Artificial reefs & their placement
Practical Action
of sediment disturbances the highest objects may still show above the sediment cloud or
project eddies and disturbances further afield.
Height can be achieved in a number of
ways, for example by using salvaged
telegraph posts or pipes, or poles
made from concrete, wood, or
galvanised iron. You could also make
ferrocement ‘fins’, or bamboo or
wooden tripods. If none of those
materials are available you can create
height cheaply using air too. Floats or
plastic containers full of air or other
buoyant items can be tied with rope to
modules. Other small items can be tied along the length of
the rope to provide crevices and surfaces on which biomass
can begin to accumulate and grow.
Eddies
6 Metres
2
Placement
Floats, plastic
containers, etc
The placement of the modules that will make up the reef is
extremely important. In most communities only small boats
will be available from which to launch the modules, and
experience has shown that although the modules seem
Synthetic
heavy on land, if they are simply tipped off the deck they
ropes
can ‘drift’ quite far as they fall through the water column.
This will result in widely dispersed modules and a very
ineffective reef.
(This may be
“Salvaged” telegraph
likened to dropping
posts – concrete, wood,
or galvanized iron pipes
or posts pr larger scrap
pipes…
individual sheets of
paper from a third
floor window; one would clearly not expect them all to
land in the same place!) As mentioned earlier, only a
concentrated collection of modules will result in a
rich and extensive marine environment.
…or ferro-cement ‘fins’…
…or
bamboo
tripods
Site selection
The most reliable way to select a site for an artificial
reef is to rely on the experience and knowledge of the
local fishermen. They will have a detailed mental
map of the depth of the water and the structure and
form of the seabed, and they will know where reefs
used to exist if they have been destroyed.
To enable the community to have control over the
creation of the reef, the following placement method has been designed to use artisanal
fishing craft and local skills and materials, and to be operable by the community themselves.
Once the community has mastered the placement method they can repair or enlarge the reef
themselves, or create new reefs as they see fit.
As this method evolved in South India, it
uses the plywood canoes that are the most
popular artisanal craft there. The method
can be adapted to suit local craft. A rig
comprising two plywood canoes is rafted
together, and a quadrapod arrangement is
assembled across them (see sketches). A
Is like this
This
3
Dispersed reef
Scattered papers