[Coral-List] Coral immortality

[Ulf Erlingsson]

Doug,

It sounds to me that you have just improved Gene's hypothesis  
substantially, since disease would explain the near simultaneous  
death also of different species. As you say it is not directly  
related to age, but of course it is indirectly related, since it  
takes some time for the community to grow so big as to be susceptible  
to the next plague attack.

Ulf

On 2011-03-20, at 22:54, Douglas Fenner wrote:

>       Thanks, David.
>       I think there are further logical problems with this idea.   
> First, we know
> that the single thing that killed more corals in the western  
> Atlantic than
> anything else was white band disease, wiping out most of the  
> populations of two
> of the three most abundant species.  White band disease is not  
> corals growing
> old, it is a disease that killed almost all in it's path, young and  
> old.
> Further, it didn't really happen synchronously, all in one year, it  
> was spread
> out over a number of years, maybe a decade or two (someone else  
> could probably
> fill us in more on the timing).  It had nothing to do with corals  
> getting old,
> so far as I know.  Cores taken in Belize by Aronson and Precht in  
> Belize show it
> was the first such event in something like 2000 years.  Well beyond  
> the lifespan
> of almost any coral species, so it couldn't be a periodic  
> synchronized die-off
> with a new generation quickly following.
>      Second, the bamboo analogy has the problem that there are 55  
> plus species
> of reef building coral in the western Atlantic.  The different  
> species of bamboo
> flower and die and start over at different times (my impression is  
> that all the
> bamboo in one forest is one species, so the whole forest dies  
> periodically and
> is reborn).  For all the coral in the west Atlantic to decline,  
> many of those 55
> species would have to grow old in synchrony.  Different species  
> have different
> typical lifespans, I'll bet you that Favia fragum has a much  
> shorter lifespan
> than Montastrea annularis.  Each one would be different.  It is  
> near impossible
> for them all to suddenly die at once from old age.  Further, any  
> observation of
> the living colonies will show a variety of sizes of any one  
> species, and thus a
> variety of ages (though fragmentation can muddy that picture), they  
> show no sign
> of being synchronized ages.  Most of them spawn every year and  
> there is a set of
> new recruits each year, instead of waiting 30 years to all spawn  
> once and die.
> (Surely recruitment is better some years than others, so some  
> cohorts have more
> individuals than others.)  No indication corals die after spawning  
> (many
> macroalgae do, they turn all their cells into gametes and spawn  
> within a short
> period early one morning and the adult individual is alive no  
> more!  But
> individuals spawn on different days in different years, and there  
> are always
> some adults left.)  One further point is that as far as I know, the  
> large
> Porites that have been cored, lay down the same thickness of coral  
> skeleton when
> they are 700 years old as when they are 10 years old, it doesn't  
> change with
> age.  That goes to the question of whether they slow down or stop  
> growing, not
> the question of whether they reach a fixed age and die, or whether  
> they have
> some aspects of senescence.  There is a core from a 700 year old  
> coral in the
> Museum of Tropical Queensland, in Townsville, Queensland, marked  
> with when
> Columbus discovered the new world (it was about 200 years old  
> already), etc.
> Stop in and check it out when you go to ICRS just a day's drive  
> north in Cairns,
> in 2012.    Cheers,  Doug
>
>
>
> Faster ice melt, higher sea levels
>
> Ice loss on Greenland and Antarctica is accelerating at three times  
> the rate of
> mountain ice loss. If it continues, this melting will dominate sea- 
> level rise
> this century.
>
> Eric Rignot at the University of California, Irvine, and his  
> colleagues compared
> calculations based on 18 years' worth of data on climate and ice  
> discharge with
> 8 years' worth of data from the Gravity Recovery and Climate  
> Experiment, which
> uses satellite measurements to assess ice mass. The authors  
> estimate that the
> rate of loss is increasing by around 36.3 gigatonnes of ice a year,  
> with a
> cumulative loss of 475 gigatonnes in 2006.
>
> http://www.nature.com/nature/journal/v471/n7338/full/471268b.html? 
> WT.ec_id=NATURE-20110317
>
>
>
>
>
> ________________________________
> From: David M. Lawrence <dave at fuzzo.com>
> To: coral-list at coral.aoml.noaa.gov
> Sent: Fri, March 18, 2011 4:12:22 PM
> Subject: Re: [Coral-List] Coral immortality
>
> I would suggest an application of Koch's postulates to causes of coral
> dieback (a forestry term) would be useful here.  Unfortunately,
> something similar has been applied to some of the recent events and,
> given that both field- and laboratory-based studies can tie these
> diebacks to anthropogenic causes (pollution, overharvesting, climate,
> etc.) that the senescence hypothesis is for the most part wanting.
>
> You're asking us to discard hypotheses that have substantial empirical
> support in favor of an hypothesis that may be all-but-impossible to  
> test.
>
> Dave
>
> On 3/18/2011 2:04 PM, Eugene Shinn wrote:
>> Good! We got to express ourselves about technical aspects of corals
>> and reefs. The subject received two kinds of responses. Those that
>> agreed that corals die of old age (mainly off-line) and those that
>> disagreed (all on-line). I would like to propose another question for
>> discussion. What if all the bamboo on earth began to die at the same
>> time? Would there be finger pointing and accusations as to who, and
>> what, caused it? I think there would be if it were not for the
>> Chinese who have been watching such events for centuries. Bamboo is a
>> major construction material in Asia and also the main food for
>> Pandas. Do some Google searching and you will find that one species
>> dies worldwide at the same time about every 125 years (associated
>> with flowering). Other species die on shorter time scales and one in
>> northern India flowers and bears fruit once every 40 years leading to
>> a plague of rats that consume much of the rice crops leading to
>> famine. Now before you say bamboo is in no way related to coral I ask
>> how do we know that corals do not naturally go through similar boom
>> and bust cycles. Who was diving and paying attention to corals and
>> coral recruitment 100 years ago? Unfortunately even the geologic
>> record is of little direct help. It is only because of the Chinese
>> historical records that we know about bamboo cycles that prevents us
>> from becoming hysterical.
>>        As for Doug Fenners remarks about sea level he is correct,
>> Massive corals in shallow water do reach the surface and can grow no
>> more. That can be seen on patch reefs in the Florida Keys. In
>> addition sea levels fluctuates and corals are killed when the sea
>> goes down. However, for the vast majority of the reef tract bordering
>> the clear blue Gulf stream the water is 20 to-30-ft deep and there
>> are hundreds of widely scattered heads that are less than 200 years
>> old. Coals there have had at least 6,000 years to grow! Why are they
>> all about the same size? And why is the reef accumulation no more
>> than 1 meter thick over the vast extent of the reef tract? Head coral
>> growth-rate is much faster than the known rise in sea level so why
>> did they not keep pace and make coral heads 20 ft high? Either, like
>> bamboo, various species died synchronously on some schedule we are
>> unaware of, or they were killed by some environmental factor i.e.
>> Hurricanes, disease, cold fronts and/or warming evens. Either way it
>> is clear that many non anthropogenic events have kept the Florida
>> reef tact from outpacing the well-known rise in sea level since the
>> last glacial maximum when sea level was more than the length of a
>> foot ball field below present I contend that many mysteries remain!
>> If only we were doing the science/research aimed at understanding non
>> anthropogenic causes of coral death. In stead we keep hammering away
>> at the "usual suspects" that is driven by NGOs and other funding
>> sources.
>>        The remarks concerning Enewetak demonstrate that the Atoll has
>> been able to keep pace with the many sea level fluctuations that have
>> occurred over the past 65 million years. I spent 2 months there
>> involved in drilling and diving. Unfortunately there are many atolls
>> that did not respond well or could not keep up with subsidence. They
>> now lie hundreds of meters below sea level and are called guyots.
>>        A Clarification: I certainly was not suggesting that corals  
>> are
>> immortal. Just the opposite! Just needed a snappy title. Also, most
>> organisms do not die of old age. They die of any number of diseases
>> when they become weakened by old age. Could that be what we are
>> seeing today? It is interesting that A. cervicornis "sticks" exposed
>> in deep trenches made by ship groundings and other causes are more
>> robust and often 2 to 3 times the diameter of those that died
>> recently. In our paper (Shinn et. Al., 2003) we carbon 14-dated 39
>> randomly collected, (actually hap-hazard), fossil sticks in reef sand
>> over a hundred mile long stretch of the Florida reef tract, We found
>> specimens that dated from 6,000 years old to the present (all near
>> the surface). What was most interesting was a convincing 500 year
>> absence of Staghorn centered at 4,500 years ago and another less
>> convincing 500 year absence centered at around 3,000 years. The
>> 4,500-year interval correlates well with a period of inferred ice
>> rafting determined from deep sea sediment cores. There were probably
>> many climate episodes during the Holocene. Gene
>>
>> Reference: Shinn, E. A., Reich, C. D., Hickey, T. D., and Lidz, B.
>> H., 2003, Staghorn tempestites in the Florida Keys, Coral Reefs, 22:
>> 91-97.
>>
>
> -- 
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