Archipelagos

  • English
  • Ελληνικα
Who We Are
The TeamThe Team
Research BasesResearch Bases
Research BoatsResearch Boats
Our EquipmentOur Equipment
PartnersPartners
SupportersSupporters
Fields of Action
Marine ConservationMarine Conservation Fisheries Shipping Risks Seagrass Meadows Coralligene Conservation Littoral Ecosystems Invasive Species Jellyfish Sea Turtles
Marine MammalsMarine Mammals Dolphins and Porpoises Whales Seals
Terrestrial ConservationTerrestrial Conservation Island Fauna Forests & Flora Freshwater Ecosystems Aegean Seed Bank
Laboratory ResearchLaboratory Research Microplastics Water Analysis Soil Quality
Projects
Aegean Marine Life Sanctuary
Eco-Navigation
FIsh4Life
Save the Aegean
Join Us
Internships in the Aegean
Remote Internships
Interns Experiences
Field Courses
News
Planting Underwater Gardens of Posidonia seagrass- a new innovative planting process
Planting Underwater Gardens of Posidonia seagrass- a new innovative planting process
Aegean Islet Conservation Project in cooperation with the University of Toronto’s Faculty of Architecture
Aegean Islet Conservation Project in cooperation with the University of Toronto’s Faculty of Architecture
Mutilated Striped Dolphin Stranded on the shores of Samos Island
Mutilated Striped Dolphin Stranded on the shores of Samos Island
Posidonia Seagrass Fruits Wash up on Our Shores – A Rare Phenomenon
Posidonia Seagrass Fruits Wash up on Our Shores – A Rare Phenomenon
View All...
Contact us
Publications
Videos
Awareness Material
Donate
Menu

The Silent Invasion

The Silent Invasion

by Kleopatra Delaveri / Thursday, 02 August 2018 / Published in Intern Experience, Marine Conservation Team, Work Journal

Beneath the waves of the Mediterranean Sea a silent invasion is taking place, unseen by anyone above. The invaders are foreign species from all over the world, allowed transport by the hand of man. And they are here to stay. These types of incursion are far from uncommon around the world, but no place is more under threat than the Mediterranean. These foreign species follow many pathways, the most prominent being the canal of Suez, first constructed in 1869 and widened multiple times, which has allowed more than 50 fish species and hundreds of invertebrates and algae to pass from the Red Sea and Indo-Pacific into the Mediterranean.

Some of these aliens are benign, doing no damage to the ecosystem or native communities. But others are not. These Invasive Alien Species (IAS) can harm native ecosystems in many ways. For one they may outcompete native species and replace them. Invasive algae may outcompete native seagrasses and change the composition and change the habitat, completely replacing the ecosystem. Invasive predators may cause trophic cascades, causing the entirety of the complex food webs to collapse.

This silent and slow invasion is one of the most dangerous and destructive threats that the Mediterranean faces today and could completely change it forever.

 

 

 

 

 

 

Our Goal

The aim of our project is to find out how many and what invasive species are present in the Aegean Sea around multiple islands. From this we can then estimate the rate at which they are spreading, the habitats and locations that are most at risk and how much of a danger they pose to native ecosystems. The information we gather can then be used to guide environmental policy to make informed actions. In the first part of the project we focused on invasive fish and invertebrates around the Greek island of Lipsi in the Dodecanese.

Methods

Five locations were chosen on different sides of the island of Lipsi. All of the sites had a mix of different seafloor types and had a depth range from about 1m to 5m, so that they could be surveyed exclusively by snorkelling and freediving. At each location 17 randomly chosen points were surveyed for fish and invertebrates within an area of about 10,000m^2. The substrate types present and other environmental data was also collected at each point.

The fish survey is the first step. It is conducted from the surface while snorkelling, identifying and counting any invasive fish species within the range of visibility whilst calmly turning on the spot, so that the invasive fish within the radius of visibility are recorded. It is important to minimise movement during this step so that no fish are scared away.

The second step is the invertebrate survey. For this a snorkeler has to freedive to the bottom and attach a line to a weight in the centre of the point. This line is then used to conduct circular surveys on the bottom and identify and count any invertebrates at the bottom. These circular surveys are conducted at 1m, 2m and 3m distance from the centre, which means that invasive invertebrates are recorded within a 3m radius.

Lastly the substratum and other environmental data such as depth and temperature are recorded.

 

Results

In all of the sites varying numbers of the Dusky Spinefoot (Siganus luridus) and the Marbled Spinefoot (Siganus rivulatus) were encountered. These two species of rabbitfish of the genus Siganus have been in the Mediterranean for a long time, first recorded in 1956 (S. luridus) and 1927 (S. rivulatus). They are both herbivorous feeding mainly on benthic algae, which puts them in direct competition with the native Dreamfish (Sarpa salpa) and the Mediterranean Parrotfish (Sparisoma cretense). They could also have a large impact on the flora by their grazing. There was a higher abundance of S. luridus than S. rivulatus at every location and a large variance of numbers recorded between locations, which is suspected to be due to the habitat being more suitable and conductive to grazing in some locations than in others.

Another invader that was sometimes encountered was the Blue-Spotted Cornetfish (Fistularia commersonii). This species came through the Suez Canal rather recently in 2000, and is the fastest spreading Mediterranean invader, having reached the south coast of Spain in 2007, only seven years after it was initially discovered. It is together with S. luridus one of the few species of fish introduced through Suez that have managed to spread to the western basin of the Mediterranean. As a rapacious piscivore its diet consists almost exclusively of small fish, especially juveniles, and more than 70% of its diet has been shown to consist of species of economic value. Therefore the damage that F. commersonii causes is not only ecological, preying on juveniles and depleting local fish populations, but also economical, for itself is considered of little to no economic value in these parts of the world.

During the surveys only a few specimens have been encountered at only two locations. A reason for this might be that both of these locations are characterised by a presence of large schools of small fish (Atherina boyeri) and juveniles of other species that are known prey of F. commersonii.

The next steps

Conducting the surveys in Lipsi is just a first step. The next step is to now implement these successful methods on various other islands around the Aegean to better determine the spread of invasive alien species on a larger scale. These methods will also be used in monitoring the changes in populations and diversity of invasive species around those islands over a longer period of time, to help us better understand how our sea is changing.

 

0
0
0
0
0

What you can read next

Daily Monitoring of Macroplastics
Archipelagos International School of the Sea Marine Ecology Team
Monitoring the artificial reefs implemented by Archipelagos Institute
Macro-invertebrates around Lipsi island

HIGHLIGHTS

  • International Visitors at the Aegean Marine Life Sanctuary Project

    International Visitors at the Aegean Marine Life Sanctuary Project

    1 June 2021
    At Archipelagos Institute of Marine Conservation an important visit took …
  • The Efkranti Award was Granted to the Archipelagos Institute of Marine Conservation

    The Efkranti Award was Granted to the Archipelagos Institute of Marine Conservation

    27 July 2020
    It was a great honor but also great moral support …
  • The President of the Hellenic Republic’s visit to Archipelagos research vessel, the Aegean Explorer

    The President of the Hellenic Republic’s visit to Archipelagos research vessel, the Aegean Explorer

    30 June 2020
    Yesterday, during the President of the Republic’s visit to the …
  • Award to Archipelagos: Best Heroic Act of Environmental Stewardship

    Award to Archipelagos: Best Heroic Act of Environmental Stewardship

    19 February 2020
    The Short Documentary Film presenting the Aegean Marine Life Sanctuary, …
  • Award to Archipelagos Institute from the International Propeller Club of the United States

    Award to Archipelagos Institute from the International Propeller Club of the United States

    6 February 2020
    We would like to thank the International Propeller Club of …

Recent Posts

  • Planting Underwater Gardens of Posidonia seagrass- a new innovative planting process

    Planting Underwater Gardens of Posidonia seagrass- a new innovative planting process

    29 June 2023
    An innovative process of planting underwater gardens of Posidonia oceanica …
  • A special three-day research expedition to the Ikaria Trench

    A special three-day research expedition to the Ikaria Trench

    19 May 2023
    Archipelagos Marine Mammal Research team took part in a very …
  • Aegean Islet Conservation Project in cooperation with the University of Toronto’s Faculty of Architecture

    Aegean Islet Conservation Project in cooperation with the University of Toronto’s Faculty of Architecture

    17 May 2023
    A new cycle of interdisciplinary on-site research of the Aegean …
  • Mutilated Striped Dolphin Stranded on the shores of Samos Island

    Mutilated Striped Dolphin Stranded on the shores of Samos Island

    12 May 2023
    A mutilated striped dolphin was found stranded on the north …
  • Posidonia Seagrass Fruits Wash up on Our Shores – A Rare Phenomenon

    Posidonia Seagrass Fruits Wash up on Our Shores – A Rare Phenomenon

    3 May 2023
    In recent weeks, at many beaches along the coasts of …
  • Sperm Whale Migration

    Sperm Whale Migration

    23 April 2023
    As we are now approaching the middle of autumn, sperm …
  • Microplastic Pollutants found in stranded Dolphins, Sea Turtles and Seals in the Aegean Sea

    Microplastic Pollutants found in stranded Dolphins, Sea Turtles and Seals in the Aegean Sea

    5 April 2023
    A new scientific publication by the Archipelagos Institute for Marine …

Subscribe to Our Newsletter

Archipelagos Institute of Marine Conservation is committed to researching and defending the biodiversity of the Greek seas and islands.

Our action is possible only with your help!

donate
  • Contact us
  • Placements

Archipelagos - Institute of Marine Conservation © All Rights Reserved || Web Design and Development by Red Web Design & Fekas Brothers

TOP