Expansion of a localized population of the introduced Stratiotes aloides (Hydrocharitaceae) in Lough Derg, Ireland
Stratiotes expansion in an Irish lake
Keywords:non-native, clonal propagation, aquatic macrophyte, population dynamics, spread
An expansion of an introduced female clone of Stratiotes aloides L. (Water-soldier) was located in a delta region on the western side of Lough Derg, Co Galway (v.c.H15), Ireland in 2007. This population was followed over a thirteen-year period. It was initially located at three adjacent sheltered localities, within sweepback bays on either side of an emerging river and within an adjacent canal. The study involved surface observations later supplemented with aerial images. The shallow water conditions, shelter and the presence of Phragmites australis appear to have supported the early establishment by retaining small S. aloides clusters amongst its stems. These clusters later merged to produce a mainly surface expanding monoculture. This enlarged from less than 1 ha to approximately 3.3 ha to occupy much of the sheltered Rossmore Bay area during this study. Flowers were first noticed in 2008, and during subsequent visits, producing infertile seed-pods. Expansion took place with the production of daughter plants. A small nearby population, 1 km to the east, within an unused harbour, did not produce an emergent phase. A small group in a shallow cut, between the two locations, disappeared during the study. Aerial images from different sources were useful to identify the expansion of the emergent stage due to the distinctive bright green coloration of surface leaves. It is unclear how this plant arrived in Lough Derg, but might have been a garden plant release. Small drifting plants, seen during wintertime, may yet colonize other regions within this lake.
Copyright (c) 2021 Dan Minchin, David Higgins
This work is licensed under a Creative Commons Attribution 4.0 International License.
Copyright and licence: Authors (or their employers) retain their copyright in articles and images published in British & Irish Botany and are not required to assign this to the Botanical Society of Britain & Ireland (BSBI). All that BSBI requires from authors is a license to publish the article in British & Irish Botany and make it freely available to all in pdf format under the terms of Creative Commons Attribution 4.0 International Public License, which also enables BSBI to reproduce components of the article in other BSBI outputs (eg. BSBI News, the BSBI website and/or the BSBI News & Views blog) for publicity purposes. The licence code can be accessed here: