Reduced tuber banks of fennel pondweed due to summer grazing by waterfowl

TY - JOUR

T1 - Reduced tuber banks of fennel pondweed due to summer grazing by waterfowl

AU - Gyimesi, A.

AU - De Vries, P.P.

AU - De Boer, T.

AU - Nolet, B.A.

N1 - Reporting year: 2011 Metis note: 4908; WAG; AnE ; AqE

PY - 2011

Y1 - 2011

N2 - In this study we investigated the effect of summer bird herbivory on the belowground tuber formation of fennel pondweed (Potamogeton pectinatus L.). Cumulative grazing pressure of four waterfowl species (mute swans, mallards, gadwalls and coots) in the summer was calculated based on timing of grazing and body mass of the grazers. The resulting grazing pressures were significantly negatively correlated with mean autumn tuber biomass in three of the four years of study. Moreover, summer grazing pressures explained more of the variance in tuber densities than water depth, sediment particle size distribution or any interactions of these variables did in the same three years. We propose that herbivory early in the summer has the most substantial impact on the clonal reproduction of macrophytes. Herbivores with a high consumption rate and early congregation for moulting may be the key waterfowl species in diminishing propagule biomass. Hence, they may present pre-emptive, time-staggered competition to consumers of the belowground biomass in autumn, such as migratory swans and diving ducks.

AB - In this study we investigated the effect of summer bird herbivory on the belowground tuber formation of fennel pondweed (Potamogeton pectinatus L.). Cumulative grazing pressure of four waterfowl species (mute swans, mallards, gadwalls and coots) in the summer was calculated based on timing of grazing and body mass of the grazers. The resulting grazing pressures were significantly negatively correlated with mean autumn tuber biomass in three of the four years of study. Moreover, summer grazing pressures explained more of the variance in tuber densities than water depth, sediment particle size distribution or any interactions of these variables did in the same three years. We propose that herbivory early in the summer has the most substantial impact on the clonal reproduction of macrophytes. Herbivores with a high consumption rate and early congregation for moulting may be the key waterfowl species in diminishing propagule biomass. Hence, they may present pre-emptive, time-staggered competition to consumers of the belowground biomass in autumn, such as migratory swans and diving ducks.

U2 - 10.1016/j.aquabot.2010.10.002

DO - 10.1016/j.aquabot.2010.10.002

M3 - Article

SN - 0304-3770

VL - 94

SP - 24

EP - 28

JO - Aquatic Botany

JF - Aquatic Botany

IS - 1

ER -