Spatial and temporal dynamics of Arabian Gulf coral assemblages quantified from remote-sensing and in situ monitoring data

Abstract

We analysed spatial patterns of coral communities mapped from IKONOS satellite imagery in combination with 8 yr of traditional ecological monitoring data and archived sea-surface temperature data to explain why coral assemblages in the SE Arabian Gulf (Jebel Ali, Dubai) are impoverished and most do not build reefal frameworks. Analysis of archive sea-surface temperature (SST) data confirmed that the area is subject to recurrent and cyclic temperature anomalies at a frequency which suggests at least a partial link to the El Nino Southern Oscillation via the Indian Ocean Zonal Mode. Classification of high-resolution (4 m pixel-size) IKONOS satellite data gave a large-scale synoptic overview of substrate zonation which, in tandem with a long-term ecological time-series study, allowed us to determine the spatial and temporal dynamics of the coral community. We show that the spatial expression of 4 coral assemblages, as mapped using the IKONOS imagery, is consistent with what would be predicted if reef development was repeatedly 'reset' on a decadal time-scale following recurring episodes of coral mass mortality induced by severe SST anomalies. Furthermore, merging the remotely sensed map of substrate distribution with a detailed bathymetric digital elevation model, revealed no evidence of any significant framework development in the past, suggesting that the cycle of temperature-induced mortality has been operating for some considerable time.