definitions and specific education were modified according to Boon et al. (2020) and Smith et al. (2011).

The questionnaire was completed by experts from 11 institutions located in EU candidate and potential candidate countries (hereinafter EU candidate countries) in the Balkans (Albania, Bosnia and Herzegovina, Montenegro, North Macedonia and Turkey), Balkan EU Member States (Croatia and Greece), and one non-Balkan EU Member State (Italy). Bosnia and Herzegovina is a potential candidate country whose application was endorsed by the EU in December 2019 ( https://ec.europa.eu/neighbourhood-enlargement/countries/detailed-country-information/bosnia-herzegovina_en). The questionnaire was completed by two different institutions from each of the three EU candidate countries (Albania, Bosnia and Herzegovina and North Macedonia) and the text was then summarized and compiled into one document per country. Only one institution from the other two EU candidate countries (Montenegro and Turkey) and the Balkan (Croatia and Greece) and non-Balkan EU Member States (Italy) completed the questionnaire.

Table 1.

Content of the questionnaire on alien species policy, education, and socio-economic issues.

Results

The responses of each country are presented in Table S1.

Discussion

The EU Regulation affects EU Member States and candidate countries by encouraging the development of activities concerning aquatic NNS in education, research, and citizen science initiatives, though this not has developed uniformly in the countries surveyed. Nevertheless, it is important to underline that as only one or two institutions per country were involved in this survey, the finding from the questionnaire may not be fully representative of the true situation.

Based on the results of this survey, countries with a coastline seem more focused on marine than freshwater environments. Citizen science initiatives on NNS are well developed in marine ecosystems in Greece (Perdikaris et al. 2017, Zenetos 2017, Giovos et al. 2019) and have begun in Albania (Tanduo et al. 2020) and Turkey (Huseyinoglu et al. 2021). Montenegro seems to be focusing NNS research and education toward the marine environment, while Bosnia and Herzegovina is focused mainly on freshwater. Bosnia and Herzegovina is considered a Mediterranean country, despite having only 20 km of coastline, but research and protection efforts towards the marine environment remain underdeveloped.

The EU Regulation has been implemented in the EU Member States (Italy, Greece and Croatia) and in Montenegro as an EU country candidate. Candidate countries are not obliged to strictly follow all EU regulations, though in this regard, Montenegro appears to be better prepared than other EU candidate countries for further implementation and development of the IAS strategy. Besides, Montenegro borders on Albania and Bosnia and Herzegovina and shares inland waters and a marine coastline with these countries. In turn, Albania and Bosnia and Herzegovina border on EU Member States (Croatia and Greece) that share river basins (e.g. the Black Sea Basin) and marine territory, which could enable the entry of IAS into EU waters. Such open invasion corridors highlight the urgency for a consensus on law enforcement and the need for a joint IAS strategy (Piria et al. 2017).

Both EU Member States and candidate countries are party to the CBD. Similarly, all countries with a coastline, except Bosnia and Herzegovina, are party to the BWM, allowing for action towards managing NNS via shipping. The BWM and the Regulation were developed in parallel, though the BWM did not make any cross reference to NIS or IAS environmental legislation, which was neither amended nor integrated to address the new environmental aspects needed for implementation (Rak et al. 2019).

The definition of NNS of Montenegro is regulated by policy acts and corresponds to the NNS definition stipulated in the policy acts of Croatia. However, in other Balkan countries, as in the EU Member States, there is no consistent definition of NNS (Boon et al. 2020). Furthermore, EU candidate countries, with the exception of Bosnia and Herzegovina, responded that native species that have expanded their range as a result of climate change are considered as NNS, contrary to the recently surveyed EU Member States (Boon et al. 2020).

National lists of alien species are still in the initial stages in EU candidate countries in the Balkans. Albania and Montenegro have included noninvasive NNS on their lists. A similar response was also given by Greece, a Member State. These results correspond with those obtained by Boon et al. (2020) who stated that countries do not restrict their consideration to IAS, and some countries (e.g. Spain) place more attention on species that are known to be invasive compared with those that are not. An additional problem with Bosnia and Herzegovina's IAS list is its complex governmental structure and lack of national legislation (Hitchner 2006). Thus, the list is only partially developed for the Federation of Bosnia and Herzegovina and does not include the Republic of Srpska.

Monitoring programmes specifically designed for alien species are generally lacking in Europe (Boon et al. 2020). The establishment of such activities is most often constrained due to a lack of funding (Piria et al. 2017). However, another problem in EU candidate countries is likely to be the low priority of environmental issues in comparison to economic welfare (Popović & Erić 2018). Nevertheless, several EU candidate countries are working on project-based monitoring activities (e.g. Turkey, Montenegro) although without any clear indication as to its permanence. Bosnia and Herzegovina and Albania still need to invest greater efforts in NNS project development, as no such projects have been identified.

The use of Risk Management Tools like AS-ISK is limited to academic institutions in both Member States and candidate countries (Simonović et al. 2013, Piria et al. 2016, Tarkan et al. 2017, Radočaj et al. 2021). Although the tool is available in almost all local languages (Copp et al. 2021) to facilitate Risk Assessment, in the field, risk management of NNS has not been conducted in any of the countries surveyed.

Educational preparedness addressing NNS was identified as poor in all countries covered by the questionnaire. Countries address NNS through educational courses related to project activities that represent the main educational practices. Albania, Bosnia and Herzegovina, Croatia and Turkey, organise undergraduate and master/PhD lectures on ecological and/or socio-economic impacts of NNS and IAS, but despite this it appears the educational preparedness is underdeveloped. According to Verbrugge et al. (2021), the main challenges for IAS education are related to the inconsistent and ambiguous terminology, communicating risk, implementing education materials, and evaluating learning outcomes. Possible topics may cover the identification, distribution and environmental biology of NNS as well as the risks associated with NNS introduction, establishment, dispersal and impacts on native species and ecosystems. Recent studies have identified examples of best practice, such as the use of smartphone applications and gaming elements, place-based education and exhibitions. The importance of open access publishing of educational materials to make them readily available was also identified (Verbrugge et al. 2021). The range of educational activities related to NNS issues could also involve summer schools, workshop activities and master classes for local school groups, as well as participation in local “citizen science” initiatives (e.g. Dickinson et al. 2010, Cardoso et al. 2017, Piria et al. 2017, Mannino & Balistreri 2018). Novel, user-friendly educational materials and tools should be developed to support the inclusion of IAS in education, either in formal or informal contexts (Verbrugge et al. 2021). The lack of formal education about NNS and the consequent low awareness of their overall impact on biodiversity and local economies may have serious implications for decision-making, such as commensurability (e.g. the impacts in natural ecosystems may be valued as more important than those in other ecosystems), context-dependency (e.g. the impacts of alien species may be valued differently inside or outside the region of interest), or personal decision biases that can lead to conflicts in NNS valuation and management (Piria et al. 2017). Public educational approaches could help to improve citizen knowledge and management, with some differences due to socio-demographic factors (Li et al. 2021). Pressure from a well-informed public could drive political actions vital to improving policy and management practices on IAS (Piria et al. 2017 and references within). Improving the design and implementation of public education could contribute to effective communication among stakeholders and the long-term management of IAS (Li et al. 2021).

In all the countries surveyed, public awareness of invasive species is not well developed and recognition of the economic value and market recognition of newly established invaders, with the potential to become commercially important, remains low. However, a good proportion of the NNS species have become established and are now economically valuable. A good example is rainbow trout Oncorhynchus mykiss in freshwaters. Citizens in Europe in general, as well as in the Balkans perceive this species as native (Kochalski et al. 2019). In addition, it is perceived as a benefit for aquaculture and well-being, but is also recognized as high risk in inland waters and the species is possibly responsible for the decline of endemic species in the Mediterranean region due to its predation (Piria et al. 2018, Radočaj et al. 2021). There is a lack of research and knowledge in Europe about the role of invasive species on livelihoods and human wellbeing and only a few case studies have focused on marine or freshwater ecosystems (Shackleton et al. 2019b). Several species are recognized as having the potential to benefit the economy, such as blue crab (Mancinelli et al. 2017) or marine species, such as rabbitfish and dusky spinefoot (Patrick Saoud et al. 2008). However, the problem remains with species without any commercial value (e.g. jellyfishes, pufferfishes), with which people (e.g. anglers) have had negative experiences (e.g. Ameiurus sp.), or which are not valued as a valuable food item (e.g. gibel carp). The impacts on livelihoods of invasive species are highly variable and depend on the socio-ecological context. These negative implications can reduce the resilience and adaptive capacity of households and communities thereby increasing their vulnerability to change. Hence, efforts for managing invasive species need to safeguard livelihoods while mitigating negative impacts (Shackleton et al. 2019b).

Some economic and financial losses arising from IAS have been reported in EU candidate countries. Albania and Montenegro referred to losses caused by marine IAS, North Macedonia to freshwater IAS, and Turkey both marine and freshwater. However, these losses are only based on complaints from fishermen and citizens, and in most of cases have not yet been fully evaluated. In general, aquatic IAS costs are likely considerably underrepresented and underreported compared to those of terrestrial IAS. It is expected that costs associated with IAS will increase over time and are expected to continue rising with future invasions (Cuthbert et al. 2021).

Although the EU Directive is in force, EU Member States covered by this research still need further NNS implementation in practice, and the development of good quality education is highly recommended. The majority of EU candidate countries in the Balkans do not possess any clear strategy or relevant acts for NNS and a lack of awareness and education were identified as critical for future NNS/IAS management. With joint effort and good communication, the development of sound programmes for management and education is essential to increase public awareness and prevent further biodiversity losses.