woensdag 20 februari 2013

2013-02-16 10:24 hrs hbos mist coming up again?


Weather : Some clouds / WNW wind 2 bft / Rain 1.1 mm / 1023.7 hpa
Divers : John, Koos, Iva, Jan, Axel,
Goal : sediment sample and secchi visibility check
Max depth : 19.3 mtr
Duration : 38 minutes
Air temp : 5.0 celsius
Water temp : 3.4 celsius minimum
Fish: > 1 Perch
Big Secchi Visibility vertical         9,5 mtr
Big Secchi Visbility horizontal      9,5 mtr
small Secchi Visibility horizontal  9,5 mtr
Dutchi horizontal                       7,0 mtr
Plants: none
Comment: First time diving with GNT wetgloves. There really warmer than drygloves underwater.
First we went via surface to measurepile and did a vertical visibility reading with the big secchi.
I guess my eyes are better than Jan's. I still could see a glimps of the disk at 10 mtr, but Jan saw it at 9 mtr. Average of those measurements is 9,5 mtr. On the horizontal still the big and smaller secchi give the same readings. Dutchi gives 2,5 mtr less as expected. That may turnout completely different when visibility becomes less then 3 meters.
From there I did a quick check on SETL H106. On it a common fishleach had settled on a corner of the plate. Both plates still are home to many shrimp. From there we descended and head 150 degrees out.
John had the courtesy to take a sediment sample from 20 mtr depth which he did ofcourse. After that we headed back to the entrypoint.  At 19 mtr mist is starting to come up although we do not know if this is caused by diver activity or a result of nutreants being released from the sediment
Length of daylight is 9:59 hrs might have something to do with the growth of algea. Temperatures are still low.
This sediment sample is full of life in the form of copepods. Comparing this sample with the one from Toolenburg from 26 mtr depth is that this sample has an uncountable quantity of copepods.


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