[Coral-List] Let's not forget the bigger ecosystem

Fri Feb 17 10:22:51 EST 2017

Thanks Dennis

That trophic cascade idea has been around for some time but without much
formalized scientific investigation. From my reading of the Caribbean
literature, I also am not really sure if one could trace it in a formalized
scientific sense. It is discussed informally among Caribbean reef
scientists and there a smatterings of the idea in various papers but I have
not seen a full conceptualization and testing of it with field data. Why
has this important idea not been more formalized, tested, experimentally
manipulated, modeled, and retested..? This is what we are supposed to do as
scientists.

It is likely that Diadema numbers recorded in many reefs before their die
off was a result of the loss of the Queen triggerfish, so why are so many
reef scientists searching to return Diadema to a baseline as opposed to a
baseline for various predators and fish herbivores?  Why has so little work
been done to estimate what baseline numbers are for Queen triggerfish and
parrotfish as compared to the larger number of studies of Diadema?  I
imagine this results from research expediency rather than the importance of
the information.

K-le wrote me and told me " It is difficult to incorporate things in your
study if they are not there...".  Ok, but there are scattered protected
areas and closures that could get some attention to determining these
levels if we examined fish abundance and biomass on a larger scale. Some
preliminary work on this was done by our group with the little data we
could organize. I believe this was just a start, however, as it does not
specifically and thoroughly address baselines of key species or functional
groups specific to the Caribbean.

http://www.nature.com/nature/journal/v520/n7547/abs/nature14358.html

We tried to do some trophic cascade work in the little time that I have had
for field work in the Caribbean but then largely studied Echinometra and
the jolthead porgy, because that is what was left in the Belize reefs that
I studied.  Nonetheless, it did suggest this cascading effect but indicated
one in tatters due to the lack of some key players, namely the queen
triggerfish and Diadema.

http://scientific-papers.s3.amazonaws.com/McClanahan_1999.pdf

A quick search on google scholar for long spined urchin and D. antillarum
produces >20000 references with a maximum citation of 640.  A search of
queen triggerfish and Balistes vetula gets around 1400 references with a
maximum citation of 60. Very few of the Balistes papers are about
ecological roles, focusing more on basic biology.

I have to think we spend too much effort on expediency and scientific
impact and not on what actual ails and could potentially heal our beloved
ecosystem.

TRM

PS.   If you find this sort of mismatch of incentives and needs
interesting, read the paper below.

ttps://
www.researchgate.net/profile/Tim_Mcclanahan/publication/230680731_Human_and_coral_reef_use_interactions_From_impacts_to_solutions/links/0c96052fc34ba1d2ff000000.pdf

On Wed, Feb 15, 2017 at 3:29 PM, Dennis Hubbard <dennis.hubbard at oberlin.edu>
wrote:

> Tim:
>
> Excellent points. My recollection for the Caribbean 'model" was that, as
> the parrotfish were eaten off the reefs, *Diadema* was picking up the
> slack, but the Queen Triggerfish was keeping them in check. While not a
> favored food fish, once other options were removed, the QT declined
> rapidly, allowing the *Diadema* to go wild. Again only a recollection,
> but some had even postulated that this was a boom-and-bust scenario for
> *Diadema* - except for that pesky microbe that appears to have come
> through the Panama Canal. Certainly this is not at the large scale you are
> advocating. However, it was a start. The fact that folks went from the
> fish/urchin vs algae relationship to a paradigm in which fish/urchins and
> coral abundances were intimately tied together illustrates how little we
> probably do understand all of this. Fortunately, as a geologist, I only
> have to think about how much they scrape, bore and grind from the reef
> edifice and don't have to understand the subtext behind the main play.
>
> Dennis
>
> On Wed, Feb 15, 2017 at 1:29 PM, Tim McClanahan <tmcclanahan at wcs.org>
> wrote:
>
>> Listers
>>
>> I often find the sea urchin - parrotfish - nutrient focus of many coral
>> reefs studies to lack the bigger ecosystem-environment picture. We each
>> measure and bring in our own interests and interpretations based on our
>> disciplinary foci.  One of my main foci has been top-down controls and the
>> larger food web interactions within environmental contexts.  Sea urchins
>> and parrotfish exist in a larger food web and so it is always challenging
>> to conclude about their ability to control the ecosystem without looking
>> at
>> their position in the larger food web-environment.
>>
>> I think the work in the Caribbean suffers from this limited foci problem
>> too often. I rarely hear Caribbean coral reef scientists on this list who
>> study and quote any work on the predators who control parrotfish and sea
>> urchins apart from humans. Certainly these functional groups are part of
>> the larger food web, so they must have their own influences and not be
>> isolated or controlling independently of impacts on their own populations.
>> Is this ecosystem-view just too complicated and difficult to study and
>> understand? Regardless, I hope reef scientists might make a better effort
>> to study the larger system when possible.
>>
>> In case readers are interested, the paper published open access in the
>> link
>> below looked at many possible controls on calcifiers in the Indian Ocean
>> and concluded the extreme temperatures and the red-lined triggerfish were
>> probably having strong and equal effects on the calcifying community.
>> There were no effects of Diadema or parrotfish but a role of Echinometra
>> via it's interactions with it's main predator - Balistapus undulatus.
>>
>> http://www.int-res.com/abstracts/meps/v560/p87-103/
>>
>> Can these regional difference be explained away as another region or
>> system?  Or could work in other systems lack this larger ecosystem
>> perspective and therefore coming to parochial conclusions? We won't know
>> until the larger ecosystems are studied in all regions and compared. I
>> think much critical work needs to be done..
>>
>> TRM
>>
>> --
>> -----------------------------------
>> Tim McClanahan, PhD
>> Senior Conservation Zoologist
>> Wildlife Conservation Society
>> Coral Reef Conservation
>> Kibaki Flats no.12
>> Bamburi, Kenyatta Beach
>> P.O. Box 99470
>> Mombasa, Kenya
>> Postal Code: 80107
>>
>> Cell Phone: Kenya +254 (0) 792 765 720 and 725 546 822
>> Skype - trmcclanahan
>> US Land lines - 530 581-7460
>> US Cell Phone - 415 260 3415
>>
>> Research papers, methods, and talks
>>
>> https://www.researchgate.net/profile/Tim_Mcclanahan
>> ___________________________________
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>>
>
>
>
> --
> Dennis Hubbard
> Chair, Dept of Geology-Oberlin College Oberlin OH 44074
> (440) 775-8346
>
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>  Benjamin Stein: "*Ludes, A Ballad of the Drug and the Dream*"
>
>
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-- 
-----------------------------------
Tim McClanahan, PhD
Senior Conservation Zoologist
Wildlife Conservation Society
Coral Reef Conservation
Kibaki Flats no.12
Bamburi, Kenyatta Beach
P.O. Box 99470
Mombasa, Kenya
Postal Code: 80107

Cell Phone: Kenya +254 (0) 792 765 720 and 725 546 822
Skype - trmcclanahan
US Land lines - 530 581-7460
US Cell Phone - 415 260 3415

Research papers, methods, and talks

https://www.researchgate.net/profile/Tim_Mcclanahan
___________________________________