  Articles and gems - Protecting sandy coasts - Marine vegetation
This is one of the sandy coast pages (first page).
Vegetation is a very important factor in the dynamics of a tidal area.
Lagoons and tidal areas in the tropics and subtropics are often protected from erosion
by mangroves or by salt marsh grasses such as Spartina.
Florida residents used to cut
mangroves to have a nicer view of the water from their properties. That proved disastrous
not only in terms of damaging the ecosystem but also in protection against hurricane-caused
surges. Vegetation traps sediments and slows down waves.
Nowadays, Florida regulations no longer allow residents to remove all the
mangroves on their property.
Not only sandy coasts undergo erosion. The area around San Diego in California is also highly
vulnerable. UCSD recently started a research project into how to stabilize the local coastline
(Source: Technisch Weekblad, April 4, 2001).
The figure below (source: CRS) dates back to 1982. Eel grasses were present in scattered
locations around Norderney then.
Seagrasses are the
nurseries and soup kitchens for many marine organisms. A healthy seagrass vegetation
generally means a healthy ecosystem. Maintaining a healthy seagrass vegetation has
become a challenge at many locations all over the world.
Seagrasses covered 6,000 to 15,000 hectares of the Dutch part of the Wadden Sea until
the middle of the 1930s. Various factors, including nutrient overload and the construction
of dams and dikes, led to the demise of the seagrasses in the Wadden Sea. Seagrasses
now cover only about 120 hectares (at the time when this page was first written, in 2001,
shortly after the field trip).
The University of Nijmegen has been studying the problem. Particularly the
increasingly dynamic character of the Wadden Sea, partly caused by the disappearance
of the seagrasses, and nutrient overload have been confirmed as the culprits.
Creating suitable areas for seagrasses to be planted may help. Other measures, such
as protecting the integrity of the sea bottom (cockle fishing!) and lowering the loads
of particularly nitrogen, may be even more important. See also this Ph.D. thesis by M.M. van Katwijk.
Final thought
The Wadden Sea area's characteristics are hotly debated in The Netherlands. Oil
companies want to drill in the area and start producing. Others are worried about what
this will do to the ecology. Would the area subside due to gas and oil winning? Or would
sedimentation be able to keep up? The answers to questions like this will have important
implications for all Wadden Islands, including Norderney.
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Waiting for the ferry
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November 24, 2007
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