Supporting data for "Marine Cryptobenthic Community Dynamics in Urbanized Coastal Seascapes"

Coastal cryptobenthic communities are fundamental to marine ecosystem functions and services, yet they remain largely overlooked in biodiversity research. As anthropogenic pressures intensify across the world, critical gaps persist in our understanding of how these communities change along environmental and spatial gradients. Using Autonomous Reef Monitoring Structures (ARMS) and COI metabarcoding, this thesis addressed these gaps in three studies built progressively from experimental manipulation to seascape-scale synthesis – revealing how environmental and spatial processes interact to drive cryptobenthic community dynamics in urbanized coastal ecosystems.<br>Chapter II is the first application of ARMS as an experimental unit: translocation of pre-seeded ARMS between marine protected areas and impacted sites revealed that communities exhibit low resistance to anthropogenic stress. Nitrogen pollution—particularly Total Inorganic Nitrogen—emerged as the strongest predictor of species richness loss, explaining over 44% of variance. This decline was not generalized: high-nitrogen environment drove high taxonomic turnover, ultimately producing divergent assemblages. Yet within six months of stress removal, communities recovered rapidly to reference states – demonstrating high resilience despite low resistance. <br>Chapter III is a three-year coral restoration experiment which demonstrated that proximity to source reefs dominantly shaped recruitment composition, revealing strong distance–decay of similarity. Active seeding – attaching coral fragments on suitable substrate – significantly enhanced cryptobenthic biodiversity compared to passive substrate deployment—unseeded controls instead trended toward oyster-dominated, lower-diversity states. However, benefits of different restoration strategies (e.g. monoculture versus polyculture) were not yet apparent, likely because restored corals lacked sufficient structural complexity to substantially influence associated communities.<br>Chapter IV synthesized 88 ARMS sampled over six years with long-term water quality data, revealing that mean chlorophyll-<i>a</i> strongly predicts normalized benthic richness, explaining close to a quarter of compositional variation. Network analysis identified clear source-sink dynamics and delineated a highly connected 'biodiversity corridor', providing critical insights for conservation planning. <br>Together, these findings demonstrate that coastal benthic communities are shaped by the combined effects of environmental and spatial processes. They are vulnerable to nutrient pollution, yet remain remarkably resilient when stressors are removed, and source populations are accessible. Effective conservation of these benthic communities must therefore integrate nutrient mitigation with the protection of spatial connectivity — twin pillars of benthic resilience in urbanized seascapes.<br>