Submerged macrophytes are thought to stabilize clear-water states of shallow lakes. The aim of this thesis was to elucidate how waterfowl herbivory can affect abundance, distribution and species composition of submerged macrophytes in eutrophic lakes. I found that in a lake with sparse vegetation, which was in a colonization phase, small plants were uprooted and large plants were heavily grazed upon. In three macrophyte-dominated lakes, grazing did not reduce biomass severely. This suggests that the risk of waterfowl grazing causing lakes to enter a turbid state is low at moderate waterfowl densities, unless the amount of vegetation is sparse or in a phase of colonization. However, waterfowl grazing can have differentiated effects on different species of macrophytes, with consequences for species composition. In autumns, migrating waterfowl can reduce belowground tubers of Potamogeton pectinatus substantially, and particularly at intermediate water depth. Mainly large waterfowl (swans) dig in the sediment and their foraging lower the competitive ability of P. perfoliatus, and P. pectinatus can dominate the heavily grazed areas. It seems like P. pectinatus, at least partly, can compensate for the reductions of tubers in autumn by producing more tubers per plant the next summer. Direct effects of waterfowl herbivory can thus be a mechanism, behind plant species depth distribution.
|Award date||2002 Mar 8|
|Publication status||Published - 2002|
Bibliographical noteDefence details
Place: Blue Hall, Ecology Building, Lund
Name: Søndergaard, Martin
Article: Marklund O., Sandsten H., Hansson L.-A., Blindow I. Effects of waterfowl and fish on submerged vegetation and macroinvertebrates. Submitted.
Article: Sandsten H., Beklioglu M. and Ince Ö. Effects of waterfowl, large fish and periphyton on the spring growth of Potamogeton pectinatus in Lake Mogan, Turkey. Submitted.
Article: Weisner S. E. B., Strand J. A. and Sandsten H. 1997. Mechanisms regulating abundance of submerged macrophytes in shallow eutrophic lakes. Oecologia 109: 592-599.
Article: Lauridsen T. L., Sandsten H. and Hald Møller P. Restoration of a shallow lake by introducing Potamogeton spp.: impact of waterfowl grazing. Submitted.
Article: Sandsten H. Waterfowl grazing on Potamogeton pectinatus tubers in relation to water depth, sediment depth and bird size. Manuscript.
Article: Sandsten H. and Klaassen M. Waterfowl foraging affects competitive ability and distribution of Potamogeton pectinatus and P. perfoliatus. Submitted.
Article: Rodríguez-Gironés M. A., Sandsten H. and Santamaría L. Asymmetric competition and the evolution of propagule size. Submitted.
The information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Limnology (Closed 2011) (011007000)
Subject classification (UKÄ)
- Environmental Sciences
- Plant ecology
- akvatisk ekologi
- Animal ecology
- Fulica atra
- alternative stable states
- water depth
- plant species composition
- propagule size
- marine biology
- aquatic ecology