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5 Coasts – A Vital Habitat Under Pressure

Living with the coasts

Living with the coasts
> For millennia, people have utilized the world’s coastal areas. Coasts provide a space for trading, supply resources and underpin fisheries. It is no surprise that societies have always struggled to gain maritime supremacy. Now, however, humankind is exploiting coastal regions to such a degree that these areas are no longer able to render all of the ecosystem services that people value and need so much. Coastal areas are degraded particularly by construction and pollution.
Coastal functions © Pietro Canali/SIME/Schapowalow/Mato

Coastal functions

> So vielfältig wie die Küstenlebensräume sind auch die Leistungen, die sie für die Menschen erbringen. Manche dieser Leistungen, wie die Produktion von Fisch, stehen vielerorts zur Verfügung, andere nur in einigen wenigen Gebieten – etwa die Bereitstellung von Bodenschätzen wie Diamanten in den Gewässern vor Namibia. Und schon seit jeher sind Küsten für den Menschen interessante Siedlungs- und Handelsplätze.

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Coastal pressures © Reuters/Damir Sagolj

Coastal pressures

> Human overexploitation constitutes the greatest threat to the coasts today. Coastal sites attract increasingly high-density building development. Coastal waters are being contaminated by pollutants or excessive nutrient run-off. And because population growth and migration continue unabated, pressure on the coasts is unlikely to diminish in future.

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Immense performance, immense pressure

Humans have been closely associated with coastal ecosystems for millennia. They have used the coasts both as a source of food and a space for trading. Archaeological finds indicate that humans navigated coastal waters in simple boats as early as 6000 years BC, for example in the South China Sea and the eas- tern Mediterranean. Coasts have also always been the arena of countless conflicts among parties seek- ing to gain political or economic dominance in a given region.
Coasts deliver many different types of services that are generically termed ecosystem services. These include the “provisioning ecosystem services”, i.e. the goods provided by the oceans such as fish or fossil resources. The “supporting ecosystem services” are of key importance. They include primary production, i.e. the production of biomass by algae through the process of photosynthesis. Primary production is in fact a precondition to marine life. In addition, there are “cultural ecosystem services” such as the coasts’ spiritual significance and their vital role in tourism. “Regulating ecosystem services” are clearly of special importance with regard to environmental pollution caused by humans. These services primarily include the cleaning function performed by coastal waters, as they significantly contribute to the degradation of nutrients reaching the oceans from intensively used arable farmland or untreated sewage.
In many cases, humans are overexploiting coas- tal waters at present, thus preventing them from per- forming their ecosystem functions. If nutrient inputs into the oceans from agriculture or aquaculture are too high, these nutrients can no longer be elimina- ted. Watercourses suffer from eutrophication, resulting in the spread of oxygen-depleted zones. Moreo- ver, industrial pollutants are a threat to coastal waters. The latter include heavy-metal-containing compounds as well as persistent chemical substances that accumulate in the food chain and cause illnesses such as cancer. Such substances include, for example, polyfluorinated compounds which have been used for years in common products such as outdoor clothing or cookware coatings.
Plastic litter is another type of pollution reaching the oceans through diverse pathways. Marine ani- mals and seabirds ingest plastic particles and die as a result. Moreover, plastic litter breaks down into microscopically small fragments. These microplastics are now present throughout the world’s oceans. Scientific studies are underway to determine the degree to which animals are ingesting and are at risk from microplastics.
Overfishing is doubtlessly one of the most signi- ficant problems currently faced in coastal waters. These waters are particularly productive, and are thus fished too intensively. Moreover, in many places fishing activities destroy seafloor habitats such as coral reefs.
Uncontrolled proliferation of settlements and the growth of coastal megacities are profoundly changing the coasts today and have led to the loss of important ecosystems such as floodplains, wetlands and mangroves. Moreover, sand extraction for build- ing projects causes widespread damage to coastal areas. A particular threat to human society is arising from the gradual sinking of coastal metropolises. This subsidence is caused, in particular, by the pumping of groundwater for human consumption. Normally the groundwater functions as an abutment to the heavy mass of buildings above. Incidences of flooding are becoming ever more frequent as a result of urban subsidence. Rising sea levels in the wake of climate change may exacerbate this situation in future.