[Coral-List] recovery of reef molluscs and corals from complete ecosystem removal

Dennis Hubbard dennis.hubbard at oberlin.edu
Mon Jun 15 10:39:38 EDT 2015

Hi Doug:

Interesting article. This is way outside of my expertise, but that's never
limited my participation.

On St. Croix, Arnold Miller did a very comprehensive mollusc survey back in
the late 70s (it was more aimed at a transect across the lagoon behind the
reef, but I would assume that the same sorts of population-dynamics rules
would apply). Not long afterward, Karla Parsons-Hubbard surveyed another
lagoon (less extensively but using the same methods) and found a totally
different molluscan community despite both lagoons being on the windward
end of the island.

Granted, a north and south exposure would encourage different critters due
to micro-oceanographic differences, so let's fast forward. Since the
original survey, Miller's group has resurveyed the same transect twice and
found totally different molluscs (as well as varying bivalve-gastropod
ratios, as I remember) each time. The final piece of this puzzle is that we
did a vibrocore study of the entire lagoon and found a molluscan assemblage
that was totally different from either the live or the "sub-fossil" (i.e.,
the dead mollusc community in the upper 30 cm or so of the sediment)
assemblages in any of these surveys from the same site). This definitely
had a different bivalve/gastropod ratio than the live or sub-fossil

I offer these observations for two reasons. First, there was no bomb blast
here and the community over time has changed more drastically (and quickly)
than I think anyone might reasonably imagine. Second, there are many papers
that compare the live and sub-fossil assemblages and compare them to
preserved Pleistocene fossil deposits on shore to infer environmental
change. Given the level of community-scale change in one site over 30+
years and the seeming disconnect between what is on or near the surface
today and what is preserved beneath (bioturbation), might we be making too
much of these kinds of comparisons?

So, my question of ignorance (I'm certainly not an ecologist) is... isn't
it reasonable to assume that communities with high turnover rates will be
highly variable over time, with or without a bomb, and that we have to be
very careful when we compare a community at one point in space or time to
anything else? And, from that, what is the temporal scale on which we might
expect coral communities to shift from seemingly random to seemingly
ordered. As a caveat, I am a firm believer in climate change, so I hope we
can set that discussion aside here. The paleo-ecological side of this is
something I've been wrestling with as one "reef paradigm" after another
seems to fall as we gather sufficient data. "The hurrier I go, the behinder
I get."



On Sun, Jun 14, 2015 at 11:05 PM, Douglas Fenner <
douglasfennertassi at gmail.com> wrote:

> Molluscs:
> Nuclear blasts shed light on how animals recover from annihilation.
> http://news.sciencemag.org/biology/2015/06/nuclear-blasts-shed-light-how-animals-recover-annihilation?utm_campaign=email-news-latest&utm_src=email
> Original article:
> Thirty-year recovery of mollusc communities after nuclear experimentations
> on Fangataufa Atoll (Tuamotu, French Polynesia).
> Proceedings B of the Royal Society 282, 2015.
> not open access, check Google Scholar (link didn't work for me).
> Corals:
> Bikini Atoll coral biodiversity resilience five decades after nuclear
> testing.  Marine Pollution Bulletin, 2008.
> available from:
> https://www.researchgate.net/profile/Richards_ZT?ev=hdr_xprf
> Cheers,  Doug
> --
> Douglas Fenner
> Contractor with Ocean Associates, Inc.
> PO Box 7390
> Pago Pago, American Samoa 96799  USA
> phone 1 684 622-7084
> "belief in climate change is optional, participation is not."
> Much-touted global warming pause never happened.
> http://news.sciencemag.org/climate/2015/06/much-touted-global-warming-pause-never-happened
> Has global warming taken a rest?  Not so fast, study suggests.  (check out
> the graph)
> http://www.livescience.com/51094-no-global-warming-hiatus-found.html
> Climate change deniers love to talk about a recent "pause" in global
> warming.  A new study says it didn't happen.
> http://theweek.com/speedreads/558971/climate-change-deniers-love-talk-about-recent-pause-global-warming-new-study-says-didnt-happen
> website:  http://independent.academia.edu/DouglasFenner
> blog: http://ocean.si.edu/blog/reefs-american-samoa-story-hope
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Dennis Hubbard
Chair, Dept of Geology-Oberlin College Oberlin OH 44074
(440) 775-8346

* "When you get on the wrong train.... every stop is the wrong stop"*
 Benjamin Stein: "*Ludes, A Ballad of the Drug and the Dream*"

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