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The structure and functioning of eutrophicated aquatic ecosystems has received considerable attention from limnologists as well as water managers in recent years. Stress has often been on pelagic food webs of deeper lakes whilst littoral systems or shallower lakes have been less thoroughly investigated. Since Dutch aquatic systems are shallow, as a rule, they form a notable exception. But here, too, the orientation was often on pelagic food webs.
The present study has a clearly different scope in that it takes the water plant as prime perspective. The editors consider water plants to be the key component in shallow aquatic ecosystems. They have compiled work on one water plant species, Potamogeton pectinatus L., and from one lake, Lake Veluwe, as a typical case, and set out to explain the fluctuations in abundance of this water plant as influenced by eutrophication. A working hypothesis on the mechanism responsible for water plant decline during eutrophication was adopted and tested in a combination of field and laboratory work. A simulation model, SAGAI, for the water plant P.pectinatus was developed and proved to fit independent data very well.
The work started out as a joint effort of a single project team in the Department of Nature Conservation of Wageningen Agricultural University, but the present volume has benefited considerably from the inputs of several invited colleagues, as the list of contributors witnesses. The editors have made an invaluable contribution to the understanding of shallow aquatic ecosystems and to their scientifically based and sustainable management.
Sommario
1. Introduction: the scope of the research project.- 2. The Zuiderzee: transformation of a brackishwater ecosystem.- 3. Twenty years of dynamics and distribution of Potamogeton pectinatus L. in Lake Veluwe.- 4. Intraspecific variation in Potamogeton pectinatus L.: a controlled laboratory experiment.- 5. Growth of Potamogeton pectinatus L. in a temperature-light gradient.- 6. Light-response curves of Potamogeton pectinatus L. as a function of plant age and irradiance level during growth.- 7. Photoperiodic effects on photosynthesis and tuber production in Potamogeton pectinatus L..- 8. Early growth characteristics of Potamogeton pectinatus L.: the significance of the tuber.- 9. Seasonal dynamics of a field population of Potamogeton pectinatus L. under various experimental light conditions.- 10. Factors contributing to light attenuation in Lake Veluwe.- 11. Allelopathic limitation of algal growth by macrophytes.- 12. Periphyton dynamics in a temperature-light gradient.- 13. Periphyton removal by freshwater micrograzers.- 14. A growth analysis model for Potamogeton pectinatus L..- 15. Interactions between aquatic macrophytes and fish in Lake Veluwe, direct and indirect effects.- 16. General conclusions and implications for lake management.- Appendices 1-4.- List of contributors.
Riassunto
They have compiled work on one water plant species, Potamogeton pectinatus L., and from one lake, Lake Veluwe, as a typical case, and set out to explain the fluctuations in abundance of this water plant as influenced by eutrophication.
