As one of the primary goals of this project is flood defense, the water level of the reservoir is kept 1 m below mean sea level by repeatedly draining the reservoir through two gates (250 m in total length). Several years before the completion of the reservoir, local fishermen began to complain about the unusual conditions they were observing in Ariake Bay, despite claims by the MAFF that the effects of the reclamation

project would be restricted to Isahaya Bay. One of the most serious changes to Silmitasertib Ariake Bay occurred in autumn of 2000, in which seaweed cultivation, the most important fishery industry in that bay, was seriously damaged by a large-scale bloom of the diatom Rhizosolenia imbricata. As seaweed is a natural competitor of phytoplankton for nutrients, the optimal season for growth tends to be late autumn to early spring, before the usual spring bloom of phytoplankton. However, in this case, the huge diatom bloom in late autumn across a wide area of the bay led to nutrient shortages in the seawater, resulting in large-scale damage to the seaweed crop. In addition, most fisheries in the bay have declined since the completion of the reservoir, while the frequency and scale of red tides, and the area of summer

hypoxia events have expanded ( Tsutsumi, 2006). On the other hand, the tidal amplitude of a peculiar RG7204 chemical structure resonance resulting from the topography of Ariake Bay has decreased in recent years, with the closing of Isahaya Bay likely contributing to this change through the modulation of tidal amplitude ( Unoki, 2004). Furthermore, the loss of the tidal flat has led to a decrease in the horizontal

tidal current, reducing the current velocity across the entire bay ( Nishinokubi et al., 2004). This reduction has been linked to smaller grains in the bottom sediment, leading to larger red tides and more frequent bouts of hypoxia ( Tsutsumi, 2006, Tsutsumi et al., 2006 and Matsukawa et al., 2014). In addition, water drained from the reservoir is frequently blamed for causing damage to local fisheries. Water quality in the reservoir ifenprodil has been steadily deteriorating every year since its completion, with environmental standards for chemical oxygen demand (COD) of 5 mg/L, voluntarily set by the Kyushu Agricultural Administration Bureau, never having been achieved despite water purification costs of over 3 billion yen every year. As a result of the eutrophication that has arisen in the reservoir, several species of cyanobacteria have begun blooming between late spring and late autumn every year. Within these algal blooms, the most dominant species is a microcystin (MC)-producing species, Microcystis aeruginosa, except in 2008 when a nontoxic Arthrospira sp. predominated. Previously, we had observed seasonal fluctuations in the concentration of MCs in the reservoir, which fluctuated in response to other environmental conditions of the reservoir (Umehara et al., 2012).