Ian
just bit of info
regarding this weed
Regarding the weed
problems in the tarn I have found that it is mainly either hornwort or
myriphillum species and not Canadian pond weed. as a keeper of Koi carp for
around 30 plus years I used to use this as spawning material in the early days
when spawning brushes where not around and even now this weed still occasionally
crops up in my pond which is generally quiet sterile and around 10000 gallons,
and I have not been able to eradicate this weed even after completely emptying
the pond numerous times it keeps making a appearance and this year is no
exception.
the one main benefit
is that it will keep the water clean and pure and generally as I have found
prevents blanket weed and the invasive strains of algae.
As I am sure you are
aware we as anglers are guilty of promoting this weed by over stocking which
raises the level of nutrients in the water. now to the crux of the tale is the
introduction of the grass carp into our lakes which was thought to be a general
cure all to remove soft weed and it did appear effective in the initial stages
but did increase the nutrient levels even further which resulted in firstly the
reduction of weed levels by the fish which was great for the angler but the down
side of this was that there was nothing to prevent the algae/ blanket weed
blooms due to the high nutrient levels which where still there. a further
result was that the algae appeared to reduce absorption of O2. this was in the
forums of many of the leading fish breeders in the early years. therefore a
difficult choice in how to deal with this weed. further to the introduction of
this alien carp into our fisheries it was found if I am not mistaken that
clarity of the water became a problem through weed disturbance from younger
growth which was on the lake bed and was softer to the carp which uprooted these
weeds from the lake bed and put silt into the higher levels of water.these weeds
whilst not directly rooted they do send enough roots down to anchor them. the
end result was cloudy water.
I hope this
information is of interest and helps in your thought on the weed front but the
main contribution to the excessive weed is the high stock levels just to keep
the angler happy.
Also how this
related to modern thinking on natural weed control I have no idea but must be
still relevant
regards
Gavin
I am becoming ever more convinced that a bit of judicious raking to create clear "bays" is the most practical and environmentally acceptable answer. If the weather holds then I may well do a small trial area on Sunday and see how easy this proves to be and what the effect is. My thought is to clear a patch up near the hut where the water is wade able and the result is unlikely to have any lasting effect on the rest of the Tarn. We shall see.
We have a day pretty much like yesterday with a fair bit of high cloud, little wind and a reasonable temperature. If this lasts till tomorrow then we should have ideal conditions for the riverfly exercise.
Ian