The Aegean. The epicenter of the Greek summer. This year, tourists will flock to it again to enjoy the cool of its islands’ shores and alleys. But environmental threats are disturbing the Aegean’s age-old equilibria. Add the ever-present geopolitical threat, and it is clear its future is hanging by a thread.

  1. Climate change

Climate change is the most serious threat of all. The Mediterranean has been identified as a climate crisis hotspot while “the Aegean Sea has entered the danger zone in terms of consequences and is warming 20% faster than the rest of the planet,” Head of Greenpeace Greece Nikos Charalambidis tells TO VIMA. According to data collected by the National Observatory of Athens, the surface temperature of the Aegean has increased by 1.5 degrees Celsius over the last 30 years.

“The Aegean Sea will experience another marine heat wave this year,” predicts Thodoris Tsimbidis, director of Archipelagos, an institute dedicated to protecting the marine environment. “From the summer maximum of 27 degrees Celsius, the water temperature normally drops to 13-15 degrees, but that hasn’t happened this year,” he notes. “If the water temperature of the Mediterranean remains very high over a long period of time, it will have multiple negative impacts on marine organisms,” adds Professor Drosos Koutsoubas, marine biologist in the Department of Marine Sciences at the University of the Aegean.

Climate change does not only affect water temperature. Rainfall, now less frequent and more intense, has also become a destructive force, as it erodes the islands, Charalambidis notes. The drier climate both increases the need for water and makes it harder to such needs, as it becomes increasingly difficult to collect rainfall.

The increase in carbon dioxide in the atmosphere also leads to more adverse marine conditions. Koutsoubas explains: “More carbon dioxide in the atmosphere eventually translates into increased acidity in our oceans. In turn, the acidification of the sea has adverse effects on the ability of numerous marine organisms, from plankton to mollusks and corals, whose skeletons contain calcium carbonate, to calcify.”

Rising sea levels is another issue, with the Mediterranean having risen an estimated 16 cm over the last century. This phenomenon reduces beaches’ surface area, creating problems for species and their habitats as well as for humans, Koutsoubas stresses.

  1. Invasive species

Global warming also leads to alien species entering the Aegean. Tsimbidis explains that the expansion of the Suez Canal in 2015 left the Mediterranean particularly vulnerable to the introduction of new species from the Red Sea and Indian Ocean. As an ecosystem with a low concentration of nutrients, the Aegean is sensitive to the introduction of new species, which, if they fail to assimilate, can displace the native ones.

According to WWF data, around 1,000 new alien species in total—including 126 fish species—have entered the Mediterranean, causing a decline in endemic species up to 40% in some areas.

This does not mean that every alien species threatens the Aegean’s sustainability. “For example, Caulerpa taxifolia, a species of algae that resembles a small grape, was considered an invasive species for a number of years. However, it has now adapted to the ecosystem and does not live at the expense of other species,” Tsimbidis notes. The goes for the lionfish, which, although not native to the Aegean, is not aggressive and is expected to remain in the ecosystem. It is also edible, so its population is further kept under control by fishing.

However, species such as the puffer fish are considered a threat. “It has proliferated in some areas, but it has not yet spread outside of these. Still, if it finds an abandoned ecosystem, its population will rise,” Tsimbidis warns.

  1. Overtourism

As a magnet for visitors, the Aegean is also under threat from the rapid growth of tourism—and yachting, in particular. “There may be over 80,000 tourist boats alone this summer,” Tsimbidis estimates, who is particularly concerned about the destruction their anchors cause the marine environment. “The anchors are destroying the underwater Posidonia meadows,” he notes, referring to the typical Mediterranean seaweed, which cleanses the sea and is protected by both Greek and European legislation.

“We need to see how many boats we can sustain. It is not possible for 20 and 30 boats to be gathered in small coves Charalambidis adds.

“In Croatia, you are not allowed to drop anchor wherever you want, and we should follow their example,” Tsimbidis stresses, suggesting the designation of “paid-for” anchor points. “This would also generate revenue for local communities, making yachting a driver for development,” he says.

Tourism also requires large volumes of water every summer, to the extent that the islands (and especially the Cyclades) are now facing a water scarcity problem. Indeed, municipal authorities now have to cut off the water supply at some hours, especially during the peak tourist season in July and August. “We need to start thinking about water management,” Charalambidis says. Food security in island regions is another issue. “With the increase in tourism, many islanders have quit the primary sector and turned to tourism, since it is more profitable,” he notes.

  1. Pollution

The rapid growth of tourism has also led to a dramatic increase in pollution. The ever-larger volumes of sewage produced on the islands during the summer, as well as the wastewater from tourist boats, all end up in the sea. Chemically treated water from swimming pools in homes and hotels also pollutes coastal ecosystems. Millions of liters laced with chemicals end up in the sea, creating problems for sea urchins, mollusks and other organisms.

Marine pollution from plastics, microplastics and nanoplastics is another major problem. “Until four years ago, we might find one fish in a thousand without microplastics in its stomach. Now every single organism in the sea has some form of plastic in them.”

Climate change is exacerbating the problem. Debris swept into the sea by storms “Daniel” and “Elias” in Thessaly last autumn created an entire island of rubbish in the Pagasetic Gulf. “Still, events of this sort are not catastrophic, since the sea is capable of dispersing these volumes,” Tsimbidis reassures.

  1. Eutrophism

Of course, the flood torrents also swept fertilizers, pesticides and insecticides from the plains of Thessaly, a region whose economy is based on primary production, into the sea. The ensuing eutrophication, i.e. the excessive increase in the sea’s nutrient concentration, leads to a reduction in the oxygen dissolved in the water. This alters the biodiversity of the ecosystem, with a few species gaining dominance and the rest being driven to extinction.

  1. Overfishing

Uncontrolled fishing is another issue. The damage done to the marine ecosystem by industrial trawlers, which uproot the seagrasses and reefs in which fish spawn, is irreversible. What makes it even worse is that 70% of the trawlers’ catch is unwanted and discarded, notes Tsimbidis.