Coldwater marine aquarium Blog 2008 March
April 10 2008

Easter vacation

It was a cold easter this year, often below freezing, so no diving or swimming. But I had quite a few nice collection trips outside. Especially on two occasions with very low tide and and high pressure. I then visited my favorite location and found it even better than I had thought. Two of my dreams were fulfilled: First I managed to get dead man's fingers (Alcyonium digitatum). That is a very common and nice soft coral growing here. They grow in shaded areas just below the tidal zone. The colonies I got are very small, about 1 cm2 each! Still I got 2 rocks with over 50 such small colonies. It will be very interesting to see the development. I now point feed them once or twice a day with a "sea squirt", a turkey baster like device from Tunze. The corals always avoid well lit areas where algae can grow. In my tank the visible ones are situated in a well lit area. So I am a bit nervous there. Hopefully it will work. The next great thing is that I got specimens of one or two of the best lookin red algae around here, namely Phycodrys rubens and/or Delesseria sanguinea, not sure about the species yet.

Kelp Bed

Kelp bed at low tide.

During Easter the tide was so low that I could wade all the way out into the belt of large kelp. The picture is of the best location I have found. What makes this particular location so special is that it is exposed to waves, big but not too big, and the place is an ice age deposit of boulders, gravel and sand. This creates lots of hiding places, and there are small rocks that I can take, with algae and animals on.


Sheltered bay from above. Dark areas are rock with algae. Lighter areas are crushed shell sand.

Laminaria hyperborea

Laminaria hyperborea, washed ashore.

I was probably wrong about the species of my new flounder. I thought it was a dab (Limanda limanda), but now I am pretty sure it is a european plaice (Pleuronectes platessa). It is still doing well. Got some nice pictures of it.

Corals at last

The dead man's fingers (Alcyonium digitatum) soft coral is probably even more common around here than I thought. In the lower tidal zone in my favorite location I found small colonies on the underside of rocks. The rocks were such that the corals received good flow, but at the same time were protected from the worst impact energy, and direct sunlight.

Urticina anemones

The two new sea anemones (Urticina eques) aren't entirely happy. We have two related species of spectacular large sea anemones here, Urticina felina and Urticina eques. I am figuring out the difference between these species now. The felina is probably adapted to a turbulent environment with lots of moving algae. It hides between rocks and always tries to find some shelter. I always find a lot of felina in turbulent tidal environments. The eques seems to be adapted to calmer waters. It sits on top of rocks like a tower and looks really spectacular. Unfortunately it seems to get very stressed by moving objects. It gives the impression of being more sessile and moves less. I have never found them in places with lots of wave action or algae. In the tank there aren't any more places where I can place such anemones without stressing them. If I have to make a choice between a densely planted algae tank and an anemone tank I'll go for the algae. But I'll make a few more tries at eques when I get the chance. Anyway I'll get more felinas. I want some that have gorgeous colors, like pink or blueish, and at the same time have nice personalities, not too shy. Anemones are confirming what some norwegian celebrities have been showing for along time: You can actually have a personality without having a brain.

New algae

I've spent quite some time the last months looking for new algae. Particularly new reds have been high on my wanted list. The search was successful. There must be at least 5 new species of reds and browns. The reds are very difficult to identify. In the literature you often find several species that look similar. In the end it may turn out to be one of the species that didn't look similar at all. Still, I have managed to identify some. These algae add a great visual impression to the tank since they make the vegetation thicker and add the red color. The combination of red, green and brown make algae tanks very nice from an aquascaping perspective. I am thinking that a standard aquascape in this kind of aquarium would consist a kelp forest of relatively large kelp specimens, preferably Laminaria hyperborea. These have a stiff stipes and can grow up and form a canopy. So you get two vertical levels. The reds and greens then form an underbrush for the forest. But this is for my next tank some time in the future.

See that little blotch of coralline algae in the upper left of the picture? To most people it is hardly visible, but to me that is one of the cooler things that has happened to the tank lately. Finally coralline algae is beginning to spread all over. Animals have been reproducing too: The sea hares have laid eggs, hermites have mated, and I am not sure if the snails are mating or just eating algae off each others shells.

Sea hare eggs

Sea hare eggs attached to algae.


This hermit male carried his girlfriend around and protected her for two weeks during the mating. Some sort of honeymoon maybe.


Hitchhiking nudibranch with internal shell.

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