SPATIAL AND TEMPORAL VARIATIONS IN GROWTH RATES AND SKELETAL DENSITY OF THE BRANCHING CORALS, ACROPORA HUMILIS AND STYLOPHORA PISTILLATA (SCLERACTINIAN: CNIDARIA) FROM GULF OF SUEZ AND NORTHERN RED SEA, EGYPT | ||||
| Al-Azhar Bulletin of Science | ||||
| Article 19, Volume 29, Issue 1-C, June 2018, Page 55-66 PDF (818.99 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/absb.2018.33764 | ||||
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| Authors | ||||
| El-Sayed, A. M.* 1; Al-Hammady, M. A.2; Nassef, A. M.1; Belasy, M. I.1 | ||||
| 1Faculty of Science, Al-Azhar University, Cairo, Egypt | ||||
| 2National Institute of Oceanography and Fisheries, Hurghada, Red Sea,, Egypt | ||||
| Abstract | ||||
| Scleractinian corals consider one of the most important reef builders in tropical and subtropical regions around the world including Red Sea. This study aimed to estimate the linear growth rates and skeletal densities for the most dominant coral species, Acropora humilis and Stylophora pistillata at the Suez Gulf and northern Red Sea during the period from summer 2015 to spring 2016. The present results showed that, A. humilis has an annual growth rate averaged 6.08±0.551 mm/y, and was low compared with S. pistillata which averaged7.37±3.488 mm/y. These rates showed seasonal and spatial variations. A. humilis recorded its highest average of 1.74±0.11 and 1.74± 0.9 mm during both autumn and winter (cold seasons), respectively, but it declined to 1.11± 0.22 mm during spring. On the other hand, S. pistillata recorded its highest average of 2.40±1.14 mm in winter and the minimum (1.08±0.74 mm) during summer. For spatial variations, the highest annual growth rate of A. humilisa veraged 6.67 mm/y at site III, declined gradually northwards to 5.99±1.28 and 5.58±1.42 mm/y at sites, II and I respectively. On contrast, S. pistillata recorded the highest annual average of 10.16±2.66 mm/y at site II but declined to 8.49 mm/y at site I and reached the lowest average of 3.46 mm/ y at site III. For skeletal densities, the annual averages recorded 1.85±0.13 g.cm-3and 2.09±0.17 g. cm-3forA. humilis and S. pistillata, respectively. These values declined to 1.71±0.24 g/cm3 and 1.90±0.26 g/cm3for the two species, respectively, at site II, but increased to 1.95±0.13 g/cm3for A. humilis at site III and reached to2.20±0.25g/cm3 for S. pistillata at site I. The seasonal fluctuations were also detected, recorded highest average of 2.18±0.312g/cm3 for A. humilis during winter at sites I and minimum average of 1.47±0.35g/cm3during summer at II; while S. pistillata reached the highest average of 2.51±0.21g/cm3 during autumn at site I, and minimum average of 1.62±0.33g/cm3 during summer at site II. | ||||
| Keywords | ||||
| Stony corals; Red Sea; Gulf of Suez; growth rate; skeletal density | ||||
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