Marine Biology (2+1)

Bottle samplers

Meyer’s water sampler : For quantitative phytoplankton collections, water samplers are ideal as required quantities of water can be collected from the desired depth by this method. Water samplers are generally used from stationary vessels. It is the simplest method chiefly used for the collection of water samples from any desired depth of shallow systems like the nearshore waters, estuaries and mangroves, where, there is no appreciable hydrostatic pressure. Meyer’s water sampler consists of an ordinary glass or Perspex bottle of about 1-2 l capacity and is enclosed with a metal band. It is weighted below with a lead weight and there are two strong nylon graduated ropes, one tied to the neck of the bottle and the other to the cork. While operation, the corked-up (closed) bottle is let down to the desired depth (using the neck rope) where the stopper is jerked open by a strong pull of the cork rope. Now the water flows into the bottle. When the bottle is full, which is known by the disappearance of air bubbles, the cork rope is released to keep the cork closed. Afterwards, using the neck rope, the bottle containing the water sample is taken out of the water column. This type of water sampler could be used up to a depth of only 20 m.