By Greenpeace International
One of the most serious threats to life in the Mediterranean bassin and indeed every part of the global ocean is climate change. Climate change is already having an impact on the marine environment and this is likely to escalate swiftly, increasing seawater temperatures and coastal erosion, altering salinity and currents and causing serious declines in biodiversity.
Sea level rise for the next century (2100) could be between 30 and 100 cm and temperature shifts of a mere 0.05-0.1°C in the deep sea are sufficient to induce significant changes in species richness and functional diversity.
Any disruption to the water column, including the impact of increasing temperature, is likely to have profound impacts on the species inhabiting it, including commercial fish stocks.
Indirect consequences may also occur as a result of temperature rise, including demands on the Mediterranean for desalinised water, a process which will create localised areas of higher salt content, thus further disrupting the fine balance of the Sea.
Although the Mediterranean region will experience negative andpotentially severe impact as a result of climate change, it could also represent a major part of the solution. There is huge renewable energy potential in Mediterranean countries, especially solar, and most of this potential is untapped. If Mediterranean countries commit to developing their renewable energy potential, climate change impacts on the Sea and region can be reduced and the region can contribute to the global solution.
The Mediterranean Sea is one of the most heavily polluted marine areas in the world. Thousands of tonnes of toxic waste are pumped directly into the sea by industry each year.
Sewage facility dumping into the Mediterranean. Photo source: ©Greenpeace
Heavy metals and persistent organic pollutants (POPs) are a serious threat to human health and marine life. High concentrations of mercury, cadmium, zinc and lead in sediments are found at “hot-spots”, generally located in the coastal zones receiving high levels of industrial effluents, solid waste and domestic sewage. These substances can travel thousands of kilometers, across national boundaries, far from their source.
This creates a serious health risk in a region where fish is an integral part of the regional diet and many people’s livelihoods depend on the sea. It also exacerbates stress on the ecosystems and marine life, which are damaged by the pollution.
Some of the world’s busiest shipping routes are in the Mediterranean Sea. It is estimated that approximately 220,000 vessels of more than 100 tonnes cross the Mediterranean Sea each year, about one third of the world’s total merchant shipping. These ships often carry hazardous cargo, which if lost would result in severe damage to the marine environment.
The discharge of chemical tank washings and oily wastes also represent a significant source of marine pollution. The Mediterranean Sea constitutes 0.7 percent of the global water surface and yet receives seventeen percent of global marine oil pollution.
It is estimated that every year between 100,000 and 150,000 tonnes of crude oil are deliberately released into the sea from shipping activities.
Approximately 370 million tonnes of oil are transported annually in the Mediterranean Sea (more than 20 percent of the world total), with around 250 to 300 oil tankers crossing the Sea every day. Accidental oil spills happen frequently with an average of 10 spills per year. A major oil spill could occur at any time in any part of the Mediterranean.
With a unique combination of pleasant climate, beautiful coastline, rich history and diverse culture the Mediterranean region is the most popular tourist destination in the world, attracting approximately one third of the world’s international tourists.
Tourism is one of the most important sources of income for many Mediterranean countries. It also supports small communities in coastal areas and islands by providing alternative sources of income far from urban centres. However, tourism has also played major role in the degradation of the coastal and marine environment.
Rapid development has been encouraged by Mediterranean governments to support the large numbers of tourists visiting the region each year. But this has caused serious disturbance to marine habitats such as erosion and pollution in many places along the Mediterranean coasts.
Tourism often concentrates in areas of high natural wealth, causing a serious threat to the habitats of endangered Mediterranean species such as sea turtles and monk seals. It is ironic that tourism in this region is destroying the foundations of its own existence. And it is inevitable that the tourists will leave the Mediterranean as it becomes more depleted of its natural beauty.
Whether intended or accidental, introduced or “alien” species can become invasive, having serious impacts in the marine environment, competing with native and endemic species for food and space, often dramatically altering the structure of communities and habitats.
The intentional release of new species can occur as a result of species being brought into an area (for example to establish aquaculture or for aquariums), and subsequently spreading into the surrounding waters. An example of this is the growth of the tropical alga, Caulerpa taxifolia, from its original introduction site at the Monaco Aquarium to covering over 40 million square meters of the Mediterranean coast.
Some species are accidentally transported in ballast water or attached the hulls of vessels and end up being released far from their origin. The North American comb jelly Mnemiopsis leidyi was introduced to the Black Sea through ships’ ballast, and reached an estimated total biomass exceeding the world’s total annual fish landings, adding to the effects of over-fishing and contributing to the near collapse of Black Sea fisheries.
Zebra Mussel Invasion in Spain Is Irreversible
The expansion of the “introduced species” zebra mussel, has not only an environmental impact because of its impact on endemic species and on the environmental balance of ecosystems, but also a great economic impact.
Mediterranean Sea Invaded by Alien Species