Dutch title: Ecomorfologische interacties in schorrenontwikkeling Funder identifier: OND1290750 (Other contract id) Period: January 2001 till December 2005 Status: Completed
PROBLEM DEFINITION:
This project addresses the scientific questions sketched above in the framework of 'species as ecological engineers'. It will focus on (a) the interaction between plants (in particular Spartina anglica) and physical conditions of currents, waves and sediment transport and (b) the interactions between plants (Spartina, Zostera) and macrobenthic animals.
OBJECTIVES:
· To describe from field studies how natural populations of Spartina, Zostera and macrobenthic animals form small-scale patterns in interaction with physical forces.
· To compare these small-scale patterns at different locations in different estuaries and link them to general conditions of flow and wave exposure.
· To relate these patterns to processes of salt marsh formation and erosion.
· To quantify the rate of growth of Spartina tussocks and evaluate the clonal competition processes involved.
· To test experimentally in the field and laboratory specific hypotheses on the processes operating.
· To develop mathematical models for the current/wave/plant/macrobenthos interactions.
· To estimate essential parameters of these models from dedicated flume experiments.
· To describe, in the context of the Paulinapolder saltmarsh study, the evolution over the past decades of the saltmarsh.
· To relate these findings to the measured dynamics in the field.
· To combine both approaches in order to predict future evolution of the marsh.
ACHIEVEMENTS 2002:
A large field observation and experiment project has been executed in the saltmarsh of Paulinapolder. This work was executed in close cooperation with partners in the Delft Cluster programme (Delft Hydraulics, RIKZ, TuDelft, IHE). A joint measuring campaign was set up to measure hydrodynamic conditions and sediment transport in relation to the expanding Spartina populations. The relative roles of saltmarsh plants and macrobenthic animals in the process were measured. A survey of shapes of Spartina tussock at different locations was executed. This information will be used as input in flume studies, to obtain information on the link between the processes, patterns and hydrodynamical conditions. The shape of the tussock was also used as reference material for sedimentation and erosion measurements in artificial tussocks made out of bamboo sticks. Flume experiments were executed both in the NIOO flume and in the wave flume of Delft Hydraulics. They used Spartina, Salicornia, Zostera noltii as well as artificial plant mimics to focus on the effect of plant stiffness by excluding morphological differences. Historical aerial photographs of saltmarsh development have been analysed in GIS. Rates and patterns of change in vegetation have been derived from this analysis. Modelling has started with a simple, principal model of saltmarsh development as a consequence of positive interactions between vegetation and sedimentation. Detailed (3-D) process-based models are being developed in cooperation with Delft Hydraulics.
PLANNING 2003:
The data sets from the large field programme will be analysed statistically, and summarised for use in modelling. Samples of macrobenthos at the saltmarsh edge will be analysed. GIS data of several saltmarshes in the Westerschelde will be added to the data set on Paulinapolder. The interaction between sea grasses, benthos and hydrodynamics will be studied in a 2-week field campaign in Indonesia. Modelling will be continued. Additional flume experiments will be performed to complete the data set of 2002. Field experiments are currently being designed, involving artificial vegetations and field flumes. Results will be combined for publication.
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