Mass transport from pollution sources to remote coral reefs in Eilat (Gulf of Aqaba, Red Sea)

Over the last decades, damage to coral reefs from pollution and over-exploitation has accelerated alarmingly. The coral reefs of Eilat are currently undergoing such severe deterioration, and it has been suggested that pollution may be responsible. The Eilat pollution sources are located 5–8 km north of the coral reefs, and it is hypothesised that the pollutants reach the reef sites by current-derived mass transport. This study aimed to test this hypothesis by determining possible occurrence of mass transport from the pollution sites to the reefs, and to determine the pathways and modes of transported pollutants. We also wished to test the applicability of the ‘fluorescently-labelled tracer’ method, as a reliable tool for assessing mass transport in coastal marine environments. The results reveal that particulate matter from pollution sites reaches the remote coral reefs of Eilat, both as bedload and suspension-load particles. Estimates suggest that the minimum velocity of fine particles (5–10 μm), as suspension load, is 0.4k m per day; while the coarse particle velocity (100–200 μm), as bedload, is an order of magnitude lower, i.e. 0.04 km per day. The results show that fluorescently-labelled tracers are a reliable and highly sensitive tool for assessing mass transport in marine environments.