The hermit crab Clibanarius vittatus kills Melongena corona solely to acquire a better fitting shell. This finding is contrary to previous studies, which found that hermit crabs of other species cannot kill gastropods or, in most instances, remove freshly dead gastropods from their shells. This interaction cannot be classified as predation because Melongena tissue was never consumed. Clibanarius killed Melongena only when by doing so they could trade up to a better fitting shell. It cannot be classified as competition because there is no opportunity for Melongena to gain from the interaction. Therefore the term “lethal eviction” is hereby proposed for this interaction. The ability to kill a gastropod to obtain a superior shell gives Clibanarius vittatus an evolutionary advantage over other hermit crab species. It is not known if the outcome of this interaction is widespread where both species occur or if it is confined to the study area. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Fish predation can have structuring effects in aquatic communities, but the most important fish predators are not always immediately obvious. Generalist fish predators often occupy similar habitats and consume similar prey making determination of their consumptive impacts difficult. Understanding these consumptive impacts is important for understanding complex wetland food webs. I collected warmouth (Lepomis gulosus), bluespotted sunfish (Enneacanthus gloriosus), and dollar sunfish (Lepomis marginatus) in two seasons from sloughs for both diet and bioenergetics analysis. Macroinvertebrates dominated diets of the three species, and nonparametric analyses revealed evidence of diet ontogeny in warmouth and potential competition for prey items among gape-matched individuals. Bioenergetics modeling revealed high levels of macroinvertebrate comsumption by these species relative to macroinvertebrate reproductive output suggesting that when combined with other sources of mortality, consumptive pressures placed by sunfish on benthic macroinvertebrates may be quite large. / by Jacob Bransky. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 147-160). / Predatory bacteria are ubiquitous in aquatic environments and may be important players in the ecology and biogeochemistry of microbial communities. Three novel strains belonging to two genera of marine flavobacteria, Olleya and Tenacibaculum, were cultured from coastal sediments and found to be predatory on other bacteria on surfaces. Two published species of the genus Tenacibaculum were also observed to grow by lysis of prey bacteria, raising the possibility that predation may be a widespread lifestyle amongst marine flavobacteria, which are diverse and abundant in a variety of marine environments. The marine flavobacterial clade is known to include species capable of photoheterotrophy, scavenging of polymeric organic substances, pathogenesis on animals, the degradation and lysis of phytoplankton blooms and, now, predation on bacterial communities. Strains from the two genera were found to exhibit divergent prey specificities and growth yields when growing predatorily. Olleya sp. predatory cells accumulated to an order of magnitude greater cell densities than Tenacibaculum sp. cells on equivalent prey cell densities. Experiments were conducted to constrain the potential of the novel isolates to affect prey communities under more environmentally relevant conditions. An investigation of the minimum number of predatory cells needed to generate clearings of prey cells found that the inoculation of individual predatory flavobacteria cells can ultimately result in dense lytic swarms. In some cases, the susceptibility of particular prey species to lysis by a flavobacterial predator was found to vary based on the growth state of the prey cells or the presence of their spent growth media. A novel methodology for the experimental study of biofilms was used to assess the impact of exposure to predatory marine flavobacteria on the release of macronutrients from prey biofilms. The Olleya sp. predator had a stimulative effect on macronutrient release while the Tenacibaculum sp. did not, further suggesting the two groups of predators are adapted to different ecological niches. / by Erin C. Banning. / Ph.D.

No description available.

Thesis (M.S.)--State University of New York at Binghamton, Biology Department, 2006. / Includes bibliographical references.

Knowledge of how individual organisms behave in their environment can provide a greater understanding of population dynamics. In a predator-prey system, the choices made by predators when foraging for prey are important aspects of behavior. Particularly in the case of a stage-structured prey population, how the predator selects prey stages once a prey patch has been located can have implications for prey population growth, predator development and fecundity, and predator-prey system dynamics. Predaceous mites of the family Phytoseiidae are important biological control agents of Tetranychus spider mites in agricultural settings worldwide. Phytoseiid species range from specialists that require Tetranychus spider mite prey in order to develop and reproduce to generalist omnivores. In studies with 13 phytoseiid species, specialized species tended to prefer T. urticae eggs as prey or have no prey-stage preference while more generalist species tended to have no prey-stage preference or prey more often on mobile immatures. Further testing with a subset of these species suggested variability among species with regard to genetic and environmental influences on prey-stage preference. The specialist Phytoseiulus persimilis also preferred to forage and oviposit in patches containing egg-biased stage distributions rather than in adjacent mobile immature-biased patches. No benefits to offspring developing in either type of patch were found in terms of developmental time or subsequent adult fecundity. However, the results of both manipulative experiments and nonlinear population models indicated potential benefits of egg-biased predation in terms of current adult female fecundity, a less severe impact of predation on the prey population, and an increased number of predator descendents during the predator-prey interaction. Considering both subjective factors and discriminant analyses, prey-stage preference performed well as an indicator for the ecological classification of phytoseiid species. The classifications of four phytoseiid species occurring on apple in central and eastern Oregon, USA, were evaluated accordingly. / Graduation date: 2004

Thesis (Ph.D.)--Memorial University of Newfoundland, 2005. / Includes bibliographical references.

Interspecific predation and cannibalism and associated rates of oviposition were assessed for adult female Metaseiulus occidentalis (Nesbitt) and Typhlodromus pyri Scheuten when provided non-limiting amounts of either eggs, larvae, protonymphs, or deutonymphs. Tests with all four stages of phytoseiids and larvae of Tetranychus urticae Koch were carried out at 25°C. At 15 and 12.5°C only larvae of phytoseiids and larvae of T. urticae were prey items. Predation by T. pyri was higher than M. occidentalis at 12.5 and 15°C, but more similar at 25°C. M. occidentalis did not feed appreciably on phytoseiid larvae at 15° and 12.5°C. Neither phytoseiid oviposited at 12.5°C when fed phytoseiid larvae, but T. pyri did at 15°C. We concluded that T. pyri was a more active predator at low temperatures and early-season predation on M. occidentalis immatures by T. pyri could contribute to displacement of M. occidentalis from apple orchards in western Oregon. The effects of prey species and prey density on the rates of inter- and intraspecific predation and oviposition of the two phytoseiid mite predators Metaseiulus occidentalis (Nesbitt) and Typhlodromus pyri Schueten were investigated through a series of laboratory experiments. Adult female predators were given mixed populations of phytoseiid larvae and larvae of a more preferred prey, the spider mite, Tetranychus urticae Koch, at different rates and proportions. T. pyri, more of a generalist predator, consistently showed higher rates of predation and cannibalism on phytoseiid immatures at most prey populations and proportions. Manly Preference Indices indicated that T. pyri switched to feed on phytoseiid immatures at higher population levels and proportions of T. urticae than did M. occidentalis. This ability to readily utilize phytoseiid immatures as prey indicated that maintaining both predators in a biological control program at low prey densities may require the use of active selective techniques that favour M. occidentalis. The differential impact of Zetzellia mali on the phytoseiids Metaseiulus occidentalis and Typhlodromus pyri was studied in laboratory experiments and by analysis of population data from experimental orchard plots containing either of the phytoseiid species, similar numbers of prey mites, and high or low populations of Z. mali. Five hypotheses were evaluated to explain why Z. mali had more impact on M. occidentalis in the field than on T. pyri.. Given equal opportunity, Z. mali adult females did not consume greater numbers of M. occidentalis eggs than T. pyri eggs nor did adult females of either phytoseiid species inflict greater mortality on Z. mali eggs or larvae through attack or consumption. There was no difference in the within tree association of Z. mali adult females with the eggs of either phytoseiid species nor were there differences in the way prey mites (all stages) were spatially partitioned between adult female Z. mali as compared with adults and deutonymphs of either of the two phytoseiids. The foraging area of adult female Z. mali and the oviposition locations of the two phytoseiids from both field and laboratory assessments were compared using spatial statistical procedures. M. occidentalis laid significantly more eggs in the primary foraging area of adult female Z. mali than did T. pyri. This spatial difference was the only factor tested which might explain the observed greater impact of Z. mali on M. occidentalis. Impact of these interspecific interactions and competition on the persistence of predatory mite guilds for the biological control of plant-feeding mites are discussed. / Graduation date: 1995

This study seeks to identify naturally occurring differences in the turbulent environment at a variety of field sites near the Skidaway Institute of Oceanography, in Wassaw Sound and surrounding bodies of water. The sites have previously been used to study predator-prey interactions. Velocity time records were recorded using acoustic Doppler velocimetry (ADV) probes at six sites on four days, with a total of 14 data sets. Differential estimate phase filtering was employed to identify erroneous velocity measurements. Less than 3% of the total samples were identified for any given data set with the exception of three sets that contained nonphysical banded bursts. Set mean velocity statistics were largely unaffected by phase filtration, while turbulent kinetic energy (TKE) was reduced in magnitude. Because the sites were exposed to waves, wave contributions to TKE and Reynolds shear stress were computed. Power spectral densities (PSDs) were computed for each velocity burst, and the contributions from wave-related and turbulent fluctuations were isolated. Wave components of TKE and Reynolds shear stress were computed. Wave contributions to turbulent characteristics for most sets were between 10-20% of the total value. Wave contributions to TKE were consistent but wave contributions to Reynolds shear stresses were irregular. Burst-average velocity statistics, TKE, Reynolds shear stress, and turbulence intensity (TI) were computed for each set. Large variability in turbulent characteristics was observed both temporally and spatially. Tidal influences were apparent as turbulent characteristics often reached absolute maximum values during the incoming or outgoing tides. No consistent trends were observed in relationships between the sites. The findings of the study emphasize the importance of applying data filtration to raw ADV data, suggest an order of magnitude of wave contributions in a particular tidal ecosystem, and demonstrate the inherent variability of turbulent characteristics. The study also illustrates the importance of considering multiple turbulence parameters for a give site, due to the lack of observed relationships between TKE, TI, and Reynolds shear stress. Further work is needed to determine if other parameters that are relevant from a flow characterization standpoint are also important ecologically.

The focus of this study was to determine the effect of clam presence and behavior on the crossflow of the ambient horizontal flow and the effect of ambient horizontal flow characteristics influence the clam feeding behavior. Hence, there is a reciprocal relationship between organisms and the physical environment, and this study ultimately addressed the role of hydrodynamics in the predator-prey relationship between bivalve clams, Mercenaria mercenaria, and their predators, blue crabs and whelks. The study concludes that clams alter the chemical odorant source characteristics and control the transmission of the chemical signal through altering the crossflow. The first part of the study is a field experiment designed to quantify the effect of the presence and behavior of clams on the crossflow of the horizontal crossflow. The second part of this study is a two-part laboratory experiment designed to isolate the influence of environmental factors on clam behavior. One experiment quantifies the unsteadiness of the clam excurrent jet velocity time record according to environmental cues such as the horizontal crossflow velocity, the density of the clam patch, and the size of the clam. The second laboratory experiment quantifies the unsteadiness of the jet velocity values according to the presence of predator cues in the upstream flow. Clams are found, using an ADV system in the field, to alter the vertical distribution of velocity according to the sediment in which they are buried. Also, turbulence characteristics, such as Turbulent Kinetic Energy and Reynolds shear stress, are altered in the presence of clams according to the ambient horizontal crossflow velocity and treatment site. The laboratory flume PIV system captured vector plots for two-dimensional planes that bisect the clam excurrent siphons and clam jet velocity time records were extracted. A fractal analysis and a lacunarity analysis of the jet velocity time records found that clams alter their jet excurrent velocity unsteadiness according to the horizontal crossflow velocity. This behavioral change may contribute to the differences in the turbulence characteristics in the field experiment. Another result from the laboratory experiments is that the effect of clam patch density on the feeding activity was dependent on the size of the organism. This size/density dependent relationship suggests that predation by blue crabs dominates the system since larger clams are no longer susceptible to blue crab predation, whereas clams of all sizes are susceptible to whelk predation. Finally, clams increase the randomness of their excurrent jet velocity values when predator cues are located in the upstream flume flow. This suggests that the presence of predators elicits clam behavior that promotes the mixing and dilution of their chemical metabolites.