Benthic vegetation in Irish marl lakes : monitoring habitat 3140 condition 2011 to 2018
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2020-10Access:
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Cilian Roden, Paul Murphy, James Ryan, 'Benthic vegetation in Irish marl lakes : monitoring habitat 3140 condition 2011 to 2018', [report], National Parks and Wildlife Service. Department of Housing, Local Government and Heritage, 2020-10, Irish wildlife manuals, No. 124, 2020Description:
Marl lakes have a rich and distinctive flora dominated by charophyte (stoneworts) and other algae and Irish marl lakes are home to charophyte species that are rare or absent from neighbouring countries. This vegetation constitutes the Habitats Directive Annex I habitat ‘Hard oligo-mesotrophic waters with benthic vegetation of Chara spp.’ (habitat code 3140). Shallow, well-mixed marl lakes are more common and larger in Ireland than most other parts of Europe, thus Ireland has significant responsibility for the protection of this habitat. However, there has been a steady erosion of habitat quality in Ireland. The benthic vegetation of 29 Irish marl lakes was analysed using data collected between 2007 and 2018. Vegetation was described using snorkelling, which provided precise data on depth distribution and species composition. The results showed that lakes in good conservation condition are characterised by a flora with few vascular plants but abundant charophytes, and a characteristic cyanobacterial (cyanophyte) crust community. Up to five vegetation zones can occur in marl lakes, each dominated by a characteristic charophyte species. The extent of the cyanobacterial crust, the number of charophyte species, the number of charophyte vegetation zones and charophyte cover as a proportion of total vegetation cover were positively correlated with euphotic depth (maximum depth of vegetation colonisation). Conversely, low euphotic depth correlated with increased proportion of vascular plants. In turn, euphotic depth is inversely related to average lake total phosphorus and water colour. It was concluded that near pristine Irish marl lakes are characterised by euphotic depth of greater than 7 m, high charophyte vegetation abundance and species diversity, a large expanse of cyanobacterial crust and a small proportion of vascular plants.Corporate name:
Ireland. National Parks and Wildlife ServicePublisher:
National Parks and Wildlife Service. Department of Housing, Local Government and HeritageType of material:
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