[Coral-List] Coring method

[Georg Heiss]

Dear Michel and coral-list,

during our work in the Red Sea and Indian Ocean we used a simple and 
inexpensive drilling method to sample cores of up to 5m length from 
coral heads. Cost of the full system was around 500 Euro or so. We 
modified the system later on, if anybody is interested in details, 
don't hesitate to contact me.

Best regards,
Georg



Detailed descriptions and photos of the tool are published in:

Heiss, G.A. (1994): Coral reefs in the Red Sea: Growth, production 
and stable isotopes.- GEOMAR Report, 34: 1-143

Heiss, G.A., Dullo, W.-Chr. and Reijmer, J.J.G. (1993): Short- and 
long-term growth history of massive Porites sp. from Aqaba (Red 
Sea).- Senckenbergiana maritima, 23/4/6: 135-141.

You can see a picture at 
http://www-user.zfn.uni-bremen.de/%7Egheiss/Personal/Drill.html

Here is some text from the methods section:

"The intention was to build a simple, cheap and small coring tool, 
which can be operated by one Scuba-diver independent from any supply 
on the sea-surface. We wanted to avoid some disadvantages of the 
already described machines for our field work as there are the large 
size of some and therefore the limited mobility and/or the need of 
energy support from a boat. A technique for gaining long coral cores 
with a handy instrument has been developed.
[...]
Due to the availability of Scuba-tanks and the need for easy handling 
from small boats we chose compressed air as the best power source for 
the drill. A commercially available RODCRAFT 4200-pneumatic drill was 
selected on the basis of its size and technical characteristics. It 
works at a speed of 2000 rpm with an air consumption of 220 l/min 
under full power. Altthough the operating pressure is 0.6 MPa (6 bar, 
manufacturer_s information), we operated the drill at a pressure of 
8-9 bar which is the pressure supplied by an ordinary first stage 
regulator for Scuba-diving. We used in the first year a SCUBAPRO Mark 
II first stage. We later improved the system by using a balanced 
first stage (SCUBAPRO Mark X) in order to have a better air supply in 
water depths greater than 10m. The air came from 15 l dive tanks, 
pressurized to 200 bar, which provides an air capacity of 3000 l. The 
connection between tank and drill was a standard industrial pressure 
hose of 2 m length. The core-cutter is a diamond-tipped steel tube of 
300 mm length and an outside diameter of 41 mm (36 mm inside) 
manufactured by DIA-G Diamantwerkzeuge GmbH, Kiel.
With this composition of the instrument we could easily obtain cores 
of 30 cm length from different massive growing genera like Platygyra, 
Porites,  Hydnophora, Favia and Favites.
The initial millimeters were drilled by turning the core barrel by 
hand several times on the coral surface. No template was necessary 
for the drilling procedure. Drilling of one 30 cm core took only a 
few minutes. Depending on the rigidity of the coral we could obtain 
up to four cores out of one 15l-tank.
[...] To get a longer record of coral growth history and regional 
climate we constructed an extension of 100 cm length to the drill 
bit. The extension is made from a 17 mm diameter steel rod with a 
screw thread attached to the core barrel. We could obtain five 130 cm 
long cores in 30 cm lengths with 100% recovery from different sides 
of the colony (Fig. 2).
[...] The core holes were filled with cement plugs after drilling to 
prevent bioerosion (see (HUDSON 1981; WINTER ET AL. 1991).
[...]

(from: Heiss, G.A., Dullo, W.-Chr. and Reijmer, J.J.G. (1993): Short- 
and long-term growth history of massive Porites sp. from Aqaba (Red 
Sea).- Senckenbergiana maritima, 23/4/6: 135-141.)



At 9:03 Uhr +0400 02.01.2005, Michel Claereboudt wrote:
>Can someone guide me to information for drilling cores in corals
>i.e. types of drill (manufacturer?), type of bits, length of bits, 
>method, tips and tricks...
>
>The purpose of these cores is to assess changes if any of growth 
>rates in the last 50-100 years in the Arabian Gulf and Gulf of Oman. 
>They will be sliced and Xrayed. There is a lot of litterature on the 
>second part of the method (xray, densitometry, fluorescence etc...) 
>but nothing (so far) on the actual drilling process.
>
>Thanks,
>
>
>Dr Michel Claereboudt
>Dpt. Marine Science and Fisheries
>College of Agricultural and Marine Sciences
>Sultan Qaboos University, Box 34
>Al-Khod 123
>Sultanate of Oman
>
>Tel: (968) 24415 249, Fax: (968) 24413 418
>email: michelc at squ.edu.om

-- 
Dr. Georg Heiss
Reef Check Europe Coordinator
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e-mail: <georg at reefcheck.de>
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