Invasive Vaucheria (Xanthophyceae) at the lower shore of the Wadden Sea

ABSTRACT

Vaucheria species have previously been restricted to upper shore habitats in the Wadden Sea (eastern North Sea, European Atlantic). In contrast to these previous observations, we have now found Vaucheria longicaulis and a distinct plastid lineage of V. velutina spreading along the lower shores, forming extensive turfs at and below low tide level under fully marine conditions near the Island of Sylt. Species and populations were identified by morphological features and reconfirmed by sequencing the plastid-encoding gene rbcL and the psbA-rbcL spacer region. We needed to modify primer sequences to successfully amplify the rbcL region of marine and brackish Vaucheria species. Due to distinct phylogenetic grouping, we can reject the possibility of niche expansions from the upper shore and propose recent introductions as the cause of the newly formed populations at the lower shore.

KEYWORDS:

• Algal turf
• Genotypes
• Species introductions
• Vaucheria longicaulis
• Vaucheria velutina

ACKNOWLEDGEMENTS

We thank the staff of AWI Wadden Sea Station Sylt and the crew of MYA II for substantial help and discussions. Malte Elbrächter, Tobias Dolch and Hanna Schade provided crucial observations on Vaucheria. Rainer Borcherding (Schutzstation Wattenmeer) organized a ground truthing campaign near Hallig Südfall. Deutsche Botanische Gesellschaft (DBG) with its section phycology is thanked for electing Vaucheria velutina alga of the year 2021. The EPSAG team and Eike Petersen assisted in lab work and sequencing.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

SUPPLEMENTARY MATERIAL

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Additional information

Funding

This work was supported by the German Science Foundation (DFG) Priority Program 1991 ‘Taxon-OMICS’ (Deutsche Forschungsgemeinschaft Project RY 173/1-1, extended to NR).