Growth Rate Evaluation of the Alcyonacean Soft Coral Sinularia polydactyla (Ehrenberg, 1834) at Hurghada, Northern Red Sea, Egypt

Abstract

Growth rate of Sinularia polydactyla has been studied to determine the changes of surface area using 2D method as modified method for measuring growth increasing. The measurements indicate to that restricted and slow growth rates in the big samples under the variable oceanographic conditions. Summer recorded the highest rates of growth. The mean growth rate of the biggest colonies recorded 51.83±4.90mm² while the small colonies recorded 20.8±6.25 mm² in summer. On contrary, autumn showed the lowest and restricted rates during. The annual growth reached 116.28±10.57 and 33.78±12.45mm²/y in the big and small colonies respectively. The growth ratio in relation to the original colonies size appears to grow with a relatively faster ratio in the small colonies (9.73±1.62% with a range of 6.67-12.68%) than the elder one (5.79±0.34% with a range of 4.37-6.72%).

The temperature changes, gonads and gametes maturation, sedimentation rates are major controlling factors affect the growth rates. ANOVA Bivariate correlation illustrated a positive relationship (without significant difference) between the growth and temperature (ºC) (at P=0.38 and R²=0.62). By comparing the present study and the available growth data of Sinularia sp., we found that, the annual growth of S. polydactyla is higher (116.28±10.57 - 33.78±12.45mm²/yr) than the previous studies.

Keywords: Growth Rate Sinularia polydactyla, Hurghada, Red Sea