How aquatic animals mix ocean water

November 23rd, 2009 - 2:48 pm ICT by ANI  

Washington, November 23 (ANI): A team of scientists has built models of how marine animals mix the waters ocean-wide and concluded that the effect may be extensive.

Modern ocean models primarily incorporate the effects of winds and tides. However, they do not generally take into account the mixing generated by swimming animals.

More than 60 years ago, oceanographers predicted that the effect of swimming animals could be profound.

Accounting for this effort has proven difficult, though, so it has not entered into today’s models.

Now, Kakani Katija and John Dabiri at the California Institute of Technology have developed a way to estimate the extent of “biogenic” mixing.

After conducting field measurements on swimming jellyfish, they built models of how animals mix the waters ocean-wide and concluded that the effect may be extensive.

“Swimming animals may contribute to ocean mixing on the same level as winds and tides,” said Katija.

“This necessitates the inclusion of biogenic mixing sources in ocean circulation and global climate models,” Katija added.

Most of this mixing is due to the displacement created by the movement of animal bodies through the water - rather than by the turbulence that is stirred up by fish as they swim.

This displacement is found to depend primarily on the shape of the animal rather than the dynamics of the animal’s swimming motion.

“Moreover, only a small part of the mixing comes from the mighty creatures that inhabit the deep,” said Katija.

Most of it is due to meeker, but much more plentiful, animals - the tiny krill, copepods, and other small critters that make up the vast majority of organisms swimming in the ocean. (ANI)

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