Alien cyanobacteria an unsolved part of the “expa

Authors: Elżbieta WilkWoźniak Wojciech Solarz Kamil Najberek Agnieszka Pociecha

Publish Date: 2015/07/16

Volume: 764, Issue: 1, Pages: 65-79

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Abstract

Some algal species have extended their native range Problems in settling on a proper definition of ‘alien’ for microorganisms have made it difficult to unequivocally assess whether their spread was natural or resulted from human intervention As direct evidence seems to be virtually nonexistent the only option is to rely on circumstantial evidence In this paper we discuss the expansion routes of three cyanobacteria species Cylindrospermopsis raciborskii Raphidiopsis mediterranea and Cuspidothrix issatschenkoi We analyse the information available for these species which are commonly regarded as alien in order to establish the context in which the migration and evolution of these microorganisms should be understood so that a proper assessment of their geographic expansion can be made A more complete picture of the expansion and evolution of microorganisms must combine many types of information including the history of local expansions ecological ranges and data from studies in morphology ecology genetics and paleolimnologyHuman activity has led to the introduction of many alien organisms in all ecosystems including freshwaters Kilroy Unwin 2011 There is ample evidence of unintentional transport of aquatic organisms in shipping ballast water trade of species for aquaria aquaculture angling fisheries etc Incagnone et al 2015 Other activities such as canal construction also facilitate invasions of aquatic alien species without physically moving them for more details see Incagnone et al 2015 All those interventions provide opportunities for species to travel long distances and colonise new areas After reaching new habitats these travellers may be recognised as alien It is well known that their impact on ecosystems can pose a threat to biodiversity in many ways including predation or herbivory competition and hybridisation altering ecosystems as a result Streftaris Zenetos 2006Different aspects of the problem of biological invasions have been discussed widely in work ranging from simple lists of alien species on local Najberek Solarz 2011 regional Kaštovský et al 2010 WilkWoźniak Najberek 2013 or global scales Lowe et al 2000 to complex analyses of their ecological and economic impacts Vilà et al 2011 Methods of assessing the impact of alien species are relatively well developed for plants vertebrates and invertebrates in terrestrial freshwater and marine environments Vilà et al 2009 In contrast changes in freshwater ecosystems due to new introductions of microorganisms cyanobacteria algae and the consequent socioeconomic impacts are poorly studied Part of the reason for this is that finding and evaluating alien microorganisms in new habitats is difficult due to their small size sometimes insufficient taxonomic expertise disagreements about a given species concept and the confusing terminology of biological invasionsDue to problems defining what an alien microorganism is their records are very often reported as exotic species Cellamare et al 2010 interesting species Zapomělová et al 2012 or first reports of a species in an area eg Manti et al 2005 Assembling the alien microorganisms jigsaw puzzle requires various kinds of information among which are proper taxonomic identification and a good description of the native range of the species so that expansion beyond the native range can be ascertainedCyanobacteria form one of the oldest groups of microorganisms with fossil remains dating back 35 billion years Schopf 2000 Due to their ability to create toxic blooms harmful algal blooms—HAB they are considered dangerous organisms which may harm water habitats and local biodiversity and reduce the value of ecosystem services such as recreational uses or provision of potable waterSome cyanobacteria are reported to be ubiquitous organisms with a nearly global distribution Jungblut et al 2009 Others are said to have extended their native range Padisák 1997 Wood et al 2014 It is very difficult to assess the native/alien status of a taxon but analyses aimed at determining the true status of these ‘alien’ ‘exotic’ and ‘interesting’ microorganisms can help elucidate their biogeography and ecology We tracked the longdistance ‘walk’ of three species of cyanobacteria through different climate zones to see whether we could reliably determine if they have indeed expanded their ranges The larger aim was to establish the context in which the migration and evolution of these microorganisms should be understood so that a proper assessment of their geographic expansion can be madeWe selected 3 species of cyanobacteria Cylindrospermopsis raciborskii Woloszynska Seenayya Subba Raju in Desikachary 1972 Raphidiopsis mediterranea Skuja 1937 and Cuspidothrix issatschenkoi Usachev P Rajaniemi Komárek R Willame P Hrouzek K Kastovská L Hoffmann K Sivonen 2005 Those three species are widely accepted as alien for temperate zone in Europe Kaštovský et al 2010 and according to the current knowledge their taxonomy is accepted Komárek 2015

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