Research examining the decline in coral reef health has accumulated over the past few decades. As such, researchers began publishing review articles (secondary literature) in an attempt to organize the growing information on coral health and its drivers. Through visualizing the current state of knowledge and research trends, synthesizing secondary literature can influence future research directions. We thus utilized bibliometric mapping and systematic mapping to conduct a second-order synthesis on coral health and its decline.
From over 300 reviews on coral health, we extracted the purpose of the review, the drivers examined, and the outcomes of coral health identified, as well as bibliometric information. We also conducted a critical appraisal of papers which self-reported to be systematic-like reviews to evaluate study rigour. We find that coral health secondary literature often is conducted with the hope it will be used in conservation decisions and focuses on coral resilience to global warming. Systematic literature often does not meet the rigour criteria of other ecological systematic research. Lastly, the field is dominated by a relatively small group of authors from institutions in high HDI countries. We hope this work identifies future directions for the field and highlights the information available to policymakers.