CLIMATE CHANGE IMPACT ON HYPOXIA AND NUTRIENT MANAGEMENT IN TOKYO BAY AND ISE–MIKAWA BAY

Abstract

 To clarify climate change impacts on hypoxia in Tokyo Bay and Ise–Mikawa Bay, we performed numerical predictions under the present (the end of the 20th century) and the RCP8.5 future (the end of the 21st century) climate conditions using an integrated river basin – coastal ocean hydro-environment assessment model. These results indicated that the sea surface temperature in RCP8.5 increases by 3–4 degrees C from that in the present, and that the decrease in primary production due to high temperature from summer to autumn was larger in Tokyo Bay, Ise Bay, and Mikawa Bay, in that order, depending on the water temperature in the sea area. In Mikawa Bay where the primary production decreased significantly, the hypoxic volume decreased in the future. Furthermore, the effects of nutrient management were evaluated. It was suggested that there were some areas where it was effective to control hypoxia with DO < 3 mg/L, but difficult to control hypoxia with DO < 4 mg/L only by loading reduction.