Sagami Bay

35.116666666667139.38333333333Koordinaten: 35 ° 7 '0 "N, 139 ° 23' 0" E

The Sagami Bay (Japanese相 模 湾, Sagami -wan, also known as the Sagami Gulf or Sagamibucht ), located in the south of Kanagawa Prefecture in Honshu in central Japan. The Miura Peninsula in the east, it separates from the Bay of Tokyo, the Izu Peninsula Peninsula they bounded to the west. It is located about 40 km southwest of the capital, Tokyo. In it, the Sagami opens.

The preceding that sea area between the Boso Peninsula to the east and the Izu Peninsula in the west to the island of Izu - Oshima is in between as Sagami - nada (相 模 滩, even Sagami Lake), respectively.

Biological research

On a just 1000 km ² measured surface with an average depth of 1,000 m one of the richest marine faunal communities of the earth is native. Ground-dwelling organisms, which are known only from deeper regions of the Pacific Ocean otherwise occur in a limited space in great variety. The exploration of these special marine fauna began with the work of the German zoologist Ludwig Döderlein (1855-1936), who was 1879-1881 at the University of Tokyo as a lecturer in science. His merit is that he made ​​the world aware of the unusual species richness of Sagami Bay first. He was also the founding of a marine biological station near put his Japanese counterparts in Tokyo in order to systematically explore the fauna of Sagami Bay. Misaki seemed a good place to be, as the peninsula between the Tokyo and Sagami Bay mainly offered logistical advantages and was easily accessible from the capital. In 1886, the construction project for the station was realized and Japan was the first time a center of marine biology research.

After the 2nd World War, various Faunengruppen the Sagamibucht on the initiative of Michi -no- miya Hirohito ( 1901-1989 ) have been processed. Hirohito was indeed more in his capacity as a Japanese emperor (posthumous as Shōwa tennō ) known, but also operated a private research station at the southern tip of the Izu Peninsula. Here he gave the opportunity to the taxonomic work by the handling of his expedition yields Japanese scientists. Thus, published by the Imperial Household extensive monographs on the crustaceans, hydroids and sponges. The impressive collections of Emperor now houses erected under modern conservation point Showa Memorial Institute in Tsukuba north of Tokyo. Only in the last 20 years, the Sagamibucht moved back into the focus of multidisciplinary research. Japanese and international scientists submitted with activities such as the Kaiko project and the Sagami project new results on the geology, oceanography and biology of the region. Especially the use of manned submersibles brought new light into the biological communities on the sea floor.

Oceanography

One reason for the high biodiversity of Sagamibucht is the meeting of two ocean currents in the area. From the space of the Philippine Islands pulls in a northeasterly direction approximately 100 km wide and an average of 24 ° C warm ocean current along the east coast of Japan. This stream enters the Sagamibucht on the northern coast of the island and leaves it in a sharp bend to the east into the open ocean. The water observed in the summer dark blue color, gave him the name Kuroshio - the black stream. Hot water and high nutrient content provide the basis for rich phyto-and Zooplanktongehalte in the sea. From the north of the hazards arising from the Bering Sea cold Kurilenstrom clips the Japanese coast to the southwest. In the Sagamibucht overlap both flows, the colder water rises in the northern part and the southern part dominated by the warm waters of the Kuroshio. However, a sharp dividing line does not exist - these seasonal shifts, often within days or even hours. Conditional form a mass extinction of many planktonic organisms that sink as organic rain in the depth and the food base of the bottom dwellers, the temperature gradient. It comes to the exchange of Pacific deep water over the Sagami Trench, a 80 km long tectonic trough, which connects the bay to the west with the Pacific Ocean.

Tectonics

Another favorable condition for the rich soil fauna is extremely varied: Relief of Sagamibucht, which already (1872-1876) was mentioned in the Challenger Expedition and owes its origin to the geological features. On the east coast of the main island Honshu meet each 2 continental and oceanic plates - the Eurasian and Okhotsk and the under it pushing Philippine and Pacific plate. In this collision zone increased since the Mesozoic and persistent volcanic and seismic activity can be observed, which ultimately formed the Japanese islands. Hazard for humans result from the side effects of tectonic movements, which are manifested in volcanic eruptions, earthquakes and known as tsunami surges. In the north- west of the bay, the epicenter of the Great Kantō earthquake of 1923, which almost completely destroyed the metropolitan center of Yokohama - Tokyo was. But the tsunami reached a height of 11 meters and buried the location in the northern part of the bay peninsula Enoshima completely under the water masses. The Sagami Bay and Sagami Trench are a part of the aforementioned subduction zone, which was defeated at this point since the early Pleistocene, ie around 1.6 million years, a setback.

Ecology

The 20th century saw the Sagamibucht probably the most fundamental changes, which remained on the deep-sea life without effect. The formation of a gigantic economic center and the related increase of the population density of the region changed dramatically. In addition, the water quality is affected by the strong entry of nutrients from the in the southeast part of subsequent shallow Tokyo Bay. The overfishing of coastal waters and use of underground networks is another serious problem. Thus, the risks to biodiversity are now less in natural conditions rather than the people themselves