Deployed artificial reef structure prototypes
1. Oyster Shell Bags
They are composed of a chicken wire frame wrapped into a tube and filled with discarded oyster shells. The structure is then sealed with more chicken wire to create a bag approximately 1m in length and 0.5m in diameter. The bags are deployed in the RIMAH site and create the bulk of the densely populated reef area. They exhibit relatively high biodiversity with some common species associated with them being damselfishes, wrasses, scorpionfishes, lionfish, moray eels, triggerfish, and groupers. The structure also exhibits a healthy cover of feather stars, sponges, and other encrusting organisms.
2. Oyster Shell Infused Tower
It is a structure consisting of an angle steel frame approximately 1.5m high and 0.5m wide. The tower structure contains two chambers stacked one on top of the other. The chambers are covered with sheets which contain oyster shell material sandwiched between two layers of metal wire mesh. There is one tower structure in the RIMAH site which lies among the oyster bags forming a densely packed reef. The tower was planned to stand upright in the water column but it was quickly tipped over by the current. The structure seems to form a contiguous reef with the oyster bags due to their proximity and similar density.
3. Oyster Chamber
The oyster chamber consists of a large cube approximately 1.5mx1.5mx1.5m with a hollow interior. The cube is created from an angle steel frame onto which oyster-infused steel mesh sheets are attached to create the walls of the chamber. Each of the walls of the structure has an opening approximately 30cm in length to allow access to the hollow chamber interior. The chamber was observed to have a high density and number of fish but low biodiversity with the vast majority of fish associated with the structure being Arabian blue striped snapper and the pearly goatfish. Although porcupine fish and damselfish can be seen occasionally.
4. Oyster Shell Gargour
Located in the RIMAH site, this structure is made by modifying the commonly used gargour fish trap by attaching a layer of oyster shell material to the base of the dome-shaped structure and covering the 1.5m high dome with palm fronds. Another small opening at the back of the gargour is created to disable the trap. These structures were associated with a very high abundance of Arabian blue striped snapper. The fish are often observed schooling inside and around the structure. This structure creates the bulk of the low-density reef section.
5. Oyster Platform (Rack)
This structure is basically the same steel frame used to create the oyster chamber but with only the top and bottom of the cube covered with the oyster shell material infused steel mesh. This structure makes up the final piece of the low-density section of the artificial reef in the RIMAH site. The base mesh layer did not survive long and quickly turned into a pile of rubble below the structure where some small damselfishes, pearly goatfishes, and snappers can be seen. The structure is also associated with a large stingray that can usually be seen lying underneath the structure. Two more structures of this prototype were installed in the DARA site. These structures were better reinforced and the structure has remained undamaged so far. This structure is associated with a large population of flower cardinalfish and some copper striped cardinalfish. A moray eel and some damselfish have also been observed on the site.
6. Wedge Rack
This structure is placed in the DARA site. It consists of a steel rebar grid bent into an acute angle with a base made of steel mesh containing oyster shell material. This structure is associated with a large number of snappers, as well as flower cardinalfish, filefish, and moray eel.
7. Bell Frame
Deployed in the DARA site, this structure is made of a steel rebar frame bent into a dome shape with two platforms made from oyster-infused steel mesh inside the dome. This structure is sparsely populated, having some association with pearly goatfish and snapper communities.
