Benthic Composition and the Dynamics of Coral-Algal Interactions in Abu Galum Protected Area, Western Coast of Aqaba Gulf

Algae undoubtedly compete with the coral in space; however, coral reefs are globally degrading due to anthropogenic activities, which results in a decrease in reef-building corals and an increase in macroalgae. Therefore, it is necessary to periodically monitor the components of the bottom associated with coral reefs to check the state of the coral reef ecosystem in order to develop integrated sustainable management to preserve this strategic treasure. Thus, the recent work focused on monitoring and assessing the status of benthic components of the coral reef ecosystem and the coral-algal interactions in Abu Galum Protected Area in an attempt to provide information about coral reef status and their conditions in this region as a model in Aqaba Gulf. The present study was carried out at El-Sokhn site in Abu Galum Protected Area during the period from January to December 2018. Nine categories constituted the benthic cover in the study area; hard coral was the main dominant category, followed by turf algae, while the lowest cover was soft coral. The underwater surveys showed that hard coral cover increased at the furthest spot from the beach and vice versa for macroalgae. Turf algae and macroalgae cover increased as a result of nutrient increases during winter, while hard coral had high cover during autumn. In all reef zones, Acropora was the most abundant coral genera, resulting in the greatest number of interactions with macroalgae that was dominated by Sargassum. The current results indicate that the hard coral was strongly inversely correlated with macroalgae, where it was decreased in reef flat zone when macroalgae increased, and it was more common when macroalgae declined at reef crest and in reef slope zones. Given the rapid shifting in tropical coral reef ecosystem dynamics, future work should explore to what extent these thresholds can reach large spatial scales to improve quantitative models of the biomass of macroalgae on coral reefs. Seasonal and long-term studies are urgently required to avoid the loss of important information associated with the trajectory and resilience of coral reef ecosystems.