Ecosystem Engineering by Seagrasses Interacts with Grazing to Shape an Intertidal Landscape

Abstract

Self-facilitation through ecosystem engineering (i.e., organism modification of the abiotic environment) and consumer-resource interactions are both major determinants of spatial patchiness in ecosystems. However, interactive effects of these two mechanisms on spatial complexity have not been extensively studied. We investigated the mechanisms underlying a spatial mosaic of low-tide exposed hummocks and waterlogged hollows on an intertidal mudflat in the Wadden Sea dominated by the seagrass Zostera noltii. A combination of field measurements, an experiment and a spatially explicit model indicated that the mosaic resulted from localized sediment accretion by seagrass followed by selective waterfowl grazing. Hollows were bare in winter, but were rapidly colonized by seagrass during the growth season. Colonized hollows were heavily grazed by brent geese and widgeon in autumn, converting these patches to a bare state again and disrupting sediment accretion by seagrass. In contrast, hummocks were covered by seagrass throughout the year and were rarely grazed, most likely because the waterfowl were not able to employ their preferred but water requiring feeding strategy (‘dabbling’) here. Our study exemplifies that interactions between ecosystem engineering by a foundation species (seagrass) and consumption (waterfowl grazing) can increase spatial complexity at the landscape level.

How habitat-modifying organisms structure the food web of two coastal ecosystems

“…Habitat modifiers, also described as 'ecosystem engineers' or 'foundation species', are increasingly recognized as important drivers of ecosystem functions [16,[21][22][23][24][25][26][27][28]. Although habitat modifiers are part of the food web like any other species (e.g.…”

Local Competition and Metapopulation Processes Drive Long-Term Seagrass-Epiphyte Population Dynamics

“…In this sub-tidal environment, there are no large grazing species, such as the geese that affect inter-tidal seagrass populations [46], [47], or the marine turtles and sirenians of tropical seagrass habitats [48], [49]. In addition, our choice of location is an archipelago with little industrial or agricultural impact or urbanization (Fig.…”

Temporal pattern in biometrics and nutrient stoichiometry of the intertidal seagrass Zostera japonica and its adaptation to air exposure in a temperate marine lagoon (China): Implications for restoration and management

“…Seagrasses, a unique group of marine flowering plants, are widely distributed along temperate and tropical coastlines of the world, and they provide numerous important ecological services to the marine environment (Costanza et al, 1997;Barbier et al, 2011). Seagrasses are prominent marine ecosystem engineers, or foundation species, as they can attenuate currents and waves (Bouma et al, 2005;Koch et al, 2009), alter nutrient cycling and food web structure (Hemminga and Duarte, 2000;Barbier et al, 2011), and control sediment erosion (Fonseca, 1996;van der Heide et al, 2012;Christianen et al, 2013). Moreover, seagrass beds are key sites for global carbon storage in the biosphere (Fourqurean et al, 2012;Macreadie et al, 2014).…”