Differential impacts of foraging plasticity by greater flamingo Phoenicopterus roseus on intertidal soft sediments

[摘要] Predation has been a central theme in marine ecological research. However, little is known about plasticity displayed by predators and its consequences for prey assemblages in marine soft-sediment ecosystems. Here, we test the repercussions of 2 different foraging behaviours exhibited by greater flamingos Phoenicopterus roseus on benthic assemblages in intertidal sandflat ecosystems in South Africa. P. roseus feeds by either (1) creating pits, which involves flamingos stirring up deep sediments with their feet; or (2) creating channels, in which their inverted bills are swept from side to side on the sediment surface. Comparisons of assemblages in newly formed foraging structures (pits and channels) with adjacent non-foraged sediments (controls) indicated that the foraging behaviours generate differential effects on benthic communities. Contrary to our hypothesis, channel foraging elicited a stronger negative impact relative to pit foraging, for which impacts were negligible. Channel foraging had strong negative impacts on macrofaunal abundance and surface-dwelling taxa such as microalgae and the amphipod Urothoe grimaldii. Our results also revealed that variation in the size of the channels constructed by flamingos, which is a more subtle form of foraging plasticity, was inversely related to its impact. In effect, smaller channels had greater impacts on community abundance than larger ones. Overall, the study highlights the contrasting effects foraging plasticity can have on prey assemblages and its key role in driving spatial-temporal heterogeneity in intertidal sandflats. The study also highlights the need to incorporate foraging plasticity into current conceptual models of predation in marine soft sediments. 

[学科分类] 海洋学与技术

[关键词] Phoenicopteridae;Predation;Intertidal;Community structure;Ecosystem functioning