Habitat structure modifies the strength of predator-prey interactions, but it remains unclear how to describe the three-dimensional spatial arrangement of structural components in a way that consistently predicts outcomes. Interstitial space may provide a useful target for measurement, but most studies use only two-dimensional methods to describe 3D space, limiting their predictive power. Using a novel technology to produce identical components, this study tests whether the 3D interstitial space of oyster shell mimics modifies the ability of blue crabs (Callinectes sapidus) to capture their mud crab prey (Eurypanopeous depressus) in mesocosms and a variety of reef-associated predators to capture tethered mud crabs in the field. To accomplish this, individual interstices were manipulated by changing either the orientation or internal shape of 3D printed shell mimics, representing possible ways natural oyster shells differ spatially on a reef. In mesocosms, 3D interstitial space strongly affected prey survivorship in both spatial arrangements, but striking variation in the ability of individual blue crabs to consume their prey in the Shape 1 structures was notable. Field tethering experiments mostly corroborated mesocosm findings, except in the shell shape treatment. These unexpected results were likely an artifact of differences in predation between field experiments and highlight the specificity of predator-prey interactions in structured habitats. Together, these results demonstrate that the 3D interstitial space created from the spatial arrangement of structural components can mediate predator foraging success independent of the widely studied density attribute, but these outcomes are further dependent on both predator and prey identity as well as individual variation. This study also identifies a potential target for quantifying the spatial arrangement of structural components and proposes that such a measure should be three-dimensional, capture both the size and shape of an interstice, and scaled to the specific predator-prey interaction in question.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-7292 |
| Date | 09 March 2016 |
| Creators | Hesterberg, Stephen Gregory |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
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