S.O.S. - Save Our Seas.

In the Mediterranean Sea, there are an increasing number of jellyfish.
These jellyfish eat the food of other animals and have destroyed the balance of the ecosystem. So why are there so many jellyfish? It's because fishermen have caught too many Atlantic bluefin tuna, wich eat jellyfish. 
Humans have also threatened the Earth's oceans and seas in other ways.
When the Suez Canal was built, for example, it introduced many non-native species to the waters of the Mediterranean Sea. Native species find it difficult to survive when they have to compete with non-native species.
Additionally, there have been a large number of oil spills in oceans and seas around the world. Also, factories release harmful materials into the sea. Many sea animals have died because of these spills and waste.
Extreme changes in climate, such as floods or droughts, have also created serious problems for a variety of ocean creatures.
Although the negative effects of human activities and climate change cannot be easily fixed, we can prevent further damage from happening. People need to understand the dangerous situations our oceans face. If we take just one step, such as no longer dumping waste into the sea, we might be able to save our oceans.