Seppo Hellsten Finnish Environment Institute Macrophytes as indicator of hydromorphological pressure in lakes and reservoirs Seppo Hellsten Finnish Environment Institute

Main aims How macrophytes and hydromorphological (Hymo) pressures are defined? How macrophytes react on hydromorphological pressures? How to evaluate the effects of hydromorphological pressures on aquatic macrophytes? Are there developed indices for hymo-pressures? Availability of hydromorphological pressure data (water level fluctuations, morphological modifications, changes in continuity) in MS? Summary and proposal for next step of intercalibration exercise

Terms WDF includes macrophytes sensu lato Hydrological regime: most MS do not use helophytes (Phragmites, Glyceria, Carex in analysis due to bad indicator value for P-pressure eulittoral species are more commonly used in Nordic countries with clear spring flood Hydrological regime: The quantity and dynamics of flow, level, residence time, and the resultant connection to groundwaters Morphological conditions: Lake depth variation, quantity and structure of the substrate, and both the structure and condition of the lake shore zone

Main effects of lake water level regulation

120,5 121 121,5 122 122,5 123 123,5 Water level (m.a.s.l.) I II III IV VI VII VIII IX X XI XII WINTER DRAWDOWN — Aquatic macrophytes => disappearance of large isoetids

Isoetes lacustris key littoral habitat of oligotrophic soft water lakes

Ontojärvi Lentua Isoetes lacustris frekv.= dots Thick line = red light attenuation Narrow line = duration of frozen bottom (plants between ice and sediments) Lentua

123,5 123 122,5 Water level (m.a.s.l.) 122 121,5 121 120,5 I II III IV DELAYED/LOWERED SPRING FLOOD 121,5 — Shore vegetation => changes in zonation/abundance 121 120,5 I II III IV V VI VII VIII IX X XI XII

Finland

Carex-zone extension

123,5 123 122,5 Water level (m.a.s.l.) 122 121,5 121 120,5 I II III IV CHANGED/NARROWED FLUCTUATION REGIME DURING SUMMER 121,5 — Shores => increased/decreased erosion 121 — Shore vegetation => changes in zonation 120,5 I II III IV V VI VII VIII IX X XI XII

Relationship between vertical extension of different helophyte species and water level fluctuation of open water period. (A), horsetail (B) and reed (C) stands and water level fluctuation of open water period in study lakes. ▲=Kallavesi, ○= Vanajavesi, □=Keitele, ●=Näsijärvi, ■= Päijänne. (Keto unpublished data).

Index by Hellsten & Mjelde 2009 Modification of the index applied by Schaumburg et al. (2004) based on the comparison of sensitive and tolerant species against eutrophication by Stelzer et al. 2005. decreasing or increasing species in regulated lakes

Decreasing species Phragmites australis Schoenoplectus lacustris Eleocharis palustris Isoetes lacustris Isoetes echinospora Littorella uniflora Lobelia dortmanna Nuphar lutea Nuphar pumila Nymphaea alba Nymphaea candida Nymphaea tetragona Myriophyllum alterniflorum Myriophyllum verticillatum Myriophyllum sibiricum Potamogeton alpinus Potamogeton berchtoldii Potamogeton compressus Ranunculus confervoides Ranunculus peltatus

Decreasing species Phragmites australis Schoenoplectus lacustris Eleocharis palustris Isoetes lacustris Isoetes echinospora Littorella uniflora Lobelia dortmanna Nuphar lutea Nuphar pumila Nymphaea alba Nymphaea candida Nymphaea tetragona Myriophyllum alterniflorum Myriophyllum verticillatum Myriophyllum sibiricum Potamogeton alpinus Potamogeton berchtoldii Potamogeton compressus Ranunculus confervoides Ranunculus peltatus Increasing species Alisma plantago-aquatica Calamagrostis sp. Juncus alpinoarticulatus Juncus filiformis Carex rostrata Elatine hydropiper Elatine orthosperma Elatine spp. Elatine triandra Eleocharis acicularis Ranunculus reptans Sparganium sp. Subularia aquatica Callitriche cophocarpa Callitriche hamulata Callitriche hermaphroditica Callitriche palustris Callitriche sp.

Decreasing species Phragmites australis Schoenoplectus lacustris Eleocharis palustris Isoetes lacustris Isoetes echinospora Littorella uniflora Lobelia dortmanna Nuphar lutea Nuphar pumila Nymphaea alba Nymphaea candida Nymphaea tetragona Myriophyllum alterniflorum Myriophyllum verticillatum Myriophyllum sibiricum Potamogeton alpinus Potamogeton berchtoldii Potamogeton compressus Ranunculus confervoides Ranunculus peltatus Indifferent species Equisetum fluviatile Potamogeton natans Sparganium angustifolium Sparganium emersum Sparganium erectum Sparganium glomeratum Sparganium gramineum Sparganium hyperboreum Sparganium minimum Sparganium natans Increasing species Alisma plantago-aquatica Calamagrostis sp. Juncus alpinoarticulatus Juncus filiformis Carex rostrata Elatine hydropiper Elatine orthosperma Elatine spp. Elatine triandra Eleocharis acicularis Ranunculus reptans Sparganium sp. Subularia aquatica Callitriche cophocarpa Callitriche hamulata Callitriche hermaphroditica Callitriche palustris Callitriche sp.

Finnish lakes

Norwegian lakes

Problems? Is there helophyte data?

Scotland

Neusiedler See

Lakes without the effect of descending ice-cover? List of sensitive species? Or should we continue with helophyte extension?

Problems? Vertical & horizontal extension data is not collected growing depth data exists, but no measurements above water level aerial data needs also an elevation model according to CEN it should Hydrological data is largely missing 2006 no wl-fluctuation data from Scotland and Austria Morphological data availability increases with RBMP

Morphologi-cally modified lakes and reservoirs?? In many cases no vegetation N/A?