Effect of hard installation on coral community succession and growth rate at Taba Heights international marina at the northern Gulf of Aqaba, Egypt.

Hard substrate plays an important role in the life of coral species, affecting their existence, percentage cover and growth rates. The purpose of this study was to determine the diversity, percentage cover and the succession of coral species on newly constructed hard substrate. Also to measure the growth rate of nine scleractinian corals. Taba Heights international marina has three quays, along the study period (2007-2017), a record of coral species in each quay were recorded and the successions of coral communities were studied.  In total, 12 coral species were recorded from all of the surveyed quays during the 10 years period, nine hard and three soft coral species. All the recorded species were found in the first quay, while the second  and third quays recorded 5 and 4 species, respectively. From the species recorded only the soft coral Xenia macrospiculata and the hard corals Stylophora pistillata, Acropora pharaonsis and Porites solida were recorded from all the three quays. At the first quay, the soft coral species were succeeded with the hard coral species. Three soft coral species were recorded at the beginning of the study at November, 2007, Xenia macrospiculata recorded a percentage cover of 5%, decreased to reach 0.3% at July, 2015, until it is totally disappeared at January, 2016 to the end of the study. The same pattern was recorded by the other two soft coral species Dindrophyllia robusta  and Sarcophyton trocheliophorum. On contrary, the hard coral species began with lower percentage cover increased gradually with successive periods during the study. The total area covered by corals was determined at each quay; at the first quay soft coral represented 5% of the total area at November, 2007 decreased to 0.4% at July, 2015 before it totally disappeared at January, 2016. On contrary, hard coral at the same quay represented 1.4% of the total quay area at November, 2007 increased to 17.5% at July, 2017. The same pattern was obvious for the other two quays but with lower percentage cover. Nine hard coral species were measured for growth rate determination five branched and four massive species during the period of study (2007-2017).  Acropora hemperichi recorded the highest rate of linear extension over the total period of study was 11.44 cm y^-1. Followed by Stylophora pistillata which recorded mean growth rate 7.52 cm y^-1. On the other hand Porites solida showed the lowest growth rate of 0.07 cm y^-1.
Over the ten years period of study, the coefficient of regression statistical analysis showed that both linear extension rate per branch for branched corals and radial growth for massive corals showed significant increase with time but with different rates.