Williams, Stephanie J.

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    The movement of white grunts (Haemulon plumierii) relative to habitat and boundaries at various spatial and temporal scales
    (2011) Williams, Stephanie J.; Appeldoorn, Richard S.; College of Arts and Sciences - Sciences; Yoshioka, Paul M.; García-Sais, Jorge R.; Lindeman, Kenyon C.; Aponte, Nilda; Department of Marine Sciences; Bird Picó, Fernando
    The relationship between the distribution, abundance, and movement of fishes to the abundance and arrangement of habitats constitutes a fundamental basis for ecosystem-based management. Defining nursery areas, essential fish habitat and trophic flows, and the design principles for marine protected areas and marine spatial planning all depend on how fish interact with surrounding habitat. This study investigates the movements of subadult and adult white grunts (Haemulon plumierii) at various scales with respect to habitat, with particular emphasis to boundaries. Acoustic telemetry tested boundary responses through displacement and identified short- and long-term movement patterns. Visual surveys at 9 sites, with video recordings at 3 sites were used to characterize behaviors and their relation to the reef-sand interface at dawn, midday and dusk. Using high-resolution bathymetry and a modified benthic habitat map, the spatial patterns of acoustic receiver reception range were examined relative to geomorphology. The study was conducted at inshore and offshore emergent reefs in southwest Puerto Rico. Twelve tagged fish were displaced from point of capture. Most were able to return, even across broad expanses of sand between two emergent reefs. Return was facilitated by short distances, increasing body size and the use of patch reefs to enhance connectivity. Over broad distances without such connectivity, boundaries were crossed only at night, and several days were spent searching for a route back. Once learned, a second displacement resulted in immediate return upon nightfall. Movements were also monitored on an additional 14 tagged fish. Temporal patterns in frequency of detection at single receivers and detection across multiple receivers indicated that twilight migrations were typical, but that total area moved was within ~300m, with occassional forays toward the forereef. Forereef, backreef and transitional areas were used differentially in time, with the reef-slope-to-sand interface acting as the primary pathway for movement. Within the general area utilized, shifting patterns of detection over longer scales indicated a more complex pattern spatial use, with periods of intense use at a specific area averaging about 7 days, with the suggestion that these may cycle on still longer scales, perhaps with a lunar periodicity. Visual surveys showed movements across the interface were more frequent at twilight, and subadults had a greater maximum distance traveled. Cross-boundary movements were facilitated by nearby patch reefs providing greater connectivity and schooling with conspecifics or other fishes. Receiver range-testing showed detection results varied depending on the geomorphology of receiver location. Maximum detection distance also depended on receiver location, and averaged only 72m.