PhD Code: MARES_11_01:
- Host institute 1: P1 - Ghent University
- Host institute 2: P6 - Stichting Koninklijk Nederlands Instituut voor Zeeonderzoek (NIOZ)
- Host institute 3: P11 - Université Pierre et Marie Curie (UPMC)
- T4 - Natural Resources: overexploitation, fisheries and aquaculture
- T6 - Habitat loss, urban development, coastal infrastructures and Marine Spatial Planning
- Magda Vincx / Marijn Rabaut
- Tjeerd Bouma
- Jean-Marc Guarini
Coastal marine ecosystems are under increasing pressure caused by expanding human activities. Quantification of ecosystem changes remains scarce. Ecosystem engineered habitats are important to maintain biodiversity and ecosystem functioning. Ecosystem engineers can exert a strong influence on ecosystem properties (Hooper et al., 2005). To understand the impact of different human activities on these habitats, it is important to understand their natural dynamics and their resilience towards a changing environment. This doctoral research will focus on coastal ecosystem engineered habitats as in many coastal sediments ecosystem engineers are known to have far reaching consequences for local biodiversity, ecosystem functioning and landscape formation (Bouma et al., 2009). Organisms that engineer sediments tend to have large effects on the ecosystem. This doctoral research will use the habitat formed by the tube building polychaete Lanice conchilega, a dominant ecosystem engineer in coastal marine areas (Rabaut et al., 2007, Van Hoey et al., 2008). The species tends to aggregate in high density patches forming gentle mounds and shallow depressions. These reefs (Rabaut et al., 2009) have specific biological, physical and temporal features. Bottom disturbance by beam trawling and hydrodynamic changes as a consequence of harbours and wind mill farms may have implications on the dynamics of this ecosystem engineered habitat. It remains however largely unknown what determines the observed reef dimensions, patchiness, elevation and long-term stability/migration. The stability of patches under beam trawl fishing pressure and under changing hydrodynamic forces (cf. Harbour infrastructures) is yet unknown but important from an ecosystem functioning and conservation point of view.
*Aims of the doctoral research
The overall aim is to understand the dynamic pattern of patches of ecosystem engineers which are under anthropogenic pressure; more specifically, intertidal L. conchilega reef patches are used as case study:
1. To understand the drivers of formation and decay of patches;
2. To quantify the stability of reef patches;
3. To map reef patch boundary evolution over time;
4. To model reef dynamics (including different impact scenarios);
As these results will be linked to existing and future human activities in coastal areas, this will allow to developing nature conservation strategies using ecosystem engineers.
1.Field work: Kite aerial photography (KAP) and reef tube densities
The spatial evolution of reef patches will be examined through an observational study similar to those of Scoffin (1982), Smith et al. (2009), and Pauly (2011). During a period of one year, a monthly survey of aerial images of reef patches will be performed in a sand flat during the spring low tide, at which time patches are exposed to air. The time series samples will be taken with a digital camera (Pentax Optio W90) fixed to a rig (refer to Pauly, 2011 for details) suspended from the kite (FlowForm 32’) line using a mechanically stabilizing Picavet suspension. The kite line has a maximum length of 100 m, allowing for broad range imagery and hence for accurate measurements of a multitude of reefs. Imagery will be collected in order to construct a time series enabling the comparison of 2D spatial fluctuations of reef patches.
Kite aerial photography (also referred as KAP) has in past years been utilized in land-based studies (Marzolff and Poesen, 2009, Planer-Friedrich et al., 2008, Siebert et al., 2004, Smith et al., 2009, Wundram and Löffler, 2008). It is a methodology that is inexpensive, easily transportable, and easily operated under coastal conditions (Pauly, 2011, Scoffin, 1982), its effectiveness in detecting the spatial dynamics of macrofaunal species in intertidal beaches is promising (Alves, 2011).
The study area is situated in Boulogne-sur-mer (Nord-Pas-de-Calais, France). It comprises a portion of 0.0943 Km2 of sheltered sand flat. The site is known for presenting a thriving Lanice conchilega community which becomes partially exposed at every low tide, enabling imagery acquisition, tube density and patch height sampling, as well as core extractions with no major logistic constrains (Rabaut et al., 2008).
2.Lab work: flume experiments
The flume facilities of the research centre in Yerseke, The Netherlands (NIOZ-NIOO-CEME) can be used to perform experiments on reef stability. The flume set up will be used to provide insights in reef edge effects by testing the hydrodynamic forcing of current flow velocities and waves. The relation between reef stability and elevation will be investigated by adding a small layer of sediment on existing reefs during 7 subsequent days. Stability of high density patches will be tested using a small flume chamber. Different patch heights will be applied. At each run one patch will be inserted into the flume chamber filled with filtered sea water generating a column of 25 cm depth. After a 10 minutes period, a middle transect of sediment height is measured with the aid of a hand held laser meter.
*Value of the research
This research will be promoted by different institutes with expertise in the field of benthic ecosystem functioning, aerial photography, complex spatial analyses, laboratory set up (flume research) and modeling. Investigating the functioning of ecosystem engineers is increasingly important for our understanding of ecosystems (Hooper et al., 2005, Wilby, 2002). Moreover, as a proper management of important engineers can protect numerous associated species and functions by expanding distributional limits for numerous species, it has been advocated to use these organisms as conservation targets (Crain and Bertness, 2006). Understanding dynamics of important ecosystem engineers is therefore important baseline information to understand (1) the impact of physical disturbance through fisheries activities on benthic ecosystems and (2) the use of ecosystem engineers in marine spatial management (including prediction of habitat loss and the impact of coastal infrastructures). Therefore, all field and lab results will be linked to the effect of physical disturbance (e.g. of beam trawl fisheries) and changing hydrodynamic forces (e.g. as a consequence of harbor and wind mill construction).
*Contribution of consortium partners
UGent-Marine Biology (Prof. Dr. Magda Vincx and Dr. Marijn Rabaut): general supervision of thesis research, kite aerial photography and experimental design.
NIOZ-NIOO-CEMA (Dr. Tjeerd Bouma): flume experiments, spatial analyses
UPMC (Prof. Dr. J.M. Guarini): modeling
Alves, R. 2011. Patch dynamics in reef formations of the tube-building polychaete Lanice conchilega, Pallas 1766. Ghent University (UGent), MSc thesis, 38 pp.
Bouma, T., Olenin, S., Reise, K. and Ysebaert, T. 2009. Ecosystem engineering and biodiversity in coastal sediments: Posing hypotheses. Helgoland Marine Research, 63: 95-106.
Crain, C.M. and Bertness, M.D. 2006. Ecosystem engineering across environmental gradients: Implications for conservation and management. Bioscience, 56: 211-218.
Hooper, D.U., Chapin, F.S., Ewel, J.J., Hector, A., Inchausti, P., Lavorel, S., Lawton, J.H., Lodge, D.M., Loreau, M., Naeem, S., Schmid, B., Setala, H., Symstad, A.J., Vandermeer, J. and Wardle, D.A. 2005. Effects of biodiversity on ecosystem functioning: A consensus of current knowledge. Ecological Monographs, 75: 3-35.
Marzolff, I. and Poesen, J. 2009. The potential of 3D gully monitoring with GIS using high-resolution aerial photography and a digital photogrammetry system. Geomorphology, 111: 48-60.
Pauly, K. 2011. GIS-based environmental analysis, remote sensing and niche modeling of seaweed communities. Ghent University (UGent), PhD thesis, pp.
Planer-Friedrich, B., Becker, J., Brimer, B. and Merkel, B.J. 2008. Low-cost aerial photography for high-resolution mapping of hydrothermal areas in Yellowstone National Park. International Journal of Remote Sensing, 29: 1781-1794.
Rabaut, M., Braeckman, U., Hendrickx, F., Vincx, M. and Degraer, S. 2008. Experimental beam-trawling in Lanice conchilega reefs: Impact on the associated fauna. Fisheries Research, 90: 209-216.
Rabaut, M., Guilini, K., Van Hoey, G., Vincx, M. and Degraer, S. 2007. A bio-engineered soft-bottom environment: The impact of Lanice conchilega on the benthic species-specific densities and community structure. Estuarine Coastal and Shelf Science, 75: 525-536.
Rabaut, M., Vincx, M. and Degraer, S. 2009. Do Lanice conchilega (sandmason) aggregations classify as reefs? Quantifying habitat modifying effects. Helgoland Marine Research, 63: 37-46.
Scoffin, T.P. 1982. Reef aerial photography from a kite. Coral Reefs, 1: 67-69.
Siebert, S., Gries, D., Zhang, X., Runge, M. and Buerkert, A. 2004. Non destructive dry matter estimation of Alhagi sparsifolia vegetation in a desert oasis of Northwest China. Journal of Vegetation Science, 15: 365-372.
Smith, M.J., Chandler, J. and Rose, J. 2009. High spatial resolution data acquisition for the geosciences: kite aerial photography. Earth Surface Processes and Landforms, 34: 155-161.
Van Hoey, G., Guilini, K., Rabaut, M., Vincx, M. and Degraer, S. 2008. Ecological implications of the presence of the tube-building polychaete Lanice conchilega on soft-bottom benthic ecosystems. Marine Biology, 154: 1009-1019.
Wilby, A. 2002. Ecosystem engineering: a trivialized concept? Trends in Ecology & Evolution, 17: 307-307.
Wundram, D. and Löffler, J. 2008. High-resolution spatial analysis of mountain landscapes using a low-altitude remote sensing approach. International Journal of Remote Sensing, 29: 961-974.
We expect to build a model describing the dynamic patterns of a specific ecosystem engineered habitat (in casu L. conchilega reefs). The research will deliver publications on the formation and decay of the patches, on the stability of reefs and on the reef patch boundary change over time. An overall research article including the human impacts on the dynamics of the habitat is to be expected (with a focus on fisheries impacts, habitat loss, changing hydrodynamics as a consequence of harbours and wind mills). The results will be important for marine managers and will be of interest for the public at large. Moreover, innovative techniques including the use of aerial photography in science are valuable in terms of publications, outreach and potential methodology for monitoring.