The interwoven nature of habitats and their acoustic fingerprints (soundscapes) is being increasingly recognized as a key component of animal ecology. Natural soundscapes are crucial for orientation in many different taxa when seeking suitable breeding grounds or settlement habitats. In the marine environment, coral reef noise is an important navigation cue for settling reef fish larvae and is thus a possible driver of reef population dynamics. We explored reef noise across a gradient of reef qualities, tested sound propagation models against field recordings and combined them with fish audio grams to demonstrate the importance of reef quality in determining which reefs larvae are likely to detect. We found that higher-quality reefs were significantly louder and richer in acoustic events (transient content) than degraded reefs, and observed that sound propagated farther with less attenuation than predicted by classic models. We discuss how zones of detection of poor-quality reefs could be reduced by over an order of magnitude com-pared to healthy reefs. The present study provides new perspectives on the far reaching effects habitat degradation may have on organisms that utilize soundscapes for orientation towards or away from coral reefs, and highlights the value of sound recordings as a cost-effective reef survey and monitoring tool

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. abstract: Many animals, such as migrating shoals of fish, navigate in groups. Knowing the mechanisms involved in animal navigation is important when it comes to explaining navigation accuracy, dispersal patterns, population and evolutionary dynamics, and consequently, the design of conservation strategies. When navigating toward a common target, animals could interact socially by sharing available information directly or indirectly, or each individual could navigate by itself and aggregations may not disperse because all animals are moving toward the same target. Here we present an analysis technique that uses individual movement trajectories to determine the extent to which individuals in navigating groups interact socially, given knowledge of their target. The basic idea of our approach is that the movement directions of individuals arise from a combination of responses to the environment and to other individuals. We estimate the relative importance of these responses, distinguishing between social and nonsocial interactions. We develop and test our method, using simulated groups, and we demonstrate its applicability to empirical data in a case study on groups of guppies moving toward shelter in a tank. Our approach is generic and can be extended to different scenarios of animal group movement. The University of Chicago Press and

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Coral reef noise is an important navigation cue for settling reef fish larvae and can thus potentially affect reef population dynamics. Recent evidence has shown that fish are able to discriminate between the soundscapes of different types of habitat (e.g., mangrove and reef). In this study, we investigated whether discernible acoustic differences were present between sites within the same coral reef system. Differences in sound intensity and transient content were found between sites, but site-dependent temporal variation was also present. We discuss the implications of these findings for settling fish larvae.

Coral reef fish larvae settle on reefs predominantly at night around the new-moon phase, after an early developmental period spent in the pelagic environment. Most sampling is conducted across whole nights, and any studies that have examined the frequency of arrival within nights have typically been limited to coarse sampling time scales of 1–5 h. Here, we present results for arrival numbers of fish caught between dusk and midnight from light traps sampled every 15 min at an Indonesian coral reef, providing the finest temporal resolution for this type of study to date. A spatial analysis by distance indices analysis, adapted to temporal data, revealed clustering of reef arrival times for many species, with an increase in catches immediately after dusk dropping off towards midnight. Importantly, the timing of clusters differed among species, indicating that different factors determine the timing of arrival among taxa. Our results support the hypothesis that larval behaviour influences the timing of arrival at a coral reef for different fish species.