woensdag 12 februari 2014

Result SETL H126 11-06-2013 t/m 04-12-2013

SETL H126 has virtually the same result as SETL H124 eventhough H126 was placed three months later then H124.

Plates still without Dreissena on august 4th.
Plates fully covered with Dreissena on sept 1st.
That puts the main focus on august where the growth on H126 and H124 have synchronized with each other.

Initially we meant to leave this plate hanging for 1 year, before replacing it.

Then we decided to change the protocol. Two permanent plates and two plates being replaced every three months. That is why we took H126 out of the water to analyze more thoroughly at dec 4th 2013. Analyzing by photos is not sufficient enough.

11-06-2013 Watertemperature was 19,0 celsius at 1 meter depth.
04-12-2013 Watertemperature was 9,0 celsius at 1 meter depth.


We show you the results H126 plate over a timespan of 6 months.

After 3 months at 15-09-2013 / 19,3 celsius.

Organisms (only took photo, no specimens)
  • Dreissena polymorpha 
  • Dreissena rostiformis bugensis
  • Freshwater sponge (Spongilla or Ephydatia)
  • Cordylophora



After 6 months at 04-12-2013 / 9 celsius.

Organisms (Photo and specimens)
  • 220 pcs Dreissena polymorpha.     
  • 22 pcs Dreissena rostiformis bugensis.
  • The ratio between D.rostiformis bugensis and D.polymorpha is 10,0% 
  • Orange specks (unknown) see microscope photos.
  • Freshwater sponge (Spongilla or Ephydatia) without emmulae.
  • Old byssus threads of the Dreissena's



Remarks:

The orange specks are also seen on H124 plate.
I have specimens on Ethanol 95%. These orange specks were also on the Belgian SETL plates in december when we visited them, so it is common.
It could also be an excrement or by-product of an organism (ie Dreissena's or Trichoptera larvae) If it is an excrement what foodsource causes the distinct orange colour.
And what organism can produce a fairly hard pellet of 0,5 mm max in size?

The ratio between D.rostiformis bugensis and D.polymorpha can be important in the future, because on plate H124 the ratio is 11,5%. Now that is not representable data as we only have two plates, but it gives an idea.

Also it is unclear why a specific area of Dreissena's were still attached to the plate. You can clearly see that from beginning of october 2013 due to the growth of the Dreissena's the 14x14 cm area became overcrowded. Many Dreissena's started to form hanging clusters and eventually let go.

See photo as you can see the first clusters hanging in de back.
This situation started around the samen date for SETL plate H124.


H126 29-09-2013 15 celsius

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