different evolutionary histories combined with limited occupation of the stressful
marine environment from terrestrial lineages (Jayatissa et al. 2002; Ricklefs et al.
2006).
Natural coastal protection, timber production, fishery, and aquaculture belong to
the ecosystem services. More than one third of the mangroves have been destroyed
during the last decades by clearing, dams and irrigation, construction of aquaculture,
and overharvesting (Hogarth 1999; Jin-Eong 2004). Changes in severity and frequencies of storms increase the pressure on mangroves in Indian ocean and Northern
America.
Sargassum brown tides are examples of the global context of coastal ecosystems.
Large amounts of Sargassum algae wash seasonally ashore on Caribbean islands,
creating a thick layer of toxic organic biomass which suffocates the mangrove trees.
The brown tides formed mid-Atlantic and are caused by nutrient loads originating
from erosion in the Amazon, Orinoco and Congo river (Van Tussenbroek
et al. 2017).
3.4 Saltmarshes
The 1960 classic study of Chapman on “salt marshes and salt deserts of the world”
already revealed the almost infinite diversity of saltmarshes, referred to as saline
areas of land bordering on the sea. In some parts of the world, they carry a highly
varied vegetation, whilst in other places only one or two species dominate. Sites
covered with vegetation frequently alternate with bare sites, often at close distance to
each other. Salt marshes can develop around dune complexes on (barrier) islands,
where water dynamics are limited, on the foreland of mainland coasts (often of an
anthropogenic origin) or on isolated mainland remnants, so-called Hallig salt marsh
islands (Esselink et al. 2017).
Generally, a saltmarsh can be divided into a seaward section (lower saltmarsh),
naturally inundated by the tide more frequently, deeper and longer than a higher
positioned landward section (upper saltmarsh), but the picture is often more complex. The area under influence of the tidal regime is generally referred to as the
intertidal zone (e.g. Esselink et al. 2017). The marshes may be intersected by
irregularly twisting creeks, that empty at low tide and fill up again at high tide,
showing their own zonation from the creek margins to the lower flats a bit further
away. Another important gradient relates to estuaries. When a river reaches the
coastal plain, it will come within tidal influences: the barrier effect of the flooding
tides reduces the flow of the river water, enhancing the deposit of sediments and as
such the development of marshes. The distance to the sea has a direct effect on the
salinity of the water, ranging from saline in open sea over brackish to completely
fresh further stream upwards in the river.
Other important factors relate to the magnitude of the tides, ranging from more
than 16 m to almost zero. The highest tide in the world is found in Canada at the Bay
of Fundy, with other extremes at the Atlantic Coasts of Great Britain and France.
Coastal Habitats, Shallow Seas and Inland Saline Steppes: Ecology,. . .
287
marine environment from terrestrial lineages (Jayatissa et al. 2002; Ricklefs et al.
2006).
Natural coastal protection, timber production, fishery, and aquaculture belong to
the ecosystem services. More than one third of the mangroves have been destroyed
during the last decades by clearing, dams and irrigation, construction of aquaculture,
and overharvesting (Hogarth 1999; Jin-Eong 2004). Changes in severity and frequencies of storms increase the pressure on mangroves in Indian ocean and Northern
America.
Sargassum brown tides are examples of the global context of coastal ecosystems.
Large amounts of Sargassum algae wash seasonally ashore on Caribbean islands,
creating a thick layer of toxic organic biomass which suffocates the mangrove trees.
The brown tides formed mid-Atlantic and are caused by nutrient loads originating
from erosion in the Amazon, Orinoco and Congo river (Van Tussenbroek
et al. 2017).
3.4 Saltmarshes
The 1960 classic study of Chapman on “salt marshes and salt deserts of the world”
already revealed the almost infinite diversity of saltmarshes, referred to as saline
areas of land bordering on the sea. In some parts of the world, they carry a highly
varied vegetation, whilst in other places only one or two species dominate. Sites
covered with vegetation frequently alternate with bare sites, often at close distance to
each other. Salt marshes can develop around dune complexes on (barrier) islands,
where water dynamics are limited, on the foreland of mainland coasts (often of an
anthropogenic origin) or on isolated mainland remnants, so-called Hallig salt marsh
islands (Esselink et al. 2017).
Generally, a saltmarsh can be divided into a seaward section (lower saltmarsh),
naturally inundated by the tide more frequently, deeper and longer than a higher
positioned landward section (upper saltmarsh), but the picture is often more complex. The area under influence of the tidal regime is generally referred to as the
intertidal zone (e.g. Esselink et al. 2017). The marshes may be intersected by
irregularly twisting creeks, that empty at low tide and fill up again at high tide,
showing their own zonation from the creek margins to the lower flats a bit further
away. Another important gradient relates to estuaries. When a river reaches the
coastal plain, it will come within tidal influences: the barrier effect of the flooding
tides reduces the flow of the river water, enhancing the deposit of sediments and as
such the development of marshes. The distance to the sea has a direct effect on the
salinity of the water, ranging from saline in open sea over brackish to completely
fresh further stream upwards in the river.
Other important factors relate to the magnitude of the tides, ranging from more
than 16 m to almost zero. The highest tide in the world is found in Canada at the Bay
of Fundy, with other extremes at the Atlantic Coasts of Great Britain and France.
Coastal Habitats, Shallow Seas and Inland Saline Steppes: Ecology,. . .
287