Use of steel slag as a substrate for coral transplantation

Use of steel slag as a substrate for coral transplantation
Tarek A. A. Mohammed, Al-Sayed A. A. Hamed, Nadia F. Habib
and Khalid M. El-Moselhy
Corresponding author: Tarek A.A. Mohammed;
National Institute of Oceanography and Fisheries, Red Sea Branch, Hurghada, Egypt.
E-mail: [email protected]
Received 10th September 2010, Accepted 26th October 2010
Abstract
Many researchers try to restore and rehabilitate corals using many different techniques allover the world. The
present study presents and applies a modern technique (according to the international patent) for coral
transplantation and rehabilitation based on using electric arc furnace-slag (EAF-slag) as a substrate for transplanted
corals. This slag is mainly composed of iron oxides (38.07-54.73%), calcium oxides (24.49-34.58%) and silicon
oxides (10.23-14.71%) as major oxides, which in general, were not changed during the experiment. In addition, a
thin calcium carbonate layer was formed on the slag surface as a result of the reaction with dissolved CO2 in water.
Three sites were selected to test the efficiency of slag for coral transplantation. 550 coral branches and fragments
were transplanted and fixed on the slag by epoxy materials. A total of 70.18% of the transplanted corals survived
after 22 months, then the ratio decreased to 49.27% after 24 months due to the effect of some interacted factors as
floods and rise of water temperature at site 3 (artificial lagoon). However, sedimentation rate and turbidity are
additional limiting factors on coral survivorship. It was finally concluded that, the steel slag is a suitable substrate
for coral transplantation, as well as for larval settlements of different species. The most survived species of
transplanted corals were Acropora, Stylophora, Favia, Favites, Goniastera and Turbinaria.
Keywords: Coral reefs, steel slag, restoration technique, Red Sea