Welcome to MEER Data Portal
The MEER portal is the web-site for scientists networking for MEER project, which is focusing on hadal trench ecosystem. The term ‘hadal’ is derived from Hades. The hadal zone differs somewhat from shallower zones because it is not simply a continuation of the preceding deep-sea environments. In fact, the progression of the environment from the continental slopes and rises to the abyssal plains eventually splits into clusters of fragmented and often vastly isolated trenches.
Wolff (1960) published the first summary of hadal research and, based on the fauna known at that time, suggested 6000 m as the minimum hadal depth. More recently, the 6000 m boundary has been revised to 6500 m (UNESCO, 2009). According to digital global bathymetry database (GEBCO), Jamieson (2015) summarized 46 hadal zones deeper than 6500 m around the planet, including 33 trenches and 13 troughs, with the Mariana trench being the world's deepest. Troughs are groups of deep-sea basins that do not originate at plate intersections, whereas trenches are V-shaped cross-section areas that are typically long and narrow, and geographically isolated from one another. Of the 33 trenches, 26 are located in the Pacific Ocean, three in the Atlantic Ocean, two in the Indian Ocean, and two in the Southern Ocean. The hadal zone covers less than 1% of the entire ocean surface area yet accounts for 45% of entire ocean depth.
Oceanic trenches, in particular, are a hallmark of convergent plate borders, which occur when two or more tectonic plates collide. Dense lithosphere dissipates or slips beneath less dense lithosphere at numerous convergent plate borders, generating trenches in the process known as subduction. Deep-sea trenches have a V-shaped cross section, with the landward side being steeper. With the develop of MEER project, our understanding of the hadal trench will be much better than ever.
