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Upwelling: The movement of nutrient-rich water from a specified depth to the surface.

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Water mass: A body of water that maintains its physical identity and can be characterised by parameters such as temperature and salinity.

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Xenophyophores: Large single-celled organisms, that are common throughout the deep-sea. They are small fragile organisms often no larger than a golf ball, which may resemble flattened discs, angular four-sided shapes or spheres.

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Zooplankton: Tiny animals with limited ability to move, which usually drift with water currents. Includes small crustaceans and larvae of many larger animals.