Grading statements — Outbreaks of disease, introduced species and pest species
No records of diseases above expected natural levels; no introduced species recorded; no outbreaks; pest populations within naturally expected levels.
Disease occasionally above expected natural levels but recovery prompt; any occurrences of introduced species successfully addressed; pests sometimes present above natural levels with limited effects on ecosystem function.
Unnaturally high levels of disease regularly recorded in some areas; occurrences of introduced species require significant intervention; pest outbreaks in some areas affect ecosystem function more than expected under natural conditions.
Unnaturally high levels of disease often recorded in many areas; uncontrollable outbreaks of introduced pests; opportunistic pests seriously affecting ecosystem function in many areas.
or
Borderline Indicates where a component or criterion is considered close to satisfying the adjacent grading statement.
Confidence
Adequate high-quality evidence and high level of consensus
Limited evidence or limited consensus
Inferred, very limited evidence
Outbreaks of disease are localised and patchy across the Region, but have generally remained stable since 2019. Increased culling effort has reduced the impact of crown-of-thorns starfish, although the potential for new outbreaks remains. Other outbreaks, such as Trichodesmium, have increased, but data are limited on a broad scale.
Since 2019, disease is known to have affected corals and turtles within the Region. The incidence of disease is expected to increase with warming temperatures and consequences could be significant. There are concerns that the Region could be affected by new outbreaks of disease occurring overseas (for example, stony coral tissue loss disease), but these diseases have not yet been observed in the Region.
Crown-of-thorns starfish outbreaks continue to affect reefs across the Region. However, in the past 5 years, increased crown-of-thorn starfish control efforts have reduced the impact of outbreaks on coral reefs, at both local and regional scales.
Since 2019, new introductions have occurred in both marine and island areas within the Region, while effective eradication programs have occurred on some islands. Biosecurity strategies and management measures are being implemented to help mitigate the risk, although some potential pathways for introduction of non-native species remain.
A long-term increase in Trichodesmium abundance has continued at the Yongala National Reference Station. High numbers of Drupella snails have been recorded at some reefs, but no outbreaks have been reported.