Schaffelke, B. | Search bioRxiv

bioRxiv2025

Beyond Coral Cover: A framework for assessing the condition of coral reef habitats and informing conservation targets

The goal of ecosystem management is to maintain healthy and resilient ecosystems over time. These attributes can be summarised under a general term widely used in management plans: ecosystem condition, defined as the overall quality of an ecosystem relative to a desired or reference state. However, measuring and monitoring ecosystem condition remains a challenge. Monitoring ecosystem condition requires a suite of ecological indicators that simultaneously capture the complexity and variability of ecological processes, while being informative and usable in management and decision-making contexts. Such indicators need to be holistic, measurable, sensitive and scalable. Here we outline a resilience-based monitoring framework for coral reefs that consolidates monitoring data and research insights into a relevant, integrated format. The framework includes indicators of ecosystem state (coral cover) and key processes (represented by recovery performance, macroalgae prevalence, community composition, and coral juvenile density). Indicators are generated and scaled from monitoring data by applying explicit, reef-specific thresholds, providing a simple but comprehensive set of ecosystem condition values. Using cases from the Great Barrier Reef, we demonstrate how the framework integrates these indicators for detailed assessments of reef habitat condition and its potential role in management. Based on these case studies, we discuss important considerations for applying this framework worldwide, acknowledging current limitations related to data availability, resolution, and the length of time series.

ecology↗

bioRxiv2019

Microbial predictors of environmental perturbations in coral reef ecosystems

Incorporation of microbial community data into environmental monitoring programs could improve prediction and management of environmental pressures. Coral reefs have experienced dramatic declines due to cumulative impacts of local and global stressors. Here we assess the utility of free-living (i.e. seawater and sediment) and host-associated (i.e. corals, sponges and macroalgae) microbiomes for diagnosing environmental perturbation based on their habitat-specificity, environmental sensitivity and uniformity. We show that the seawater microbiome has the greatest diagnostic value, with environmental parameters explaining 56% of the observed compositional variation and temporal successions being dominated by uniform community assembly patterns. Host-associated microbiomes, in contrast, were five-times less affected by the environment and their community assembly patterns were generally less uniform. Further, seawater microbial community data provided an accurate prediction on the environmental state, highlighting the diagnostic value of microorganisms and illustrating how long-term coral reef monitoring initiatives could be enhanced by incorporating assessments of microbial communities in seawater.\n\nImportanceThe recent success in disease diagnostics based on the human microbiome has highlighted the utility of this approach for model systems. However, despite improved prediction and management of environmental pressures from the inclusion of microbial community data in monitoring programs, this approach has not previously been applied to coral reef ecosystems. Coral reefs are facing unprecedented pressure on a local and global scale, and sensitive and rapid markers for ecosystem stress are urgently needed to underpin effective management and restoration strategies. In this study, we performed the first assessment of the diagnostic value of multiple free-living and host-associated reef microbiomes to infer the environmental state of coral reef ecosystems. Our results reveal that free-living microbial communities have a higher potential to infer environmental parameters than host-associated microbial communities due to their higher determinacy and environmental sensitivity. We therefore recommend timely integration of microbial sampling into current coral reef monitoring initiatives.

microbiology↗