[Coral-List] Parrotfish loss drives reef decline

Risk, Michael riskmj at mcmaster.ca
Fri Feb 17 09:40:48 EST 2017

   Good day, all.

   Partly a response to the posts by Ilsa and Joe, and partly housekeeping…

   In an earlier post, I referred to what I think is the only Caribbean example
   of what happens when the water is cleaned up. This occurred at Worthing,
   Barbados. There was a semi-enclosed lagoon tucked in behind a huge offshore
   bar.  That  lagoon was stagnant, heated up…WQ was crap, one could find
   recently-dead Diadema and corals.

   Beginning in the early 2000’s, the beach eroded-this was accelerated by the
   passing  of  Hurricane Lili on 2002. Blew the back end off the lagoon,
   suddenly filling it with (relatively) clean water passing east-to-west.

   Over the next year, corals (typical Caribbean sediment-resistant species)
   recruited to the area; numbers of fish increased, as well as numbers of
   reef-associated molluscs. The only surprising element here would seem to be:
   this is the only Caribbean example we have of the influence of cleaner

   There is an abstract describing this (Risk et al.), in the 2008 ASLO Summer
   Meeting in St John’s NL. Writing up the full paper was on my bucket list-but
   the project was done with Baird and Associates, and I will no longer work
   with them.  What you see in the Abstract is all you are likely to get. The
   experiment has ended now, with regrowth of the blocking bar. The ambient WQ
   on Barbados is probably not good enough, anywhere on the island, to support
   healthy reef growth.

   Ilsa’s efforts quantifying the bones of dead reefs are to be commended-but
   as  she  points  out, grazing is now destroying habitat. What is more,
   bioerosion increases in lockstep with nutrients-so those bones are being
   gnawed  on  from  the  outside and destroyed from the inside. So Joe’s
   observation is correct: sponges now rule.

   The boring sponge fauna seems to be circum-global, probably because they
   pre-date the critters in which they bore. The only major species seemingly
   restricted to the Caribbean is the faecal bioindicator Cliona delitrix- I
   have been told that huge red colonies of the sponge, many square metres in
   area, can now be seen from a light plane in the passes in Florida.

    In a series of older papers, Kobluk, James and Pemberton document what
   happened: borers are ancient. The “modern” fauna is virtually complete by
   the Devonian. When a mass extinction comes along and wipes out their hosts,
   the borers hide in hardgrounds, waiting for the rise of the next skeletal
   group. They are down there now, waiting.

   Re Parrotfish: it is likely that Diadema was always the dominant grazer in
   the Caribbean. In a series of elegant older papers, my old mate Sammarco has
   compared biological processes between the Caribbean and the Indo-Pacific.
   Coral larvae in the Caribbean settle on the tops of the substrate where they
   would be easy prey for visually-cued fish, whereas Indo-Pacific coral larvae
   are cryptic-even when grazing pressure is removed. Basin-wide changes in the
   behaviour of coral larvae are unlikely to have risen spontaneously in the
   last century.


   On Feb 17, 2017, at 7:15 AM, Pawlik, Joseph <[1]pawlikj at uncw.edu> wrote:

   Hi all,

   Dr. Kuffner's perspective paper makes some interesting points about "wimpy"
   corals and Caribbean reef resilience.  Branching Acropora spp. certainly
   took  a  hit from disease in the 1980s and haven't recovered, but some
   important reef-building species (Orbicella, Montastrea) seemed to fade more
   gradually, with ever decreasing growth rates.

   We've  proposed  the "vicious circle" hypothesis for why this might be
   happening -- a feedback loop between sponges and seaweeds. Seaweeds quickly
   took over free space after the double-whammy of coral and Diadema die-offs,
   with slower-growing sponges taking years longer to recruit and hold space.
   Seaweeds exude labile dissolved organic carbon (DOC) which is a food source
   for sponges, and sponges pump-out nutrients that fertilize the seaweeds.
   This  loop  not  only benefits sponges and seaweeds, but also seawater
   microbes, which may alter the microbiome of corals in negative ways.
   Sponge cover on Caribbean reefs is now about the same as coral cover, but
   sponge biomass is likely orders of magnitude greater.  Sponges turn-over a
   substantial portion of the the water column above the reef on a daily basis.
   Further, the sponge fauna of the Caribbean is strikingly different from that
   found  on  most  Indo-Pacific reefs (dominated by foliose phototrophic
   species),  suggesting  that  Caribbean  sponges adapted to a different
   nutritional environment, where DOC from seaweeds or terrestrial sources is
   more available. We speculate that the continued success of octocorals (sea
   fans and whips) on Caribbean reefs may be similarly explained, given their
   high surface area and upright growth into the water column.
   Our group has seen a 122% increase in giant barrel sponges on reefs in the
   Florida Keys, with a 40% increase in sponge biomass for 2000-2012, and these
   increases are evident on reefs across the Caribbean. If these demographic
   trends continue, the "vicious circle" may turn many Caribbean coral reefs
   into sponge reefs.

   [2]Pawlik, J.R., Burkepile, D.E., Vega Thurber, R. 2016. A vicious circle?
   Altered  carbon and nutrient cycling may explain the low resilience of
   Caribbean coral reefs. BioScience, 66: 470-476

   [4]McMurray, S.E., Finelli, C.M. and Pawlik, J.R. 2015. Population dynamics
   of giant barrel sponges on Florida coral reefs. Journal of Experimental
   Marine Biology and Ecology, 473: 73-80
   [5]McMurray, S.E., Johnson, Z.I., Hunt, D.E., Pawlik, J.R., Finelli, C.M.
   2016. Selective  feeding  by the giant barrel sponge enhances foraging
   efficiency. Limnology and Oceanography, 61: 1271-1286
   [6]Loh, T.-L., McMurray, S.E., Henkel, T.P., Vicente, J. and Pawlik, J.R.
   2015. Indirect effects of overfishing on Caribbean reefs: sponges overgrow
   reef-building corals. PeerJ, 3: e901  DOI: 10.7717/peerj.901


   Joseph R. Pawlik, Professor
   Department of Biology and Marine Biology
   UNCW Center for Marine Science
   5600 Marvin K Moss Lane
   Wilmington, NC  28409   USA
   [7]pawlikj at uncw.edu; Office:(910)962-2377; Cell:(910)232-3579
   Website: [8]http://people.uncw.edu/pawlikj/index.html
   PDFs: [9]http://people.uncw.edu/pawlikj/pubs2.html
   Video Channel: [10]https://www.youtube.com/user/skndiver011


   From: [11]coral-list-bounces at coral.aoml.noaa.gov <[12]coral-list-bounces at cor
   al.aoml.noaa.gov> on behalf of Kuffner, Ilsa <[13]ikuffner at usgs.gov>
   Sent: Thursday, February 16, 2017 9:18 AM
   To: Risk, Michael
   Cc: Eugene Shinn; coral list
   Subject: Re: [Coral-List] Parrotfish loss drives reef decline

   Interesting discussion, indeed. I invite those interested in this topic to
   see the following review / perspectives paper:
   Kuffner, I. B., and L. T. Toth (2016) A geological perspective on the
   degradation and conservation of western Atlantic coral reefs. Conservation
   Biology 30:706-715.
   Abstract: Continuing coral-reef degradation in the western Atlantic is
   resulting in loss of ecological and
   geologic functions of reefs. With the goal of assisting resource managers
   and stewards of reefs in setting
   and measuring progress toward realistic goals for coral-reef conservation
   and restoration, we examined reef
   degradation in this region from a geological perspective. The importance of
   ecosystem services provided by
   coral reefs—as breakwaters that dissipate wave energy and protect
   shorelines and as providers of habitat for
   innumerable species—cannot be overstated. However, the few coral species
   responsible for reef building in the
   western Atlantic during the last approximately 1.5 million years are not
   thriving in the 21st century. These
   species are highly sensitive to abrupt temperature extremes, prone to
   disease infection, and have low sexual
   reproductive potential. Their vulnerability and the low functional
   redundancy of branching corals have led
   to the low resilience of western Atlantic reef ecosystems. The decrease in
   live coral cover over the last 50 years
   highlights the need for study of relict (senescent) reefs, which, from the
   perspective of coastline protection
   and habitat structure, may be just as important to conserve as the living
   coral veneer. Research is needed to
   characterize the geological processes of bioerosion, reef cementation, and
   sediment transport as they relate to
   modern-day changes in reef elevation. For example, although parrotfish
   remove nuisancemacroalgae, possibly
   promoting coral recruitment, they will not save Atlantic reefs from
   geological degradation. In fact, these fish
   are quickly nibbling away significant quantities of Holocene reef
   framework. The question of how different
   biota covering dead reefs affect framework resistance to biological and
   physical erosion needs to be addressed.
   Monitoring and managing reefs with respect to physical resilience, in
   addition to ecological resilience, could
   optimize the expenditure of resources in conserving Atlantic reefs and the
   services they provide.
   Best regards,
   P.s. The original title for this manuscript was "Atlantic coral reefs:
   Standing on the shoulders of giant wimps." Rest assured, the "wimps" in the
   title was referring to the species of coral that built western Atlantic
   coral reefs, not to the founding fathers of reef geology.
   Ilsa B. Kuffner, Ph.D.
   U.S. Geological Survey
   St. Petersburg Coastal & Marine Science Center
   600 4th Street South
   St. Petersburg, FL 33701
   Email: [14]ikuffner at usgs.gov
   Tel: (727) 502-8048
   Fax: (727) 502-8001
   On Wed, Feb 15, 2017 at 10:23 AM, Risk, Michael <[17]riskmj at mcmaster.ca>
   >    Good day..
   >    I  hesitate  to weigh in here, but I thought I would offer some random
   >    thoughts.
   >    The Kramer et al. paper is a very nice piece of work, using up-to-date
   >    techniques  (some  of  which  are beyond my limited comprehension). My
   >    compliments to the authors.
   >    None of us should be surprised by verification of the importance of
   > grazing
   >    in reef systems. Personally, I think that ever since Stephenson and
   > Searles,
   >    Odum and Odum, Gerry Bakus and Kaneohe Bay, the vast majority of coral
   > reef
   >    research has simply been fine-tuning what we already know.
   >     There  are  some aspects of the paper that are worth considering
   >    First of all, few people in this world have looked at more well core
   > than
   >    have Gene, and he notes that abundance estimates from teeth must be
   > taken
   >    with  a grain of sand (forgive me). I note that cores were taken by "a
   >    combination  of  push-coring  and vibra-coring", which produces large,
   >    relatively  undisturbed  samples  but  means that you cannot core reef
   >    framework. Authors are to be commended on their good dating techniques
   > (age
   >    reversals can be used as a proxy for storm transport, which might have
   > been
   >    worth noting), and one of their three sites records information of the
   > time
   >    scale of most interest to us: post-1900 (but there the resolution tails
   > off
   >    a bit).
   >    This new (to me) CCM technique for teasing out causality seems to be a
   >    powerful tool, but I note it works if you only consider two variables:
   > as in
   >    this  case.  Of  course, nutrient proxies would have been difficult to
   >    obtain-but nonetheless possible.
   >     Personally,  I  am  not  surprised  at  the  lack of correlation
   with Diadema..
   > If
   >    we look closely at Gardner et al., we see that the precipitous decline
   > in
   >    Caribbean reefs began prior to 1960. The dieoff in populations of
   > Diadema is
   >    in no way reflected in that decline-the line continues its sad progress
   >    without a blip.
   >    My concern here is that there may be a tendency to apply these results
   > to
   >    rehabilitation efforts, and concentrate on bringing back the fish. It
   > is my
   >    impression that people with a mostly biological focus tend to believe
   > that
   >    reefs will recover if the grazers come back, whereas those with a more
   >     varied  background  in chemistry and geology take a more nuanced
   >    As  far as I know, there is only one example from the Caribbean of the
   >    response to an increase in water quality. No one should be surprised to
   >    learn that the reef came back. Equally, no one should believe the reefs
   > will
   >    come back if only the grazers come back.
   >    Mike
   >    Risk, Michael
   >    [1][18]riskmj at mcmaster.ca
   > References
   >    1. [19]mailto:riskmj at mcmaster.ca
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   Risk, Michael
   [24]riskmj at mcmaster.ca


   1. mailto:pawlikj at uncw.edu
   2. http://people.uncw.edu/pawlikj/2016BioSciencePawlik.pdf
   3. http://people.uncw.edu/pawlikj/2016BioSciencePawlik.pdf
   4. http://people.uncw.edu/pawlikj/2015JEMBEMcMurray.pdf
   5. http://people.uncw.edu/pawlikj/2016McMurrayLO.pdf
   6. https://dx.doi.org/10.7717/peerj.901
   7. mailto:pawlikj at uncw.edu
   8. https://mail.uncw.edu/owa/UrlBlockedError.aspx
   9. https://mail.uncw.edu/owa/UrlBlockedError.aspx
  10. https://www.youtube.com/user/skndiver011
  11. mailto:coral-list-bounces at coral.aoml.noaa.gov
  12. mailto:coral-list-bounces at coral.aoml.noaa.gov
  13. mailto:ikuffner at usgs.gov
  14. mailto:ikuffner at usgs.gov
  15. http://coastal.er.usgs.gov/crest/
  16. https://www.usgs.gov/staff-profiles/ilsa-b-kuffner
  17. mailto:riskmj at mcmaster.ca
  18. mailto:riskmj at mcmaster.ca
  19. mailto:riskmj at mcmaster.ca
  20. mailto:Coral-List at coral.aoml.noaa.gov
  21. http://coral.aoml.noaa.gov/mailman/listinfo/coral-list
  22. mailto:Coral-List at coral.aoml.noaa.gov
  23. http://coral.aoml.noaa.gov/mailman/listinfo/coral-list
  24. mailto:riskmj at mcmaster.ca

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