Spatial and Temporal Biodiversity Patterns of Coral Reef Cryptofauna on the Arabian Peninsula

Abstract

Coral reef cryptobenthic communities are largely understudied yet they contribute to the large majority of coral reef biodiversity. The main aim of this dissertation was to understand the effects of the organic C, temperature, surrounding benthic communities, salinity, catastrophic events, time, and limitations to dispersal of the cryptobenthic communities. Using 54 ARMS along the Saudi Arabian Red Sea coast, we found that temperature, chlorophyll-a concentration, and photosynthetic active radiation affected the number of OTUs of the cryptobiome, i.e., its biodiversity. We found temperature, energy available, and benthic structure to be associated with distinct cryptobenthic communities and to influence its diversity patterns. These environmental conditions affected differentially the abundance of specific organisms. We also investigated the inter-annual patterns of variability of this biological component in the central Red Sea. We deployed and collected ARMS in four reefs along a cross shelf gradient in three sampling periods spanning 6 years (2013-2019). This period included the 2015/2016 mass bleaching event. We observed cross shelf differences in community composition to be consistent over time and maintained after the bleaching event. However, turnover was significantly higher between prebleaching and post bleaching sampling years than between post bleaching comparisons. Cryptobenthic communities of 2019 presented a slight return to prebleaching composition. In light of predictions of returning bleaching events every 6 years, the observed return might not be sufficient for reaching a full recovery. We investigated the relative contribution of two ecological theories: the neutral theory (associated with the limitations to dispersal and therefore geographic distance) and the niche filtering (associated with environmental conditions that limit colonization). We used 50 ARMS collected from the north, central, and south Red Sea, the Arabian Gulf, and Oman Gulf. We found that limitation to dispersal and environmental filtering to influence beta diversity. However, the geographic distance had a better fit with the beta diversity patterns observed, suggesting a preponderance of the neutral theory of ecology explaining the community patterns. This dissertation provides fundamental information on characterization of the cryptobiome in the Arabian Peninsula.