Background/Question/Methods Compensatory mechanisms arising from direct and indirect top-down trophic interactions can mediate abiotic determinants of the expansion of opportunistic taxa, and promote ecosystem resilience against trophic simplification. Metacommunity theory provides a framework to understand how processes occurring across scales interactively contribute to patterns in space-use of opportunistic taxa, and may therefore help identify relevant buffering mechanisms following their expansion. However, patterns of space-use and trophic interactions must be explicitly documented prior to linking pattern and process. We applied a landscape ecology framework to longitudinally document spatial dynamics of coral reef benthic cyanobacterial mats at the level of individual mats (patches) and reef site (metacommunity). Over a ~7-week period from May – July 2019, we tracked mat communities (n=53) using repeat photographs, alongside site-scale cover of mats from photoquadrat surveys at a single fringing coral reef site in Bonaire, Caribbean Netherlands. To quantify landscape statistics (ex: fractal index, landscape division), we developed a novel patch-matrix approach. We concurrently documented trophic interactions with bacteriophages using paired meta’omic sequencing and with reef fishes across 5 reef sites using video surveys. Finally, we experimentally tested for an effect of fish predation on patch spatial dynamics using a field-based enhanced predation experiment (n=27 patches). Results/Conclusions Over the 7 weeks, we documented substantial localized patch extinction (43.4% of patches), alongside stable, or increasing total metacommunity abundance (K-W; p < 0.001). Patch extinctions were temporally asynchronous, occurring across 14 unique dates. Community fractal shape index significantly increased during patch death phase (GAM; p < 0.05), suggesting top-down mechanisms contribute to community extinction. Predation rates differed significantly among fish species (GLMM; p < 0.01), but not among distinct reef sites (GLMM; p > 0.05). Transformed bacteriophage abundances (centered-log ratio transform) were highest at the border between macroscopically living and degraded mat tissue, and lowest in dead tissue. Interestingly, we found no effect of experimentally enhanced predation on proportional community patch extinction (K-W; p > 0.05). Overall, our results suggest the mechanisms controlling coral reef benthic cyanobacterial mat spatial dynamics differ across scales and levels of ecological organization, resulting in ephemeral individual communities and stable metacommunities. Similar to other metacommunity systems, spatiotemporal asynchrony in local patch extinction likely contributes to the observed metacommunity stability. Intra-site heterogenous predation pressure (GLMM; Random effect variance 4.10 ± 2.02 SD) may reduce metacommunity synchrony. We argue that benthic cyanobacterial mats may represent an important emerging model system for use in metacommunity theory.
