Estimations of Nutrient Fluxes and Nutrient Load from Waterfowls at a Tidal Flat in the Tokyo Port Wild Bird Park

Abstract

It is said that tidal flat have high biological productivity and high self clarification in coastal water area. In Japan, tidal flat has disappeared and the ability of water clarification has fallen down as a result of coastal reclamation accompanied with industrialization. In this paper, we observed water quality over 2 tidal cycles and calculated nutrient load from waterfowls at a tidal flat in the Tokyo Port Wild Bird Park to estimate the self clarification by tidal flat. In conclusion, we found the following results.(1) Function of this tidal flat is net source of phosphorus and net sink of nitrogen and chlorophyll-a in summer.(2) Nutrient load from great cormorant (Phalacrocorax carbo) is the largest amount among waterfowls and the peak value is obtained in October. However, this value is not so large compared to nutrient fluxes.