[Coral-List] Acidification & Boring Erosion

Sun Dec 9 14:45:10 EST 2012

Bonjour ma petite choux.

Aline, I apologise for omitting mention of your (excellent) work. I was momentarily stunned by the graphic reminder that few coral reef biologists know the first thing about bioerosion.

Christine, thank you for reminding me how old I am. I will see you later about this matter.

There are several take-home messages here.

1. the "reef community" needs constant, acerbic reminding that we have known for 40 years that bioerosion is the single most important ordering process in the carbonate balance of reefs. To ignore this is to doom the field to continuing failure.

2. it is up to us eroders to spread the word: as my farmer friends up here say, "You can fix ignorant, but you can't fix stupid."

3. we not only need more attention paid to this field, we need some rapid-assessment techniques. In fact (see 1, above) we need these a lot more than we need many of the present techniques being touted to assess reef "resiliency." I can see two obvious candidates, and there are no doubt more:
	-application of Aline's technique, in which blocks are set out and scored for microendoliths (which is itself a continuation of Kobluck's work in the early 70's)
	-rapid sponge assessment, a la Kate Holmes.

By now, it should be obvious that no coral reef assessment technique is complete without an assessment of rates of bioerosion.

Mike

On 2012-12-09, at 2:10 PM, aline.tribollet at ird.fr wrote:

> Thanks Christine for your message and inputs. You are right Mike, bioeroders need desperately more attention, especially in the context of global change (rising seasurface T°c and OA). But good work is undergoing from Christine Schoenberg, Max Wisshak, myself, and others.
> 
> Here is the reference of my paper on the effects of OA on microborers:
> Tribollet A, Godinot C, Atkinson M, Langdon C (2009) Effects of elevated pCO2 on dissolution of coral carbonates by microbial euendoliths. Global Biogeochem. Cycles 23: GB3008, doi: 10.1029/2008GB003286
> 
> Aloha,
> Aline Tribollet
> 
> 
> -----Message d'origine-----
> De : Christine Schoenberg [mailto:C.Schoenberg at aims.gov.au]
> Envoyé : dimanche 9 décembre 2012 09:13
> À : Michael Risk; coral-list at coral.aoml.noaa.gov; andyroo_of72 at yahoo.com
> Cc : Max Wisshak; aline.tribollet at ird.fr
> Objet : RE: [Coral-List] Acidification & Boring Erosion
> 
> Hi all,
> 
> thanks for free advertising, Mike! One of our papers was just published in PLoS ONE - more to come. Aline Tribollet has actually done OA work before we did - on microendoliths, with similar results. And lately similar approaches seem to appear everywhere.
> 
> 
> Presently available experimental results show that sponges and microendoliths erode more in lower pH. Makes sense when you consider that they erode chemically. Some natural gradients of bioerosion were linked to pH gradients in the field, but this kind of study is very tricky, because often you cannot exclude many of the other gradients that also strongly influence bioerosion. But there is also some ongoing work near CO2 seeps, which may be a bit more conclusive. So, evidence and interest are growing. Already there are strong indicators that at least chemical bioerosion will significantly increase in future and that endolithic organisms are comparatively sheltered against environmental changes that harm reef builders (= double whammy: they survive where reef builders die AND increase their activities). Presently, on some reefs sponge bioerosion alone was estimated to be larger than the local calcification (as shown by Mike himself years ago in the Caribbean and from the Mexican Pacific). We need more budgets to find the patterns.
> 
> Andrew aked: >Should this be part of our climate change adaptation planning?
> 
> Most certainly, and people like Mike Risk are always urging to pay bioerosion more attention. He already pointed some of the below points out as early as 30+ years ago:
> 
> - Many bioeroders are filter feeders or rely on dissolved nutrients, and bioeroder abundances and bioerosion rates increase with decrease in water quality, as was shown numerous times.
> - Epilithic bioeroders such as sea urchins have benefited from overfishing.
> - Endolithic bioeroders do not appear to suffer as much from heat events such as reef builders do, but it looks as if they can take advantage of recent reef mortality and spread faster.
> - Some bioeroders can be spread around by fragmentation, i.e. we may also have to worry about an increase of storm frequencies. My own experience showed that on a storm-trashed reefs bioeroding sponges may do just fine.
> - And, chemical bioerosion increases with OA, as shown for microendoliths and sponges.
> And all of this interacts as well...
> 
> However, bioeroders are understudied, cryptic critters that are often not easy to identify, and conditions are so very different from reef to reef to whatever other habitat, and methods vary all over the field. It would be good if we could share a bit more and standardise some of our approaches to generate more meaningful data faster and over larger scales. And what we desperately need is 'before-after' data or time series.
> 
> Cheers, Christine
> 
> Dr. Christine Schönberg
> Australian Institute of Marine Science
> Oceans Institute at The University of Western Australia
> 39 Fairway
> Crawley
> WA 6009
> Australia
> ph +61-8-63694042
> ________________________________________
> From: coral-list-bounces at coral.aoml.noaa.gov [coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Michael Risk [riskmj at mcmaster.ca]
> Sent: Saturday, December 08, 2012 10:39 AM
> To: andrew ross
> Cc: Coral List (coral-list at coral.aoml.noaa.gov)
> Subject: Re: [Coral-List] Acidification & Boring Erosion
> 
> Hello Andrew.
> 
> Yes, you have hit the nail on the head. Acidification will certainly accelerate bioerosion.
> 
> Many of the common bioeroding critters employ chemical dissolution as part of the process. The most common, ubiquitous eroders in photic waters are the boring algae. There is no piece of reef coral that does not contain boring algae. They bore purely by chemical means, seeking out the crystal surfaces with the highest free energy and secreting a variety of organic acids. In sponges, a protoplasmic loop secretes carbonic anhydrase, etching the perimeter of a chip-amoebocytes then rip that chip off the surface. The actual chemical part of the process is only a few %, but will obviously be accelerated.
> 
> Sadly, there is still a dearth of research in this field: although bioerosion is a process which is volumetrically more important in reef carbonate budgets than coral growth, the coral reef community continues to pay little attention. Fortunately there is some good work on acidification appearing now-I especially recommend papers by Christine Schoneberg and Max Wisshak.
> 
> Mike
> On 2012-12-07, at 11:21 AM, andrew ross wrote:
> 
>> List,
>> With discussion about acidification related reef erosion is there an elephant in the room in boring organisms? Admittedly my experience is primarily in very broken systems, but for me it's common to be able to tear chunks of hard reef away with my hands. When I look inside the hole I've made I see little but sponge, plus scrambling cryptic beasties. This has been my observation in obviously "enriched" locations like Montego Bay (Jamaica) and on less obvious sites such as St. Mary to the East, where our recent visitor Hurricane Sandy demonstrated the issue on a much larger and messier scale. I found this condition particularly notable when I could not break bits off at the more remote Pedro Banks this past spring.
>> 
>> Can we expect that boring erosion be increased under a reduced ocean pH? Can we expect this to occur additively, or might these processes work in synergy?
>> 
>> Should this be part of our climate change adaptation planning?
>> 
>> Andrew Ross
>> UWI (Mona)
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> 
> Michael Risk
> riskmj at mcmaster.ca
> 
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Michael Risk
riskmj at mcmaster.ca