- 期刊
Sea Level Rise, causes, consequences, and environmentally friendly techniques aimed at coastal protection: online educational and informative resources - Part 3
摘要
The article presents informative and educational resources, downloadable for free from the internet, that deal with the role played in wave attenuation by salt marshes, beaches and dunes, shellfish reefs and sea grass beds. Such resources consist of text, graphs, images and videos and can also be used for teaching units in the school. The energy of waves propagating into the shallow waters of a salt marsh is attenuated by both the depth-induced wave breaking and the forces that vegetation exerts. A salt marsh can trap sediment, if available, and rise its elevation thus coping with sea level rise. Some salt marshes are being restored, while others are threatened by human activities. Wide beaches and large dunes contribute to dissipate wave energy, thus protecting people and coastal properties. Often such ecosystems suffer erosion; the article presents papers on beach nourishment, dune protection, restoration and enhancement. Bivalves filter the water and create a clear environment that supports the life of aquatic grasses that, in turn, contribute to bottom stabilization. Artificial oyster reefs, besides attenuating waves, currents and erosion, provide other ecosystem services. Some quoted articles deal with possibilities and limits for natural or aquacultured macroalgae or seagrasses, to locally protect calcifying organisms, such as bivalves and corals, from the adverse effects of ocean acidification. In fact, the excess carbon dioxide present in the water can be used for their photosynthetic activity. Seagrasses may contribute in attenuating waves and they are more effective in doing so if occupying a large part of the water column. Globally, seagrasses are lost at a rate of 1.5% per year as a consequence of anthropisation. Among the impacting factors for seagrasses there is sea level rise. This is particularly true in turbid waters, where even a small change in depth leads to a heavy reduction in available light, whereas does not apply to such an extent for clear water environments.