GoM Lamellibrachia

Stephane Hourdez hourdez at sb-roscoff.fr
Sun Feb 13 18:58:06 EST 2000

Hi guys,

I think that Nature papers are a very big challenge to write. They are 
necessarily very short and thereby could be misleading. I know Chuck 
Fisher's group and can tell you that the sample contains about 500 
individuals (which is very big  for a study on deep-sea animals). 
Unfortunately, things like statistics are not welcome in papers for Nature. 
Ted Williams is a very good statistician and land ecologist, teaching at 
PennState University. He retired about one year ago. I'm sure another 
paper will be submitted soon with much more data analyses and other 
data. The curves they applied are commonly used by people studying 
growth in natural populations. In that sense, their study is serious.  

It is true that "throughout their lives" is misleading. Actually, one should 
refer to Fig. 2 legend to understand the meaning of that phrase. In the 
legend, it is said that the maximum growth rate was estimated on the 10% 
highest growth values for EACH SIZE CLASS. These are worms which 
are considered as being in the best conditions and growing accordingly. 
On these data, another curve can be adapted and we can thus calculate 
the age of a worm which always grew at the highest growth rate and find 
around 80 years. The fault is not really the authors' but Nature's format 
where details of experiments and calculations are usually given in 
Figures' legends ...  

I agree, our growth is non-linear but also it stops after 20 years or so ... 
These worms keep growing. Now, these results are only estimates (better 
estimates than earlier ones published a few years ago !) and gave us an 
interesting subject to discuss. The main interest is the difference or 
growth between Riftia and these Gulf of Mexico Lamellibrachia. The life-
span of hydrothermal vents ranges from a few months to about 10 years 
on the East Pacific Rise. The Gulf of Mexico seeps are probably stable 
for thousands of years ... Adaptations to each environment are very 
interesting to study and we have here two very good examples !  

Although Nature can be criticized, I think that it is very good for us when 
one of our favorite "pets" is the subject of a paper in this Journal.  

Wormly,			Stephane

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