An application of artificial reefs to reduce organic enrichment caused by net-cage fish farming: preliminary results
This study is summarised as evidence for the following.
Construct artificial reefsAction Link
Construct artificial reefs
Between 1999 and 2000, a controlled study in the Gulf of Aqaba, Red Sea (Angel, 2002) found that an artificial reef structure placed below a fish farm became colonised by a variety of organisms with potential to remove organic matter produced by farmed gilthead sea bream, Sparus aurata. Both artificial reefs were rapidly colonised by a range of species; algae, small invertebrates, and macro fauna, compared to the control site. Biomass was greatest on the reef under the fish farm. Fish were seldom observed at the control site but numerous at both artificial reefs (886 and 1,185 below and west of the fish farm, respectively). Chlorophyll a was used as an indicator of filtration efficiency and was most efficient at intermediate current speeds (15 to 35% filtration). Two triangular-shaped artificial reefs, made of porous polyethylene, with a total volume of 8.2 m3 were deployed at 20m depth: one below a commercial fish farm and the other 500m west of this farm. A control site was established with no artificial reef structure 10m south of the fish farm. Plates were attached to the reef to allow sampling without disturbing the integrity of the reef structure. Three plates were removed from each reef every other month and were photographed, identified, counted, dried and weighed. Every two months, the fish populations were counted by visual diver surveys and video recordings reefs. Chlorophyll a was measured using a fluorometer. The experiment was conducted over one year.