[Coral-List] surveys in the tsunami area

[John McManus]

A bit long -- read on only if interested in blast fishing and coral breakage
surveys.

It is generally quite difficult to differentiate blast-fishing damage from
other sources of damage. Holes in the hard reef substrate are generally NOT
due to blasting, but are usually erosional features or remnants thereof. 

Corals broken by blasting are often washed away soon after. Collections of
coral rubble can be from many causes, and often form due to hydrodynamics.

I only consider a blasting ID reliable when standing branching or vertical
platy coral colonies are clearly broken in a radiating pattern from an
identifiable center. Blast patterns such as this are usually 0.5 to 2 meters
in radius.  Be careful that wave damage can also cause circular breakage,
though the center will not be as clearly defined. 

Bombs are usually made from beer or gin bottles thrown from boats, though
occasionally actual dynamite or grenades are used. These will not do much to
the bottom other than make a temporary dent in sand and the coral breakage
mentioned. Some are used for pelagic fish. Those intended for fish hiding in
coral are usually not used much below 40 feet because of difficulties
retrieving fish the fish that sink (only some float). Occasionally, one
finds cases where bombs have been planted in coral colonies or clumps --
usually those laden with hiding fish. In these cases, large chunks of thick
clumped coral may be broken out. However, one often sees a similar effect
from heavy anchor damage. Again, look critically for circular patterns. 

Damage from the tsunami will probably be primarily in large swaths to total
flattening of corals on a reef slope. Watch for freshly-broken coral bases
in marginally-affected areas (the major hits should be obvious!). It will
help if you look for bits of living coral in the crevasses of otherwise dead
corals -- a hint as to recoverability. 

The ReefBase Aquanaut method was designed for comparative analytical surveys
of this kind, with a strong emphasis on transect deployment, repeatability,
and quantification of coral growth forms (which I always find helpful in a
"Crime Scene" context). It covers fish and benthic invertebrates, algae,
etc. as well. The method emphasizes systematic sampling for non-scientists,
but works well in a true stratified random or cluster sampling design. 

This is sold out, so write me for a scanned copy of the manual. 

If you are not doing analyses for which knowledge of growth forms is useful,
perhaps the ReefCheck method will suffice. 

Wave-breaking reef crests may have been torn up. If so, this may be
extremely important, potentially leading to serious coastal erosion
(something merely knocking over corals is much less likely to do). 

I will be looking forward to your reports!
 

McManus, J.W., M.C.A. Ablan, S.G. Vergara, B.M. Vallejo, L.A.B. Meñez,
K.P.K. Reyes, M.L.G. Gorospe and L. Halmarick, 1997.  ReefBase aquanaut
survey manual. International Center for Living Aquatic Resources Management
Educ. Ser. 18, Philippines, 61 p.  

See also:

McManus, J.W., Nañola, C.L., and Reyes, R.B. 1997. Effects of some
destructive fishing methods on coral cover and potential rates of recovery.
Environmental Management. 21(1): 69-78.


Cheers!


John
 
____________________________________
 *** Please note new phone numbers (361 now 421) ***
 
John W. McManus, PhD.
Professor, Marine Biology and Fisheries
Director, National Center for Caribbean Coral Reef Research (NCORE)
Rosenstiel School of Marine and Atmospheric Science
4600 Rickenbacker Causeway, Miami, FL, 33149
305-421-4814, 305-421-4820,       Fax: 305-421-4910
www.ncoremiami.org
jmcmanus at rsmas.miami.edu
 

-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov
[mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Silvia Pinca
Sent: Friday, February 04, 2005 9:21 AM
To: coral-list at coral.aoml.noaa.gov
Subject: [Coral-List] surveys in the tsunami area 

Dear colleagues,
 
I will be leaving soon with a small group of scientists from the University
of Genova to visit the area around west Sumatra to determine the effect of
the tsunami on the reefs of the region. Do you have any suggestion on how to
best quantify the damage so that it could be compared to other hit areas and
how to surely determine differences between dynamite damage (quite common
there) vs wave impact damage?
Thank you for your opinion,
Sincerely
 


Silvia Pinca, Ph.D.
Marine Science Program Coordinator
College of the Marshall Islands
P.O. Box 1258, Majuro, MH 96960
ph. (692)-625-5903
spinca at nras-conservation.org
milviapin at yahoo.com
www.nras-conservation.org
		
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