OK.. the two aquaculture books I have discuss algae blooms, hot temps and loss of
oxygen. they dont talk about other plants of any kind being able to deplete the
oxygen like that. the reason may be a surface to volume ratio for uptake of oxygen.
the surface area of the roots of plants are small compared to the overall surface
area of all the algae in an algae bloom. the roots of plants that are above water
only extract oxygen from a small area of the top of the water, like water hyacinths
and lettuce. Algae occupies every square inch of the entire water column.
there is a trade off in floating plants. yes, they decrease the area for gas
exchange, OTOH, floating plants shade and as a result cool the water. algae wont
grow in shade. but when I say "above the surface" I am thinking more about plants
like iris, reeds, water celery, etc. that actually stand up out of the water.
so the treatment for a pond where fish are gasping is not to pull the plants out, but
to aerate the water and get rid of the conditions that are fueling the algae bloom.
In doing a search for info, I ran across this site
Water Plants 101 A basic Introduction to the physiology and ecology of aquatic
plants By Dave Huebert http://www.hallman.org/plant/huebert.html
Ingrid

(Doug Quarnstrom) wrote:

wrote:
: need to cite your sources then. Ingrid

I will certainly do so if I can locate them.
However, even if surface plants do not take oxygen
out at night, ones that spread a great deal will
certainly reduce the surface area for gas exchange
and may be problematic for that reason alone.

One might request your sources as well...


doug

: (Doug Quarnstrom) wrote:

: wrote:
: : It isnt the plants that are above the water that remove oxygen at night. it is the
:
: Not according to what I have read.