SPATIALAND TEMPORAL DYNAMICS OF CORAL SETTLEMENT IN CORAL REEFS OF QATAR

Abstract

Coral reefs are fundamental in supporting biodiversity and vital to the economically significant fishing industry that supplies food to society and provides livelihoods to fishermen and their families. Coral reefs are facing a decline in their coral cover worldwide including Qatar. The renewal of coral colonies is limited by a lack of either coral reproduction or coral larvae settlement or coral settlers' survival and growth. Our core research question is: "Is settlement occurring in the coral reefs of Qatar?". Five natural reef sites were investigated to detect spatial and temporal patterns of coral settlement. Settlement tiles were deployed and retrieved over a three-year study from 2019 to 2021. Settlement rates varied spatially and temporarily at all the investigated sites. Sheraoh Island had the highest average settlement rates throughout 2019-2021, with 106, 343, and 42 settlers/m2/day in Q4 2019, Q3 2020, and Q3 2021, respectively, among all sites and seasons. The exception was in Q4 2020, where MM had the highest average settlement rate with 15 settlers/m2/day. However, Fasht East Halul had the lowest average settlement rates in Q3 in both years 2020 and 2021 with zero settlers/m2/day whereas BZ and UAA had the lowest average settlement rates in Q4 in both years 2019 and 2020 with zero settlers/m2/day. Several factors might affect the settlement process, such as currents in the Arabian Gulf, where larvae could settle in adjacent reefs. However, no settlement was observed during the winter and spring seasons. Furthermore, coral settlement seemed to be negatively correlated with coral cover and richness. Additionally, Qatar's reefs contain both reef-building and non-reef- building settlers, with the majority being reef-building species, however, Acropora was absent in all the sites.