Abstract Many waterbirds used to feed mainly on land but spend a considerable amount of time at waterbody for roosting. These waterbirds are known to bring a considerable amount of nutrients from terrestrial to the aquatic ecosystem with their faeces. In small waterbody, large congregations of waterbirds can cause huge nutrient loading to the lake. This sometimes may exceed 70% of the total lake nutrient budget. The present study intends to investigate the importance of waterbirds in terms of nutrient loading with faecal matter. The study was conducted at a shallow, eutrophic lake with high winter avian congregation and negligible anthropogenic nutrient input. Daily dropping production by individual waterbird, elemental concentration in dropping, individual species count and lake use pattern by waterbirds have been taken into consideration for the nutrient loading estimation by waterbird. Waterbirds were found to be the most important nutrient source to the lake, contributing about 89.5% of total nitrogen (N) and 89.9% of total phosphorous (P). Waterbirds contribute 370 kg year−1 (17.68 g m−2 year−1) and 67 kg year−1 (3.21 g m−2 year−1) of N and P, respectively, to the waterbody. Among waterbirds, Dendrocygna javanica was found to contribute the most amount of nutrients to the lake. Apart from waterbirds, precipitation was found to be the second important nutrient source to the lake. It was found that the lake receives most of the nutrients during winter due to high winter avian congregations. The present study concludes that waterbirds are the most important nutrient source for the studied lake. This study highlights the potential of waterbirds as a eutrophicating agent and future research should include it in eutrophication research if present at a high number. After all, this kind of study in the tropical/subtropical region is lacking and this study could put a light on the importance of waterbirds in this kind of system.
展开▼
