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The Great Temperature Debate

By Various Authors. Posted to Reefkeepers emailing list, Sunday the 23rd to Thursday the 27th of May 1999.


Ron Shimek

The tank is reaching about 88 degrees in the apex of the lighting cycle. Last year ran about 82. It has fans on the sump as well as the top of the tank not to mention four computer fans in the canopy. I have done everything I can think of short of floating ice blocks in the sump. Animals don't seem any worse for wear so I am not exactly in a panic yet.

Given that they are just getting into the normal range for coral reefs (82-84 deg as average), I would suspect that instead of being in a panic, they are figuratively breathing a sigh of relief.

Do you see any harm in the tank approaching 88-89 degrees? I imagine that there are parts of the natural reef that go above and beyond these temperatures. I would venture to guess that these temperatures aren't maintained long term though

No harm. My tanks routinely will reach those temperatures in the summers. During two diving trips to Palau (richest coral diversity in the world....), one trip in April, one trip in September, the temperatures in the diving zone averaged about 89 degrees. Cool upwelling water measured 86 degrees, and hot water coming off the shallow lagoonal flats was about 95 deg.

What's your baseline temp? Do you run it at 85 degrees year round or step it up for the summer months to avoid massive temp swings?

My baseline is 84 deg.

Most natural reefs have massive temperature swings, though, on any scale you wish to measure, daily, monthly, annually, so that is not a big deal.

Based on that information I guess I will leave well enough alone. At what temperature do you think one might begin to see problems?

I would worry about prolonged (several days- couple of weeks) temperatures above 90 deg. One thing, if your system has been normally kept at 82-84, the organisms in it will be a lot more tolerant of the higher temperatures than if they have been kept in the cold (75-80).

With that in mind, my tank is beginning to reach 85 degrees during the day and about 84 at night. How large do temperature fluctuations need to be before it becomes detrimental to reef inhabitants?

Fluctuations are really not a problem - in some higher latitudinal reefs the fluctuations are enormous. There are data from Johnson Atoll, showing fluctuations on the order of 20 deg F in a single day (from about 72 deg to about 92 deg), and guess what... The reef's still alive...

What is more important are the extremes and the duration of the extreme values. Temperatures over 90 for any extended period is a problem, particularly for corals normally kept at cooler temperatures. I would watch the temperatures and attempt to control the environment so that temps over 90 are avoided.

Mike Kirda

The funny part about this statement is that I can remember that just a few years ago, most of us were concerned about the tank going above 80. What do you think has caused this revelation that everyone seems to be seeing?

I would credit Ron Shimek for most of it. MACNA 8 he gave a lot of data re: real reefs vs. our tanks. Temps are one thing that really stood out. I also tend to think that those who were advocating lower temps, mainly D+S, did so with the (mis)understanding that the increase in temps would lead to a drastically lower O2 level. The thing is, the totals do not matter as much as the saturation levels do. If the water is at 100% saturation with respect to O2, then who cares? In any case, the absolutes do not drop that much anyway...

Jimmy Chen

I also tend to think that those who were advocating lower temps, mainly D+S, did so with the (mis)understanding that the increase in temps would lead to a drastically lower O2 level.

Another story is that lower temps will cause the livestock to be at a lower metabolism rate then higher temps. Hence the reduction on O2 requirement and food requirement. This in term means less waste is being produced in the tank and so it means longer water change cycles and whatever else.

Ron Shimek

However, for corals from high temperature areas (particularly the Palau- Malay Peninsula-New Guinea are that accounts for over 70 percent of the coral species) this lower metabolism generally also leads to death...

Consider if these corals could tolerate lower temperatures in nature, they be living in areas that had the lower temperatures.

Bob,

So if an animal is collected from water in the 74-78 degree range(typical for collection areas in Fiji) are we slowly killing it by subjecting it to mid 80 degree temps with the resulting higher metabolism?

No, those animals found in fringing areas, outside the center of the distributions (what is called the center of adaptive radiation) have a wider range of tolerances - in this case temperature tolerances - and can survive in the outer areas. These animals will generally do better at the conditions at the center of the range, in this case, temperature. So if you collect an animal from Fiji or the Florida keys, and keep it at the temperature of the richest appropriate reefs (for example Palau and Belize) respectively, the animal will do better as it will be living under its optimal conditions.

With all of the scientific data about coral reef water temps that climb even into the low 90's, do we know how many of these studies were done in the same areas as coral or fish collecting is done? It would seem like a rather significant point to consider.

The data from temperatures and coral diversity I used in my article come from studies that pretty much predate the reef hobby and the recent period of global warming. I did not use data from these correlations that were collected after about 1975-1980. In other words, collecting influences and recent warming events are immaterial to the argument. To determine the appropriate conditions for most of our corals, take a look at Veron's book (for example), take a look at the range maps shown, and superimpose those maps on the maps of global coral diversity. Use the conditions at the center of that data.

Individual temperatures at the edge of the ranges are immaterial. Corals disperse rather well and over a few hundred to a few thousand years, the larvae can island-hop to all the places where the coral can SURVIVE. Relatively few of these places are places where the coral can THRIVE. Typically the organisms from the outer reaches are growing very slowly (too cold) and not successfully reproducing (as there are no downstream habitats that are successful). The net result of this is that they are genetic dead-ends and will not contribute to any changes in the gene pool. Basically they are space fillers.

Most corals simply cannot naturally survive out of areas where the temperatures are less than 80 deg as an average, and the number of species can be found in these areas is significantly lower than those in the centers of the ranges. The moral of the story... If you want to see what a coral reef can really look like, go to the reefs within the center of the area of adaptive radiation. High latitude reefs (most of the GBR, by the way) have many fewer species and reduced communities overall.

Bob Mankin

Ron,

I don't disagree with your assessment about coral species diversity as a whole, but we're not working on that scale. We are talking about a limited subset of species that are typically available in the trade. Without data to support higher densities within given areas for ONE particular species and limiting that data to those found in the trade, you cannot even assume the higher temperature theory that you suggest. All that is being shown is that certain species won't survive out of the higher average temp range. Is there data showing that the species you and I are trying to keep are coming into play for sure? Also, who is to say that we aren't witnessing the middle of an evolutionary phase where one particular species is moving from the WARMER temps to the COOLER temps? Is there scientific data to conclusively strike this down?

I guess what I'm seeing is this theory being floated based on species diversity, but little else. Are there studies that support the "SURVIVE vs. THRIVE" idea? Growth rate studies, for example?

I dropped over the edge with the suggestion that optimal conditions for South Pacific species would also be optimal for Carribean speices. I just can't stretch to accept that one. Certainly could be wrong though.

Ron Shimek

I don't disagree with your assessment about coral species diversity as a whole, but we're not working on that scale. We are talking about a limited subset of species that are typically available in the trade.

Surely. But those species still have distributions related to temperature.

Also, who is to say that we aren't witnessing the middle of an evolutionary phase where one particular species is moving from the WARMER temps to the COOLER temps? Is there scientific data to conclusively strike this down?

Yeah, pretty much. The data that are available on coral distributions and diversities from fringing areas indicate that during periods of prolonged temperature fluctuations, when it gets cooler, the number of species and absolute abundances of corals typically drop and vice versa.

If you postulate a tendency for a coral to survive better at cooler temperatures, you have to come up with a natural selective pressure that forces this outcome. So far the only reef coral that seems even moderately well adapted to temperatures below 80 F, is Pocillopora damicornis, which has the lower grow rate optimum temperature. This probably accounts for its widespread distribution, but it comes at a cost, in that while it is a dominant coral species in cooler areas, it is not a dominant species in the warmer areas.

I guess what I'm seeing is this theory being floated based on species diversity, but little else. Are there studies that support the "SURVIVE vs. THRIVE" idea? Growth rate studies, for example?

Possibly for P. d., but no others. The problem comes in that most of these cooler areas are in areas that have limited self-recruitment from sexual reproduction, so that organisms with the best genotypes from these areas do not easily reproduce in them.

I dropped over the edge with the suggestion that optimal conditions for South Pacific species would also be optimal for Carribean speices. I just can't stretch to accept that one. Certainly could be wrong though.

Check out growth rate studies done on corals by one Raymond Highsmith about 20 years ago. He looked at corals from the most diverse Caribbean reefs (around Belize) and found growth rates and temperatures comparable to those of the Indo-Pacific.

Below is list of his papers should you want to check this out...

  • Highsmith, R. C. 1979. Coral growth rates and environmental control of density banding. Journal of Experimental Marine Biology and Ecology. 37:105-125.
  • Highsmith, R. C., R. L. Lueptow and S. C. Schonberg. 1983. Growth and bioerosion of three massive corals on the Belize barrier reef. Marine Ecology Progress Series. 13:261-271,illustr.
  • Highsmith, R. C. 1981. Lime-boring algae in hermatypic coral skeletons. Journal of Experimental Marine Biology and Ecology. 55:267-281,illustr.
  • Highsmith, R. C. 1981. Coral bioerosion at Enewetak: agents and dynamics. Internationale Revue Der Gesamten Hydrobiologie. 66:335-375,illustr.
  • Highsmith, R. C., A. C. Riggs and C. M. d'Antonio. 1980. Survival of hurricane-generated coral fragments and a disturbance model of reef calcification/growth rates. Oecologia (Berlin). 46:322-329,illustr.
  • Highsmith, R. C. 1980. Burrowing by the bivalve mollusc Lithophaga curta in the living reef coral Montipora berryi and a hypothesis of reciprocal larval recruitment. Marine Biology (Berlin). 56:155-162,illustr.
  • Highsmith, R. C. 1980. Passive colonization and asexual colony multiplication in the massive coral Porites lutea Milne Edwards & Haime. Journal of Experimental Marine Biology and Ecology. 47:55-67,illustr.
  • Highsmith, R. C. 1980. Geographic patterns of coral bioerosion: a productivity hypothesis. Journal of Experimental Marine Biology and Ecology. 46:177-196,illustr.
  • Highsmith, R. C. 1979. Corals: the inside story. Dissertation Abstracts International B Sciences and Engineering. 40:2561.

Donna ???

I'm no scientist but I'm thinking that there's no absolutes here. I'm not a scuba person either, but I've done enough snorkling to feel temps change with the currents. The general temp of an area might be 84, or 78, or whatever, but there are pipelines of current much colder or warmer that exist in these general areas and corals are scattered throughout these areas.

I can tell you that I've got a green bubble coral in my 180 that runs at about 80 degrees - it's huge and still growing. And I've got a beige bubble that no matter where it is in that tank - it's not happy. Once I put it in my 30 gal that runs at 77/78 it expanded again to it's normal look. Now it could be other factors, like lighting, water flow, inhabitants in the tank, but temp might be a major factor too.

Bob Mankin

Donna,

I completely agree that there are no absolutes in this discussion. Could be those corals came from different locales and were used to different temps.

My concern is the belief that mid 80 degree temps are desirable. Granted, our captive reefs can and will tolerate these temps, but I'm not so sure that steady maintenance at say 85 or 86 degrees is a good thing. Most of my reefkeeping in the last 6 years has been centered around SPS corals, so filter my comments accordingly, but if my tanks climb to 85 or 86 during the hot summer months, they just don't look good at all. FWIW, I've always kept my SPS tanks at or about 80 degrees, partly due to Ron's comments years ago and some of the questions it got me to asking, but also partly out of necessity. It's pretty hard to keep a reef lit with 400W halides, big tank return and skimmer pumps at anything below 80 without really running a chiller hard.

As was pointed out in another post, the average temp around the Solomon Islands is about 82 degrees. The upper extreme they see from collection areas is about 86 and you almost never see anything less than 78 degrees. Coral species diversity around that island group is considerably better than what you would find around the Fiji group where temps average 6 degrees less at the collection sites. But I have a problem with the idea that taking a coral from the cooler waters of Fiji and transplanting it over the course of a week into mid 80 degree temps is a good thing. That species of coral has adapted to the temps it was collected in over many generations. Just because diversity is better at higher temps doesn't mean the coral is going to like it. The idea is just flawed from a simple logic standpoint, at least in my mind. I mean, you don't collect an animal from the temperate waters of California and expect it to live at tropical temperatures of our reef tanks. How and where does one draw the line at what sort of temp adaptation the coral can handle?

Also, there seem to be some intangibles once you cross from natural to captive reefs. A point I've raised before, but no one seems to want to consider it. For some unknown reason conditions found in nature don't always carry over to the captive environment. I'll limit this to temperature for this debate; I speak to the collectors in the Solomon Islands on a weekly basis. A few weeks back we were discussing temps as I was curious what levels they typically see. While 86 was mentioned as an upper extreme and 82 about the average, it was found that the holding systems at the collection station need to be run 2-4 degrees cooler in order for the animals to look their best. They just don't open up as well when maintained at the same temps found on the reef. Why is anyone's guess, but this is an observation made over years of collecting and not just some gut feeling. For whatever reason it correlates to what I've seen with my own tanks. So what gives? I have no idea. My theory has been that captive reefs have some sort of "fudge factor" that must be accounted for and attempting to run them exactly at natural reef conditions may, and I emphasize that word, not be the ideal. Just this man's opinion.

Dallas Warren

Bob,

I don't disagree with your assessment about coral species diversity as a whole, but we're not working on that scale. We are talking about a ...

I am having difficulty understanding why there is a problem with thinking on the scale of the full distribution of species. If you do this, then this will tell you all the information you need to know on what is required by corals in general to live and thrive (whether we can find it is another thing but ...). I only see it as a logical extension to see that if you have a distribution then the region in the center is where the conditions are best for the organisms to live. This could have a bit of variation if there is abrupt changes in an important physical condition i.e. no substrate to settle and live on, but no theory is all encompassing. There is always exceptions to the rule.

limited subset of species that are typically available in the trade. Without data to support higher densities within given areas for ONE particular species and limiting that data to those found in the trade, you cannot even assume the higher temperature theory that you suggest. All that is being shown is that certain species won't survive out of the higher average temp range. Is there data showing that the species you and I are trying to keep are coming into play for sure? Also, who is to

All you have to do to see this is look at a species distribution for the particular species you are interested in. Pull out Veron and have a look at the genus/family distribution maps. Then, as Ron suggested in an early message, superimpose on top of that an average surface temperature contour map. The majority of the tropical species you will find overlap in the regions of higher temperature.

say that we aren't witnessing the middle of an evolutionary phase where one particular species is moving from the WARMER temps to the COOLER temps? Is there scientific data to conclusively strike this down?

We are always in the middle of an evolutionary phase ;-) But on the time scale we are on with the corals whether things are altering or not is of no consequence, we would not be able to see it. Unless there is some abrupt change that tips the balance we would never be able to observe it unless we had a long enough observation period (centuries).

But just remember the time scale that the corals have been living for in the locations they are found in. If they were not suited to the zones they settled in then they would have been eliminated totally from there by other species that are much more successful. That is the way it is with any living ecosystem, the species better adapted to those conditions will dominate.

I guess what I'm seeing is this theory being floated based on species diversity, but little else. Are there studies that support the "SURVIVE vs. THRIVE" idea? Growth rate studies, for example?

I look at it this way. As you increase the temperature from the lower limit for corals of about 20oC you see the number of species found increasing to an upper limit around the 30oC mark. On a coarse scale lets say you want to have a reef tank, large variety of different species. At which end of the spectrum would you keep your tank at, or would you recommend someone else to keep theirs at based on this information? The higher the temperature you settle at the more different corals that you will be able to maintain in the reef system.

As for the "survive vs thrive" idea, well that is pretty simple. If a coral is thriving in a particular zone then you will see lots of it around. If it is just surviving then it will be present in very low numbers or will not gain a foothold. Although there is a lot more facts than temperature that will influence whether the coral can settle and thrive in a zone, but is one of the most important, and has been shown as such.

Anyway, very interesting discussion .....

Ron Shimek

Hi Bob,

My concern is the belief that mid 80 degree temps are desirable.

Yup. All those corals in the Indo-Pacific reefs must be suffering tremendously.

Granted, our captive reefs can and will tolerate these temps, but I'm not so sure that steady maintenance at say 85 or 86 degrees is a good thing.

First, nobody is saying to keep anything at 85 or 86. I recommend 82-84 degrees. The animals will do as well at 85 and 86 as they will at about 80-82.

That species of coral has adapted to the temps it was collected in over many generations.

Wrong. You don't know where the coral's parents were from. The larvae come from upstream spawners, and given the currents prevaling in most of these area, the general flow is from warmer areas to cooler. If you are collecting an animal that has asexually reproduced by fragmentation for several hundred years even, you are still seeing only one generation.

You are discussing physiological accomodation to temperature, not evolutionary adaptation. Really the only coral that has been shown to have a decent growth rate at about 78 is Pocillopora damicornis. However, it has a second growth optimum at 84 degrees.

Just because diversity is better at higher temps doesn't mean the coral is going to like it.

Animals are found where they can live. Simply put, coral survival has been 1) correlated to temperature (i. e. = higher temps give conditions that allow more species of corals to survive, and 2) experimentally shown to survive better at the higher temperatures characteristic of the diverse reefs, and 3) experimentlally shown to have growth optima 82-84 degrees.

The idea is just flawed from a simple logic standpoint, at least in my mind. I mean, you don't collect an animal from the temperate waters of California and expect it to live at tropical temperatures of our reef tanks. How and where does one draw the line at what sort of temp adaptation the coral can handle?

Look at where the species is found in nature... If most species of corals are found living at areas that average about 84 deg F, and if most of these species grow best at those temperatures, it rather follows that if you want those species to be healthy, you maintain them at those temperatures.

, it was found that the holding systems at the collection station need to be run 2-4 degrees cooler in order for the animals to look their best. They just don't open up as well when maintained at the same temps found on the reef. Why is anyone's guess, but this is an observation made over years of collecting and not just some gut feeling.

I would guess that they are 1) stressed from the movement into the holding systems, and 2) the holding systems have something in the plumbing that effects the animals in the facility. Similar problems are occasionally encountered at marine laboratories, and the most common problem is alteration of food supply due an increased amount of suspension feeders in the plumbing. But the stress factors of collection and handling are likely also great. Also keeping animals at about 2-4 degrees cooler than normal, will reduce their metabolism to a point where they can get by on less - albeit the tradeoff is that it makes them less able to handle stresses.

James Wiseman

While it is interesting to learn again (I think we did this last year too) that natural reefs have the highest species diversity in warmer waters, what does this really teach us about the optimal temperature for our tanks? So far, NO ONE has given any substantive information about what TANK TEMPERATURES are optimal to help our corals THRIVE...(I'm afraid this includes you too Ron.) Natural reef temperatures - yes...optimal tank temperatures - no. Are they the same? I think not.

While we've compared and contrasted our tanks to natural reef environments many times, I think we can all agree that they are not natural reef ecosystems. (What do you get when you place indo-pacific corals on TBS rock afterall...-) To me this means that we can learn so much from nature, but only so much. This is where the true value of experienced hobbiests comes in. Hobbiests usually know best what's best for their animals...at least the ones that experiment and learn for themselves.

What do the hobbiests that have been keeping corals for 8-10 years think about the temp question????? Are our tanks more successful at higher temperatures? Well, duh! Of course they are better now, but that's due to a lot of things...I'm specifically asking about temperature. What say you?

Gary Robinson

I am having difficulty understanding why there is a problem with thinking on the scale of the full distribution of species.

Think of it this way

The maximum diversity of reptiles and amphibians is heavily weighted toward the tropics.

The majority of reptiles and amphibians for sale at a local store where you buy your animals are collected in North America.

Now, what temperature are you gonna keep your vivarium?

I see Bob's point.

Now, the peculiar thing about the ocean is this idea that the corals in cold temp areas are actually the downstream children of warm temp areas. Of course the same logic implies that the corals in warm water areas are themselves the downstream children of....corals in the cold water areas on the other side of the warm area. It is rather peculiar. One could even argue the cold water corals are the more prolific since they have the most children (those which settle in the warm water areas) whereas the warm water corals are the least prolific (since their children wash out to another cold water area) and thus have the least influence on evolution.

I like these thought experiments. -)

Dallas Warren

Gary,

The maximum diversity of reptiles and amphibians is heavily weighted toward the tropics.

So, if you are going to have a vivarium (cool word, never new that one) with a high diversity of different reptiles in it, what conditions would you choose? If it was me I would be aiming for tropical temperatures.

The majority of reptiles and amphibians for sale at a local store where you buy your animals are collected in North America.

Not in my case ;-)

Now, what temperature are you gonna keep your vivarium?

That depends on the particular reptile that I am going to keep, as I highly doubt people keep a wide variety of different species in the one enclosure.

I think this is very different to what we are talking about. We are talking about keeping an aquarium full of a wide variety of different coral species, all of which have a particular distribution range. Interesting thing is the distribution range of most of these overlap and concentrate in the higher temperature zones .....

Bob Mankin

I am having difficulty understanding why there is a problem with thinking on the scale of the full distribution of species. If you do this, then .....

Apples to oranges here guys. You've more than made your point about greatest diversity areas with the map overlay idea. That's not what I'm debating.

The problem is this in a nutshell; the bulk of the coral imports into the US at this time are collected in waters much cooler than the 82-84 degree temperatures being suggested. That's a fact. Focusing on the individual collected coral now, how do you conclude that this individual can re-acclimate to higher temps just because its cousins are found in areas centered around higher average temps? If you want to suggest genetics allows it, fine, just be sure to quote the studies and field excercises that prove it. My experience and that of others has been different. You have either assumed acclimation is a no-brainer for the coral or you have simply overlooked it. I don't know which. Specific individual corals now. We are not talking in the generalities of a whole species.

So if you are saying the coral can and will adapt, on what do you base this? Have you considered that the individuals within a species on the fringes of distribution may be there for a reason? Besides having been pushed there by currents, perhaps there's been a mutation that makes them better suited for a cooler climate and less suited for the warmer clime from which they were released. The possibilities here are numerous. Distribution maps mean little in this debate because collection stations aren't paying attention to them. So let's set 'em aside and start discussing acclimation, because it is a real issue if you wish to advocate these higher temperatures. Your advice could just as easily be stressing or killing animals needlessly. Not suggesting it is, but I think it's a good idea to nail down what we're attempting to do here. When I see statements like "corals slowly being killed at 76 degrees" based on a distribution map, well, those are harsh statements with questionable links to the evidence offered to support them.

Nathan Cope

G'day Bob,

Apples to oranges here guys.

Well, who is to say that the difference between adaptive radiation and acclimatisation to a temperature are even comparable to the difference between an apple and an orange? For all we know the difference might only be like the difference between a Navel Orange and a Valencia Orange or it could be the difference between comparing a Navel Orange grown in a cool climate (and not very successfully) to a Navel Orange grown in a warm climate like California (very successfully).

Optimal temperature ranges are pretty much applicable to organisms all over the planet. Take a Navel orange tree that is growing (albeit slowly and not fruiting) from a cool climate and transplant it in a warm climate and it will start to fruit. The same happens in the ocean. Take a species that has its optimal temperature range in a warm climate and move it to a cool climate where it is not found in abundance and for the majority of species, it will not breed....it will grow, although slowly but it will not sexually reproduce (for corals, asexual reproduction is really just another growth form). On the other hand, take a species that has its optimal temperature range in a warm climate but has been growing in a cool climate and then move it to a warm climate and it takes off in growth and it attempts to reproduce sexually.

Temperature is just another limiting factor like light. Obviously corals can tolerate different levels of light, although it should be obvious to even a fairly new hobbyist that the lower the light level, the slower the growth. Corals can obviously be moved to different lighting regimes and adapt to the new level, but their growth rate differs depending on the light available not on how close the level of light available is to what light was available at their original settling point. The same species of coral will grow at the same rate (once time is allowed for acclimatisation) regardless of the light level they had at the point of their original settling. The same goes for temperature.

Look at humans for example, those in cooler climates have adapted to the climate only because they are able to keep themselves warm via shelter and clothing. The internal biology has not changed - humans could not survive in many places in Europe if not for clothing and shelter, yet in the warmer climates, it is simple and they do not need to wear much in the way of clothes. In the cooler cliimates, more energy is expended by the body in an attempt to keep it warm, so more food is needed. In the warmer climate, on the other hand, this energy isn't wasted, so humans are able to survive on lower food levels. Can you take a human from a cold climate and move it to a warm climate? Yes, of course. Will that human do better living in the warmer climate? For humans, that is a very subjective thing, but certainly from a biological point-of-view, they will not need as much energy input.

Now, fish are obviously cold-blooded and they have no thermoregulatory system so they don't waste energy in this process. From a biological outlook though, the temperature they are living at is very important. The reason for this is to do with body chemistry. There are innumerable enzymes in an organism that operate properly only within a fairly narrow temperature range. Animals evolved (not acclimatised) to live within certain temperature ranges need to stay within that temp range because if they don't, then their body chemistry doesn't work efficiently. There is an incredibly complex chain of events derived from the function of a bodies enzymes and when they cease to function properly (due to incorrect temp), then other functions are compromised too and it results in less than optimal health reproduction and longevity. The complex nature of these enzyme interactions doesn't allow for an organism to just "adapt" over a short period of time, these sorts of changes are more evolutionary and span a far greater period of time than the average person thinks. The time taken for these things to change is measured in thousands to millions of years and when they do finally make the evolutionary leap, they are a different species.

Focusing on the individual collected coral now, how do you conclude that this individual can re-acclimate to higher temps just because its cousins are found in areas centered around higher average temps?

I know it may seem like a matter of semantics, but they are not cousins, they are siblings. A cousin would be another species in the same genus, for example. Perhaps it is the fact that you are seeing them as somewhat relatively removed from each other in a biological sense that there is this difference of opinion.

From a biological point-of-view, why do you think a species of coral can't re-acclimate to the optimal temp? What biological process would stop it from being able to do this?

If you want to suggest genetics allows it, fine, just be sure to quote the studies and field excercises that prove it. My experience and that of others has been different.

As Ron stated earlier, the corals from the GBR are from cooler waters than what is considered optimal. All my corals are either from GBR or Ningaloo reef (north-west coast of Australia and roughly the same temp as the GBR). All of them are being kept at 28-29 C in my aquarium and are doing fantastically. They thrive much more than they did two years ago when I had them at a lower temperature and temperature is the only thing that I have changed over this period of time.

The only thing that I can suggest that may cause you to have difficulty with corals at the temp Ron is talking about is that you have some sort of filtration set up that causes problems with oxygen levels at higher temps - maybe a trickle system, fluidised sand filter, a sand bed that you regularly vacuum or not enough water agitation/movement.

You have either assumed acclimation is a no-brainer for the coral or you have simply overlooked it.

In my experience and all the others that I have talked to in Australia, it seems to pretty much be a no-brainer for the coral.

I don't know which. Specific individual corals now. We are not talking in the generalities of a whole species.

Now, if you were talking about a whole species, I could understand it. There are some species that do better in cooler waters, but these ones will be sparse in warmer waters. Pocillopora damicornis is an example, although this is a tropical species. As Ron stated, its more abundant in cooler waters than warmer waters.

So if you are saying the coral can and will adapt, on what do you base this? Have you considered that the individuals within a species on the fringes of distribution may be there for a reason?

Yes, they are there for a reason. The currents were too strong for them to swim against, so they were forced to settle in cooler parts. If they drift into the extreme colder parts, they can't survive at all. In the luke warm areas, they can survive, but only just. Over here in Western Australia, we have the Leeuwin current which comes down from the northern end of our coast (tropical) and ends up about 3/4 of the way down around the temperate area where I live. During the Winter months (which is when this current is flowing), lots of tropical species of various phyla can be found just off our coast around an island (Rottnest)in the middle of this current. These species come down as plankton during the Winter months, settle and grow. We are able to find Coral-banded shrimp out there in abundance around this time (about now). As soon as Summer comes, this current drops off and even though the water starts to warm up, it doesn't get as warm as the Leeuwin current was and so most species die off. A few species manage to survive the whole year round, so are obviously able to handle the quite extreme change in temperature from Summer to Winter. Some of these species are corals and they are all stunted and very slow growing. Unfortunately, I don't have a reference on this as it is a work in progress being done by the WA Museum. I'll let you all know as soon as it is finished though.

Besides having been pushed there by currents, perhaps there's been a mutation that makes them better suited for a cooler climate and less suited for the warmer clime from which they were released.

The chance of a mutation that had caused a favourable effect is low (this is a genetic fact), but still, this would make it a different species of coral anyway.

The possibilities here are numerous. Distribution maps mean little in this debate because collection stations aren't paying attention to them.

The location from where they are being collected has little impact, except for the fact that the corals have to be acclimatised to an aquarium with a higher temperature when first introduced, the same as you do with any animal you introduce to your aquarium.

When I see statements like "corals slowly being killed at 76 degrees" based on a distribution map, well, those are harsh statements with questionable links to the evidence offered to support them.

If you understand the biology behind the impact of temperature on an organism, it is not a harsh statement.

Mike Kirda

I see Bob's point.

I do too. I also believe Donna when she says that one of her LPS corals acts differently at different temps. The arguement is that corals should be kept at normal reef temps, and for the areas of highest coral density/diversity, that is around 85 degrees F. A major caveat in all this- watch your animals. I know for a fact that Ron would not argue that you have to maintain X temp even though your prized coral is stressed by that extra few degrees... His point was always that temperatures as recommended in the past, 72 - 75 degrees F, are too low and probably more harmful, stress-wise, than the lower metabolism can likely handle over time. Better to have them at a more normal 80 to 85 degree range- I think he specifically recommended 82-84...

Now, the peculiar thing about the ocean is this idea that the corals in cold temp areas are actually the downstream children of warm temp areas. Of course the same logic implies that the corals in warm water areas are themselves the downstream children of....corals in the cold water areas on the other side of the warm area. It is rather peculiar.

Only peculiar because it doesn't work that way...

One could even argue the cold water corals are the more prolific since they have the most children (those which settle in the warm water areas) whereas the warm water corals are the least prolific (since their children wash out to another cold water area) and thus have the least influence on evolution. I like these thought experiments. -)

I do too, but for different reasons...

You mention an interesting fallacy, Gary, and I am glad it was brought up. Oceanic currents are not just in circles... There are also upwellings and areas where warmer, higher salinity water (which is denser than normal NSW) goes straight to the deep. Much of the oceanic currents are due to these upwellings. The current does not travel from these lower temp areas to higher temp, then to lower temp again... At least not in the way you think it does. In a way, you can think of the highest diversity areas as being at a fountainhead, and all coral spawn goes outward from there. How is that possible? Upwelling. Landmasses. There are specific directions currents flow. And for the most part, the spat goes out on a great diaspora. Riding the wave of the upwelling. And it reaches as far as Central America, at least for those few species that can survive the cold temps there. In most ways, a spawn in the Galapagos Islands is wasted. Anything downstream is likely lethal to the coral...

A more interesting thought experiment is to what degree global warming is messing with these currents... There is some research that seems to show an increasing negative effect- so that the spawn does not reach as far...

Ron Shimek

Bob,

Focusing on the individual collected coral now, how do you conclude that this individual can re-acclimate to higher temps just because its cousins are found in areas centered around higher average temps?

It seems that there is a lot of variation in where the corals are coming from, but I have seen numerous corals offered for sale from Palau, Indonesia and other areas well within the high diversity - high temperature regions

I think there are some other problems as well. You have not shown that the coral HAS acclimated to the cooler areas in any real sense. It can survive. This is not acclimation. You need to compare reproductive output and growth of individuals one species within and outside of the areas of greatest diversity. If the animals have adapted then there will be no difference...

If you want to suggest genetics allows it, fine, just be sure to quote the studies and field excercises that prove it.

I can download a data base of about 2000 articles on coral biology for you. You can sort it out. I would say the common answer here would be that basic biological knowledge based on the animal's physiology would support the statements I have made. The papers by Highsmith that I listed earlier will give some comparative growth rates for starters.

My experience and that of others has been different. You have either assumed acclimation is a no-brainer for the coral or you have simply overlooked it.

Well, to be to the point, it has to be a no brainer, as they don't have any.

I haven't overlooked acclimation at all. Within the range of the corals, their metabolic rates will increase in areas of warmer environment and decrease in cooler ones. At the lower temperatures, enzymatic production will be less, and will be less efficient the farther away from optimal temperatures. There simply is no documented adjustment to the cooler temperatures; the organisms can persist there - and within the realm of that environment may thrive - but in comparison to their conspecifics in warmer areas they are just holding on. Obviously to settle this point, what is needed are reciprocal transplant experiments, however I will make the prediction that none will ever be done, simply because no funding agency would waste its money on a project with such an obvious outcome - and no researcher in this era of publish or perish would waste their time working on such a problem.

Have you considered that the individuals within a species on the fringes of distribution may be there for a reason?

For broadcast spawners, they are where they are because of the luck of the draw.

Besides having been pushed there by currents, perhaps there's been a mutation that makes them better suited for a cooler climate and less suited for the warmer clime from which they were released.

Oh, maybe so, unfortunately none has been documented - except the P. damicornis growth patterns that I have mentioned before. But even it will do better in warmer environments than in cooler ones.

Distribution maps mean little in this debate because collection stations aren't paying attention to them.

No but the animals surely are influenced by the causitive agents of such distributions.

So let's set em aside and start discussing acclimation, because it is a real issue if you wish to advocate these higher temperatures.</i></p> <p>Yes. And you need to show that corals from cooler environments are in any way adapted to those environments.</p> <p>Good luck.</p> <p><i>Your advice could just as easily be stressing or killing animals needlessly.</i></p> <p>Care to take bets???</p> <p><i>When I see statements like "corals slowly being killed at 76 degrees" based on a distribution map, well, those are harsh statements with questionable links to the evidence offered to support them.</i></p> <p>No, there are very significant and meaningful reasons why such distributions are found. Knowledge of the animals physiology and ecology will show why the organisms are distributed the way they are. Distributions as strongly correlated with physical factors as these are, have a causative effect also correlated with the physical factors if they are not directly driven by the factors. In any case, it is up to individual who claims the animals at the edges of broadcast-spawning distributions are thriving, to prove that.

If you can show that these populations are self-reproducing and that the animals in them have a capability of contributing significantly to the next generation in their region, that is a first step. However, with corals, that has not been shown.

Ron Shimek

Gary,

What about the corals in the Hawaiian Islands? Are they not self-reproducing?

Generally not. They reproduce, but the larvae are headed for the California coast....

I think the generally accepted rationale is they are seeded from elsewhere in Polynesia.

Bob Mankin

You have not shown that the coral HAS acclimated to the cooler areas in any real sense. It can survive. This is not acclimation. You need to compare reproductive output and growth of individuals one species within and outside of the areas of greatest diversity. If the animals have adapted then there will be no difference.

It if a coral larvae was brought into a cooler clime by currents, settled and spent it's entire life there, wouldn't that by common sense tell us that it is acclimated to that cooler temp? If it hadn't acclimated, it would have perished, plain and simple.

I can download a data base of about 2000 articles on coral biology for you. You can sort it out. I would say the common answer here would be that basic biological knowledge based on the animal's physiology would support the statements I have made. The papers by Highsmith that I listed earlier will give some comparative growth rates for starters.

I don't think I said thanks for the earlier references, so I'm doing so now. Good stuff.

However, my point is these references only get us so far. Then you have to talk practical experience, which is what I'm offering here. We can analyze field studies and species/thermal distribution maps until our eyeballs fall out of our head, but in the practice of captive reef keeping, who's to say what is valid and what is not? My point was simply that the majority of animals available in the aquarium trade in the US at this time will not tolerate temperatures of 84-85 degrees for any long term period. There certainly will be exceptions to this statement, but generally speaking I think it's pretty accurate. And IME anything over 82 or 83 starts causing significant stress. All the distribution maps in the world can't change that fact and I don't pretend to know all the hows and whys of it, but in this case and for this debate, the scientific study of the natural environment does not seem to carry over to the captive one. Don't know how to put it any simpler than that. If you've got anecdotal data(since that is really all I've offered here) from a significant number of captive reef keepers besides yourself, I'd love to hear it. Long term practical experience only please.

There simply is no documented adjustment to the cooler temperatures; the organisms can persist there - and within the realm of that environment may thrive - but in comparison to their conspecifics in warmer areas they are just holding on.

No documented adjustment to cooler temps? Are we forgetting that the hobby, generally speaking, has been keeping, growing and propagating corals at these cooler temps for many, many years? And obviously you are ignoring the fact that just about any piece of coral you will see at any LFS today will have come from waters cooler than the 82 degrees that you promote. Some from waters as much as 6-8 degrees cooler. You keep mentioning Palau and New Guinea. Based on my availability lists, there is little to nothing in the way of corals being exported from those locations at this time.

Oh, maybe so, unfortunately none has been documented - except the P. damicornis growth patterns that I have mentioned before. But even it will do better in warmer environments than in cooler ones.

I think your earlier post stated the growth rates to be about the same at 78 versus 84. But in your mind it's better at 84 because......it happens to support your argument perhaps?. FWIW, it's been my experience that P. damicornis does seem to have higher temperature tolerance than many of the other commonly kept stony corals.

Yes. And you need to show that corals from cooler environments are in any way adapted to those environments.

I think the fact they are living there says they've adapted. It's not like they moved in last week or something.

Care to take bets???

Ahh, but I wouldn't have anything more data to support my side than what we already have. And from that you have already developed your conclusions as I have developed mine.

Distributions as strongly correlated with physical factors as these are, have a causative effect also correlated with the physical factors if they are not directly driven by the factors. In any case, it is up to individual who claims the animals at the edges of broadcast-spawning distributions are thriving, to prove that.

Wow, convenient way to dispute what might go against your already held beliefs. But not to worry, I'm not trying to change those.

If you can show that these populations are self-reproducing and that the animals in them have a capability of contributing significantly to the next generation in their region, that is a first step. However, with corals, that has not been shown.

With that statement, you are suggesting that any new coral larvae that takes up residence in a place like Fiji, Tonga or the GBR were brought in by the currents alone and that none of the resident broadcast spawners have had any luck having their larvae settle locally. A bold statement that can neither be proven nor disproved by the current studies. But what does the logical side say to you on that one, Ron? Should we be running around telling these corals that they have no business being there because they are slowly freezing to death?

I'll bow out of this debate now as it's going nowhere fast. You made up your mind on this one long ago, Ron, and I'll let that be. If the thread has sparked some thought for those reading it, then it's been a good thing. Thanks for taking the time to participate.

Steve Wolfe

It if a coral larvae was brought into a cooler clime by currents, settled and spent it's entire life there, wouldn't that by common sense tell us that it is acclimated to that cooler temp? If it hadn't acclimated, it would have perished, plain and simple.

There's a huge difference between an organism's chemical reactions working a little bit differently (or at a different rate) because of a different temperature, it's another for an organism to develop new or different chemical reactions to adapt to changed conditions. The former can happen anywhere from instantly to over several days/weeks/whatever, the latter generally happens over centuries or millenia.

In the case of these corals, yes, the chemical reactions can change a little to allow them to live in cooler waters. Many proteins will have different tertiary structures in different temperatures. But these animals have not had the time to develop new or different mechanisms to deal with cooler climates, they are still running on the same core of chemical reactions, meaning that when put back into their optimal climates, they will do better.

A very close example is the color change in many animals due to temperature - in colder climates, some animals (like rabbits) will grow white hair, to help camouflage themselves. Put them back into a warm climate, the hair grows it's "normal" color again. That doesn't mean that the rabbit has evolved to thrive in the lower temperatures, just that it does have the means to at least survive them.

However, my point is these references only get us so far. Then you have to talk practical experience, which is what I'm offering here. We can analyze field studies and species/thermal distribution maps until our eyeballs fall out of our head, but in the practice of captive reef keeping, who's to say what is valid and what is not? My point was simply that the majority of animals available in the aquarium trade in the US at this time will not tolerate temperatures of 84-85 degrees for any long term period.

Well, here we run into more "practical experience", many of us have tanks that run at 84-85 (or higher, some tanks get into the 90's in the summer), and haven't seen any mortalities. If the majority of animals we have couldn't survive it, then I'm sure it would have been self-evident by now.

There certainly will be exceptions to this statement, but generally speaking I think it's pretty accurate. And IME anything over 82 or 83 starts causing significant stress.

I used to keep my tank at 82, now it stays between 83 and 85 (summer's warming it up more). The corals have never grown more quickly, but again, that's anecdotal evidence, I haven't gotten out the ruler for them. )

If you've got anecdotal data(since that is really all I've offered here) from a significant number of captive reef keepers besides yourself, I'd love to hear it. Long term practical experience only please.

There's plenty of anectdotal evidence if you check the archives. This topic comes up pretty often. usually once person asks "help, my tank is getting hot this summer, the water is up to 86 degrees!" Someone generally responds "Is anythign stressed in the tank?" the usual answer is "No... everything's doing fine."

Bob Mankin

........But these animals have not had the time to develop new or different mechanisms to deal with cooler climates, they are still running on the same core of chemical reactions, meaning that when put back into their optimal climates, they will do better.

Should I assume you've also drawn this conclusion based on the species density bit or do you have some new information to offer?

Well, here we run into more "practical experience", many of us have tanks that run at 84-85 (or higher, some tanks get into the 90's in the summer), and haven't seen any mortalities. If the majority of animals we have couldn't survive it, then I'm sure it would have been self-evident by now.

Maybe I should have been clearer. Long term maintained temperatures is what I'm intersted in, not temporary spikes. I'm well aware of what a closed system can handle. My own system has seen as high as 93.6 on the upper end(chiller mistakenly unplugged) to 62.3 on the low side(controller crosstalk caused chiller to stay on). That doesn't mean I want to keep it at either extreme for experimentation sake. I experienced mortality at both ends of the range there, with the latter being pretty severe.

But your input is appreciated. This is not a debate of right or wrong, rather an excercise to arrive at a general consensus. So with you, Ron, and I'll go ahead and count Nathan, that makes 3 of you so far out of what......400 on the list that(or an estimated 250K marine hobbyists in the US) are believers in this higher average temperature is "optimal". Anyone else?

There's plenty of anectdotal evidence if you check the archives. This topic comes up pretty often. usually once person asks "help, my tank is getting hot this summer, the water is up to 86 degrees!" Someone generally responds "Is anythign stressed in the tank?" the usual answer is "No... everything's doing fine."

I don't think panic about 86 degrees is called for either, though I do see stress at 86 in my systems. Call it a trained eye or call it paranoia, as a maintained temperature I certainly wouldn't suggest it.

Keith Redfield

Well, I'll chime in. I split the difference at about 82 and get concerned 86 top end (I usually get dino blooms at that point). Bob's concerns have merit in that there will be genotypic variation in protein composition and structure that may show up in those settled in cooler waters (if someone actually ever does the study). In other words larvae settling/surviving there may have a set of proteins better tuned for those cooler temps. Nature is a bell curve and there is significant variation in DNA and protein structure amongst even individuals within a species.

The fact that the center of adaptive radiation coincides with warmer temps does not preclude this possibility. (but let's not forget the effect of temperature on mutation rate either)

Mike Kirda

Maybe I should have been clearer. Long term maintained temperatures is what I'm intersted in, not temporary spikes. I'm well aware of what a closed system can handle. .......... I don't think panic about 86 degrees is called for either, though I do see stress at 86 in my systems. Call it a trained eye or call it paranoia, as a maintained temperature I certainly wouldn't suggest it.

Bob,

I see where you are going with this, and, No, I don't think there is any data to support it either way. You are correct in that closed systems can behave differently than nature, although I would argue that they act more like them than not. Unless you are running some sort of chemical soup... Basically you want to see a comparison of ... What? at different temps of, say 78 and 85? What would you measure and how?

Let's try to figure it out on list what it is you would want to compare, design a little thought experiment, then let us see what we can do to make it happen... Humor me- I might be able to get it to happen...

Steve Wolfe

Should I assume you've also drawn this conclusion based on the species density bit or do you have some new information to offer?

Pretty simple genetics and molecular biology. All of the chemical reactions in an animal are carried out based on information stored in the DNA. Like my genetics professor always drilled into us, "genes code for proteins". Every tissue in an an animal is the end result of genetic codes in the DNA. Every chemical reaction (within reason) is the end result of codes in the DNA. In them little helixes, there is a tremendous amount of information - but it is a finite amount.

The reason that you and I don't grow wings is that we simply don't have the codes in our DNA to make wings grow. It's possible that over long periods of time, we could develop the code to grow wings through mutations. But we're talking millions of years, not a year or two.

All this talk about chemical reactions is because that is basically what life is - very complex systems of chemical reactions. Like any chemical reactions, the ones in our bodies can be greatly influenced by temperature. When you consider just how incredibly exact some of these reactions must be in order to sustain life, it's amazing that anything in this world can live... but back to the point at hand.

The reason lower temperatures kill corals isn't because the coral just doesn't like it, or that the tissue is frozen (well, that would kill it, but that's another case). It's because the rates of chemical reactions are altered with the temperature. It's easy to say that "metabolism is slowed" with lower temperatures, but in reality, it's even more complex Different reactions will have their rates altered by different amounts by a change in temperature - so, one reaction may go at 1/2 speed (just as an example) because of a drop of X degrees, while other reactions may go 3/4 or 1/4 the speed. That really becomes an issue when several of the reactions are linked together, or depend on each other.

Let's look at an example - people. Our bodies need to be at a certain temperature, plus or minus a small margin of error, because our chemical reactions don't operate correctly (or at the right speed) outside of that narrow band. Our DNA has information that keeps our "core" temperature in that range. When it's hot, we sweat. When it's cold, we shiver. those are simple, obvious mechanisms, it's actually a lot more detailed than that, but that's enough for now.

When you take a person and put him in cold weather, they will shiver more, and will notice the cold less - but you have not developped any new information in the person's DNA to alter their ability to keep warm, or to live with core temperatures outside of that narrow band. Eskimos still need to have their bodies the same temperature as peoples from the equator. )

As a side note, humans can't live if their core temperature is more than about 3 to 5 degrees outside of the correct value even for relatively short periods of time. The fact that corals can live for some time at even 10 degrees out of the "perfect" amount is a tribute to their ability to cope.

In the corals' case, you can take the coral out of it's normal environment, and it will probably survive. Just how long it survives depends on how far it is out of it's normal environment, and severl other factors, like how much food/energy is available to it.

However, you're not actually changiing the DNA of the animal at all - which means you still have the same set of genetic information that determines the animals' physical and chemical properties. that means that the animal hasn't actually "changed" itself to new conditions - it doesn't make the coral "learn" or "adapt" to be more fit to live in those conditions.

For an organism to actually change, meaning for it to have a different set of genetic information stored in it's DNA, that takes a lot of time. Why? Well, an animal can't just say "Woo, I'm cold, I better get cracking on changing some of them nucleotide pairs". basically, evolution is made up of random mutations that just happened to work out for the good - on accident. Considering how many safeguards there are to prevent mutations, that alone can makes evolution happen very slowly. But when you consider that most mutations either have no real effect or very severe effects, it puts it into even better perspective. Getting a noticeable but manageable mutation that is actually useful is pretty darn infrequent. )

It's possible that a set of corals could change, evolve, speciate, whatever term you choose to pick, but it takes time - and lots of it. it's not impossible at all, otherwise there wouldn't be cold-water corals. But the evolutionary time scale is much, much larger than our tanks or our hobby has been around - unless you're lucky enough to win the Lottery every year for the next 30 years or so, I don't think you've found any corals that have actually changed what makes them them, their genetic information, in any substantial way so as to make them truly adapt to different temperatures.

Sorry that I took so long, and went off on so many tangents. I just really, really love genetics. I was going to become a genetic researcher, but hey, in that business, you're either the head of the lab, or you're just a fly-counter... and I don't want to count flies for 20 years. )

As an aside, there are lots of evolutionary turns that people have taken that are good examples of how difficult it is to get a manageable mutation that works for the better. One would be obsessive-compulsive disorder. In a very small degree, it can be a good thing, a very high percentage of successfull people have at least a little bit of it. The chemical changes are very, very small - and it only takes an almost infinitessimaly small change from there to turn it into a "bad" thing. Even though the chemical differences are unbelievably tiny, there's a huge difference between being driven to do things well, and becoming incapacitated with fear if your shirt isn't tucked in at precisely the right angle. ) Genes are incredible things, they are....

James Wiseman

Remember, if your core body temperature changed 6 degrees for any substantial time, you'd be dead. )

Steve,

I think this is BOB'S POINT EXACTLY!!!! (Not to put words in his mouth though...)

If the bulk of sps corals are imported from Fiji, where water temp is considerably lower than 84...shouldn't the 6 degree (the number from your human your analogy, but the point still stands) temp rise have SOME adverse effect? Take coral X from Fiji---->4 days later plop it in our tanks at a 6 degree higher temperature. Does the coral sigh, "Ah, I've been waiting all my life to get to this temperature!" or does it stress it out? I hope that majorly anthropomorphic sentece gets my point across...-)

Steve Wolfe

I think this is BOB'S POINT EXACTLY!!!! (Not to put words in his mouth though...)

I would say it's pretty close to it, if not his exact point...

If the bulk of sps corals are imported from Fiji, where water temp is considerably lower than 84...shouldn't the 6 degree (the number from your human your analogy, but the point still stands) temp rise have SOME adverse effect?

Well, it's possible. But how do you know that the temperature that they are in now is already having an adverse affect, and raising it back up wouldn't solve the problem? ) If Ron's argument is true, that most of the corals around fiji are there because their larvae drifted from warmer waters, than that would be the most logical. On the other hand, if most of the fijian larvae are actually from fiji, there's a better chance that Bob is correct.

Take coral X from Fiji---->4 days later plop it in our tanks at a 6 degree higher temperature. Does the coral sigh, "Ah, I've been waiting all my life to get to this temperature!" or does it stress it out? I hope that majorly anthropomorphic sentece gets my point across...-)

It really could go either way. Take a person who's lived most of his life on the verge of hypothermia, and put him in a warm room - he'll surely say "Ah, I've been waiting all my life for this!". On the other hand, take someone from the "correct" temperature, move them to a colder one, they could freak out. It all depends on if they're in the "best" (or at least "good") environment to start with, and if you're putting them in a "better" or "worse" environment.

Bob Mankin

I would say it's pretty close to it, if not his exact point...

Ding, ding, ding, ding.....

Congratulations gentlemen.......you are our winners......please come on down and collect your prizes

(Gawd I gotta lay off those huge lattes in the morning)

Take coral X from Fiji---->4 days later plop it in our tanks at a 6 degree higher temperature. Does the coral sigh, "Ah, I've been waiting all my life to get to this temperature!" or does it stress it out?

And that's the $64,000 question I think needs answering.

... It all depends on if they're in the "best" (or at least "good") environment to start with, and if you're putting them in a "better" or "worse" environment.

But touting "optimal" temperature for a captive system strictly based on a natural species density map might get you laughed at if you were doing a peer reviewed scientific paper and that's the only evidence being offered in support of the theory. The only person from the scientific community who I've seen use the term and to go further to say cooler temps are slowly killing corals....is Ron. He may be spot on and offering us all insightful information about what these corals are being subjected to(trying to offer as much credit as possible here). But call me a cynic, I need a little more than one person's opinion or interpretation of the available data. My point in burning up the bandwidth here was for all of us to learn if those additional opinions or data are there to support his ideas. The growth studies in the Carribean didn't do it for me - we're talking about the Indo-Pacific. The P. damicornis study was inconclusive, so for me at this point, the answer is no. Others are welcome to draw their own conclusions.

Further, my possibly ignorant common sense side says, if a coral comes to me with vibrant colors and for all intents and purposes LOOKS healthy and thriving, I'm gonna want to keep it in roughly the same conditions it was taken from. An "if it ain't broke, don't fix it" mentality. If it came from Fiji or the Solomons, it wasn't collected in 82-84 degree water. Period and Amen.

Very few black or white issues in this hobby, but a whole bunch of grey. I said earlier I was bowing out of this one, so time for me to shut up now.

Ron Shimek

Bob,

It if a coral larvae was brought into a cooler clime by currents, settled and spent it's entire life there, wouldn't that by common sense tell us that it is acclimated to that cooler temp? If it hadn't acclimated, it would have perished, plain and simple.

No, you are incorrect. If it was within the range of conditions it could survive in, there would be no need to acclimate. The problem is that at the limits of distributions, the organisms cannot get enough energy to reproduce successfully. Basically they are space occupiers. Given the long potential life span of corals, and the variability of the reef environment, this is a good strategy. They can literally live long enough for conditions to change for the better. For what it is worth, we are now coming out a long - maybe 300 years or so period of cooler than normal sea water temperatures (if temperatures are averaged over geological time). These corals in cooler areas may well have been there since the last good warm period.

However, my point is these references only get us so far. Then you have to talk practical experience, which is what I'm offering here.

No. I am afraid you are not talking practical experience. You are talking impractical experience.

My point was simply that the majority of animals available in the aquarium trade in the US at this time will not tolerate temperatures of 84-85 degrees for any long term period.

That is simply pure and utter BS. If you can't keep them alive at that temperature, then there are other things wrong with your systems.

but in this case and for this debate, the scientific study of the natural environment does not seem to carry over to the captive one.

It certainly does, if you try to emulate the natural environment.

No documented adjustment to cooler temps? Are we forgetting that the hobby, generally speaking, has been keeping, growing and propagating corals at these cooler temps for many, many years?

The hobby has NOT been sexually propagating any corals. NADA.

If you can keep an animal alive long enough to allow it to heal after breaking it, that is a form of propagation, but not one that will keep the hobby growing in the long run.

Some from waters as much as 6-8 degrees cooler. You keep mentioning Palau and New Guinea. Based on my availability lists, there is little to nothing in the way of corals being exported from those locations at this time.

Pity. I would spend some time looking for other suppliers.

I think your earlier post stated the growth rates to be about the same at 78 versus 84. But in your mind it's better at 84 because......it happens to support your argument perhaps?

No, because it grows faster.

="">I think the fact they are living there says they've adapted. It's not like they moved in last week or something.

They haven't adapted at all. If they had adapted they would have growth rates comparable to their siblings in warmer climates. They are just surviving.

Ahh, but I wouldn't have anything more data to support my side than what we already have

Which unfortunately is absolutely none.

Ron Shimek

Bob,

Congratulations gentlemen.......you are our winners......please come on down and collect your prizes

And unfortunately it doesn't work that way for any exothermic animals. Sorry.

First, there is NO core temperature. Secondly, if you lower the temperature about 6 degrees below optimum - say 78 from 84, the animals' metabolic functions drop by about 45%. Called the Q10 law, and is a common rule in invertebrate physiology.

The only person from the scientific community who I've seen use the term and to go further to say cooler temps are slowly killing corals....is Ron.

Limited reading....

Scott Fleming

Wow, this is a interesting discussion. One I most likely should stay out of. However, I believe that one's tank should speak for itself. From all that I have read it seems that Ron's tanks are doing rather well. Animals included.

As reading would have it, here is what I found

Year around temperatures 77 - 86 F The Reef Aquarium Vol. I.

70 - 80 F for best results with 74 - 76 F ideal. Any higher or wide fluctuations are harmful to FISH due to the incidence of saltwater ich (cryptocargon irritans)(sp). The Reef Aquarium Vol. I.

From a quarterly mag, (keeping a reef aquarium)
Saudi Arabia 27(n) latitude 52.5(min) - 97.1(max) F
Quatar 24(n) latitude 57.3(min) - 96.7(max) F
Abu Dhabi 25(n) latitude 60.7(min) - 96.7(max) F
Florida 25(n) latitude 55.9(min) - 91.0(max) F
Heron Island (GBR) 23(s) latitude 60.7(min) 95.0(max) F
Bermuda 32(n) latitude 61.3(min) - 84.2(max) F
Fulf of Aqaba 29(n) latitude 68.0(min) - 82.4(max) F

It also goes on to say that most prefer a general temperature range from 75.2 - 82.4 F, although they have encountered hard corals in inter tidal waters with temperatures of up to 98.5 F during the summer months(Red Sea Jeddha). Also that this is a point often overlooked by the marine aquarists...

From what I can see, a temperature of 85 is not that far off from what I have read.

James Fox

I have kept my tank at 80�, 82�, and most recently 84�f. Last summer my tank hit 86�. Most of the coral seemed fine, but at 84� & above some (at different times) bleached. They were Stylophora pistillata, what I believe to be Pocillopora verrucosa, and an unidentified acropora. All survived & regained color, with the exception of the acropora. All the coral in my system, seem to do very well in the 80-82� range. I realize this is all anecdotal but...

Important note (8th Februrary 2000):
... but I have a monkey wrench to throw into my brief contribution...

When I posted my statements to the list, I was using a cheap glass thermometer. Recently that thermometer broke, and I replaced it with a digital one. It seems the original was not accurate (based upon the more recent digital readings). Where the glass thermometer. read 82�f, the digital read 86.7�f! This could mean that what I once thought was 84�f, could have been closer to 90�f. No wonder I witnessed a bleaching event! This also means, for about the last year or so, my tank has been running between 86-87�f. FWIW, the S. pistillata never fully recovered. Everything else seems to have done fine.

Since the digital thermometer addition, I've reduced the tank temperature to fall between 81-82�. It's only been a few days, so it's too soon to see how this change will affect my system (if at all).

Bob Mankin

Jim,

Thanks for contributing.

Your experiences pretty closely match my own, with the exception that I don't let them drift to 84 anymore. 80-80.5 is what my controller is set for. Save for when chiller has gone haywire, it stays in a nice narrow range.

Oops, just noticed your Pocillopora sp. kinda conflicts with Ron's reference study, but then you said it did recover.

Nathan Cope

G'day Bob,

So why is the assumption made it carries straight over? Because a contributor to the discussion has a doctorate and said it's so?

Both Rob Toonen and Eric Bornerman have in the past said the same thing as Ron. Neither have a doctorate (I don't know about Eric, but Rob is currently working on one, though). Besides Bob, if I wanted expert advice on a commercial computer situation, who do you think I'm going to go to? My next door neighbor's kid who is a so-called "computer whiz" or to a professional who works in the field and fully understands the architecture behind a system set up and its integration into the commercial world? Hey, call me an idiot if you like (I mean that! Call me an idiot in your next post if you honestly think this decision would make me one and I won't complain one bit...although I may tell you what I think of you ;-)) but that makes perfect sense to me.

I mean no disrespect to you Bob as I have no more professional biology knowledge than you do, but I'm certainly going to go for the professional over the hobbyist when it comes to making decisions based on biology, too. Add to that the fact that I do keep my corals at the temps that Ron recommends and they are doing amazingly well and as I said, they are from cooler waters (although I don't know how much cooler because the GBR covers a wide range of temps from one end to the other) and I can't see anything wrong with Ron's suggestion.

My question was quite serious. In my experience my tanks do best at 80. At 82 things start to close up and at 84 animals looked stressed. If temps stay that high for any length of time, I can experience bleaching of pigments or complete loss of animals.

You know what I've been thinking the whole way through this thread when you and (I can't remember who the other guy was) were saying that they couldn't keep their corals above 80 due to the symptoms mentioned above and I thought thats funny because it is just like my corals when they go above 32C for any length of time. It just occurred to me that maybe there is something wrong with your thermometer. Its a long shot but I've heard lots of people complaining about their thermometers being inaccurate, so I calibrated mine (it ended up being correct though).

If keeping them at 84 were the deal, it would be a no brainer for me. My lights and pumps will push it that high by themselves. I'd be saving money with the chiller not running so hard. No ax to grind or hidden agendas here.

Well, not necessarily. It wouldn't be the first time that someone had refuted somebody elses opinion because they just didn't want to be seen as being wrong. Not saying thats what is happening here, but just because it would be convenient in some ways for someone to be wrong doesn't mean that they will admit that they are.

Maybe it's simply a case of easing up to that temp and allowing the animals to settle down over the course of a few days. I don't know.

Maybe, although I've always been fine with just a 20 minute float in the bag.

Ron Shimek

Mike,

I didn't bother with Fiji- being further from the Equator, the water is likely cooler, but I would not guess on temps at this time...

There are more data than you can shake the proverbial coral at.

Do a search on sea surface temperatures - knowing that oceanographers consider the sea surface temperatures to go down to about a 100 m.

Here is one URL to start with where you can get effectively real time temperatures - find the lat-long of any of your desired sites in the Central Pacific (Fiji, Solomons, Tonga) and you can look on the map. Or if you know where they are just look.

http//www.pmel.noaa.gov/toga-tao/realtime.html

Eric Borneman

I was not following this thread, until I saw esteemed James post a summary which piqued my interest. I take it this had to do with the fabled "ideal" once again. Without having having the full thread, but knowing from experience what these things entail and some views of some of the participants, allow me to put forth my ecological/biological viewpoint, if I may.

I suspect Ron was stating the positive attributes and tolerance of animals to higher and varying temperatures. I think it amazing enough that in five years, hobbyists have gone from believing 76 was ideal to about 80. I personally run my tanks even higher - 84. But as James stated, no one has done any real measurements, to my knowledge. However, what good what it do? The assumption of this is that animals, collected from various locales, various depths, various reef zones, all have some ideal temperature. This is lunacy. Our animals are collected from areas where 76 and 90 can both be "ideal", so to speak.

Now, Ron's general view of increased metabolism and greater growth is biologically sound to a certain limit. There is an upper and lower limit, and it is based on an almost case by case basis. Furthermore, temperature interacts with a number of other variables, including irradiance, UV, nutrient loading, degrees of competition, etc. There is are many excellent studies discussing the interactions and effects of temperature on coral reefs and coral reef biota. I'd be happy to provide some to those interested.

Be all that as it may, coral reefs are one of the most temperature sensitive biomes on Earth. It doesn't take a rocket scientist to read headlines about increased sea surface temperatures and all the bleaching (which, btw, caused 75-90% mortality over many reefs last year, even in the "bleaching proof" Pacific reefs). The bleaching has been linked almost entirely to the warm waters which, fwiw, were in many cases significantly below what would be considered an upper thermal limit for others and in some cases lower than what we keep our quaria set. The thing is, corals live within a few degres C of their upper limits even under "ideal" conditions. This is long term, not short term. There are many which live in areas which are exposed to sometimes huge hourly or seasonal variances in T - the Gulf of Oman is especially studied in this regard. Some of the Red Sea areas get blasts of cold air that can chill exposed corals down to 50F and then later on, they are regularly bathed in 90F + water. There have been studies to examine this phenomena, and transplanted corals usually do not live. It appears that corals from these areas (and lagoons, tide pools, etc.) are specifically suited and tolerant of such temperatures. Same with some of the high latitude reefs where water temperatures get quite low. This should be obvious as the diversity of species in such areas is always less.

OK, that said, where does that leave us with our tanks? Once again, we don't know the location where animals were collected. Likely, most are coming from easy-to-collect areas where it is shallow and probably subject to some degree of temperature variation on a daily or hourly basis. Thus, our animals are probably quite suited to a variation in temps, all of which may be seen as the range of "ideal." Certainly we know that deep water animals will not be exposed to as much variation, and likely less upper thermal stress, although cool upwellings may make them more tolerant tolower thermal levels.

Our tanks are not ideal in many ways, and therefore pushing the upper limit is, imo, a little risky, given the interaction of variables. However, the repurcussions of keeping tansk at lower temps that are probably near the lower limits of collected animals, and also in terms of the productivity and reproduction of the community, is probably equally detrimental. I don't think 84 is pushing the upper limit for most reef corals, although 86-88 might be. Heliopora, otoh, will love it. In terms of those who see problems at 76 or 86, then address it. To say that a tank runs better at 82 v 80 or 82 v 84 is pretty much ridiculous. There is rarely, if ever, that kind of thermal stability anywhere and effects of 1C or less, if it exists, is probably being primarily caused by conditions other than temperature.

Anyway, that's my posturing, fwiw.

Ron Shimek

Bob,

My question was quite serious. In my experience my tanks do best at 80. At 82 things start to close up and at 84 animals looked stressed. If temps stay that high for any length of time.

So what is it about your systems that is causing animals to be stressed out at these temperatures. I seem to recall you added significant amounts of additives? As the metabolic rates speed up, the deleterious results of such additives would become more apparent and faster.

Do you feed enough that the animals have the food that is necessary? At 84 degrees the animals would need about 1.6 times the amount of food as they would require at 78 deg.

Dallas Warren

> Damn having to go to sleep and have some important work to do when this sort of discussion is going on ;-) Quite a few points have come up that I would have liked to raise myself, lets see if I can swim through the multitude of posts .....

Apples to oranges here guys. You've more than made your point about greatest diversity areas with the map overlay idea. That's not what I'm debating.

I have not quite seen someone point it out explicitly, but here is what it boils down to with the two camps the optimum conditions a coral (any particular species) can be kept in is that of

# which it was originally found.
versus
# where the largest population density/concentration is found.

The problem is this in a nutshell; the bulk of the coral imports into the US at this time are collected in waters much cooler than the 82-84 degree temperatures being suggested. That's a fact. Focusing on the individual collected coral now, how do you conclude that this individual can re-acclimate to higher temps just because its cousins are found in areas centered around higher average temps? If you want to suggest

OK, couple of people have given examples of this, but let me try another track that might help to illustrate the point. Ignore temperature for the moment, and lets take a look at light intensity. Take a particular species of Acropora, you find extensive colonies on a reef within 2 meters of the surface. It is one of the dominant coral species to be found in that location. Now, go down the slope a bit into deeper waters, say down to 10 meters. You find another colony of that coral species there, possibly fragmented from the original coral. It is no longer the dominant species, and is not as extensive. If you then took a cutting from both of the colonies, where would you then keep each of them in respect to light intensity? At the conditions they were found in, or that optimum for that coral species (which is obviously at the higher light level, shown by the fact its growth rate is larger and it can dominate the zone)?

Steve made a point in one of the later emails, each individual of a species genetic code is the same. They have the same biology, the same sequence of reactions, and the same optimum conditions for all of those to occur. It does not matter at all where the particular species happens to be living at any moment in time, it could be under extreme conditions that it just happens to be able to survive. But the fact remains those are not the optimum for that coral. If you want the best health and growth out of it, then simply provide those conditions. Anything less/more and its health/growth will suffer.

genetics allows it, fine, just be sure to quote the studies and field excercises that prove it. My experience and that of others has been different. You have either assumed acclimation is a no-brainer for the coral or you have simply overlooked it. I don't know which. Specific individual corals now. We are not talking in the generalities of a whole species.

Yep, we are on the same wavelength in that respect I think.

Lets take this lighting analogy a bit further. Say you take the coral fragment that came from 10 metres, and because the optimum lighting level is at 2 metres you want to place it under that lighting. Do you then place the coral there under the full intensity of the light present at 2 metres? Of course you don't, you have to give the coral time to acclimatise to that lighting level.

Same deal with temperature, rapid changes are bad, they are what causes all of the problems.

So if you are saying the coral can and will adapt, on what do you base this? Have you considered that the individuals within a species on the

Because each individual of the same species has exactly the same genetic information, and therefore the same body layout, reaction steps etc, so each will react to the same physical conditions in the same way.

fringes of distribution may be there for a reason? Besides having been pushed there by currents, perhaps there's been a mutation that makes them better suited for a cooler climate and less suited for the warmer clime from which they were released. The possibilities here are

If that is the case then, they are either not of the same species any more, or they are a sub-species. If that is the case, then you cannot make the same judgements about that coral until you know what makes it different from the original species it split off from. If it is more tolerant of lower temperatures, then if you look at its species/sub-species distribution you will see this. (damn says Bob, there are those damn distribution maps again ;-) ) The higher concentrations/densities will be in these locations that are optimum for that species/sub-species.

numerous. Distribution maps mean little in this debate because collection stations aren't paying attention to them. So let's set 'em

I see where you are making this distinction, and I do beg to differ ;-) We are just interpreting this differently.

Lets see if I can put this another way. Lets take a mountain, on which it is forested from top to bottom. Start at the bottom and work your way up and you will find that the balance of tree species found at each altitude different. Species found dominant at the bottom will be very rare and grow poorly at the top. Visa versa for those found near the bottom. The reasons are various, temperature, rainfall/run off, soil quality etc. You want to grow these trees somewhere else, so what conditions do you use to grow it? You collect one of the high altitude trees from somewhere mid way, its growth is a bit stunted, and it is having a hard time. Do you then use these same conditions to then grow it in, or do you go for those which you know it will do better under? i.e. those conditions found at higher altitude.

Can you see the parallels?

aside and start discussing acclimation, because it is a real issue if you wish to advocate these higher temperatures. Your advice could just as easily be stressing or killing animals needlessly. Not suggesting it is, but I think it's a good idea to nail down what we're attempting to do here. When I see statements like "corals slowly being killed at 76 degrees" based on a distribution map, well, those are harsh statements with questionable links to the evidence offered to support them.

I wasn't actually saying that, so I wont go to the trouble of defending it .....

I do too. I also believe Donna when she says that one of her LPS corals acts differently at different temps. The arguement is that corals should be kept at normal reef temps, and for the areas of highest coral density/diversity, that is around 85 degrees F. A major caveat in all this- watch your animals. I know for a fact that Ron would not argue that you have to maintain X temp even though your prized coral is stressed by that extra few degrees... His point was always that temperatures as recommended in the past, 72 - 75 degrees F, are too low and probably more harmful, stress-wise, than the lower metabolism can likely handle over time. Better to have them at a more normal 80 to 85 degree range- I think he specifically recommended 82-84...

A very valid point. If a particular coral species reacts adversely after sufficient time to allow the coral to acclimatise or the change is done slow enough so it does not shock them, then obviously those conditions are not its optimum condition. I don't think anyone here has implied or said to ignore the corals in your tank. Watch them very closely. They will soon tell you when they are unhappy, or over the moon and going nuts with growth.

Personally I keep my own tank in the region of 27-28oC (81-82.5oF). Temperature goes down a bit in winter, goes up a bit in the summer. Nothing actually complains within this temperature range at all, mainly because the variations occur over a relatively long period. The only adverse effects I have noticed is when it reaches the region of 31oC (88oF). Only then do things react adversely. All of the other reef keepers down here that I have had contact tend to keep their tanks down at the 24-25oC (75-77oF) mark. I can honestly say that the coral growth rates they see across many coral species is far less than anything I can generate. This is allowing for other variations, such as the important one of light intensity.

Temperature is just another limiting factor like light. Obviously corals can tolerate different levels of light, although it should be obvious to even a fairly new hobbyist that the lower the light level, the slower the growth. Corals can obviously be moved to different lighting regimes and adapt to the new level, but their growth rate differs depending on the light available not on how close the level of light available is to what light was available at their original settling point. The same species of coral will grow at the same rate (once time is allowed for acclimatisation) regardless of the light level they had at the point of their original settling. The same goes for temperature.

Exactly the point I was making. To determine the optimum conditions of any species you have to look at the conditions at which it thrives in nature. And that includes the entire range over which it is found. If you limit yourself then you could end up missing the optimum conditions in that particular zone/region you missed out.

The location from where they are being collected has little impact, except for the fact that the corals have to be acclimatised to an aquarium with a higher temperature when first introduced, the same as you do with any animal you introduce to your aquarium.

Good point. Acclimatisation applies to any physical parameter. Organisms take time to adjust to new conditions. Change things too fast and they react negatively.

It if a coral larvae was brought into a cooler clime by currents, settled and spent it's entire life there, wouldn't that by common sense tell us that it is acclimated to that cooler temp? If it hadn't acclimated, it would have perished, plain and simple.

Yes, it has acclimatised to those conditions. It has managed to sustain itself sufficiently not be over run or eaten by something else. But this is very different to the optimum conditions for keeping that particular species. Acclimatise it to those, then you will see its growth rate will improve.

However, my point is these references only get us so far. Then you have to talk practical experience, which is what I'm offering here. We can analyze field studies and species/thermal distribution maps until our eyeballs fall out of our head, but in the practice of captive reef keeping, who's to say what is valid and what is not? My point was simply

Well, in my case if you provide the conditions optimum for them in nature in a captive reef then you will have success. If it does not appear to be the case then you are missing something. One of the parameters is not optimum and are adversely effecting the coral in some way. It could be something obvious such as light intensity, or something not so obvious such as defensive/offensive chemicals give off by other corals within the same system.

that the majority of animals available in the aquarium trade in the US at this time will not tolerate temperatures of 84-85 degrees for any long term period. There certainly will be exceptions to this statement, but generally speaking I think it's pretty accurate. And IME anything over 82 or 83 starts causing significant stress. All the distribution

Have they actually been acclimatised to those conditions to start with, and allowed long enough to do so?

>No documented adjustment to cooler temps? Are we forgetting that the hobby, generally speaking, has been keeping, growing and propagating corals at these cooler temps for many, many years? And obviously you are

Well, weren't they 20 years ago keeping some marine fish alive in an aquarium? If you want the best health and growth out of an organism purely and simply you must provide it with the optimum conditions. And temperature is a very important factor here. Lets say you can draw some type of map of physical condition for a coral, and you end up with something that looks like a mountain range. The altitude of any point is how well the coral species will grow under those conditions. Change the conditions and you will either move up or down, determined by the local topography. Just because people have been keeping, growing and propagation corals at these cooler temperatures for many, many years does not mean you are at the peak. There is a chance they can be pushed further. And this is obvious in terms of other parameters as well (which ones yet is anyones guess) but the corals do not yet regularly sexually produce.

>Maybe I should have been clearer. Long term maintained temperatures is what I'm intersted in, not temporary spikes. I'm well aware of what a closed system can handle. My own system has seen as high as 93.6 on the upper end(chiller mistakenly unplugged) to 62.3 on the low side(controller crosstalk caused chiller to stay on). That doesn't mean want to keep it at either extreme for experimentation sake. I experienced mortality at both ends of the range there, with the latter being pretty severe.

That certainly shows how incredible life is doesn't it? A temperature range of 30oF and no huge mortalities. Damn life is cool ;-) Can I ask the sort of time frame of the temperature drops that happened on the system?

Well, I'll chime in. I split the difference at about 82 and get concerned 86 top end (I usually get dino blooms at that point). Bob's concerns have merit in that there will be genotypic variation in protein composition and structure that may show up in those settled in cooler waters (if someone actually ever does the study). In other words larvae settling/surviving there may have a set of proteins better tuned for those cooler temps. Nature is a bell curve and there is significant variation in DNA and protein structure amongst even individuals within a species. The fact that the center of adaptive radiation coincides with warmer temps does not preclude this possibility. (but let's not forget the effect of temperature on mutation rate either)

In effect they will actually be a sub-species, so the optimum conditions for the species it came from no longer holds .... If such a variation does occur, then it will become another species, because it has different adaptions to the original one.

If the bulk of sps corals are imported from Fiji, where water temp is considerably lower than 84...shouldn't the 6 degree (the number from your human your analogy, but the point still stands) temp rise have SOME adverse effect? Take coral X from Fiji---->4 days later plop it in our tanks at a 6 degree higher temperature. Does the coral sigh, "Ah, I've been waiting all my life to get to this temperature!" or does it stress it out? I hope that majorly anthropomorphic sentece gets my point across...-)

Apply the same statements to lighting James, and see what you come up with. You would be down right silly to take a coral from low light levels then hit it with high light levels. Same deal with temperature. As I have made the point previously ......

Nathan Cope

G'day Bob,

Not to put words in your mouth, but wouldn't the "in your tank" part be the one we most care about?

Of course, but "in your tank" is not "in my tank". In my opinion, this is the importance of this whole temperature debate. Sure, you say the corals in your tank seem to do better at a lower temp. I'm willing to believe that for whatever reason corals in your tank just don't seem to be healthy at a higher temperature - I don't know why, it could be something as simple as your tank having very poor gas exchange or not enough nutrient input to sustain the corals at a higher metabolism, but the fact remains, that my corals do do better at 28C.

So, where does this leave us? My tank runs best at a high temp, yours runs best at a lower temp. If a beginner comes to me and says, "What temp do I run my tank at?", what do I say? Well, that's pretty easy to answer because I had the exact same question last night at our local marine aquarium society meeting.

I said to them, "The optimal temperature according to science is 28-29C. Now, I run my tank at 28C and everything looks great. There are some people who say that the best temp is 24C and there are various reasons. Some people think that corals collected from colder areas have got used to the cold temp and cannot handle being raised to a higher temp, I don't subscribe to this theory because my corals are collected from colder areas and do fine at a higher temp. Others say that it is better to keep them at a lower temp because their metabolism is slowed down and therefore they produce less waste and need less food. Thats fine if you don't have the knowledge to provide good filtration that can handle normal waste levels and high nutrient levels, but with our current methods of filtration, this just isn't necessary. The other reason why some people may not be able to keep corals at the optimal temp according to science is that there is something not quite working correctly in their captive reef system such as low gas exchange or not enough nutrient input. So, the long and the short of it is, keep your aquarium at 28-29C and if you end up having problems with your animals at that temp, try looking for a reason, but if you can't find it, lower your temp until you do find the problem."

I was thinking increased metabolilsm = increased aging process = shorter lifespan and, of course, the flip side for slower metabolism. Call it that flawed simple logic of mine.

Yes, I agree with that, it does sound logical to the layman and I thought the same until I read some biology texts. It turns out that lowering the temp causes all these stresses on the organisms because their enzymes don't function at the correct rate. As Steve explained, normally all the enzymes are running at the same speed, but when the temp is lowered, one type of enzyme might now run at 1/2 speed whereas another type of enzyme that it has to do biological "business" with is now running at 1/4 speed, so the synchronisation is all thrown out. Now, these are all fairly large figures and the actual speed difference might only be a hundredth of a percent, but when it is running continuously for an organisms lifespan, it will have a significant affect. The resulting stress causes the animal to virtually be "worn out" if you like. For corals, for example, which pretty much have an indefinite life span, this is a sad situation because it can mean that they just end up dying. Others that are a more tolerant of a wider range of temperatures just end up hanging in there, slowly growing and not really reproducing.

Now, one more thing that no-one has mentioned yet (I don't think) is the fact that some people are saying their corals don't handle higher temps very well and the way they prove this is by saying that their corals bleach. That is a fair enough symptom as far as I'm concerned, but it just occurred to me while typing this, that the problem might actually be with the zooxanthellae. We know that most organisms have a range of temperature that they can tolerate and of course, that would also cover the symbiotic algae inside the coral. I think I've read that the symbiotic algaes in corals can differ from location to location and in different depths, so it makes sense that some algaes may have evolved to live in narrow temperature bands that can't handle a move to a warmer or cooler temp.

Maybe this is the reason why some people have trouble moving corals from cooler climates to a warmer in tank temp. This does not mean that this temp is best for the coral, all it means is that the temp is best for the algae. In a bleaching situation though, if the coral is able to hold on long enough with its nutritional reserves, we know that algae will repopulate a coral and a different algae can be used. I would suggest in this case that the temp be raised extremely slowly over a number of months to allow a simple algal transitioin. Then again, as I pretty much only thought out this theory as I was typing it, it could be a complete load of crap. )

Dallas Warren

Nathan,

inside the coral. I think I've read that the symbiotic algaes in corals can differ from location to location and in different depths, so it makes sense that some algaes may have evolved to live in narrow temperature bands that can't handle a move to a warmer or cooler temp.

Actually, the particular species of zooxanthellae can vary within a particular coral, individuals and location. It is really very variable. And the coral having more than one single species of zooxanthellae in stock at any one time makes a lot of sense for the coral too. If conditions happen to vary then it still has a species that will be able to handle it without too much trouble. All that is required is the majority of the zooxanthellae is ejected (equate this to bleaching) then they are allowed to repopulate again (I suspect both from the water and for those left within the tissue) and the coral is then better suited to the conditions there.

Maybe this is the reason why some people have trouble moving corals from cooler climates to a warmer in tank temp. This does not mean that this temp

It would work in the other direction as well.

is best for the coral, all it means is that the temp is best for the algae. In a bleaching situation though, if the coral is able to hold on long enough with its nutritional reserves, we know that algae will repopulate a coral and a different algae can be used. I would suggest in this case that the temp be raised extremely slowly over a number of months to allow a simple algal transitioin. Then again, as I pretty much only thought out this theory as I was typing it, it could be a complete load of crap. )

That is entirely possible ;-) but it does make a lot of sense. Will be interesting to see what others have to say about it.

The field to do with the symbiosis of zooxanthellae and corals is really in its infancy. Who knows what amazing and interesting facts will be discovered.

A survey of hobbyists was suggested to help to gain some useful captive data .... and this bit followed.

Mike Kirda

I need suggestions on number 4, as in what would be a good indicator to show for growth, inches, %? etc

Here are a few methods of choice out of Coral Reefs: research methods:

  1. Dye coral with Alizarin red- creates a ring in the skeleton. You can then slice a branch and measure the growth past the ring.
  2. "Buoyant weight technique"- in essence, you mount and weigh the coral in specific intervals using a three beam scale modified to weigh corals underwater...
  3. Geometrical relationships- Explained more fully in Chapter 42- I don't want to even try to explain the math right now...
  4. TMCRA Vol.2 uses a volumetric measurement- measures the colony in length,width, height and multiplies them. Uses the volume as a method of comparison...
  5. Maybe easiest for us to measure growth from branch tip to base on a monthly basis... Linear growth measurements...

4 and 5 are easiest, but not of the highest utility... 1 will have a nice side benefit (makes new frags...). 2 would be ideal- growth is calcification for hard corals. But not everyone has a triple beam balance available to convert to this purpose...

Ron Shimek

If you set up to use a series of sacrificial (experimental corals): Alizarin Red S has some adverse metabolic effects. Dose the tank with Tetracylcine, doesn't have to be much. The coral incorporates this into its skeleton. It glows under UV light, so you have a banded skeleton. Do this on a regular basis or use it as a baseline.

Other considerations:

  • How do you measure/monitor temperature?
  • How many experimental replicates - you cannot use just one animal or one tank?
  • How long do you run the test? I would suggest at least one year, perhaps two or three (seasonal effects can be significant even in captive animals).
  • If you really are doing nice things for your coral and it gets to reproductive size, then the growth rate will drop as it starts to use metabolic energy for gametes. How will you take this into account?

Mike Kirda

There are more considerations....

I am sure that there are more than I can conjure up... That's why I suggested fleshing this out on-list. Most important is that I don't want this to end up merely as a validation of my own beliefs. What I believe could be wrong.

Alizarin Red S has some adverse metabolic effects. Dose the tank with Tetracylcine, doesn't have to be much. The coral incorporates this into its skeleton. It glows under UV light, so you have a banded skeleton. Do this on a regular basis or use it as a baseline.

I'd use it as a baseline only. Dose in small tank for what, like 12 hours?

How do you measure/monitor temperature?

Heater/chiller controller set for narrow range.

How many experimental replicates - you cannot use just one animal or one tank?

As many as is practical. The two tanks that are very nearly identical are both 750 gallons, so I shouldn't run out of room... I'm thinking of frags from several colonies... I could theoretically do quite a few...

How long do you run the test? I would suggest at least one year, perhaps two or three (seasonal effects can be significant even in captive animals).

Well, at a minimum, six months. Likely far longer... two-three years is a good possibility...

If you really are doing nice things for your coral and it gets to reproductive size, then the growth rate will drop as it starts to use metabolic energy for gametes. How will you take this into account?

I have no clue. I suspect that it will not run long enough to get the animals to that point. Any ideas? I still am not positive that growth rates will be good indicator of stress anyway. What do you think?

Ron Shimek

I'd use it as a baseline only. Dose in small tank for what, like 12 hours?

Depends on how active the coral is at calcifying at the time when you are doing the baseline. I would suggest setting organisms in a small tank and letting them sit for a day or two, or until you feel that they are behaving normally. I would suggest bumping the temp up to at least the low 80's (calcification is more rapid at this temperature and if the rest of the run is done at lower temps, this short period won't matter, but it will allow more incorporation of tetracycline into the skeleton). I would keep them in the tetracyline solution for about 12-24 hours, use about 0.1 to 0.01 percent tetracycline solution.

Heater/chiller controller set for narrow range.

No good. Take readings with a good thermometer at least a couple of times a day. Recording thermometer running to a computer would be better yet.

As many as is practical. The two tanks that are very nearly identical are both 750 gallons, so I shouldn't run out of room... I'm thinking of frags from several colonies... I could theoretically do quite a few...

Go to your local ESU (Enormous State University) and talk to a stats prof, or definitely call and pick their brains. You can easily pass a point where the increase in replicate numbers doesn't give you any increase in statistical validity. It would be better to run smaller groups of replicates from numerous species rather than a lot from one or few species. If you want some stats help long distance or in processing the data, I would be glad to help.

Well, at a minimum, six months. Likely far longer... two-three years is a good possibility...

This is good. Probably two years is good "shoot for" period. If you have several treatments (groups of replicates) you could harvest at, say, 6 month intervals and see if there is any change with time.

I have no clue. I suspect that it will not run long enough to get the animals to that point. Any ideas?

I think it will run long enough to see changes, particularly in the warmer treatment where growth will be more vigorous.

Ideas...Yes. Break off a small fraction of the animals at the beginning and get "ash-free dry weight" of the tissue (basically you take a small sample, dry it in a desicattor, weigh it to, say, 0.01 gram, then incinerate it in a muffle furnace at 500 deg C, the weigh the sample again. This gives you the weight of living tissue per gram weight of skeleton. This sounds involved isn't really; many high schools have the equipment to do such stuff as do community colleges and they will often let you use the material.

You need a good scale and muffle furnace, though. This is standard process, so there are many written protocols for it should you need more detail, or I can provide you with more information.

I still am not positive that growth rates will be good indicator of stress anyway. What do you think?

It is a "whole organism" stress gauge and works reasonably well. It is commonly used in biological research. It also has the advantage of being comparable to rather vast literature pool on coral growth rates. Probably the best indicator would be numbers of gametes produced per unit mass of tissue, but I think this would the search for the holy grail here.

Agreed. I have no idea yet what the protocol is, but I will find out soon. I believe that they monitor it a couple times per day as a matter of course...

Good that should work. If two times a day, it would be best if the reading were 12 hours apart.

It would be better to run smaller groups of replicates from numerous species rather than a lot from one or few species. Given a normal colony, seems like 3 frags in each tank (for a total of six) would be ok.

Try for more (a bigger fragee to begin with). With most of the standard stats, you loose 1 or 2 degrees of freedom right off the bat depending on a test. With 3 replicates, loosing 2 d. f. leaves you with only one degree of freedom, and that means that any difference you find will have to be HUGE to show any degree of statistical difference. Shoot for 6-10 replicates - so a total of 12 to 20 for 2 tanks.

Obviously I can do more from the same species, but would not be genetically identical. If I shoot for, say, 10 different species, three frags in each tank, then that would give me 30 data points spread across ten species,

No. For stats that would give 1 point (each one a mean (= average) value) in each tank for each species. For a test like this you will be testing the difference between the average values in each tank for each species. You get a better average (less variance) with more replicates, but you don't gain data points.

with the only main variable being temperature. I could do more if necessary, but I do not want this to turn into a full time job, either.

There will be plenty of experimental error to go around here. Yes, just stick to one variable. - So... the tanks have to be devoid of all live rock (to avoid problems with variations with currents) and should be illuminated as identically as possible. The fragments should be placed randomly in the tanks (mark off the bottom in a grid, number the intersections, and use a random number generator to locate spots for each individual).

Live sand and water variables could be real problems as will feeding. You will have to ensure that both tanks get a super abundance of food to make sure that neither system suffers food deprivation (whose effects could cause low growth thus confounding the experiment and making the results invalid).

Created by liquid
Last modified 2006-11-25 18:50
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