My D.Phil. focused on fish populations in mesophotic coral ecosystems (MCEs). MCEs occur in tropical regions extending from depths of 30 m to approx. 150 m, and are often connected to shallow coral reef ecosystems, where it is suggested they provide an important reservoir of recruits for coral and fish populations. Their importance to overall reef resilience in the face of human disturbances such as overfishing is largely unknown and there is a lack of evidence for whether fish populations on shallow coral reefs and adjacent MCEs are connected.