Browsing by Author "du Plessis, Darren Scott"

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    Temporal interactions with flamingo foraging plasticity: ecological effects on basal resources and benthic heterogeneity
    (2018) du Plessis, Darren Scott; Pillay, Deena
    The role of predation as a structuring agent of communities has been a focal area of research in marine ecology. Conversely, studies focusing on foraging plasticity, particularly by shorebirds, and consequences for benthic community structure, heterogeneity and ecosystem functioning have been limited in marine soft-sediments. Temporal interactions with foraging plasticity is an even greater knowledge gap. The primary goal of this dissertation was to expand on current understanding of foraging plasticity and the broader ecological role of Greater Flamingos as predators in marine sedimentary ecosystems. The specific aim was to test the long-term effects of different foraging structure sizes (which is a subtle form of foraging plasticity) on sedimentary assemblages following foraging disturbances. In situ comparisons of large and small foraging structures created by the flamingos with adjacent non-foraged sediments (controls) indicated that small channels had greater concentrations of sediment organic matter relative to large channels following feeding. Additionally, small feeding structures supported greater abundances of the burrowing amphipod Urothoe grimaldii and the grazing gastropod Assiminea globulus along with elevated size-specific sediment deposition rates. These results shed light on the differential timedependent impacts flamingo foraging plasticity can generate on basal trophic resources and higher consumers. Results also showed that irrespective of size, feeding channels made by flamingos generally became enriched with microalgae following foraging, with this enrichment effects spilling over into non-foraged controls sediments. This indicates that foraging by flamingos has the potential to create resource islands that become enriched with microalgae over time, with effects spilling over into adjacent non-foraged areas. Importantly, these positive effects may oppose the negative effects of bioturbation by burrowing sandprawns on productivity, which is a dominant process in the study area. This study emphasizes the importance of Greater Flamingos in regulating basal resource supply, community structure and spatio-temporal heterogeneity and has highlighted the need for predation models within sedimentary environments to incorporate time-dependent effects of foraging plasticity into current thinking.