‘Only introduced’ or ‘invasive’: spread of the alga Aulacoseira ambigua f. japonica from Asia to Africa and Europe | „Zgolj preseljena“ ali „invazivna“: širjenje alge Aulacoseira ambigua f. japonica iz Azije v Afriko in Evropo

English. Many non-native algal species are found in waters all over the world. Many terms are used to describe such organisms that have expanded their distribution. However, a unified model or concept remains to be defined, as how biological ‘invasions’ are seen depends on the perspective. Understanding invasive organisms is important for biodiversity, science policy and water management. During monitoring sampling at Slivniško Lake (Slovenia) in 2016, the curved diatom Aulacoseira ambigua f. japonica Tuji & D.M. Williams was identified. This species originates from Japan, from where it was described more than 100 years ago. The chronology of the published distributions of A. ambigua f. japonica defines its spread from Japan to Asia, then to western Russia and South Africa, and now to central Europe. This study provides further evidence that A. ambigua f. japonica has become established in Europe (Slovenia), as supported by light microscopy and scanning electron microscopy. To the best of our knowledge, this is the first qualitative and quantitative description of A. ambigua f. japonica in Europe. It has been suggested that the shape of these algal colonies is significant for the interpretation of ecological information, and indeed, also in the present case, spiral colonies were found in this eutrophic water body. Although curved cells and colonies can also be interpreted as (sub)populations or morphological variants, only detailed molecular studies can reveal if these also have taxonomic significance.

Slovenian. V vodah po vsem svetu najdemo veliko tujerodnih vrst. Za opis organizmov, ki se širijo, je v uporabi veliko različnih pojmov. Kaže se potreba po opredeliti enotnega modela ali koncepta, saj je videnje bioloških “invazij” odvisno od perspektive. Razumevanje invazivnih organizmov je pomembno za biotsko raznovrstnost, znanstveno politiko in upravljanje z vodami. Med spremljanjem vzorčenja na Slivniškem jezeru (Slovenija) leta 2016 smo med drugim določili tudi ukrivljeno diatomejo Aulacoseira ambigua f. japonica Tuji & D.M. Williams. Ta vrsta izvira iz Japonske, kjer je bila opisana pred več kot 100 leti. Kronologija objavljenih pojavljanj A. ambigua f. japonica opredeljuje njeno širjenje iz Japonske v Azijo, nato v zahodno Rusijo in Južno Afriko, zdaj pa v osrednjo Evropo. Ta raziskava vsebuje dodatne dokaze, da se je A. ambigua f. japonica uveljavila v Evropi (v Sloveniji), podprte s svetlobno mikroskopijo in vrstično elektronsko mikroskopijo. Gre za prvi kvalitativni in kvantitativni opis A. ambigua f. japonica v Evropi. Oblika algnih kolonij je lahko pomembna za razlago ekoloških informacij; v danem primeru so bile v evtrofnem vodnem telesu najdene spiralne kolonije. Čeprav so ukrivljene celice in kolonije lahko interpretirane tudi kot (sub)populacije ali morfološke različice, lahko le natančne molekularne študije razkrijejo, če imajo ti morfotipi taksonomski pomen.