The “Alien Invasion” in the Mediterranean Sea is a very hot topic in the scientific world at the moment.

Alien Species in the terrestrial realm (on land) are already known for hundreds of years. Animals were brought from one continent to another for various reasons, which resulted in uncontrollable increases in populations. A world-wide known example for this is the European rabbit (Oryctolagus cuniculus) which was introduced to Australia in the 18^th century by the first fleet of ships going this way. Those rabbits turned into a true mammalian pest and caused a damage of millions of dollars on crops.
Those so called Alien Species do not only exist on land but are also very common in our oceans and seas - but what exactly is an invasive Alien Species?

"Invasive Alien Species (IAS) are animals and plants that are introduced accidentally or deliberately into a natural environment where they are not normally found, with serious negative consequences for their new environment. They represent a major threat to native plants and animals." (European Commission)

At the south coast of Crete (Greece), where our Marine Field Station is based, most Alien Species come from the Red Sea. Research groups found out that more than 1000 Alien Species are found in the Mediterranean Sea.

These species, also known as non-indigenous species, can cause big problems not only for the environment but also for human economy and health. In order to recognise the impact of these organisms it is very important to monitor them and conduct appropriate research.

Pic. 1 Lionfish, Pteroise miles

This particular species reproduces at an astonishing fast rate while feeding on our native fish. The continuous increase in Lionfish poses a major threat to the indigenous fish species which needs to be controlled by us. Apart from the Lionfish there are many more Alien Species at our diving grounds which need to be closely monitored.
If you would like to learn more about those species you are more than welcome to visit us at our Marine Filed Station in Plakias at the South Coast of Crete. Twice a week our Marine Biologists give free presentations on changing topics in front of the diving school. Just come and join!

In order to monitor the population of the Lionfish and other Alien Species the entire work force of the Dive2gether helps us. During every Fun Dive our colleagues count the individuals of the pre-determined target species they spot, more detailed data such as depth and substrate they were found on are gathered when spotting a Lionfish.

A couple of weeks ago our Marine Field Station had a visit from Dr. Carlos Jimenez and his PhD Student Vasilis Andreou who are working for the Enalia Physis – Environmental Research Centre on Cyprus, where the Lionfish population increased already to a problematic level.
During their stay in Plakias the two scientists held two presentations about Lionfish and the threats they pose to the local eco system and gave more insight about what they could already observe on Cyprus.

The first talk was in front of the Dive2gether Crew, the second one in front of a group of local stakeholders of Plakias. For that we invited members of the local harbour police, fishermen and owners of hotels and restaurants to join us in our classroom and get more knowledge about what is happening underwater at the moment and why the beautiful Lionfish and other Alien Species can evolve into a serious problem for them and the local community.

Pic. 2 Presentation about Lionfish given by Vasilis Andreou to Stakeholders of Plakias	Pic. 3 Paul Koblens, Martina Stockinger, Carlos Jimenez, Christina Braoun and Vasilis Andreou

In order to preserve the native species that belong to the Mediterranean Sea it is very important to gather more information about the invasive Alien Species and their impact on their environment. Only if we understand these mechanisms we can take action!

The Marine Field Station of Plakias is already looking forward to a productive collaboration with Dr. Carlos Jimenez and Vasilis Andreou.



Written by Martina Stockinger
Edited by Eva Hintschich