Sensory landscape impacts on odor-mediated predator-prey interactions at multiple spatial scales in salt marsh communities

This collection of research examines how changes in the sensory landscape, mediated by both odor and hydrodynamic properties, impact odor-mediated predator-prey interactions in salt marsh communities. I examined these interactions at a variety of spatial scales relevant to mobile benthic predators and in different sensory landscapes in an effort to determine and elucidate mechanisms mediating the context-specificity of predator-prey interactions in these environments.;I investigated the role of oyster reefs in mediating interactions between odor-mediated predators (blue crabs [Callinectes sapidus] and knobbed whelks [Busycon carica]) and prey (hard clams [Mercenaria mercenaria]) associated with those oyster reefs. Both field and laboratory experiments show predator-specific responses to oyster reef odors and structurally-induced turbulence that are a result of their species-specific perceptual capabilities. These results indicate that oyster reefs can have negative indirect effects on associated prey species because of changes in the sensory landscape that enhance predator foraging success.;In order to explore other mechanisms that could mediate the sensory landscape perceived by predators, I designed a series of experiments to examine how within-patch prey density and distribution influenced predator foraging behavior and success. We exposed patches of hard clams in four combinations of density (high and low) and distribution (aggregated and random) to naturally occurring densities of blue crab and knobbed whelk predators to assess patterns of predation in the field. Predator-specific patterns of predation that are dependent on prey density and distribution within patches, suggests that the abundance and refuge characteristics of prey patch types will be dependent on the dominant predator's identity.;To better understand the constraints and context-specificity of foraging efficiency and success for time-averaging predators in turbulent environments, I challenged knobbed whelks in a laboratory flume to navigate toward and locate hard clam prey in spatial configurations that varied in the magnitude of individual prey plume mixing and cross-stream odor spread. The ability of whelks to effectively utilize temporal integration mechanisms to extract information from prey patch odor plumes allows them to maintain foraging success despite differences in the distribution of individuals within aggregations, and may enable whelks to occupy specific sensory niches that could reduce competition with other odor-mediated predators over resources.;I examined the ability of blue crabs to mediate hard clam distributions as a possible mechanism helping to shape prey distributions in the field. I exposed patches of hard clams to different predator exposure treatments (no predator control, predator odor cues, and access by naturally occurring predators) in the field to assess the ability of predator odors and actively foraging predators to change prey distributions. Exposure to actively foraging predators resulted in clams assuming random distributions within patches because of increased movement, but there were no changes in clam distributions mediated by predator odors. In contrast, both actively foraging predators and predator odor cues reduced growth rates in clams relative to no predator cage controls.;I sought to characterize the variation in turbulent flow parameters that odor-mediated predators may be exposed to in these estuary systems. I did this by measuring velocity time series at multiple locations within four sites across Wassaw Sound, GA at times corresponding to variation in large-scale tidal forcing (neap, normal, and spring tides), and using six acoustic Doppler velocimeters (ADVs). I found that there was significant predictive ability (based on correlation coefficients) of turbulent flow dynamics within sites between locations up to 20 m distant, but the predictive ability between sites seems to be a function of separation distance. This suggests that characterization of flow environments need to be assessed for each site but that characterizations at multiple locations within sites are not necessary (at least up to 20 m distant). Mean values of turbulent flow parameters are both site- and tidal type-dependent, indicating impacts on odor-mediated predator-prey interactions may be very context-dependent and the time and place of observations and experiments needs to be considered in data interpretation. (Abstract shortened by UMI.)...