Coastal ecosystems are under pressure

Coastal ecosystems worldwide bring an enormous value in ecosystem services to humans, however, they are facing increasing pressures due to climate change and human expansion. Twenty years ago, a comparative study of two coastal ecosystems – the Northern Adriatic and the Chesapeake Bay in the US – studied common issues these coasts face. These include nutrient pollution, overfishing, and limitations in jurisdictional management. Now, twenty years later, researchers observed striking changes in the two locations, as they respond to the increasing anthropogenic pressures as well as climate change.

Different ecosystems, similar issues

The Chesapeake Bay and Northern Adriatic both get their freshwater and nutrient inputs by one river (the Susquehanna River in the former and the Po River in the latter). Moreover, both systems have the same size of watersheds and they both host about 18 million people. Meanwhile Chesapeake is a shallow, long and narrow bay relatively isolated from the coastal ocean. The Northern Adriatic is a wide, relatively deep system better connected with the southern Adriatic Sea and Mediterranean Sea. Most semi-enclosed coastal ecosystems in the world under the influence of rivers have similar nutrient pollution as the two systems. Therefore, the results of the study can serve as good comparison to other coastal systems as well.

Human activities as well as ongoing processes of climate overheating have strongly impacted both locations. Both ecosystems have experienced negative impacts on important habitats and related ecosystem services. The Northern Adriatic has also experienced an increase in toxic phytoplankton events, outbreak of jellysfish and a decrease in the mean size of fish.

The unmissable impacts of climate change

Coastal ecosystems are impacted by the changing climate in various ways. Climate-driven changes include ocean warming, sea level rise, intensified wind storms and changes in annual rainfall. These changes have already altered both studied ecosystems and will lead to a series of ecological consequences. For example, warm water species of the south will invade northern habitats, and native species will migrate northward. Moreover, coral reefs will continue to shrink due to coral bleaching.

Coastal communities and habitats are also at risk from sea level rise and related increasing coastal flooding and erosion. In the future, coastal communities will be subject to stronger storm surges and higher flood levels. These processes will have a strong impact on major cities and agricultural lands in the vicinity as well. In the Northern Adriatic, sea level rise directly correlates with an increase in the frequency of floods in Venice. St Mark’s Square now floods more than 60 times a year, compared to only four times a year in 1900. Without effective action, within 50 years this kind of flooding will follow with nearly every high tide. All coastal infrastructure will be impacted by rising sea levels. The salinity of coastal estuaries will contaminate the groundwater and important coastal habitats, such as tidal marshes that support many species of birds and fish will be under pressure.

WILDCoasts must be protected

It is important therefore to investigate how coastal ecosystems respond to external pressures and how humans manage coastal ecosystem services. Is is clear that the observed changes to the ecology of coastal ecosystems is impacting not only the biodiversity, but various other ecosystem services. Contrary to common belief, coastlines that governed by natural processes and non-intervention principles are Wilderness. These WILDCoasts are unique coastal habitats that represent the best and wildest coasts in Europe. Therefore, we must focus on the preservation of these habitats the same way we advocate the protection of mountainous, riverine or any other type of habitats.

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