Variation in skeletal extension, density and calcification of the Scleractinian coral Porites lobate across the northern Persian Gulf

Abstract

In chronological and geochemical studies of coral reefs, the annual coral growth bands function as an indicator for monitoring environmental change. In this study, the annual linear growth rates were measured in two core samples of Scleractinian coral Porites lobate collected from two geographically distinct islands across the northern Persian Gulf Using CoralXDS, the linear extension rates, densities, and calcification rates for each x-rayed samples were evaluated The mean (±SE) for extension (cm.yr−1), density (g.cm−3), and calcification (g.cm−2.yr−1) rates in Kharg Island within the period of 1985 to 2015 were 1.04 ± 0.05, 2.09 ± 0.01 and 2.17 ± 0.1, respectively and in Hendourabi Island within the period of 1999 to 2016 were 1.09 ± 0.07, 2.02 ± 0.02 and 2.19 ± 0.14, respectively The mean for a linear extension, skeletal density, and calcification rates were nearly 10% lower, 60% higher and close to the global average rates, respectively. No association was found between SST as independent variable and extension, skeletal density and calcification rates as dependent variables in both islands at this study. This suggests that the high inter-annual variability of growth parameters in this region might be the underlying reason for the poor association among these parameters with SST. The difference in the results of this study with others elsewhere in the world might be linked to the severe environmental stress under which reef-building corals occur in the Persian Gulf.