[Coral-List] The battle for biodiversity (Diadema)

[Martin Moe]

Dear list,
I think I sort of made a mistake, perhaps more in the sense of allowing the 
mouth (fingers in this case) to make comments before the brain has had a chance 
to fully explore the implications of the comment. Maybe I’m the only one that 
has ever done that.
 
As an aside to John Bruno, who is well aware of my Diadema culture work, in my 
post on spiny lobster distribution and biodiversity I made the comment.
 
“On another marine species larval distribution note, I have Diadema larvae now 
at 

day 69 that are finally showing signs of readiness for settlement.”
 
Now this is true, but it isn’t the whole story and erroneous implications on 
Diadema larval life and distribution, i.e., that Diadema normally spent 70+ days 
in the plankton, could be the result. And given the great importance of this 
keystone herbivore to western Atlantic coral reefs, this would not be helpful. 
First of all essentially any culture of marine organisms is not “normal”. A 
controlled environment, unnatural nutrition, ecological interactions, abnormally 
dense populations, and many other factors preclude a “normal”, but hopefully 
optimum, developmental situation for the larvae. In my case, environmental 
factors such as turbulence, water quality, nutrition, and ciliate competition 
affect growth and development and the morphology of the larvae is not normal. 
Also there is a great range in time of development to competency for 
metamorphosis between different larvae culture runs. The earliest that juveniles 
have been produced is 28 days and the latest about 50 days. Typically, rudiment 
development begins at about day 22 or so and most metamorphosis takes place 
between days 35 and 45. The longest I have held larvae is 86 days and no 
metamorphosis occurred. At this point with the current run, 70 days, the larvae 
are quite large with large internal rudiments, and although they “look” 
competent, and despite introduction of biochemical cues, settlement and 
metamorphosis is not occurring, yet. There is a great deal yet to be learned 
about larval development of Diadema and all I know at this point is that these 
larvae apparently have great plasticity of morphology and development time and 
their environment (pelagic and benthic) apparently has a great influence on 
where and when they settle. A few more little difficulties need to be worked out 
but the basics are in hand and I hope that between Dave Vaughan, Tom Capo and 
me, we will soon have the techniques established for large scale production of 
Diadema juveniles for use in coral reef restoration research.
 
Martin Moe



________________________________
From: Martin Moe <martin_moe at yahoo.com>
To: "Bruno, John F" <jbruno at unc.edu>; "<coral-list at coral.aoml.noaa.gov>" 
<coral-list at coral.aoml.noaa.gov>
Sent: Tue, November 30, 2010 9:25:26 AM
Subject: Re: [Coral-List] The battle for biodiversity

John, Thanks for the clarification on the variability of genetic structure, I'm 
sure the actual situation is far more complex in time and distance than we 
realize, but given the longevity of the larval phase of P. argus, and the 
patterns of water currents in the broad area, I think it is reasonable to 
assume, with your caveat well considered, that the likelihood of reproductively 
separate populations of P. argus is not great. But whatever the actual case may 
be, when it comes to exploitation, perception, even engineered perception, 
becomes reality, and often such perception becomes the basis for regulation. Too 

often regulation that would offer functional reproductive protection for a 
species (to say nothing of the need for ecological protection) is not enacted 
because the burden of proof that such regulation is needed can not be met to the 

satisfaction of the fishing industries. And the response after the profits have 
been made and the resource is in trouble, is "Gee, I guess we were wrong. 
Shucks, now we have to go after a less profitable species." Of course we can't 
paint all fishing efforts with the same brush, but it seems to happen all too 
often.

On another marine species larval distribution note, I have Diadema larvae now at 

day 69 that are finally showing signs of readiness for settlement. 


Martin




________________________________
From: "Bruno, John F" <jbruno at unc.edu>
To: "<coral-list at coral.aoml.noaa.gov>" <coral-list at coral.aoml.noaa.gov>
Sent: Mon, November 29, 2010 9:22:50 PM
Subject: [Coral-List] The battle for biodiversity


A case in point is the spiny lobster fishery of Florida. It has been shown
through analysis of mitochondrial DNA (Silberman, et. al., 1994) that, as
expected, genetic analysis shows no evidence of genetic structure in the spiny
lobster (P. argus) population, which is consistent with a high gene flow
throughout the population. This also indicates that the population of spiny
lobsters in Florida is dependent on larval influx from Caribbean sources.


Martin, thank you for that really interesting post, especially your insights on 
the response of lobster fishers to NOAAs catch shares plan.  Not to suggest that 

I know anything about lobster population genetics, but the lack of genetic 
structure within a population (or among populations) doesn't necessarily mean 
strong demographic connectivity and that result certainly doesn't indicate that 
"the population of spiny lobsters in Florida is dependent on larval influx from 
Caribbean sources".  For one, a relatively small degree of migration between 
subpopulations can be enough to genetically homogenize them without creating 
much if any demographic connectivity.  Even if there were effective demographic 
connectivity between Florida and Caribbean populations, that would not 
necessarily mean the Florida populations were a sink and wholly dependent on 
larval subsidies.

JB

John Bruno
Associate Professor
UNC Chapel Hill
www.brunolab.net<http://www.brunolab.net>







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