Question: What affects the rate of pulsing of Silver Xenia (Xenia elongata)?
Introduction: There are many theories about what makes different species pulse or not pulse, and a certain amount of annecdotal evidence. I would like to test some of these and quantify their effect on one species of pulsing xenia. These experiments will answer a few basic questions such as - How does each factor affect pulsing alone? What are the ideal conditions for maximum pulsing? Is pulsing an all or nothing phenomenon or does it happen faster or slower under different conditions?
Variables to test: Time of day, photoperiod, feeding, lighting, pH/alkalinity. Since this is a lot to test, I intend to use the same animals (corals) for multiple trials with (eg) 5 days (M-F) for acclimation to a new regimen, then take observations on the weekends. If there is no obvious damage to the corals, then trials could be run back to back, or if there is damage, then recovery times could be added, but the least destructive experiments will be carried out early and (possibly) more destructive experiments later. Water quality parameters will be monitored as well (hopefully one of the high feeding groups will cause high nitrates so this can be tested as well). In addition, if any animals look unwell or if pulsing stops altogether, a trial will be stopped early to preserve the health of the corals. I have proposed 8 weeks of trials which should give plenty of time for some recovery weeks and some opportunities for the frags to heal longer than a week (depending on how they look).
Response variable: Pulsing rate (eg pulses per minute), averaged for eg 3 polyps per organism, and 3 organisms per test group.
Methods:
Setup: Mason Jar with 1" of new (washed) aragonite sand. 1 tbsp of "live" sand from my display tank. Glue 1 stalk of xenia onto 1 large seashell on sand. Airstones will be used for circulation. Water changes will be eg. 10% daily. There will be three test groups each containing 3 jars (total of 9 individuals). Each set of 3 jars will be in a secondary container with fresh water with an aquarium heater and circulation (for temperature stability). Topoffs with RO/DI water will be done in the morning and evening. 1 ammonia badge will be used per group and nitrates will be tested weekly. A very small cycle may occur in the initial weeks, but it will be monitored carefuly and I expect it to have minimal effects due to the tiny (or even negative) bioload present.
Discussion point - I was going to do this in bare glass since xenia love smooth surfaces, but I decided to add a small amount of coarse sand to provide at least a minimal ability to process wastes into nitrates. This would require something to put the xenia on, so I have decided on seashells, which I have a few around that should do nicely.
All groups will start out with baseline conditions using a single flood lamp suspended over the three jars. Each week a condition will change with group 1 being lower than normal, group 3 being higher than normal and group 2 remaining the same as a control (At the end of the week that condition will go back to normal and a different condition will be changed).
Base (control) Conditions: 12h light, 6.5k lightbulb (CFL for minimal energy use / heat production), 12" from top of jars, low (eg 1 drop/day) phyto/zoo mix, 75F, no pH / alk additives. Using instant ocean reef crystals at 1.026 SG (with mixing and heating for 24 h). The food can slowly be adjusted to determine how much can be added without seeing detectable nitrates.
Week 1: Frag / heal. Take baseline readings. Take time of day readings (eg 1 hour before lights on, 1 hour after lights on, mid day, 1 hour before lights off, 1 hour after lights off, mid night).
Week 2: Photoperiod. No light, 12 hours, 24 hours.
Week 3: Photointensity. 6", 12", 24" from the tops of jars.
Week 4: Photocolor. 3.5k, 6.5k, white (self ballasted 10k?) or led?.
Week 5 (might need 2 weeks to reach appropriate nitrate levels and a week after to return to normal): Food / nitrate. no food, low food (x ml), high food (x ml). This will have to be tested and adjusted accordingly.
Week 6: Temperature. 68, 75, 82F. (I was going to do 70, 75, 80 degrees, but since I could only do 3 groups, I wanted to use a condition that would be a little uncomfortable, but not lethal. Temperature changes would occur over several days).
Week 7: pH / Alkalinity. Add (x drops) of nothing (group 2), pH/alk up (limewater) (group 3), or pH down (vinegar) (group 1) and measure pH/alk levels and pulsing daily. The idea is to slowly get slightly out of comfortable range, but not to kill them. In general the plan is to take measurements, then treat, then wait 24 hours for equilibration before measuring again.
Week 8: How fast will they go? Puting them under "ideal" conditions as determined by the previous tests and measure rate.
May have to stop water changes during weeks 5 and 7 to get water quality changes.
Materials:
12 Mason Jars
nitrate test kit
3 secondary containers
3 heaters
3 temperature stickers
3 reflectors
3 6.5k bulbs
1 low color bulb
1 high color bulb
Standardized food preparation
Salt
pH up - eg Limewater
pH down - eg Vinegar
test kits - pH, Alk, nitrates
Data analysis: Using basic tools in Excel I will look for both dose response (linear regression) and differences between groups (ANOVA).