I'm in the middle of my move and have limited time, but I'll chime in for a second.
First of all, thanks for introducing this topic, Larry. And thanks for providing a detailed description. I've actually been evaluating this method for a while now and have not decided yet if it will provide significant advantages for most shrimp larvae or not.
Just a few more things to avoid confusion here. First, it's actually spelled "Kreisel" (not Kriesel) and the full name is actually "Planktonkreisel" (now the google searches should be a lot more fruitful). The Planktonkreisel was first used (i.e. developed) by the "Biologische Anstalt Helgoland" (Biological Institute Helgoland) in Helgoland (an island in the North Sea), Germany in the 60s for rearing and culture experiments with "ctenophores, a chaetognath and meroplanktonic organisms." Here is the abstract of the original paper from the 60s:
http://www.springerlink.com/content/p6n4q07588k00m82/
"Kreisel" in German is a word that can be used for rotating/spinning things/devices. (The meaning of "Plankton" should be clear
)
Here is *one* design that you hit right away when you do a google search:
http://www.mbari.org/midwater/tank/tank.htm
There have been many, many papers published about various Planktonkreisel designs, but, unfortunately, most of you won't be able to access them unless you are at a university or have a subscription to an expensive scientific article delivery service.
Second, the strict definition of the word "pelagic" in most dictionaries is: "found in open sea: relating to, living, or occurring in the waters of the ocean or the open sea as opposed to near the shore" Examples: pelagic fish, pelagic bird populations etc...etc. In other words, pelagic is used for animals living away from the shore, more or less "in the middle of the ocean/sea." Although "pelagic" is normally used in a marine context it has also been used by scientists to describe "pelagic" animals in large, ocean-like lakes like the rift lakes in Africa. You do see some erroneous defintions floating around on the internet that describe pelagic as the opposite of "benthic." That is not accurate. "Pelagic" does not really relate to any life-stage of an animal, hence using the word "pelagic stage" would also be erroneous. Pelagic really just means "in the open sea (or large lake)" and it could refer to a bird, a fish or even "pelagic sediments" on the ocean floor.
When talking about larval stages of animals one usually says "planktonik" as the larvae form part of the ocean zooplankton. Zooplankton can be pelagic, but does not necessarily have to be as near-shore waters can also be plankton-rich. Plus, judging from the distributions of many freshwater shrimp with marine planktonic stages, the larvae of many (maybe even most?) species seem to stay relatively close to the shore, some even staying around in mostly brackish waters. So, "larval stage" (when referring to larvae in general) or "planktonic stage" (when referring to the larvae out in the wild as part of the zooplankton) would be the correct way of describing that particular stage in a shrimp's life.
Anyway, just clarifying things as it is important that hobbyists learn to use the correct terms (when they have actually reached the stage where they hae to use these words, that is
)
Thanks again for bringing up the topic, Larry! Your input is greatly appreciated.
You might want to start a new thread to keep track of your progress once you are ready.