[Coral-List] Why are Caribbean reefs less resilient?

Pawlik, Joseph pawlikj at uncw.edu
Thu Apr 28 08:41:08 EDT 2016

Hi all,

My co-authors and I are pleased to send out an advance version of a paper that may explain the decades-old mystery of low resilience of Caribbean reefs:

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, doi:10.1093/biosci/biw047.
You can download the PDF here:
http://bioscience.oxfordjournals.org/cgi/reprint/biw047?ijkey=G9guzzgJPShDIhA&keytype=ref <http://bioscience.oxfordjournals.org/cgi/reprint/biw047?ijkey=G9guzzgJPShDIhA&keytype=ref%20>

The paper proposes that Caribbean reefs are different because of localized cycling of nutrients and dissolved organic carbon, particularly between sponges and seaweeds, with negative consequences for corals. It builds on recent and past evidence that:
-  there is a lack of a relationship between fish abundance, seaweed cover and coral cover in the Caribbean
-  seaweed fertilization from fish pee may swamp grazing effects by herbivorous fishes
-  seaweeds and corals produce DOC in large quantities
-  sponges consume DOC as most of their diet, and release nutrients for seaweeds
-  sponge biomass is large and increasing in the Caribbean, it is negligible on most Indo-Pacific reefs
-  Caribbean sponges are not phototrophic (net carbon fixers), unlike Indo-Pacific sponge dominants
-  Caribbean reefs are in a mixing bowl, with large DOC inputs from major rivers
-  altered DOC and nutrient cycling changes the coral microbiome, reducing coral health
-  cycling of nutrients and DOC between sponges and seaweeds is good for them, bad for corals

Note that our synthesis does not invoke terrestrial sources of nutrients, but localized cycling of nutrients and DOC. Additionally, this synthesis may help to explain how atmospheric dust (African dust) has contributed to reduced Caribbean reef resilience, why Caribbean sponge communities have evolved to be very different than those on Indo-Pacific reefs, how gorgonian octocorals came to flourish on shallow Caribbean reefs, and why floating mats of seaweeds have increasingly been washing up on Caribbean beaches.  Much of this is speculative, but the paper provides a framework for future research.



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

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