Hulisz 2011). Various animal and plant taxa are adapted to high and/or fluctuating
salt concentration, little freshwater and desiccation. Vascular plant families which
regularly occur in saline flats are e.g. Chenopodiaceae (Salicornia, Sarcocornia,
Suaeda, Enchylaena, Sclerolaena, and many others), Plumbaginaceae
(e.g. Limonium), Poaceae (Puccinellia) and Aizoaceae (e.g. Gunniopsis in
Australia). Many genera represent higher species numbers inland than in coastal
saltmarshes.
Salt steppe, brackish swamps or halophytic shrubland, salt lakes and crusts of salt
without any vegetation but characteristic fauna can be found in the surrounding of
depressions, sources or running saline or brackish waters In many cases the salinity
of soils and waters is not stable and may change periodically in relation to the
precipitation regime, or increases or decreases over a long time (Williams 1978;
Westhus et al. 1997; Luo et al. 2013, 2017).
4 Species Diversity and Threatened Biota
4.1 Diversity
In general, the biodiversity, i.e. number of species or individuals per unit area, and
biomass declines when comparing coastal to deep sea regions. However, as the
scientific exploration of the deep sea is expensive and the community of ecologists
working on deep sea ecology is small, also the knowledge on the deep sea is limited
(Tittensor et al. 2010).
The diversity of organisms at higher taxonomic levels is much greater in the seas
than on the land. This fact has to do with the high age of oceans and the long
evolutionary history (Goetting et al. 1988; Mora et al. 2011).
Taking into account that only a very small proportion of the Earth’s surface is
covered by coastal habitats, the amount of species and endemism adopted to the this
small transition zones is high. In general, tropical regions harbour higher marine,
coastal and near-coastal biodiversity and almost the whole range of marine biodiversity hotspots in comparison with higher latitudes (Roberts et al. 2002; Worm et al.
2005; Ramírez et al. 2017).
4.2 Threatened Biota and Threats
Table 2 gives an overview of numbers of threatened species in shallow (subtidal)
coastal waters. According to the numbers in this table, the related habitats are highly
vulnerable and impacted by humans. Figure 1 gives an example of a recent vegetation dieback at Bonaire.
The Pacific Ocean harbours the largest number of critically endangered (CR) or
threatened species (CR, EN, plus VU). The Indian Ocean and Atlantic Ocean are
Coastal Habitats, Shallow Seas and Inland Saline Steppes: Ecology,. . .
293
salt concentration, little freshwater and desiccation. Vascular plant families which
regularly occur in saline flats are e.g. Chenopodiaceae (Salicornia, Sarcocornia,
Suaeda, Enchylaena, Sclerolaena, and many others), Plumbaginaceae
(e.g. Limonium), Poaceae (Puccinellia) and Aizoaceae (e.g. Gunniopsis in
Australia). Many genera represent higher species numbers inland than in coastal
saltmarshes.
Salt steppe, brackish swamps or halophytic shrubland, salt lakes and crusts of salt
without any vegetation but characteristic fauna can be found in the surrounding of
depressions, sources or running saline or brackish waters In many cases the salinity
of soils and waters is not stable and may change periodically in relation to the
precipitation regime, or increases or decreases over a long time (Williams 1978;
Westhus et al. 1997; Luo et al. 2013, 2017).
4 Species Diversity and Threatened Biota
4.1 Diversity
In general, the biodiversity, i.e. number of species or individuals per unit area, and
biomass declines when comparing coastal to deep sea regions. However, as the
scientific exploration of the deep sea is expensive and the community of ecologists
working on deep sea ecology is small, also the knowledge on the deep sea is limited
(Tittensor et al. 2010).
The diversity of organisms at higher taxonomic levels is much greater in the seas
than on the land. This fact has to do with the high age of oceans and the long
evolutionary history (Goetting et al. 1988; Mora et al. 2011).
Taking into account that only a very small proportion of the Earth’s surface is
covered by coastal habitats, the amount of species and endemism adopted to the this
small transition zones is high. In general, tropical regions harbour higher marine,
coastal and near-coastal biodiversity and almost the whole range of marine biodiversity hotspots in comparison with higher latitudes (Roberts et al. 2002; Worm et al.
2005; Ramírez et al. 2017).
4.2 Threatened Biota and Threats
Table 2 gives an overview of numbers of threatened species in shallow (subtidal)
coastal waters. According to the numbers in this table, the related habitats are highly
vulnerable and impacted by humans. Figure 1 gives an example of a recent vegetation dieback at Bonaire.
The Pacific Ocean harbours the largest number of critically endangered (CR) or
threatened species (CR, EN, plus VU). The Indian Ocean and Atlantic Ocean are
Coastal Habitats, Shallow Seas and Inland Saline Steppes: Ecology,. . .
293