Should we be striving to keep all parameters constant?

[MikeG]

Thought I would just start a discussion.

One reason to have fluctuation in our tanks and to not shoot for all stable parameters.

I have always thought that my daily temp swing of 2-4 degrees could be helpful in helping corals survive an enviornmental stess. I had a temp spike about 2 months ago where we had a warm day and I had turned all the fans on and closed all the canopy and stand doors. Got home from work to find the tank at 88. I had no losses and everything looked healthy throughout the time. I brought the temp down slow and never saw any losses 2-3 months later. This is an SPS tank.

The following was taken from
http://www.advancedaquarist.com/2006/8/aafeature/view

Although strong water flow is beneficial for helping corals resist bleaching, living in a really stable, comfortable environment can reduce a coral?s tolerance to occurrences of thermal stress. In the 2005 study by McLanahan et al (9), researchers surveyed reef zones around the island of Mauritius which differed mostly in their abundance of water flow. The study discovered that coral bleaching was most prevalent on the reefs which received the most constant and abundant water flow. Although this finding contradicts the majority of the literature regarding the relationship between water flow and coral bleaching, the paper explains that the most affected corals had reduced acclimation to minor stress events. Since the most affected corals were acclimated to a very stable temperature and constant high water flow environment, the corals did not have to acclimate to minor stress events so they were less able to tolerate an anomalous high temperature event. The ecologically dominant corals which suffered the most bleaching due to this temperature anomaly were Acropora and Montipora species.

 

[MikeG]

No comments?

 

[Casino]

Ive alsways said if you have a healthy system you corals and fish can survive a small swing in parameters. Now, a big fast swing is another story...no matter how healthy your system is it wont be able to take it. All systems need to adjust to changes. The slower the better the chances are for survival. Ofcourse this dosent mean you can have a very slow temp or ph or any other parameter go extremely high or extremely low and not expext some casualties. As long as its a slow swing and its keeped withing a marginal state your system will adjust accordingly.

 

[MikeG]

Now, a big fast swing is another story...no matter how healthy your system is it wont be able to take it.

I don't necessarily agree with this. The experience I shared above was an 8 degree temp increase in at most 3 hours. I would consider that pretty extreme. I had no casualties. Is this aided by the fact that my corals are use to a temperature fluctuation and were able to better cope with the stress? I am not advocating that letting your tank fluctuate is a good thing to do, but there is quite a bit of research out there that supports some fluctuation.

 

[Casino]

The experience I shared above was an 8 degree temp increase in at most 3 hours.

3 hours is enough time for a system to adjust to a temp swing. Now if you have a temp swing of 8 degrees in lets say 20 mins. expect some casualties. There really isnt much time to adjust to that. Now my piont is that even if you gradually have the temp increase lets say to 95 or 96, dosent matter how long it took to get there its going to get ugly cause now its not the ability of your tank to adjust to the raise in temp, its the ability to survive the temp. This would also apply if the temp got down to lets say 70 degrees.

 

[RichConley]

I'm not convinced that parameter fluctuation makes a difference. As far as temperature, a 10degree swing in an hour or so isnt unheard of (tide change, cold ocean water going to the reef, then changes so warm lagoon water is going to reef).

I'm not convinced fluctuation in other parameters makes a difference either. I think its more of staying inside a certain range. I havent noticed any difference between my Alk being rock solid at 9 dkh, or bouncing around between 7 and 11, but if it touches 6, I start getting tissue recession. Same with temperature, anywhere below about 86 seems to be fine, if i hit that, things start to show problems.

 

[Casino]

I'm not convinced that parameter fluctuation makes a difference. As far as temperature, a 10degree swing in an hour or so isnt unheard of (tide change, cold ocean water going to the reef, then changes so warm lagoon water is going to reef).

I'm not convinced fluctuation in other parameters makes a difference either. I think its more of staying inside a certain range. I havent noticed any difference between my Alk being rock solid at 9 dkh, or bouncing around between 7 and 11, but if it touches 6, I start getting tissue recession. Same with temperature, anywhere below about 86 seems to be fine, if i hit that, things start to show problems.

Exactly! Swings happen in the oceans all the time. It just dosent happen in an instant. It takes time and everything in the ocean adjusts to it. Now in a closed inviroment like our tanks its a little diffrent. Things in the ocean are use to the swings but not a very low or a very high swing. Our tanks might forgive a day of parameters getting a couple degrees high or low, or even in your case 8 degrees. The reasons you didnt notice any casualties is that 88 degrees altho high isnt deadly high unless its keep there long enough. You came home and you corrected to problem. It got hot slowly and it adjusted to the temp. Now if you came home and found the temp at 90+ then we might be discussing a diffrent scenario. I guess to answer your original quention, I dont think you need to have your parameters so rock steady but the more steady the better.

 

[Liam]

i think you will find temperature is the ONLY parameter that varies greatly in the ocean,typically up to about 10 degrees but usually far smaller swings.

 

[MikeG]

Exactly! Swings happen in the oceans all the time. It just dosent happen in an instant. It takes time and everything in the ocean adjusts to it. Now in a closed inviroment like our tanks its a little diffrent. Things in the ocean are use to the swings but not a very low or a very high swing. Our tanks might forgive a day of parameters getting a couple degrees high or low, or even in your case 8 degrees. The reasons you didnt notice any casualties is that 88 degrees altho high isnt deadly high unless its keep there long enough. You came home and you corrected to problem. It got hot slowly and it adjusted to the temp. Now if you came home and found the temp at 90+ then we might be discussing a diffrent scenario. I guess to answer your original quention, I dont think you need to have your parameters so rock steady but the more steady the better.

Yes there are swings in the ocean, but the research that I cited as well as others that I have read comment on regions of the ocean where temperature is not that variable seem to tolerate stress to a lesser extent as observerved as a greater bleaching event and less percent recovery after insult. I know this is not the only parameter and there are many other variables.

 

[Richard]

Around the sept time frame my tank hit 85 and after that I lost 2 lg caps and my povona started to receed.
My tank also have a daily wide temp swing from 77-sometimes to 82. But after the temp spike to 85 the corals went south.

 

[smithcreek]

I wonder if the corals that survived on the part of the reef that had more temp swings were genetically better suited to that environment. Even within a species some individuals are better suited for one particular environment than others are.

 

[FishHead]

i'm not sure what to make of that article regarding water flow and coral resistance to stress.

on one side you have this:
"determining where coral are most resistant to environmental stresses which cause coral bleaching and where they will be most likely to recover from those stresses. In a review of the published accounts of coral bleaching events. One of the recurring details West and Salm discovered in their review is that corals which incurred little to no bleaching or rapid recovery almost always occurred in areas which experienced rapid flow from being in channels or strong currents."


then the contradictory study:
"Although strong water flow is beneficial for helping corals resist bleaching, living in a really stable, comfortable environment can reduce a coral’s tolerance to occurrences of thermal stress. The study discovered that coral bleaching was most prevalent on the reefs which received the most constant and abundant water flow"

one is saying coral is "most resistant" to stress in high flow areas.
other is saying coral is "less resistant" to stress in high flow areas.

how unconstant would you want to make conditions? and how much effort would you need to take to systematically accomplish that?

I think i'll just keep the flow flowing and keep the temp under 86.. as well as keep lights off during water changes...

 

[MikeG]

My point wasn't to try to make parameters fluctuate on purpose, but I have seen many threads stating that your tmp should only fluctuate like one degree, two if you must. Any more than that is not good. I just wanted to bring up whether this is the best thing or unnecessary assuming that we are also keeping salinity, pH, and alkalinity as stable as possible as well.

 

[smcnally]

I personally let my temp fluctuate a few degrees. It's just my opinion though.

 

[RichConley]

i'm not sure what to make of that article regarding water flow and coral resistance to stress.

on one side you have this:
"determining where coral are most resistant to environmental stresses which cause coral bleaching and where they will be most likely to recover from those stresses. In a review of the published accounts of coral bleaching events. One of the recurring details West and Salm discovered in their review is that corals which incurred little to no bleaching or rapid recovery almost always occurred in areas which experienced rapid flow from being in channels or strong currents."


then the contradictory study:
"Although strong water flow is beneficial for helping corals resist bleaching, living in a really stable, comfortable environment can reduce a coral?s tolerance to occurrences of thermal stress. The study discovered that coral bleaching was most prevalent on the reefs which received the most constant and abundant water flow"

one is saying coral is "most resistant" to stress in high flow areas.
other is saying coral is "less resistant" to stress in high flow areas.

how unconstant would you want to make conditions? and how much effort would you need to take to systematically accomplish that?

I think i'll just keep the flow flowing and keep the temp under 86.. as well as keep lights off during water changes...

I disagree that those studies are contradictory. The first one says high flow leads to less bleaching. The second one says that thermal stability leads to more bleaching in times of thermal swing.


I've had my tank spike to 90 without really any losses. I dont run a heater though,so my temp swings 5 or 6 degrees on some days.

 

[FishHead]

I disagree that those studies are contradictory. The first one says high flow leads to less bleaching. The second one says that thermal stability leads to more bleaching in times of thermal swing.

well the author of the article apparently did:
"Although this finding contradicts the majority of the literature regarding the relationship between water flow and coral bleaching"

if the two studies were comparing totally different parameter situations then why mention them both within the scope of the article?

"high flow leads to less bleaching" under what conditions?
wouldn't thermal swings" be considered an 'environmental stress"?