Tinyreef- my sincere apologies, the paper is by Widdig. If you can't find it on Google please let me know. I'm about ready to walk a copy over to you!
I have been reviewing the papaers by Fabricious and by Widdig the last few nights. They are very interesting, but come to no conclusion. Some points I take home: Fabricious established that they take up phyto, but I don't think she established that the phyto was not inside a zooplankton below 100 microns. She had one feeding experiment in which she used filtered seawater with phyto additions determined microscopically to not have zooplankton contaminants- but showed no data about pheopigment digestive changes or polyp counts(I THINK- there's a lot of data here in the method section and I'm going over it again tonight).
So, I suspect the phyto is getting into the dendros inside small zooplankton. Obviously, they need the pigments to make the colors for whatever purpose that serves. So, I believe that they take phyto: I just don't think it has been shown that they take up phyto directly.
Fabricious used microscopic dissection to show very rare retention of zooplankton in wild collectedc polyps. However, her data showed only large (>750 microns) zooplankton; obviously, her method was missing the ciliated protozoa and other plankton in the range of 50-300 microns. It seems that only the tough, mobile, zooplankton- the very ones that would be hard to catch- were present in her samples. That means to me that her microscopic methods weren't picking up the soft bodied smaller zooplankton.
Also, her clearance studies on zooplankton was done by using catch from a 100um net- probably too large for the organisms of interest.
I have been comparing the feeding mechsnisms on my dendro with those of the Nephthyigorgia (chili coral). Their construction is similar; both have tentacles, with small pinnules. However, the chili coral is about 8-10 times the polyp size of the dendro. The chili coral takes 800 micron baby brine shrimp very easily. The dendro has obvious tentatular capture of golden pearls at 5-50 microns, but as Fabricious notes, releases larger partifcles after about 50 seconds on average.
The dendro clearly shows tentacular capture and feeding response to golden pearls.
The pinnules of the dendro are, as Fabricious notes, in the range of 60-80 microns. In order to stimulate 2-3 pinnules at a time and trigger a feeding response, it is likely that the particles of interest to this organism would be in the range of 50-200 microns. This would be typically ciliated protozoa, as well as pelagic eggs. Small zooplankton in this range would havae to be stuffed with phyto- they have very little else to eat.
Another reason I think they don't eat phyto primarily is that they are not the best design for it. Soomething like a mucous net would be much more effective, such as internal to a sponge.
It may very well be that the smallest golden pearls- the 5-50 micron size- are too small. The proper size may be the 50-100 or slightloy larger. I'm going to try those.
Mary reports ingestion of baby brine shrimp. I've tried it, but I can't convince myself yet that they are being swallowed. I'm still working on it with my jeweler's loupe. In any event, a baby brine shrimp (newly hatched) is 800 microns, which is the exact size of the oral disk; having been frozen, it's likely easy to capture, and may make a good substitute for a protozoa. They may be a little large, so being immediately newly hatched may be important.
Tinyreef, Fabricious has some excellent methods sections I would like your thoughts on. She has carefully done polyp growth counts at different flow rates. She reports best growth at 12-15 cm/sec, which I guess is about 6 inches/second flow. She used five hours on, 3 hours off; I'm going to go with her flow regimes for awhile.
She also reports their preference for manmade surfaces, the fact that they are early colonizers, and their rapid growth of 8%/day in the wild, by polyp count. She clipped branches, put them in an aquarium "with running seawater" (?open or recirculating is not stated), and they regularly attached in 10 days. This period of rhizoid formation, where the branchlets attach to the pvc, in my view raises suspicions about the validity of the paper by Widdig- he just cut them and tested them during a time when they were still adapting to the cut. If they were triggered for rhizoidal growth after the amputation, it's quite possible that any conclusions he reached regarding their feeding behaviour should only be applied to recently amputated specimens. Fabrisious used adapted, settled colonies on PVC plates.
So: my current take-home lessons.
1) Flow of 6 inches/second. Slack times of 3 hours don't hurt, alternating with 5 hours of flow.
2) They grow best on vertical PVC in the wild, and are early colonizers. We should be able to adapt her methods to the aquarium.
3) Tentacular capture looks best for frozen BABY brine (800 microns) to 50 microns, no smaller. Ideal size may be around 200 microns, enough to hit a few pinnules in the net and trigger a response.
4) All successes to date tend, I believe, to have VERY clear water.
I've amended my new setup of 55 over a 55 sump. Very slow flow into the sump (a trickle) to allowlong retention of food. I'm going to feed only zooplankton substitutes at 50-300 micron size. I've added a Deltec hang on skimmer rated for 180 gallons to the sump. There is an 8 inch sand bed with sulfur granules in the bottom (I regret this now as I hope this doesn't add another variable I don't need), some chaeto, and will be dosing supplements and silica. I will be using times flow to 6 inches/second. Also, will be plating out dendro branchlet frags on bundles of PVC pipes and suspending them from the top to eliminate disturbance from benthic creatures (nothing worse than finding an amphipod pulling stuff out of a dendro polyp in the middle of the night!). I'm going to order the VorTech pumps and use 4 for the top 55 gallon. I will have no substrate in the culture tank to prevent advection of the food, and will clean the glass regularly to add phyto to the system (I will keep a brown dusting going with macroalgae grow fertilizer with silica). And, will add ozone and carbon- the Deltec is easy to work with this way. The skimmer will be at the front of the refugium sump, and will add bread to the back part of the sump, so the ciliates won't all get sucked into the skimmer.
i've been slowly reading those and others i've found since last we "spoke".
