[Coral-List] Black Reefs

Greg Challenger gchallenger at msn.com
Fri Sep 9 12:21:12 EDT 2011

We have been involved with the assessment of approximately 60 large vessel groundings on coral and have noticed or are aware of localized algae growth on several (excluding typical succession / temporary algae growth on disrupted areas as observed after any dramatic physical disturbance of substrate).  Two examples I can recall offhand include Rose Atoll and another that had been sitting for approximately 20 years on the reef crest on Mona Island Puerto Rico (Regina ?).  The Rose Atoll case is documented (http://www.botany.hawaii.edu/basch/uhnpscesu/pdfs/sam/Schroeder2008AS.pdf)
The algae on the latter was largely leafy greens of the Ulva/Enteromorpha variety. Iron-limitation certainly makes sense.  I am sure there are likely many others since 60 is pretty small number relative to vessel casualties on coral reefs.  Our qualitative observations indicate that if water circulation is good or the vessel is below approx 5 meters, this condition appears to not be likely; however, some of the wrecks have been removed so we are unable to comment on longer term observations in all instances (other than the numerous wreck dives that we have all seen).  I have not observed the condition described herein and would love the opportnity if I ever am nearby....coordinates???. 

Greg E. Challenger
Marine Scientist/Principal
Polaris Applied Sciences, Incorporated
12525 131st Ct NE Kirkland, WA 98034 
425-823-3805 fx 
206-369-5686 cell 
visit us at: www.polarisappliedsciences.com


> From: szmanta at uncw.edu
> To: ceo at lindorm.com; coral-list at coral.aoml.noaa.gov
> Date: Fri, 9 Sep 2011 11:23:09 -0400
> Subject: Re: [Coral-List] Black Reefs
> Many of the structures I have seen coated with corals are not in keys but in Bahamas, lower Caribbean. I think the effects of the metals in the ship hulls has much to do with the nature of the substrate the wreck is on.
> *************************************************************************
> Dr. Alina M. Szmant
> Professor of Marine Biology
> Center for Marine Science and Dept of Biology and Marine Biology
> University of North Carolina Wilmington
> 5600 Marvin Moss Ln
> Wilmington NC 28409 USA
> tel: 910-962-2362 fax: 910-962-2410 cell: 910-200-3913
> http://people.uncw.edu/szmanta
> *******************************************************
> -----Original Message-----
> From: coral-list-bounces at coral.aoml.noaa.gov [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Ulf Erlingsson
> Sent: Thursday, September 08, 2011 1:03 PM
> To: Coral Listserver Listserver
> Subject: Re: [Coral-List] Black Reefs
> The Florida Keys are not iron limited, but there are some tropical waters that are, and in such a location the addition of a ship wreck can conceivable have a huge impact and provoke a growth spur of algae. 
> The other point I want to make is that the ships aren't made of "iron" but steel... Which implies that they are an alloy of iron, and as such, one must also consider what the alloying elements are.
> Ulf
> On 2011-09-08, at 11:23, Eugene Shinn wrote:
> > I agree with Alina, Steve, and Charles, regarding "Black Reefs." 
> > Could it be the teak wood that is the problem? It can't be iron. I 
> > worked as a salvage diver in the Florida Keys in the 1950s recovering 
> > scarp iron from turn of the century wrecks. Lots of coral grew on them 
> > except for where they were discouraged by dynamite. In the 1980s we 
> > documented the effects of oil wells drilled on coral reefs off of Key 
> > West. In the 1950s there was little concern for the environment so 
> > abundant iron objects and cables were discarded at the drill sites. 
> > Today there is more oral there because the iron objects created more 
> > surface area for coral growth than the adjacent natural bottom. The 
> > bottom is not black! The latest Department of Interior edict issue 
> > called "The Idle Iron project" implemented by the Bureau Of 
> > Environment and Minerals Regulation and Environment (BOEMRE ) formerly 
> > MMS, directs the various energy companies (at great expense) to remove 
> > more than 600 idle offshore oil and gas platforms in the Northern Gulf 
> > of Mexico. As divers in the area know, these offshore rigs are 
> > incredible artificial reefs and likely more productive than all the 
> > natural reefs in the Northen Gulf of Mexico. They also support coral 
> > growth as well as a wide variety of fish from the surface down to 
> > whatever depth in which they are located. They are not Black Reefs! 
> > There is now a growing effort to save them called SAVE THE BLUE. 
> > Listers will be hearing more about that later. Gene
> > --
> > 
> > 
> > No Rocks, No Water, No Ecosystem (EAS)
> > ------------------------------------ -----------------------------------
> > E. A. Shinn, Courtesy Professor
> > University of South Florida
> > Marine Science Center (room 204)
> > 140 Seventh Avenue South
> > St. Petersburg, FL 33701
> > <eshinn at marine.usf.edu>
> > Tel 727 553-1158---------------------------------- 
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