Ebb-tidal current: flow of water in a given direction that takes place between high water and low water.

UNESCO: L O S S A R Y

Tidal current: movement of water in a constant direction caused by the periodic rising and falling of the tide.

UNESCO: L O S S A R Y

As the tide rises, a flood-tidal current moves in one direction and as the tide falls, the ebb-tidal current moves in the opposite direction.

UNESCO: L O S S A R Y

Once the pair of gametes connect, they become a larva that drifts and swims in the tidal current, propelling itself by means of a little organ ringed with cilia called a velium.

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And times are still tough for middle-class Americans, who have been swimming against the current for years before this economic tidal wave hit.

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Martin Wright, managing director of Marine Current Turbines, said Strangford Lough had one of the strongest tidal currents in the British Isles and was therefore "a perfect location for us to test a pre-commercial device".

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