Brian the Great wrote:
>>srgable at mail.nitco.com (SLURF) wrote:
>> >What do plants that live in water do during winter months?
>> > Thanks a million,
> > Jessie
>> They freeze.
The maximum density of water occurs at 4 oC which is why ice forms at
the surface (normally, cold water is more dense than warm water and
sinks, but between 0-4 oC the colder water is less dense and rises).
That means that unless the lake or pond freezez completely there will
still be liquid water below the ice surface. This is how some fish and
other aquatic animals survive the winter. Once formed, the layer of ice
insulates the water beneath from futher cooling to an increasing extent
as it thickens, which slows down the rate of ice formation.
Aquatic plants could survive in this water without freezing. However, a
more serious problem is the low light levels and short days during the
winter which limits photosynthesis. Terrestrial plants have evolved may
ways of surviving the winter in a dormant state to avoid this problem.
Have aquatic plants evolved similar strategies?
Dr. A.J.Travis, | mailto:ajt at rri.sari.ac.uk
Rowett Research Institute, | http://www.rri.sari.ac.uk/~ajt
Greenburn Road, Bucksburn, | phone:+44 (0)1224 712751
Aberdeen AB2 9SB, Scotland, UK. | fax:+44 (0)1224 716687