Abstract: Flocks of migratory waterbirds gather frequently in wetland stopovers and wintering grounds. The foraging and excreting activities of waterbirds affect nutrient contents in their habitats, with their excreta as a crucial external nutrient sources. Nitrogen and phosphorus are important indicators of nutrient levels in lakes. Therefore, it is important to understand the effects of nutrient input by waterbirds on soil nitrogen and phosphorus. Here, we investigated waterbird population and soil nitrogen and phosphorus contents at 0-10 cm layer in the shoal of Shengjin Lake in China. The effects of the waterbird’s migratory visits on the nutrient status of the shoal soil were analyzed by the means of variance, correlation, and stepwise regression analyses. We identified the main waterbird species that affected the soil nitrogen and phosphorus levels. The results showed that, compared to the control shoal without waterbird visits, the total nitrogen, total phosphorus, nitrate, and ammonium contents were significantly higher in the habitats that harbored the flocks. Due to the large amounts of organic nitrogen and phosphate introduced by waterbirds droppings, the correlations of total nitrogen vs. nitrate nitrogen, total phosphorus vs. nitrate nitrogen, and total phosphorus vs. pH in the shoal soils were significantly affected by bird activities. Soil nitrogen and phosphorus contents increased with waterbird population, among which geese were the main waterbirds that caused the increases of soil nitrogen and phosphorus contents. Our results are of great significance for understanding the environmental behaviors of nitrogen and phosphorus in lake shoals.

Key words: waterbird, nitrogen, phosphorus, nitrate nitrogen, ammonium nitrogen, Shengjin Lake.