Weekly Debate

[Debater]

This week's debate:

If our reef tanks are far from being natural, would it be wise to try to keep our tank temperatures at natural levels? Or do we want to keep the temperature below normal to minimumize chances of reaching stress levels that can activate RTN since there is an hypothesis that says that RTN starts when theres a secondary stress under warmer temps? What is your opinion on this issue?

Remember, this a debate, so don't treat it as a newbie that is trying to get information. State your opinion and, if available, use material that will back up your opinion. Tell others why that you think they are wrong, respectfully, of course.

If you have an idea on a topic that would be good to debate about, please let one of the ops know or email me by hitting the email icon below this post.

 

[Anonymous]

I really cant see any reason to keep a reef tank colder than in nature. The problem is the temp difference is huge. I have been diving in the sea of Cortez when the water temp was 72 and when it was 90.

I think more important than what temp is the consistency of temp. I have seen sps kept at all different temps, mine included. However, I have lost them where there were temp spikes or drops.

RR

 

[suckair]

I agree with Righty. I think we should consider temperature shifting more than just a specific temperature. I shift my temperature all year from a low of 74 to a high of 82. I notice that every fall my Anemone spawns during my first temperature shift.

One of my favorite dive sites swings quite a bit.. 77 in the winter to 85 in the summer. One thing that is hard to deal with is that most of us mix our critters so they all don't come from the same region so you just have to find a happy middle ground.

food for thought

Randall

 

[Minh Nguyen]

Why would one consider keeping corals at unatural temperatures equal to less stress? Too warm of a temperature means stress to the coral. This does not mean cooler is better.
Corals have optimal temperature. Too cold or too hot is stressfull for them.

Minh

 

[randy holmes-farley]

I think we need to be very careful about what unnatural means. Many corals that we keep grow perfectly well in their natural environments in the 70's.

Ron's data is that more species grow in the warmer habitats. That is different than his contention of saying that cooler waters stress corals, especially those that come from those waters to begin with.

 

[Anonymous]

There is a GREAT paper that relates coral health to changing seasons and temperatures in the Bahamas. I'm proud to say I have been a part of this project for the last 3 years. The first paper was published before my joining the lab, but the next one will have a data set comprising almost 8 years of information. This is one of the very few papers I've seen published that has a long term ecological survey on a coral reef study. In the past, there has been work done on the effects of nutrient addition over time, but rarely do they last for a decade. The Principal Investigator would like to continue this very project onward to span 20 years of material. Unfortunately, it is becoming increasingly difficult to obtain funding for a LTER project.

Back to the subject, the corals have greater tissue biomass, greater zooxanthellae densitites, and greater chlorophyll densities after being subjected to a cool growing season. There is generally a one month delay following a seasonal temperature drop and then the health of the coral increases until the following warm spring.

Additionally, a grad student in our lab is finishing his thesis work on coral reef restoration. He reports high mortality in attempts made in summer, and almost 100% survival of frags placed on reefs in winter. The only difference we have correlated is elevated sea temperatures because irradiance at the site does not change seasonally.


Fitt, W.K., F.K. McFarland, M.E. Warner, G.C. Chilcoat. 2000. Seasonal cycles of tissue biomass and zooxanthellae densities in Caribbean reef corals. Limnol. Ocean 45: 677-685.


My answer? Cooler is not only better because it allows you a greater buffer against crossing the 30 C bleaching threshold, but also because it results in best coral health. Also, the proteins involved in photosynthesis in zooxanthellae are very thermally sensitive and break down at high temps.

Lastly, I will add the caveat that warmer temperatures do result in higher metabolic activity in corals, and thus may promote growth. So, there is a fine medium between keeping the temps up to prmote growth, and keeping the temps cool to promote health. This medium is likey very different depending on both the coral species, and the genotype of the zooxanthellae found within each different coral.

 

[Len]

I think we need to be very careful about what unnatural means. Many corals that we keep grow perfectly well in their natural environments in the 70's.

Ron's data is that more species grow in the warmer habitats. That is different than his contention of saying that cooler waters stress corals, especially those that come from those waters to begin with.

Just to add to this point, I was in southern Okinawa a few years back and noticed how cool their waters were. The waters were teeming with life, with huge stands of Acropora as far as the eye can see. I completely agree that one needs to careful when making blanket inferences of "natural" and "unnatural."

 

[jamesw]

I'm not sure if everyone caught this article in the last issue of Advanced Aquarist:

http://www.advancedaquarist.com/issues/ ... /media.htm

A recent paper in the Journal of Marine Biology discusses a new pathogenic bacteria V. coralyticus which causes what looks to me like RTN.

To quote from Charles Delbeek's media review:

In this paper Ben-Haim and Rosenberg describe how they were able to isolate a previously unknown pathogenic bacterium Vibrio coralyticus YB from colonies of Pocillopora damicornis collected from the coast of Zanzibar (in fact they found 15 strains of Vibrionaceae that were dominant in diseased colonies but not healthy ones, but V. coralyticus YB was the most virulent). They were able to inoculate healthy colonies with this bacterium (by adding it to the water and by putting an affected coral into direct contact with a healthy piece) and produce the same symptoms of rapid tissue loss resulting in death within a few weeks. They were also able to infect other colonies of P. damicornis collected from the Red Sea (ambient water temperature of collection area was 22-26°C) with the same bacterium.

And more importantly:

In experiments of disease transmission at differing temperatures it was found that no symptoms appeared after inoculation at 20 and 25°C after 20 days (68-77°F), but that 100% of the tested fragments showed disease and died at 27 and 29°C (80.6-84.2°F) after just 16 days (the rate was slightly faster at 29°C than 27°C).

When the pathogen was introduced into aquariums with a temperature of 80.6 to 84.2 ALL OF THE CORALS DIED!

Thoughts?

Cheers
James Wiseman

 

[Jim5]

I remember reading the thread "The Great Temperature Debate" a couple years ago in which the question of temperature was impressively discussed at length. It seems to me that until the effect of temperature is put to the test in a controlled experiment, the answer may never be known. I am not sure that extrapolating results from the reefs will always imply the same result will happen in our reef tanks since there are many differences between the two. For example, the amount of zooplankton is vastly different. Unfortunately, I do not have the space to carry this out, but wouldn't it be possible to set up heaters on a large reef tank so that there is a temperature gradient from one side to the other and then observe fragments from the same coral for growth along this gradient. (I can think of several reasons why this may not work such as coral competition, uneven lighting, water movement variables, etc.)

 

[DK]

In the summer, most of us are fighting high heat levels in our tanks. I have tried to keep it from exceeding 82degF but not always. Based on information from the boards and reading, it seemed like this was a reasonable upper limit. In the winter, we struggle (with heaters) to keep the temperature up. For me, I try to keep it above 78 degrees. From what I see here, I shouldn't vary this scheme.
When there are few changes to a system, salinity, lighting,water motion, Ph,Nitrate, temperature swings,etc, every thing grows. It is those changes that mess things up! The problem for me is that I can't stop tinkering...........

A question-- If you see an SPS coral start to loose tissue, should we then isolate it to a lower temperature enviornment?

 

[wildbill]

The most important factor will be temp control. Years ago I kept my tank at around 77, now its 80. In my set-up even a 2 degree rise effects my corals. Normally my temp is rock solid but a month ago my chiller was on the fritz and the tank went up to 82-83. I noticed tissue recession on my 8 year old plate coral. Also some bleaching in various other stoney's . The others were from sps to capricorn's. I fixed the problem and a couple of days lately all was well.

Bill

 

[Anonymous]

most of the reports i've been reading lately seem to definitely correlate bleaching with higher temps in the wild-here's one more account(there have been quite a few, lately ) :
2002 Coral Bleaching Event in the Southern Arabian Gulf (United Arab
Emirates)

A research team consisting of scientists from the Dubai
Municipality/National Coral Reef Institute (Nova Southeastern University,
Fort Lauderdale, USA)/UAE Environmental Research and Wildlife Development
Agency/Karl-Franzens- University Graz/Vrije Universiteit Amsterdam found
significant bleaching on coral reefs in the Arabian Gulf at the nearshore
site of Jebel Ali (Dubai, between Jebel Ali port and Ras Hasyan) and the
offshore island Sir Abu Nuair.

In Jebel Ali all corals were bleached white, with only few individuals
(among them Acropora downingi recruits) partially bleached or unbleached.
According to reports by DM and ERWDA, the bleaching started during the last
week of August when sea surface temperatures reached up to 37 degrees near
Dubai. In Sir Abu Nuair, the bleaching was more patchy and heaviest among
massive corals, less among Acropora spp. No significant mortality was found
yet, and recovery is still possible. Over 90% of bleached corals still had
tissues and had not yet incurred even partial mortality. At the same time,
no bleaching was observed on reefs at the same latitude in the Arabian Sea
on Oman's Musandam Peninsula near Ras Lima and Geziret Lima.

The team was led by Mohammed Abdelrahman Hassan Deshgooni of Dubai
Municipality, Nasser Shadoor of ERWDA, and Bernhard Riegl of the National
Coral Reef Institute of Nova Southeastern University. For further inquiries,
please contact Bernhard Riegl at [email protected].


Richard E. Dodge, Ph.D.
Dean
Nova Southeastern University Oceanographic Center
8000 N. Ocean Drive
Dania, FL 33004

NSUOC http://www.nova.edu/ocean/
NCRI http://www.nova.edu/ocean/ncri/index.html

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[Anonymous]

Back to the subject, the corals have greater tissue biomass, greater zooxanthellae densitites, and greater chlorophyll densities after being subjected to a cool growing season. There is generally a one month delay following a seasonal temperature drop and then the health of the coral increases until the following warm spring.

I don't know if this in itself suggests greater coral health at higher temps. A tree has a pretty low chlorophyll density in january, but check it out in june. Still healthy all year round.

 

[Anonymous]

It's funny how some people see temps like 82 degrees as an upper limit, when this is about the average temp of a reef in nature. I keep my reef at 82 or so all the time, that way when there is a heat spike in summer the temp difference isn't so drastic.
Jim

 

[esmithiii]

According to reports by DM and ERWDA, the bleaching started during the last
week of August when sea surface temperatures reached up to 37 degrees near
Dubai.

Do you realize how hot 37C is? 98.6F!!

My tank reaches 83F every day. All my corals seem healthy and happy, and I am seeing significant growth.

Ernie

 

[Lady Godiva]

I think that as long as the tempature is within a range that is considered acceptable, and the tempature is consistent, you would be less likely to see problems. When tempatures in a tank spike or drop, I think the corals suffer as a result of the change and not necessarily what the resulting tempature is (within reason of course). I rarely get sick - colds, flus etc.. but, when I do, it's usually when the season changes, cold to warn or warm to cold.

Karen

 

[Mouse]

Woohoo Mass-debate, he he he he.

sorry i couldn't help it auuuugh :lol:

 

[Chucker]

Mouse, "help it" next time please.

 

[delbeek]

I think the problem here is that people get fixated on a "number" and this becomes the be all and the end all. We saw it with ORP, we see it with calcium, alkalinity and now with temperature. There is NO reef in nature that has a constant temperature, they all experience ranges, the further north or south you go from the equator, the greater those ranges become (not including those areas that have upwelling). To attribute an "average" tempertature to the world's reefs is simply not an appropriate approach IMHO. To say your tank will "do best" at said temperature is similarily not valid. If one is going to argue that we should be approximating nature as closely as possible, then do so ... fluctuate your temperatures over the coarse of a year. Combine that also with changes in photoperiod and throw in moon phases and by golly ... you may actually see more spawning take place as well.

 

[Len]

Spawning occurs on a regular basis in my tank. It's controlled by an Aquacontroller using a simulated moon phase and seasonal temperature variation. Works like a charm in inducing spawning. Of course, I can't say that a mass spawning event is desirable in a captive ecosystem as small as our aquariums.

I keep it my aquarium temperatures at around 80 degrees, much lower then record temperatures within 15 degrees of the equator. I do this mainly because my tank is heavily stocked, and I believe it's more prudent to slow all the processes down, if not just to give me time to make necessary adjustments when equalibriums go out of flux. THere are, of course, other reasons.