Recent weather prevented a sea dive due to high winds and poor viz of late. A freshwater recce dive was organised at Llyn Gwynant This site was a previously unknown to the Club however we had a successful dive from
the little gravel beach by the road.
6 of us took bearings across the lake in 3 pairs. 1
pair headed across to Elephant Rock and recorded a depth of 12ms. The other 2
pairs remained in the shallower waters which extend quite a long way across from
the beach, and contain abundant weed beds. There seems to be a very clear
cutoff depth of about 5ms after which there is very little weed.
Visibility
was measured using an Opalometer and came in at 10-11 opals out of 12 ( a simple
method of ascertaining clarity). If you're interested in making your own water
clarity very very low tech device go to http://www.opalexplorenature.org/ (part
of Natural History Museum activities)
 |
 |
Green sacs, unknown -lots of these
around weeds
|
< The green weed on lake bed picture is a nice shot
of a stonewort bed, most probably Chara sp. (Nitella is the other common genus
but this is
usually a bit more transparent). Chara virgata has been recorded from Llyn Gwynant in 2007 so it could be this one. Looks like quite a healthy bed.
usually a bit more transparent). Chara virgata has been recorded from Llyn Gwynant in 2007 so it could be this one. Looks like quite a healthy bed.
A lot of filamentous algae, growing mainly over Isoetes by
the look of it.>
< Most
likely to be a water mite. There are quite a few species of water mite and some
of them are bright red. They tend to swim through the water column in a busy
manner. Adults are predatory, juveniles parasitise water beetles and
bugs.
Various Sponges were spotted....Spongillida
sp - USB microscope 25x mag.
Various weeds were evident as was a water beetle!!
