Submerged macrophytes as indicators of the ecological quality of lakes

Summary 1. We analysed submerged macrophyte communities from 300 Danish lakes to determine the efficacy of different species, maximum colonisation depth (Cmax) of plants as well as coverage and plant volume inhabited (PVI) as indicators of eutrophication. 2. Most species occurred at a wide range of phosphorus and chlorophyll a (Chla) concentrations, but some species of isoetids (Lobelia, Isoetes) and Potamogeton (Potamogeton gramineus, Potamogeton alpinus and Potamogeton filiformis) were mainly found at low nutrient concentrations and hence may be considered as indicators of nutrient poor conditions. However, species typically found in nutrient-rich conditions, such as Elodea canadensis and Potamogeton pectinatus, were also found at total phosphorus (TP) <0.02 mg P L−1 and Chla <5 μg L−1 and therefore cannot be considered as reliable indicators of eutrophic conditions. 3. Submerged macrophyte coverage, PVI and the Cmax were negatively correlated with TP and Chla. However, variability among lakes was high and no clear thresholds were observed. At TP between 0.03 and 0.07 mg P L−1 plant coverage in shallow lakes ranged from nearly 0 to 100%, whilst at concentrations between 0.10 and 0.20 mg P L−1 only 29% of the lakes had coverage >10%. Cmax was found to be a useful indicator only in deep lakes with unvegetated areas in the deeper part, whereas the use of coverage was restricted to shallow lakes or shallow areas of deep lakes. 4. Overall, submerged macrophytes responded clearly to eutrophication, but the metrics investigated here showed no well-defined thresholds. We developed a simple index based on species richness, presence of indicator species, coverage and Cmax, which might be used to track major changes in macrophyte communities and for lake classification.

[1]  János Korponai,et al.  Abrupt shift from clear to turbid state in a shallow eutrophic, biomanipulated lake , 2009, Hydrobiologia.

[2]  Ole Vestergaard,et al.  Macrophyte decline in Danish lakes and streams over the past 100 years , 2000 .

[3]  Erik Jeppesen,et al.  Water Framework Directive: ecological classification of Danish lakes , 2005 .

[4]  T. V. Madsen,et al.  The impact of grazing waterfowl on submerged macrophytes: In situ experiments in a shallow eutrophic lake , 1996 .

[5]  Engineering and biological approaches to the restoration from eutrophication of shallow lakes in which aquatic plant communities are important components , 1990 .

[6]  D. Spence.  Factors Controlling the Distribution of Freshwater Macrophytes with Particular Reference to the Lochs of Scotland , 1967 .

[7]  Marten Scheffer,et al.  Climate‐related differences in the dominance of submerged macrophytes in shallow lakes , 2009 .

[8]  K. Sand‐Jensen,et al.  Alkalinity and trophic state regulate aquatic plant distribution in Danish lakes , 2000 .

[9]  Mark V. Hoyer,et al.  Factors affecting the maximum depth of colonization by submersed macrophytes in Florida lakes , 2007 .

[10]  K. Murphy.  Plant communities and plant diversity in softwater lakes of northern Europe , 2002 .

[11]  C. A. Duigan,et al.  Vegetation communities of British lakes: a revised classification scheme for conservation , 2007 .

[12]  Geoff Phillips,et al.  Classifying aquatic macrophytes as indicators of eutrophication in European lakes , 2008, Aquatic Ecology.

[13]  M. Hammershøj,et al.  Does the impact of nutrients on the biological structure and function of brackish and freshwater lakes differ? , 1994, Hydrobiologia.

[14]  Christine M. Mayer,et al.  Quantification of Historical Changes of Submerged Aquatic Vegetation Cover in Two Bays of Lake Ontario with Three Complementary Methods , 2007 .

[15]  Cassandra James,et al.  Nitrate availability and hydrophyte species richness in shallow lakes , 2005 .

[16]  E. Jeppesen,et al.  Response of submerged macrophytes in Danish lakes to nutrient loading reductions and biomanipulation , 2003, Hydrobiologia.

[17]  P. Soranno,et al.  Relationships between lake macrophyte cover and lake and landscape features , 2008 .

[18]  Erik Jeppesen,et al.  Does high nitrogen loading prevent clear-water conditions in shallow lakes at moderately high phosphorus concentrations? , 2005 .

[19]  J. Lachavanne,et al.  Influence of water eutrophication on the macrophytic vegetation of Lake Lugano , 1992, Aquatic Sciences.

[20]  A. Middelboe,et al.  Depth limits and minimum light requirements of freshwater macrophytes , 1997 .

[21]  B. Moss,et al.  Control of ecosystem state in a shallow, brackish lake: implications for the conservation of stonewort communities , 2008 .

[22]  Erik Jeppesen,et al.  The Structuring Role of Submerged Macrophytes in Lakes , 1998, Ecological Studies.

[23]  E. Jeppesen,et al.  Impact of submerged macrophytes on fish-zooplankton-phytoplankton interactions : large-scale enclosure experiments in a shallow eutrophic lake , 1995 .

[24]  Stephen R. Carpenter,et al.  Effects of submersed macrophytes on ecosystem processes , 1986 .

[25]  Mark Honti,et al.  Distribution of submerged macrophytes along environmental gradients in large, shallow Lake Balaton (Hungary) , 2008 .

[26]  B. Jupp,et al.  Limitations on Macrophytes in a Eutrophic Lake, Loch Leven: I. Effects of Phytoplankton , 1977 .

[27]  B. Rørslett.  Principal determinants of aquatic macrophyte richness in northern European lakes , 1991 .

[28]  Shallow lakes, the water framework directive and life. What should it all be about? , 2007 .

[29]  K. Sand‐Jensen,et al.  100 years of vegetation decline and recovery in Lake Fure, Denmark , 2008 .

[30]  Erik Jeppesen,et al.  Shallow lake restoration by nutrient loading reduction—some recent findings and challenges ahead , 2007 .

[31]  Stefan Sandrock,et al.  Restoration of submerged vegetation in shallow eutrophic lakes – A guideline and state of the art in Germany , 2006 .

[32]  Bill Freedman,et al.  Environmental influences on aquatic plants in freshwater ecosystems , 2006 .

[33]  M. Palmer,et al.  A botanical classification of standing waters in Britain: Applications for conservation and monitoring , 1992 .

[34]  S. Weisner,et al.  Mechanisms regulating abundance of submerged vegetation in shallow eutrophic lakes , 1997, Oecologia.

[35]  Erik Jeppesen,et al.  Trophic structure, species richness and biodiversity in Danish lakes: changes along a phosphorus gradient , 2000 .

[36]  S. Schneider.  Macrophyte trophic indicator values from a European perspective , 2007 .

[37]  B. Kronvang,et al.  Nationwide monitoring of nutrients and their ecological effects: state of the Danish aquatic environment , 1993 .

[38]  Jan Köhler,et al.  Lake responses to reduced nutrient loading - an analysis of contemporary long-term data from 35 case studies , 2005 .

[39]  O. Pietiläinen,et al.  Chlorophyll reference conditions for European lake types used for intercalibration of ecological status , 2008, Aquatic Ecology.

[40]  J. Downing,et al.  A Century of Change in Macrophyte Abundance and Composition in Response to Agricultural Eutrophication , 2004, Hydrobiologia.

[41]  Erik Jeppesen,et al.  Top-down control in freshwater lakes: the role of nutrient state, submerged macrophytes and water depth , 1997 .

[42]  S. F. Mitchell.  Primary production in a shallow eutrophic lake dominated alternately by phytoplankton and by submerged macrophytes , 1989 .

[43]  O. Pietiläinen,et al.  Chlorophyll–nutrient relationships of different lake types using a large European dataset , 2008, Aquatic Ecology.

[44]  H. Schubert,et al.  Primary production in two shallow lakes with contrasting plant form dominance: A paradox of enrichment? , 2006 .

[45]  G. Andersson,et al.  Seasonal changes of mechanisms maintaining clear water in a shallow lake with abundant Chara vegetation , 2002 .

[46]  H. Mäemets,et al.  Coverage and depth limit of macrophytes as tools for classification of lakes , 2007 .

[47]  A. Melzer,et al.  Macrophyte-based assessment of lakes - a contribution to the implementation of the European Water Framework Directive in Germany , 2005 .

[48]  N. Willby,et al.  Using aquatic macrophyte community indices to define the ecological status of European lakes , 2008, Aquatic Ecology.

[49]  Erik Jeppesen,et al.  Lake Restoration by Fish Removal: Short- and Long-Term Effects in 36 Danish Lakes , 2008, Ecosystems.

[50]  M. Scheffer,et al.  Alternative equilibria in shallow lakes. , 1993, Trends in ecology & evolution.

[51]  Horacio Zagarese,et al.  Phytoplankton and primary production in clear-vegetated, inorganic-turbid, and algal-turbid shallow lakes from the pampa plain (Argentina) , 2009, Hydrobiologia.

[52]  Arnulf Melzer,et al.  Aquatic macrophytes as tools for lake management , 1999, Hydrobiologia.

[53]  A. Melzer,et al.  Macrophyte-based bioindication in rivers – A comparative evaluation of the reference index (RI) and the trophic index of macrophytes (TIM) , 2009 .