Sava River Basin Management Plan Background paper No. 7 Invasive alien species March 2013 Supported by the Sava River Basin Management Plan Table of Contents 1 Introduction ........................................................................................................................ 1 2 Identification of main invasion gateways, routes and corridors in Europe ................................................................................................................................... 2 3 Sources of information regarding the Sava River Basin .................................. 4 4 References ............................................................................................................................ 7 List of Figures Figure 1: Main European invasive corridors (Panov et al., 2009) ............................................ 3 Figure 2: Assessment units within Southern Invasion Corridor ............................................... 4 List of Annexes Annex 1: List of Terms/Definitions Annex 2: List of pathways of IAS introductions in Europe with descriptors for assess- ment of pathways, currently operating in the assessment unit (Minchin et al. 2007, modified) Annex 3: The draft list of IAS within Sava RB (based on the DAISIE list of the worst in- vasive alien species in the Danube River Basin and Black Sea) Background paper No.7: Invasive alien species Sava River Basin Management Plan 1 Introduction During the last century, there is an increasing concern in relation to the mainly human- aided dispersal of species beyond their natural range of distribution. Humans have served as both accidental and deliberate dispersal agents of biota for over 500 years. The consequences of biological invasions are diverse and can alter fundamental ecologi- cal properties such as dominant species in a community, productivity, nutrient cycling and thus can alter the structure and function of the ecosystem (Mack et al. 2000). An- thropogenic distribution of plants and animals is considered within the major threats to the biodiversity (Grigorovich et al. 2003). Aquatic ecosystems are not exception con- cerning this aspect of disturbance. Ballast water of ships, deliberate fish stocking and in- troduction into aquaculture were pointed as prospective agents of dispersal of non- indigenous fish species (Gherardi et al. 2009). The purpose of this document is to give the basic information on the state of the art of knowledge on alien aquatic species within the Sava River Basin, as well as the develop- ment of the methodology of the risk assessment. Having in mind gaps in our knowledge about the distribution and abundance of invasive alien species, their influence to native biota, as well as the current gaps in addressing in- vasive alien species in European river basin management, there is an apparent need for basin-wide actions to deal properly with this issue. Parts of European inland waterways that are highly biologically contaminated are prob- ably irreversibly changed with respect to composition of fauna and flora. Some commu- nities are now dominated by alien species. In some water bodies alien-dominated com- munities have shown very stable composition of dominant species for over a decade. Ac- cording to Arbačiauskas et al. (2008) such newly established communities may be de- fined as xenocommunities, in analogy to xenodiversity (Olenin at al. 2007). Canals can provide conduits for species to spread between previously separate biogeo- graphic regions either by active movement, drift and/or as a result of ship transport (bij de Vaate et al., 2002; Galil et al., 2007). Categorization of species as indigenous (i.e., native) or non-indigenous (i.e. alien) is not a routine work. Owing to the huge and long-term historical global movements of the biota, human-aided and natural, as well as due to the lack of relevant data that would either support or disprove classification of particular taxa as native or alien, it is clear that there are many species that cannot be reliably assigned to either category. Alien species are those that take up residence in a biogeographical area, such as a river catchment, where they were previously unknown (Arbačiauskas et al. 2008). The alien invasive species is defined as an alien that becomes established in natural or semi natural ecosystems or habitat that is an agent of change and threatens native bio- logical diversity. In their native habitat, where they have genetically and ecologically evolved, these organisms may not be a high risk proposition. However, when aquatic and terrestrial species are transported to ecosystems outside their established range, problems can be caused for native organisms, disturbing the balance of natural commu- nities by altering the populations, the community structure, ecosystem structure and function. There are several different terms used for those taxa that are newly occurring in a cer- tain geographical area: Background paper No.7: Invasive alien species 1 Sava River Basin Management Plan The species that are not demonstrably native or introduced are defined as crypto- genic (Panov et al 2009). This case introduction of an organism(s) is the deliberate or unintentional (accidental) transfer and/or release, by direct or indirect human agency into the wild, or into locations in geographical areas that are not completely isolated from the surrounding environment. The taxa (species, subspecies, race or variety) are not native and the invasion is a collection of events and processes re- lated to appearance and impacts on communities and ecosystems of alien species. Translocation is the introduction of a species from one part of a political entity (country) in which it is native to another part of the same country in which it is not native. Native or indigenous refers to taxa that occur naturally in a geographical area, with dispersal occurring independent of human intervention, whether direct or indirect, intentional or unintentional. Non-native or non-indigenous refers to a taxa that does not occur naturally in a ge- ographical area, i.e. it did not previously occur there or its dispersal into the area was mediated or facilitated directly or indirectly by humans, whether deliberately or unintentionally; invasive organisms are native or alien species that spread, with or without the aid of humans, in natural or semi-natural habitats, producing a sig- nificant change in composition, structure, or ecosystem processes, or cause severe economic losses to human activities. Acclimatized species (or taxa) are those that are able to complete part or most of their life cycle in the wild in an alien environment or climate, but are unable to re- produce and sustain a population without the support of humans. Naturalized refers to a non-native taxa that, following introduction, has established self-sustaining populations in the wild and has been present of sufficient duration to have incorporated itself within the resident community of organisms, achieving or overcoming geographical, environmental and reproductive barriers. Vagrant refers to taxa that, by natural means, moves from one geographical region to another outside its usual range, or away from usual migratory routes, and that do not establish a self-sustaining population in the visited region. Casual refers to introduced species that is unable to sustain without human aid despite its obvious ability to reproduce its population. 2 Identification of main invasion gateways, routes and corridors in Europe Four principal invasion corridors in Europe have been identified (Panov et al. 2009 - Figure 1): The Northern corridor: linking the Black and Azov seas with the Caspian Sea via the Azov - Caspian waterway including the Volga-Don Canal, and with the Baltic and White seas via the Volga-Baltic waterway including the Volga-Baltic Canal, and the White Sea - Baltic Sea waterway, including the White Sea - Baltic Sea Ca- nal. Background paper No.7: Invasive alien species 2 Sava River Basin Management Plan The Central corridor: connecting the Black Sea with the Baltic Sea region via Dnieper and Bug-Pripyat Canal, with Nemunas River branch connected to Pripyat and Bug by Oginsky and Augustov canals, correspondingly. The Southern corridor: linking the Black Sea basin with the North Sea basin via the Danube-Main-Rhine waterway including the Main-Danube Canal. The Western corridor: linking the Mediterranean with the North Sea via the River Rhône and the Rhine-Rhône Canal. Figure 1: Main European invasive corridors (Panov et al., 2009) These principal corridors are interlinked via two additional invasion corridors: the Southern meridian corridor linking the Northern, Central and Southern corridors on the south, and the Northern meridian corridor, linking the Northern, Central, Southern and Western on the north (Figure 1). This complex system of navigable waterways and inva- sion corridors can be considered as an European inland water invasion network (Figure 1), with estuaries of large European rivers (Don, Danube, Dnieper, Neva, Odra, Rhine) and lagoons (Curonian, Vistula) serving as entries to the main invasion corridors and considered as “invasion gateways”. The Sava River has been defined as a branch of Southern Invasive Corridor (Panov et al. 2009) – see Assessment unit 9 at Figure 2, which underline that the river is under the high invasive pressure. Background paper No.7: Invasive alien species 3 Sava River Basin Management Plan Figure 2: Assessment units within Southern Invasion Corridor 3 Sources of information