[Coral-List] Mystery Event - Lankayan Island, Sulu Sea, Sandakan

Szmant, Alina szmanta at uncw.edu
Thu Aug 23 20:58:18 EDT 2007

What about some tectonic event releasing trapped water?  One would think that this would be detected by seismologists, but who knows...
Dr. Alina M. Szmant
Coral Reef Research Group
UNCW-Center for Marine Science 
5600 Marvin K. Moss Ln
Wilmington NC 28409
Tel: (910)962-2362 & Fax:  (910)962-2410
Cell:  (910)200-3913
email:  szmanta at uncw.edu
Web Page:  http://people.uncw.edu/szmanta


From: coral-list-bounces at coral.aoml.noaa.gov on behalf of Bob Buddemeier
Sent: Thu 8/23/2007 2:17 PM
To: William Allison
Cc: coral-list at aoml.noaa.gov
Subject: Re: [Coral-List] Mystery Event - Lankayan Island, Sulu Sea, Sandakan

A few comments ---

1. Water that has lethal effects only in the top few meters of
island/atoll coastal waters needs to be positively buoyant (lower
density) with respect to tropical/subtropical surface water.  Water that
is "cold" or from deep enough to be suboxic because of oceanic processes
will almost certainly be negatively buoyant; if it were forced to the
surface by some mechanism (internal wave? gas upwelling?) it would be
likely to rather quickly sink and be over-ridden by incoming surface
water unless it were trapped by the right combination of geomorphology
and currents.

2.  25 ppt salinity water would be positively buoyant; presumably due to
the addition of meteoric water.  The chemical alteration tends to
suggest interstitial water from the geologic structure ("groundwater"). 
Anoxic, sulfide-dominated environments commonly occur in reef/island

3.  Hydrogen sulfide is certainly foul smelling, as is rotting tissue,
but they have different odors, and if the anoxic water is the source of
the kill the sulfide would be detectable immediately/first, while it
should be many hours if not days before dead organisms could accumulate
and decompose enough to generate that  characteristic odor.

4.  Some kind of pulsed release of anoxic "groundwater" in significant
quantity would be an unusual event -- interstitial water does not become
anoxic unless it has a long residence time, which normally is
accompanied by lack of pathways or reservoirs for high-volume flow. 
This suggests (as the discussion has considered) some sort of trigger
event that shifts the system.  In addition to the things already
mentioned, other precursor  events to look for would be unusually high
rainfall/recharge, spring tides (maximum pressure loading/unloading),
and recent human alteration of the surface or subsurface hydrology
(altered recharge again).  Another thing to look for would be human
alteration of subsurface biogeochemistry -- e.g., garbage or sewage
disposal into a zone that was previously not anoxic and in reasonable
communication with the external water.

5.  The ocean-side-only effect is consistent with a "groundwater" origin
for atolls, since the lagoon is normally maintained at a slightly
positive head with respect to the ocean by wave set-up and cross-reef
transport; this means that the direction of subsurface flow will
normally be oceanward.

For all of the above and much much more, see:Vacher, H. L. and T. M.
Quinn, Eds. (1997). Geology and Hydrogeology of Carbonate Islands.
Developments in Sedimentology 54. Amsterdam, Elsevier.
Bob Buddemeier

William Allison wrote:
> Arthur, I am thinking along the same lines as you for a cause in
> Maldives. Dark, foul-smelling water was reported along with fish
> kills. Deeper water is reported anoxic. Other causes seem improbable.
> Incidentally there was a mystery kill in the Caribbean a few years ago
> - should be in coral-list archives - although volcanic gas was a
> suspect there, I don't know if it was ever resolved.
> Bill
> On 8/22/07, Arthur Webb <arthur at sopac.org> wrote:
>>  It's interesting you mention an atoll event.  I was in Kiribati in the
>> Central Pacific during Christmas 2003 and at that time there were reports of
>> mass mortality along the ocean side coasts of at least 2 atolls in the group
>> (Abemama and I think Nonouti).  These atolls are tectonically stable and are
>> far from any active plate boundaries and are thousands of kilometers from
>> any significant land mass with surface run off.  Additionally, both of the
>> islands mentioned above have small populations who live a traditional
>> subsistence lifestyle (few vehicle's, no electricity or reticulated water,
>> few imported products, no intensive agriculture, etc) in relatively pristine
>> terrestrial and marine environments.
>>  Whilst I did not witness the event I did travel to Abemama about 2 months
>> after and the same story was repeated time and again that there was so much
>> dead marine life on the ocean side reefs (and not the lagoon side) that
>> "windrows" of dead fish lined the shores (both pelagic and reef associated
>> species were mentioned).  The people here too indicated the intolerable
>> smell and plague of flys which followed but this seemed very much associated
>> with the decaying marine life not the time of the event.
>>  I must say this utterly stumped me! These atolls are ancient seamounts
>> which rise steeply from 3.5 4.0 km depth and the outside living reefs where
>> the dead fish were first witnessed are the very upper living rim of these
>> oceanic slopes.  They are high energy environments and the concept of water
>> residence times barely even applies and as mentioned there is no tectonic or
>> terrigenous influence to speak of.  Last, people reported that some had
>> taken and eaten fish which was sluggishly floating (near death I guess)
>> immediately following the event with no ill effect and otherwise of those I
>> spoke to there was no living memory or oral history of such an event having
>> happen before.
>>  My only thought was that through some freak anomaly of deep currents a slug
>> of very cold and or deoxygenated water moved up the slope persisted for long
>> enough to cause damage then sank again ............. anyway since we're on
>> similar subjects I'd be interested if there's any similar stories or ideas
>> out there.
>>  Thanks,
>>  Arthur Webb
>>  Coastal Processes Adviser
>> SOPAC Pacific Islands Applied Geoscience Commission
>>  Postal Address: Private Mail Bag, GPO, Suva, Fiji Islands
>>  Street Address:  241 Mead Road, Nabua, Fiji Islands
>>  Tel: +679 338 1377 Fax: +679 337 0040
>>  Email: arthur at sopac.org
>>  Website: <<http://www.sopac.org <http://www.sopac.org/> >>
>>  William Allison wrote:
>>  Several months ago something very similar was described at a Maldivian
>> atoll. I'll try to track down particulars.
>> On 8/22/07, Don Baker <reefpeace at yahoo.com> wrote:
>>  Dear Coral-L:
>> Several months back, an event happened at Lankayan Island, north of
>> Sandakan, Sabah, Malaysia (Sulu Sea), that resulted in the death of corals,
>> sea cucumbers, giant clams and other marine life - from shallow water to
>> approximately 3 meters.
>> During this event, the seawater smelled putrid and noxious, whereas, it was
>> initially assumed to be from all the dead marine life. The water salinity
>> was measured at or near 25ppt, and very unusually strong currents were
>> present near the southern portion of the island's shallow reefs. Wave force
>> was rough at about 1 to 1.5 meters. The weather was sunny without any
>> rainfall either at the island region nor on the North Borneo 'mainland.'
>> Please refer to this publication with regards to page 9 / Sandakan Sub Basin
>> and Sulu Sea Basin.
>> http://www.doe.gov.ph/ER/archives/win_opp/cd/petropot.PDF
>> The nearby islands to closest to Lankayan Island are the Philippines Turtle
>> Islands - with Buan Is. the closest and to the south west. Buan Is. is
>> classified as a "mud origin' type island mass, whereas, decades ago there
>> existed active mini mud volcanoes there.
>> Observation by the local fishermen in the same Turtle Island region have
>> seen many large, upwelling mud plumes flowing from the under the sea
>> (perhaps pushed out by the natural gas pressure in the Sandakan Basin edges
>> near North Borneo?).
>> In short, this event seems to point more so to a natural cause rather than
>> from runoff from the N Borneo coastal regions. The lowering of the seawater
>> salinity was also significant as well as higher than normal water
>> temperatures in the same area. Could this also be a combination of 'ancient
>> freshwater' also extruding along with the mud and perhaps natural gas?
>> Lastly, the seawater visibility (noted by the tour divers in their
>> complaints) was very poor [< 3 meters at times]. The color was 'gray' the
>> same as the mud on Buan.
>> Can anyone recommend an institution to confirm the cause of this event? Has
>> anyone observed or know of any similar events worldwide? What would be the
>> best way to monitor and gather data if this event is natural and caused by
>> the oil/gas/'old' water? Is this event also dangerous with regards the
>> Lankayan Island's proximity to such a event?
>> Any advice, assistance, comments are welcome.
>> Don Baker
>> Reef Guardian Co-Founder
>> Sabah, North Borneo
>> Malaysia
>> Alternate Email: donbjr95 at hotmail.com
>> "Dedication and motivated direction in achieving specific goals related to
>> the care and protection of living things is not necessarily a guaranteed
>> formula for success. Success is, more often than not, a direct result of a
>> person's passion in addition to the above formula." [Don Baker, Marine
>> Conservationist/Activist, 1998]
>> ---------------------------------
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Dr. Robert W. Buddemeier
Kansas Geological Survey
University of Kansas
1930 Constant Avenue
Lawrence, KS 66047 USA
e-mail: buddrw at ku.edu
ph (1) (785) 864-2112
fax (1) (785) 864-5317

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