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dc.contributor.advisorCresswell, Will
dc.contributor.authorKenworthy, Nigel
dc.coverage.spatialx, 177 p.en_US
dc.date.accessioned2018-02-23T11:56:47Z
dc.date.available2018-02-23T11:56:47Z
dc.date.issued2018-01-29
dc.identifier.urihttps://hdl.handle.net/10023/12775
dc.description.abstractPrevious research into bottom-up processes on saltmarshes has mainly focused on the influence of plant succession on herbivores. This study will present original research exploring the influence of bottom-up processes in a saltmarsh ecosystem between three trophic levels: Orchestia, redshanks, and sparrowhawks. Density dependence, may be the dominant top-down effect when higher numbers of sparrowhawks and redshanks are present, and may mask top-down and bottom-up trait effects which are constant. Bottom-up effects begin to emerge when cold conditions force redshanks from muddy creeks onto the saltmarsh to forage for Orchestia, because their primary prey, Corophium become less available. Larger flocks form and feeding on Orchestia requires them to balance a need to profit from the best available feeding patches and to be vigilant to sparrowhawk attack. Redshank vulnerability is compounded, because Orchestia hide in cold temperatures, so probing in the soil with their heads down makes them more vulnerable to sparrowhawk attack. Larger flocks may be able to exploit areas closer to sparrowhawk-concealing cover at the terrestrial boundary because they feel safer in greater numbers. Warmer temperatures make Orchestia more active which attracts redshanks, which can simultaneously feed and be vigilant because they peck and catch crawling and jumping Orchestia with their heads up. Consequently, increased flock size may temporarily depress Orchestia abundance, so that redshanks become spaced, leaving isolated individuals more vulnerable to attack. Therefore, it is a temperature-dependent bottom-up process which impacts upon both Orchestia and redshank behaviour, which then may influence the hunting success of sparrowhawks. Whether the characteristics of this saltmarsh ecosystem and the trophic dynamics can be compared to other examples is questionable. Saltmarshes probably differ in their topography and the way in which environmental conditions affect them that then defines which species are present and how these species interact.en_US
dc.language.isoenen_US
dc.publisherUniversity of St Andrews
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/*
dc.subjectOrchestiaen_US
dc.subjectRedshanken_US
dc.subjectSparrowhawken_US
dc.subjectBottom-up effectsen_US
dc.subjectTrait-mediated interactionen_US
dc.subjectSaltmarshen_US
dc.subjectStarvation-predation risk trade-offen_US
dc.subject.lccQH541.5S24K4
dc.subject.lcshSalt marsh ecologyen
dc.subject.lcshMultitrophic interactions (Ecology)en
dc.subject.lcshSalt marsh ecology--Scotland--East Lothianen
dc.subject.lcshMultitrophic interactions (Ecology)--Scotland--East Lothianen
dc.subject.lcshOrchestia--Scotland--East Lothianen
dc.subject.lcshRedshank--Scotland--East Lothianen
dc.subject.lcshEuropean sparrowhawk--Scotland--East Lothianen
dc.titleThe influence of bottom-up effects on trophic cascades : a case study of Orchestia (Amphipoda) affecting redshank (Tringa totanus) predation risk in a saltmarsh ecosystemen_US
dc.typeThesisen_US
dc.contributor.sponsorNatural Environment Research Council (NERC)en_US
dc.contributor.sponsorUniversity of St Andrewsen_US
dc.type.qualificationlevelDoctoralen_US
dc.type.qualificationnamePhD Doctor of Philosophyen_US
dc.publisher.institutionThe University of St Andrewsen_US


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