Effect of passage through duck gut on germination of fennel pondweed seeds*

With 1 figure and 3 tables Abstract: Vertebrates are important seed dispersers for many plants. In addition to transport of seeds, ingestion often affects the proportion or rate of seed germination. We present one of the first studies comparing the effects of different waterbird species on the seeds of a subcosmopolitan pondweed, Potamogeton pectinatus. We also pre-sent the first comparison of the effects of digestion by ducks (mallard Anas platyrhyn-chos, shoveler A. clypeata and wigeon A. penelope) and physical-chemical “simulation of digestion ” on pondweed seed germination. In two experiments differing in the length of the preceding stratification period, two to three individuals per duck species were force-fed 150 seeds each. Average retrieval, total germination and germination rate did not differ significantly between duck species. Germination rate was higher for duck ingested seeds, intermediate for scarified seeds (i.e. after mechanical removal of the epicarp+mesocarp) and lowest for the controls and acid treated seeds, independ-ently of the length of the stratification period. Total germination, however, did not dif-fer significantly among duck-ingested, scarified, control and acid treated seeds. Conse