The question often comes up, "Can you culture pelagic copepods without live phyto?" I've been very successful at culturing Apocyclops panamensis using live phyto, specifically Isochrysis (T-Iso and C-Iso). I've also recently added Thalassiosira weissflogii to the menu. Andy Berry has clearly demonstrated that Apocyclops can be cultured using live Oxyrrhis marina as a feed, which he considers to be much easier than culturing phyto. Nonetheless, many hobbyists still would like to be able to use preserved phyto pastes to culture a pelagic copepod directly. Accordingly, I am going to conduct a long overdue experiment to see if I am able to culture Apocyclops using preserved phyto products.
I'd like at this point to explain that my methods employ some aspects one might expect to find in a "real" scientific experiment such as the use of a couple of controls and consistent treatment of the various cultues, except for the food provided, but most definitely lacks other aspects necessary for "real" science, such as replicates or objective quantification of the amount of food given, or objective quantification of the results. I am not a "real" scientist. I'm just a hobbyist who is a plankton geek. Still, I think there might be some value to what I am doing here. Another note I'd like to add is that two of the preserved phyto foods I'm using are definitely "past their prime". They have been in my fridge for quite some time, and are, frankly, past their "best used by" date. That said, they have no funky smell, and I am successfully feeding some happy Tigriopus with them, so they aren't all that bad. I can, and am willing to repeat this experiment with some fresh preserved phyto products should the opportunity arise. I just don't have a lot of fresh phyto paste on hand at the moment, and still got inspired to go ahead and start this experiment with the materials on hand.
I have taken 1 liter of a very dense Apocyclops panamensis culture that has been cultured using a combination of live Isochrysis galbana (C-Iso strain) and live Thalassiosira weissflogii. The liter of Apocyclops I used was taken from the supernatant of a slightly larger volume that was placed into a graduated cylinder, after the sediment in the culture was allowed to settle. I strained that liter of Apocyclops through an 80 micron sieve, and backwashed it into a clean container with 1500 ml of clean, fresh, seasoned artificial salt water at a specific gravity of 1.026 (Instant Ocean). Now, I have 1500 ml of a "clean" Apocyclops culture with no appreciable amount of live phyto present.
I took that 1500 ml of clean Apocyclops culture, and divide it evenly between five 500 ml Erlenmeyer flasks, making sure to keep the culture stirred so as to distribute the copepods between the five flasks as evenly as possible. I labeled the flasks with the numbers 1 through 5. Each flask was fitted with a foam stopper that had a rigid airline tube inserted through the center of it, which reached to within appx. 1 cm of the bottom of the flask. Each rigid airline was fitted with a flexible airline vinyl tube which was in turn affixed to an air distribution manifold, which in turn was supplied with air from a pump. The five individual valves for each flask were adjusted to provide approximately 4-6 bubbles per second.
Each flask will be fed 30 ml of food each day. Flask #1 will get straight, undiluted dense live phyto. Flasks #2 through #4 will have their food added to 30 ml of water. With the exception of flask #5 (the starvation control), the food density of each food type will be adjusted to visually match the density of the food given to flask #1 (the live phyto control) as well as I am able. The feeds for each flask will be as follows:
1) Live phytoplankton, a mix of Isochrysis and Thalassiosira.
2) RotiGrow Nanno, a Nanochlorpsis-based preserved phyto paste.
3) A "home brew" smorgasbord consisting of a combination of the following Reed Mariculture products: RotiGreen, N-Rich Plus, Thalassiosira weissflogii, Shellfish Diet 1800.
4) Reef Nutrition "Phyto Feast".
5) Plain salt water (a starvation control).
Flasks #2, #3, and #4 will also be given an ChlorAm-X solution, in an amount I estimate is appropriate for the amount of phytoplankton being fed.
After approximately 6 or 7 days, the 500 ml flasks should be full. At that time, I will transfer the contents of each flask into clean 1000 ml flasks, after turning off the air for long enough to allow the sediment to settle, and attempting to avoid transferring the sediment into the new flask. I will attempt to transfer the same amount into each new flask, i.e., the starvation flask will likely have very little sediment, but that doesn't mean I will transfer more volume from that flask than the others. After the transfer to the new flasks, I will increase the daily amount of feed from 30 ml to 50 ml. That will give approximately 10 or 11 more days before the 1000 ml flasks are full, for a total of from 16 to 18 days of the experiment. At that point, I'll figure out what to do, based on the results so far.
I will view the contents of each flask daily, and estimate the density of the culture in each flask, using a subjective scale ranging from 0 through 5, as follows:
0: No live copepods visible at all.
1: Very, very few live copepods visible.
2: A small number of live copepods visible.
3: A moderate but healthy culture of copepods.
4: A strong and somewhat dense culture of copepods.
5: An extremely dense culture of copepods.
As of right now, the flasks have all been prepared as described above, and have all been fed their first feeding. Each flask rates a "4" tonight, since a level "5" culture was diluted from 1000 ml to 1500 ml to prepare the flasks. I'll keep you all posted!
<message edited by JimWelsh on Sunday, September 25, 2011 2:38 PM>