A survey of the benthic macrophytes of three hard-water lakes: Lough Bunny, Lough Carra and Lough Owel Irish Wildlife Manuals No. 70 A survey of the benthic macrophytes of three hard-water lakes: Lough Bunny, Lough Carra and Lough Owel Cilian Roden and Paul Murphy Citation: Roden, C. and Murphy, P. (2013) A survey of the benthic macrophytes of three hard-water lakes: Lough Bunny, Lough Carra and Lough Owel. Irish Wildlife Manual s, No. 70. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht, Ireland. Keywords: hard-water lakes, marl, charophytes, cyanobacterial crust, macrophytes, groundwater Site list: 000688, Lough Owel; 001774, Lough Carra/Mask Complex; 001926, East Burren Complex Cover photos: Chara tomentosa and Chara curta at 3m in Lough Owel. © NPWS The NPWS Project Officer for this report was: Dr Áine O Connor, Aine.O'[email protected] Irish Wildlife Manuals Series Editors: F. Marnell & R. Jeffrey © National Parks and Wildlife Service 2013 ISSN 1393 – 6670 Hard-water lake survey ___________________ Contents Executive Summary..................................................................................................................................1 Acknowledgements ..................................................................................................................................1 Introduction...............................................................................................................................................3 Methods.....................................................................................................................................................5 Site descriptions ........................................................................................................................................6 Lough Bunny.........................................................................................................................................6 Lough Carra...........................................................................................................................................6 Lough Owel...........................................................................................................................................7 Vegetation classification and mapping....................................................................................................9 The nature of lake vegetation ...............................................................................................................9 Lough Bunny.......................................................................................................................................13 Krustenstein.....................................................................................................................................13 Marl ..................................................................................................................................................13 Chara curta.......................................................................................................................................13 Chara rudis/Nupar lutea community.............................................................................................13 Schoenoplectus lacustris stands......................................................................................................15 Chara globularis ..............................................................................................................................15 Nitella community...........................................................................................................................15 Cyanobacterial mat community .....................................................................................................15 Vegetation of springs or depressions .............................................................................................15 Lough Carra.........................................................................................................................................15 Krustenstein.....................................................................................................................................16 Chara curta.......................................................................................................................................16 Chara tomentosa..............................................................................................................................16 Chara rudis ......................................................................................................................................16 Hard-water lake survey ___________________ Chara globularis.............................................................................................................................. 16 Elodea canadensis and Myriophyllum verticillatum ................................................................... 16 Chara denudata .............................................................................................................................. 16 Vegetation of dolines...................................................................................................................... 18 River-mouth communities ............................................................................................................. 18 Lough Owel ........................................................................................................................................ 18 Krustenstein .................................................................................................................................... 18 Chara curta...................................................................................................................................... 18 Chara rudis...................................................................................................................................... 18 Chara globularis.............................................................................................................................. 20 Chara denudata .............................................................................................................................. 20 Aquatic angiosperms...................................................................................................................... 20 Vegetation of dolines at the southern end of Lough Owel .......................................................... 20 What is the characteristic vegetation of marl lakes? ........................................................................ 20 Vegetation maps................................................................................................................................. 25 Maximum depth of macrophytes and community type.................................................................. 37 The flora of marl lakes ........................................................................................................................... 38 Chara tomentosa................................................................................................................................. 38 Chara aculeolata ................................................................................................................................. 38 Chara rudis ......................................................................................................................................... 39 Chara denudata .................................................................................................................................. 39 Chara globularis/ Chara virgata ........................................................................................................ 39 Myriophyllum alterniflorm ............................................................................................................... 39 Ranunculus sp. .................................................................................................................................... 40 Historical comparison............................................................................................................................ 41 Flora and vegetation........................................................................................................................... 41 Lough Bunny................................................................................................................................... 41 Hard-water lake survey ___________________ Lough Carra.....................................................................................................................................41 Lough Owel .....................................................................................................................................42 Water chemistry ..................................................................................................................................43 Lough Bunny ...................................................................................................................................43 Lough Carra.....................................................................................................................................44 Lough Owel .....................................................................................................................................45 The current conservation status of the lakes .........................................................................................46