RESTING BUDS OF POTAMOGETON AS FOOD FOR M UTE SWAN (CYGNUS-OLOR) AT LAKE FEDERSEE (SW-GERMANY)

Authors
Citation
H. Gunzl, RESTING BUDS OF POTAMOGETON AS FOOD FOR M UTE SWAN (CYGNUS-OLOR) AT LAKE FEDERSEE (SW-GERMANY), Journal fur Ornithologie, 134(3), 1993, pp. 345-347
Citations number
1
Language
TEDESCO
art.tipo
Note
Categorie Soggetti
Ornithology
Journal title
ISSN journal
0021-8375
Volume
134
Issue
3
Year of publication
1993
Pages
345 - 347
Database
ISI
SICI code
0021-8375(1993)134:3<345:RBOPAF>2.0.ZU;2-O
Abstract
In the highly eutrophicated, shallow Lake Federsee no submersed macrop hytes grew, until 1982 a waste water pipeline around the lake was put in operation. In 1983 Potamogeton crispus began to colonize the lake a nd its abundance increased from year to year. The growth cycle, howeve r, remained very short and the macrophyte always died off between the end of June and the middle of July, after having developed large numbe rs of resting buds. Simultaneous with the increasing canopies of Potam ogeton a rise of Mute Swans in summer and autumn was observed, and bec ause of the absence of Potamogeton and other new food plants it was su ggested that at this time the bird mainly feeds on the resting buds of Potamogeton. This was confirmed by investigation of excrements, which sometimes consisted mainly of remnants of resting buds. Therefore it is supposed that Mute Swans essentially affect the recolonization of t he lake by Potamogeton crispus and by this way also slow down the re-e stablishment of a diverse flora and fauna.