Status assessment of the rare aquatic plant Groenlandia densa (L.) Fourr. (Potamogetonaceae) in the Western Balkans

ABSTRACT

Groenlandia densa is globally a widely distributed species; it has been recorded in the majority of the countries of the Western Balkans. However, the knowledge on its extant distribution in this particular area is limited and even controversial. In order to address this issue by tracking changes in species distribution over time and elucidating its current status in this area, we carried out a comprehensive survey of available literature sources and herbarium data, and performed field surveys. In Bosnia & Herzegovina, Montenegro and Croatia the species is most probably regionally extinct, while in Albania, Macedonia, Slovenia and Serbia G. densa occurs with only sparse records. Therefore, the most recent overview confirms this species as exceptionally rare in the Western Balkans. In Northern Europe the populations are declining due to various factors such as changes in climate and hydrology, prolonged periods of drought and irregular flooding, inappropriate water management, urbanization, eutrophication, etc., and in the Western Balkans we have observed the same general trend. As a threatened species, G. densa urges for active conservation measures and thus our recommendation would be to reassess this species at the European level.

KEYWORDS:

• Endangered plants
• aquatic vegetation
• macrophytes
• pondweed
• population decline

Acknowledgments

The authors wish to thank their colleagues Nejc Jogan (LJU) and Mateja Germ from Slovenia, Ermana Lagumdžija (SARA) from Bosnia & Herzegovina, Nevena Kuzmanović (BEOU) and Marijan Niketić (BEO) from Serbia, Renata Ćušterevska (MKNH) from Macedonia, Snežana Vuksanović from Montenegro and Zoltan Barina from Hungary (BP), for their assistance through literature and herbarium searches. The authors extend their thanks to the two anonymous reviewers for providing the most valuable comments on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplementary material for this article can be accessed here.

Additional information

Notes on contributors

Vedran Šegota

Vedran Šegota, is the curator of the herbarium collection Herbarium Croaticum (ZA). He studies flora and vegetation of Croatia from the aspects of diversity, ecology and conservation, including vascular plants and bryophytes. He is involved in a comprehensive study of Croatian macrophytes, within the course of the national monitoring.

Contribution: he participated in the extensive field search and checked all the relevant literature and herbaria. He prepared the manuscript and contributed to the figures.

Bojan Zlatković

Bojan Zlatković, is a researcher at the Faculty of Sciences and Mathematics, University of Niš. His work is mainly oriented toward phytochemistry, but he also participates in floristic studies.

Contribution: he performed the IUCN assessment, participated in the extensive fieldwork and provided comments on the manuscript.

Dragana Vukov

Dragana Vukov, is an associate professor at the Faculty of Sciences, University of Novi Sad. Her work mainly includes studying aquatic flora and vegetation from different aspects.

Contribution: she contributed to the extensive fieldwork and provided comments on the manuscript.

Antun Alegro

Antun Alegro, is an associate professor at the Faculty of Science, University of Zagreb. His work includes studies on the diversity of vascular plants and bryophytes, plant ecology, geobotany, phytosociology and phytogeography. He is the principal researcher in a comprehensive study of Croatian watercourses and associated vegetation within the course of national monitoring.

Contribution: he contributed to the extensive field search, and helped improve the manuscript.

Nikola Koletić

Nikola Koletić, is a PhD student at the Faculty of Science, University of Zagreb. His PhD includes studies on tufa formations in karstic environments. He is mainly involved in studying the aquatic vegetation of Croatia, including bryophytes and algae.

Contribution: he contributed to the extensive field search, provided useful comments on the manuscript and helped with the figures.

Nina Vuković

Nina Vuković, is a postdoctoral researcher at the Faculty of Science, University of Zagreb. She is studying floristic diversity and tackles conservation issues, particularly regarding rare and endangered, as well as invasive, plants. Her main areas of research are the terrestrial orchids, invasive plants and aquatic vegetation of Croatia.

Contribution: she contributed to the extensive field work, contributed to the assessment of the conservation status, and was responsible for the correction and the improvement of the article.

Anja Rimac

Anja Rimac, is a PhD student at the Faculty of Science, University of Zagreb. Her thesis involves studying the ecology of Croatian macrophytes, and her work is mainly focused on bryophytes and aquatic vegetation.

Contribution: she participated in the extensive field work and provided useful comments on the manuscript.