title: Effects of wind waves versus ship waves on tidal marsh plants: a flume study on different life stages of Scirpus maritimus.
abstract: Recent research indicates that many ecosystems, including intertidal marshes, follow the alternative stable states theory. This theory implies that thresholds of environmental factors can mark a limit between two opposing stable ecosystem states, e.g. vegetated marshes and bare mudflats. While elevation relative to mean sea level is considered as the overall threshold condition for colonization of mudflats by vegetation, little is known about the individual driving mechanisms, in particular the impact of waves, and more specifically of wave period. We studied the impact of different wave regimes on plants in a full scale flume experiment. Seedlings and adult shoots of the pioneer Scirpus maritimus were subjected to two wave periods at two water levels. Drag forces acting on, and sediment scouring occurring around the plants were quantified, as these are the two main mechanisms determining plant establishment and survival. Depending on life stage, two distinct survival strategies emerge: seedlings present a stress avoidance strategy by being extremely flexible, thus limiting the drag forces and thereby the risk of breaking. Adult shoots present a stress tolerance strategy by having stiffer stems, which gives them a higher resistance to breaking. These strategies work well under natural, short period wind wave conditions. For long period waves, however, caused e.g. by ships, these survival strategies have a high chance to fail as the flexibility of seedlings and stiffness of adults lead to plant tissue failure and extreme drag forces respectively. This results in both cases in strongly bent plant stems, potentially limiting their survival.
authors: Ecosystem Management Research Group, Department of Biology, University of Antwerp, Wilrijk (Antwerp), Belgium.
authors: Alexandra
authors: A
authors: Silinski
authors: Federal Institute of Hydrology, Koblenz, Germany.
authors: Maike
authors: M
authors: Heuner
authors: Ecosystem Management Research Group, Department of Biology, University of Antwerp, Wilrijk (Antwerp), Belgium.
authors: Jonas
authors: J
authors: Schoelynck
authors: UMR 5023 LEHNA, Université Lyon 1, CNRS, ENTPE, Villeurbanne, France.
authors: Sara
authors: S
authors: Puijalon
authors: Federal Institute of Hydrology, Koblenz, Germany.
authors: Uwe
authors: U
authors: Schröder
authors: Federal Institute of Hydrology, Koblenz, Germany.
authors: Elmar
authors: E
authors: Fuchs
authors: Department of Civil Engineering, Ghent University, Zwijnaarde (Ghent), Belgium.
authors: Peter
authors: P
authors: Troch
authors: Royal Netherlands Institute for Sea Research, Yerseke, The Netherlands.
authors: Tjeerd J
authors: TJ
authors: Bouma
authors: Ecosystem Management Research Group, Department of Biology, University of Antwerp, Wilrijk (Antwerp), Belgium.
authors: Patrick
authors: P
authors: Meire
authors: Ecosystem Management Research Group, Department of Biology, University of Antwerp, Wilrijk (Antwerp), Belgium.
authors: Stijn
authors: S
authors: Temmerman
mesh_terms: D029785:Cyperaceae / Q000502:physiology*; D018520:Plant Shoots / Q000502:physiology; D012639:Seeds / Q000502:physiology; D012767:Ships; D055871:Tidal Waves; D053833:Wetlands; D014919:Wind