Scientists with suction

Author
by Blair
Publish date
1 May 2011
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I recently accompanied Richard Marchant to the Shoalhaven River where he studies the animals that platypus eat. Thanks to the suction sampling tool we used, I'll never look at a common household vacuum cleaner the same way again.

The underwater vacuum we used is a quite different to that used to clean carpets: suction, in this case, created by bubbles are injected near the base of a pipe. The bubbles rise to the top, sucking water upward as they go.

Diving for platypus prey Richard Marchant diving with the air-lift sampler, which works like an aquatic vacuum cleaner.
Image: Julian Finn
Source: Museum Victoria
 

When placed over a river bed or sea floor, small animals and sand are also sucked up with the water. A mesh bag covering the top of the pipe acts like a sieve; the sand passes out but the animals remain trapped.

This method of suction sampling typically nets catches of crustaceans, insects, and insect nymphs – important food chain species that can be identified and counted for research.

Richard emptying air-lift sampler Emptying the mesh bag of the air-lift sampler.
Source: Museum Victoria
 

The machine sounds weird too: a dull rumble through a dive hood, perhaps a cross between a V8 car engine and thunder.

The air-sucking principle of the vacuum means people refer to it as an 'air-lift'. It’s a nifty invention and a system used by many aquatic biologists at one time or another in their career.

Links:

MV News: Linking the food chain

Video: Studying the diet of platypus

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Rod 2 May, 2011 09:22
Another great blog -- fantastic work guys!
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