Marine reserves shape seascapes on scales visible from space

Area of Science:

• Marine ecology
• Remote sensing
• Conservation science

Background:

• Marine reserves are crucial for restoring marine ecosystems and protecting large ocean areas.
• Monitoring ecological responses at the scale of marine reserves is challenging.
• Herbivory is a key factor in coral reef ecosystem health.

Purpose of the Study:

• To quantify the prevalence, size, and causes of grazing halos across the Great Barrier Reef.
• To assess if marine reserves influence herbivory and habitat structure at large scales.
• To demonstrate the utility of remote sensing for monitoring ecosystem changes in marine protected areas.

Main Methods:

• Screening 1372 reefs and measuring features of 214 reefs using high-resolution satellite imagery.
• Combining satellite data with remote underwater videography and on-site assays.
• Analyzing 'grazing halos' as indicators of herbivory and ecological interactions.

Main Results:

• Grazing halos are more prevalent in marine reserves, particularly older ones (approx. 40 years).
• Marine reserves show predictable changes in reef habitat structure visible from space.
• The study detected macro-patterns in reef species interactions using satellite imagery.

Conclusions:

• Marine reserves can shape large-scale habitat structure by altering herbivore importance.
• Reserves may have a greater role in ecosystem restoration than previously understood.
• Freely available satellite imagery can now detect ecosystem responses to protection in remote reefs globally.