of the coastal surf and currents, the characteristic of the tidal system, and fluctuations
in sea level help to refine basic classification schemes. Transnational schemes of
classifications on habitat or plant community level and with respect to biogeography,
ecology, structure and species composition have been published by, among others,
Davies et al. (2004), Janssen et al. (2016), IUCN (2019), and Pätsch et al. (2019).
Plant communities at the coast with the same structure and a comparable species
composition may be called saltmarsh. These are generally assigned to specific
coastal vegetation units, whereas their inland counterpart, called salt steppes, are
mostly assigned to grasslands. Like other names for habitat types or vegetation units,
many of them are defined in different ways. Moreover, different names are sometimes used for the same unit. Therefore, we try to unify the terminology.
With respect to the mentioned classification schemes, related groups of habitats
can be ordered as described in Table 1.
In the following, we briefly consider environmental conditions including human
influence of selected habitat types from the marine environment to the shoreline, and
from coast to inland.
3.1 Coral Reefs
Corals are marine invertebrates (Anthozoa). Many of them use the photosynthesis of
symbiotic microscopic algae (Zooxanthellae). Therefore, they need sunlight and
prefer clear water. However, nearly as many deep-water coral species without
symbiotic algae exist. Corals, algae and sponges are reef-building organisms. Most
reefs occur in shallow tropical marine environments between latitudes 38
N and 25
S. Deep and cold water coral and sponge reefs, bioherms or banks exist to a smaller
extent outside of the Tropics, for example in the North Atlantic, Canadian Arctic and
Antarctic continental shelves (Freiwald and Roberts 2006).
All these systems provide habitat to a multitude of other species and are rich
e.g. in terms of fish, mollusc, crustacean, echinoderm, sponge, and tunicate species.
They cover less than 0.1% of the marine ground. However, it is estimated that they
harbour round about a quarter of all marine species (Murphy 2002; Hopley 2011).
Coral reefs have an important function as fish nurseries and are therefore, ecologically, closely linked to other coastal habitats (Unsworth et al. 2008).
Damage and decline of coral reefs are caused by destructive fishing, tourism,
land-based pollution and runoff, and climate effects including severe weather,
temperature stress and coral bleaching (Cesar et al. 2003; Rinkevich 2008). Interactions within the disturbance factors often lead to an exacerbation of the situation
(Ellis et al. 2019). Coral reefs belong to the most charismatic ecosystems in the
world. The attraction to humans results in a massive coral reef tourism. This has both
effects positive and negative ones. The recent challenge is to intensify nature
conservation efforts and to reduce disturbance (Lirman and Schopmeyer 2016;
Finea et al. 2019).
284
C. Hobohm et al.
in sea level help to refine basic classification schemes. Transnational schemes of
classifications on habitat or plant community level and with respect to biogeography,
ecology, structure and species composition have been published by, among others,
Davies et al. (2004), Janssen et al. (2016), IUCN (2019), and Pätsch et al. (2019).
Plant communities at the coast with the same structure and a comparable species
composition may be called saltmarsh. These are generally assigned to specific
coastal vegetation units, whereas their inland counterpart, called salt steppes, are
mostly assigned to grasslands. Like other names for habitat types or vegetation units,
many of them are defined in different ways. Moreover, different names are sometimes used for the same unit. Therefore, we try to unify the terminology.
With respect to the mentioned classification schemes, related groups of habitats
can be ordered as described in Table 1.
In the following, we briefly consider environmental conditions including human
influence of selected habitat types from the marine environment to the shoreline, and
from coast to inland.
3.1 Coral Reefs
Corals are marine invertebrates (Anthozoa). Many of them use the photosynthesis of
symbiotic microscopic algae (Zooxanthellae). Therefore, they need sunlight and
prefer clear water. However, nearly as many deep-water coral species without
symbiotic algae exist. Corals, algae and sponges are reef-building organisms. Most
reefs occur in shallow tropical marine environments between latitudes 38
N and 25
S. Deep and cold water coral and sponge reefs, bioherms or banks exist to a smaller
extent outside of the Tropics, for example in the North Atlantic, Canadian Arctic and
Antarctic continental shelves (Freiwald and Roberts 2006).
All these systems provide habitat to a multitude of other species and are rich
e.g. in terms of fish, mollusc, crustacean, echinoderm, sponge, and tunicate species.
They cover less than 0.1% of the marine ground. However, it is estimated that they
harbour round about a quarter of all marine species (Murphy 2002; Hopley 2011).
Coral reefs have an important function as fish nurseries and are therefore, ecologically, closely linked to other coastal habitats (Unsworth et al. 2008).
Damage and decline of coral reefs are caused by destructive fishing, tourism,
land-based pollution and runoff, and climate effects including severe weather,
temperature stress and coral bleaching (Cesar et al. 2003; Rinkevich 2008). Interactions within the disturbance factors often lead to an exacerbation of the situation
(Ellis et al. 2019). Coral reefs belong to the most charismatic ecosystems in the
world. The attraction to humans results in a massive coral reef tourism. This has both
effects positive and negative ones. The recent challenge is to intensify nature
conservation efforts and to reduce disturbance (Lirman and Schopmeyer 2016;
Finea et al. 2019).
284
C. Hobohm et al.