Coldwater marine aquarium Blog 2009 July
July 27 2009

Final update

With some rocks out

Some of the rocks taken out.

I'm sorry to say so, but this will be the last update of this blog. The reason is that I have gotten a new apartement, and recently I emptied the tank. The picture above is taken the night before I started emptying it. It was a stressing 4 day process to empty the whole thing, get rid of rocks, sand and animals, and clean everything including the equipment. Not very fun either. So I didn't take many pictures. The sheer amount of rocks was ridiculous. I really don't remember having put that many in. They took up a significant portion of the volume. I had to make two trips in my car to get of them all.

Some observations

Posthorn worms on the back wall

Notice how the worms grew in the shaded area behind the rocks.

One of the most successful animal species was the posthorn worms. There were many of them in plain view, but the real concentrations were in shaded areas. I wonder why. On the picture you can see the great concentrations on the back wall. But only in places that used to be behind rocks. I wonder if it was the light, the lower current, or simply greater access to food that made them stay in those places. I estimated there to be 43000 individuals of 1 mm or large diameter on the walls. On the rocks there must have been over a hundred thousand. Another successful species was the sea vase (Ciona intestinalis). These grew in the same shaded places as the worms. I had no idea that there were such great numbers of them. Some of the larger rocks in the lower parts of had hundreds of individuals on them. The rocks and back walls had many colonies of a small, white type of sponge. There was even a large nudibranch, 6 cm diameter, feeding on them. I think it must have been feeding on the sponges since it looked just like them, which is often a good indicator with nudibranchs. I was amazed at the survival rate of various animals in the rockwork. I found a vast number of brittle stars. I imagine most of them must have survived. I could probably have kept many more. The number of worms was great. Some of them had grown a lot. The largest, probably a Neanthes virens was between 30 and 40cm long. I regret not taking a picture of that one! The 3 hairy crabs (Pilumnus hirtellus) were alive and well.

Future plans

Sea squirt

Sea vase (Ciona intestinalis)

I will not set up a new display tank immediately. I will probably be without aquariums for some months depending on various factors. The current tank will be sold/given away because I don't want that particular shape in a future system. So there is no need to wait for any new blogs in the near future. As you may have understood from earlier updates, I have a dream of developing a new feeding system for benthic, nonphotosyntetic animals. After 2 years of feeding 5 times a day I have learned to appreciate an automatic feeding system. Both for my own sake and the animals'. The first tanks I set up after this will probably reasearch tanks. I may set up a system with two smaller tanks where one is a plankton refugium for the other. With such a system I'll be able to study plankton growth and feeding responses from various animals. The ultimate goal is to set up a display tank with nonphotosynthetic animals fed only by a plankton refugium. That is one thing that is absolutely clear: The next display tank will be only for nonphotosyntetic organisms. When I'll be able to set up a new display will of course depend on the result of the research. It may take a long time to find solutions that I am happy with.

Phyto tank

The phyto tank test started out much the same as the bottle experiment, only with more rapid growth in the start. The water turned really green after about two weeks. After about four weeks however, the water got gradually cleaner until it seemed free of plankton. So this setup was not as stable as the bottle culture setups, oddly enough. I was kind of expecting it to be more robust. There are a number of possible reasons. Obviously new experiments are be needed.

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