Understanding the cues that drive larval fish settlement is critical for managing reef systems under stress. Reef sound is increasingly reported to influence fish recruitment, yet the physical and acoustic environment in which larval fish settle varies in space and time. Accordingly, testing potential settlement cues under different conditions is vital for understanding their ecological importance. We conducted 2 sets of field playback experiments in St. John, US Virgin Islands, one nearshore (10 m depth) and the second ‘offshore’ (25 m depth), to assess the effects of reef soundscape playback on settlement rates of multiple reef fish families. In each experiment, nightly currents were quantified and we replicated the diel soundscape cycle using high, low, and control (silent) amplitude recordings from nearby reefs. The first experiment revealed significant current-based, down-stream reduction in larval fish catches in subsurface light traps and a significant effect of increasing amplitude of reef playbacks on larval lizardfish (Synodontidae) catches. In the second, offshore experiment which had no current effect, increasing reef playback amplitude led to a significantly greater catch of parrotfish (Scaridae) larvae and decreased larval pelagic fish catch. Total reef fish larvae only showed attraction to reef playbacks at the most nearshore site. This work demonstrates that while sound can play a role in the settlement of certain reef fishes, responses are influenced by multiple factors, including larger-scale physical processes, underscoring the need to consider the scale of soundscape cues for reef fish settlement within an oceanographic context.

The aim of this study is to compare and contrast the treatment fields designed using CT versus conventional orthogonal X-ray simulation in the treatment of patients with rectal cancer given preoperative chemotherapy and radiotherapy. Nine patients participated in this study. The coverage of treatment fields, the volume of treatment fields, and the position of the anorectal junction in relation to the inferior border of the obturator foramen as the delineator of the pelvic floor were evaluated in each patient using CT and conventional orthogonal X-ray simulation. The results demonstrated undercoverage of the anterior border of the lateral fields of up to 2.5 cm in seven of nine patients when conventional orthogonal X-ray simulation was compared to CT simulation. In addition, the inferior border of the obturator foramen proved to be a poor delineator of the pelvic floor with the anorectal junction situated up to 2 cm superiorly in seven of nine patients. In conclusion, CT simulation is superior to conventional orthogonal X-ray simulation when designing treatment fields for patients with rectal cancer.