Analysis of seasonal changes in water qualities in eutrophic reservoirs in a flat low-lying agricultural area using an algae-based ecosystem model. (Special Issue: Sustainable water and land management in tidal areas.)

摘要

In this study, a one-box ecosystem model evaluating four algal groups (green algae, blue-green algae, diatoms/dinoflagellates, and cryptophytes) was constructed for three eutrophic reservoirs in a flat, low-lying agricultural area. These reservoirs are used as agricultural water resources, and they differ in characteristics such as water depth, storage capacity, and vegetation. Water quality surveys of the chlorophyll-a concentration of each algal group, total organic carbon (TOC), dissolved organic carbon (DOC), total nitrogen (TN), total phosphorus (TP), and dissolved oxygen (DO) were conducted weekly, from July to November 2009, to verify the validity of the ecosystem model. The model evaluated seasonal changes in water qualities for the different eutrophic reservoirs and could estimate the dynamic characteristics of nutrients related to the seasonal changes in algae. The study showed promising results and the model could be used to simulate the relationship between phytoplankton and nutrients, as well as seasonal changes in the species composition of algae during the brief but critical period when strong eutrophication occurred.