The , also known as the Black or or the is a north-flowing, warm ocean current on the west side of the North Pacific Ocean basin. It was named for the deep blue appearance of its waters. Similar to the Gulf Stream in the North Atlantic, the Kuroshio is a powerful western boundary current that transports warm equatorial water poleward and forms the western limb of the North Pacific Subtropical Gyre. Off the East Coast of Japan, it merges with the Oyashio Current to form the North Pacific Current. The Kuroshio Current has significant effects on both physical and biological processes of the North Pacific Ocean, including nutrient and sediment transport, major pacific storm tracks and regional climate, and Pacific mode water formation. Additionally, the current's significant nutrient transport results in a biologically rich ecoregion supporting an important fishing industry as well as diverse marine food webs. The South China Sea for example has relatively low nutrient concentrations in its upper waters, but experiences enhanced biological productivity due to the input from the Kuroshio Current Intrusion. Ongoing research centered around the Kuroshio Current's response to climate change predicts a strengthening in surface flows of this western boundary current which contrasts the predicted changes in the Atlantic Ocean's Gulf Stream. Physical properties The Kuroshio is a relatively warm ocean current with an annual average sea-surface temperature of about , is approximately wide, and produces frequent small to meso-scale eddies. The Kuroshio originates from the Pacific North Equatorial Current, which splits in two at the east coast of Luzon, Philippines, to form the southward-flowing Mindanao Current and the more significant northward-flowing Kuroshio Current. East of Taiwan, the Kuroshio enters the Sea of Japan through a deep break in the Ryukyu island chain known as the Yonaguni Depression. The Kuroshio then continues northwards and parallel to the Ryukyu islands, steered by the deepest part of the Sea of Japan, the Okinawa Trough, before leaving the Sea of Japan and re-entering the Pacific through the Tokara Strait. It then flows along the southern margin of Japan but meanders significantly. At the Bōsō Peninsula, the Kuroshio finally separates from the Japanese coast and travels eastward as the Kuroshio Extension. The Kuroshio Current is the Pacific analogue of the Gulf Stream in the Atlantic Ocean, transporting warm, tropical water northward toward the polar region. The Kuroshio's counterparts associated with the North Pacific Gyre are the: east