In a few decades, will we recognize the Mediterranean as we know it today? Many scientists fear not, unless more drastic measures are taken to protect it. The invasion of alien marine species through shipping, fish farming, aquarium trade, but primarily through the Suez Canal, especially after its latest enlargement last August, endangers the unique biodiversity of the Mediterranean, batters its fisheries, and often threatens public health.
The adoption of an updated Mediterranean Action Plan concerning invasive species will be on the agenda of the 19th Session of the Parties to the Barcelona Convention for the “protection of the Mediterranean Sea from pollution,” which takes place 9-12 February in Athens. Exactly 40 years ago, the 21 countries surrounding the Mediterranean, as well as the European Union, adopted the Mediterranean Action Plan of the United Nations Environment Programme.
The outcomes of this Session are expected to be “very disappointing” according to Bella Galil, marine biologist at the National Oceanographic Institute of Israel, who orchestrated a worldwide petition by scientists in order to take measures to mitigate the invasion of alien species from the Suez Canal. Marine biologist Anastasios Eleftheriou, the first director of the Institute of Marine Biology of Crete which is now part of the Greek Centre for Marine Research (HCMR), also predicts the outcome of the Session to be “not at all satisfactory.”
The scientists’ concerns stem from the fact that “the Suez Canal is not referred clearly and explicitly as part of the overall Action Plan” explains Maria del Mar Otero, a specialist on invasive species issues at the Mediterranean Cooperation Centre of the International Union for Conservation of Nature (IUCN). “This is called willful blindness” notes Ms. Galil. “Egypt is deaf, while large organizations have not really taken any initiative” says Mr. Eleftheriou.
Ms. Otero, who will participate in the Session next week in Athens representing IUCN, notes that, nevertheless, the new integrated program for monitoring and assessing the condition of the Mediterranean that will be adopted, will be aiming to investigate trends in the abundance, and temporal and spatial distribution of alien, and in particular, invasive species.
“The situation is particularly complicated. There are some online and TV reports claiming that Egypt has carried out an environmental impact assessment and the results showed there is no negative impact. But this report has never been submitted to the EU, meaning that the EU has no idea of their methodology” says reporter Rachel Bishop who recently published an op-ed in The New York Times on this issue.
The species that have invaded
The species that entered the Mediterranean Sea following the opening of the Suez Canal in 1869 are called Lessepsian immigrants and their presence in our area is not a new phenomenon. The marbled spinrfoot [Siganus rivulatus] first appeared in the Mediterranean in 1924, while the dusky spinefoot [Siganus luridus] made its first appearance in 1931. The painfully stinging jellyfish Rhopilema nomadica was first recorded in the Mediterranean in 1976. It is today commonly encountered along Israel’s shores where it drives tourists away from the beaches and clogs seawater intake pipes used to cool power plants and operate desalination facilities.
“Today in Israel, over half of the fish living in waters shallower than 50 meters are Lessepsian species” says Dori Edelist, a marine biologist from the University of Haifa and the National Oceanographic Institute of Israel. According to the results of his research, the numbers of alien species are gradually reduced in greater depths. But with the recent deepening of the Suez Canal, the outlook for the future of the Mediterranean at greater depths is ominous. “A group of species living in deep waters in the Red Sea, previously unable to enter the Mediterranean because the canal was too shallow, have now able to pass through the Suez Canal” says Ms. Galil.
“The deepening [of the Suez Canal] is perfectly reasonable and necessary for present-day navigation,” but [Ms. Galil] adds that a large portion of the scientific community insists that such projects cannot be carried out today without taking the necessary environmentally protective measures, such as locks and salinity barriers.
Until a few decades ago, a number of different natural impediments offered some protection, preventing many alien species from reaching the Mediterranean. The canal was narrower and shallower, and its length was large, making the creation of a current difficult. Furthermore, the canal crossed hypersaline lakes which formed a hostile environment for the majority of species. Today, the increased volume and flow of water in the canal has flushed out the old extreme salinity barriers.
Currently, more than 1,000 alien species have been found in the Mediterranean according to a recent study by marine biologist Stelios Katsanevakis, a professor at the Department of Marine Sciences at the University of the Aegean. Mr. Katsanevakis, who studied the change in the number of new alien species per decade in the Mediterranean for each invasive pathway – shipping, fish farming, aquarium species trade, and the Suez Canal, observed the doubling of the rate of appearance of new Lessepsian species from the mid-20th century. Specifically, while in the 1950s fewer than 40 Lessepsian species have been identified, during the past decade, 80 new species have appeared in the Mediterranean.
In a counterclockwise path
“As they enter the Mediterranean Sea, these species follow a counterclockwise path” says Mr. Katsanevakis, explaining that they travel from Egypt to Israel, to the Turkish coastal waters, and eventually enter into the Aegean Sea. “The Aegean Sea forms a barrier, resulting in only a small number of these alien species being able to spread to the western part of the Mediterranean,” points marine biologist Costas Papaconstantinou who has been the Director of the Institute of Marine Biological Resources of HCMR for over two decades. The Greek peninsula, the deep seas between the Peloponnese and Crete, and between Crete and the coast of Africa, constitute still an obstacle to coastal invasive species.
According to records established by Mr. Papakonstantinou, in 2014 Greece had 42 Lessepsian species. “In 1990, only 11 species were identified in Greek seas as Lessepsian immigrants” says Mr. Papakonstantinou. “The rates show that this is a violent colonization that over time may change the ecology of the seas” he adds.
In Greek seas
In Greece, the invasive species that have caused the greatest negative impact are the two species of the genus Siganus: the aforementioned S. rivulatus and S. luridus. “They are both herbivorous species and behave like goats in the mountains – they eat everything!” says Mr. Katsanevakis, explaining that in the southern Aegean, previously lush algae meadows are now reduced to bare rock. “The role of algae is the same as that of forests on land. They provide food, shelter, and support a rich biodiversity which is also important for fisheries” says Mr. Katsanevakis.
In Crete, fishermen face an even greater problem, the spread of the toxic Lessepsian species [Lagocephalus sceleratus]. “This species is caught in large quantities by various types of fishing gear and damages both fishes and fishing gear” notes biologist-ichthyologist Nota Peristeraki from the Institute of Marine Biological Resources and Internal Water of HCMR. “The Lagocephalus is a high-level predator feeding on many species of commercially important fish, thus reducing their populations” says Mr. Katsanevakis. “It has very sharp teeth and tears the fishing nets to steal his catch” he adds.
“The first time Lagocephalus was spotted in Greece was June of 2005 at the northern coast of Crete” says Ms. Peristeraki whose group was among the first to warn the Greek public of its health risk. “The Lagocephalus contains tetrodotoxin in its innards, gonads and skin. It is a neuroparalytic toxin which, if consumed, may become fatal without immediate medical care” says Ms. Peristeraki.
A recent visitor in Greek seas is the impressive lionfish that possesses venomous spines. It first appeared in the summer of 2015 in Rhodes. According to scientists this Lessepsian fish is here to stay and is expected to create a lot of problems in coming years in the Mediterranean. “This is a voracious fish-eating species consuming the fry of other fish” says Mr. Katsanevakis, explaining that in the Florida and Caribbean regions, it has already caused major damage. “There, they have tried fishing and spearfishing competitions to reduce its population, but to no avail” he adds.
“Very few of the invasive species have positive economic value” says Ms. Galil. One such example is a type of tropical prawn (Penaeus pulchricaudatus), which is sold at very high prices in the market. “This morning in Israel, they were going for $60 a kilo” says Ms. Galil. But in order for such species to become financially beneficial and profitable, it means that they must have occupied large areas and in the process having displaced some local native species of the Mediterranean. “Species are not like Legos: removing a green brick and replacing it with a white one. Species have evolved through a complex system of interactions” explains Ms. Galil.
Global warming encourages Lessepsian immigrants
Climate change has played a key role in worsening the problem of invasive Lessepsian species in the Mediterranean. “We have a geometric increase of identified species in recent years due to the heating of the Mediterranean” says Mr. Papakonstantinou, explaining that as the temperature of Mediterranean waters increases, they provide a friendlier environment for the thermophilic species from the Red Sea. “The issue of climate change creates problems anyway, especially when the Eastern Mediterranean is so accessible to the waters of the Red Sea” says Mr. Eleftheriou.
There are many people maintaining that the opening of only one entry point is not sufficient for a species to establish itself in a new environment and become invasive. “For this to happen in an ecosystem, two conditions must be met simultaneously: an access pathway such as the Suez Canal or ballast and hull fouling of ships, as well as the new environment” says Francois Simard, deputy director and senior advisor for fisheries at the Global Marine and Polar Program of the IUCN. “The alien species become invasive because the environment has been degraded. In a strong and healthy environment, it is more difficult for new species to establish themselves because there is no space for them” Mr. Simard explains.
“It’s easier for someone to enter a room with two persons in it and occupy space, rather than a room with ten persons in it. It would need more competition” said Drossos Koutsoubas, Professor at the Department of Sea Sciences of the University of the Aegean and Chairman of the Board of the Agency of the National Marine Park of Zakynthos. “The presence of marine protected areas ensures the good quality of the marine environment and great species diversity” he adds.
For a good catch of fish …
The proper functioning of an ecosystem, according to George Kokkoris, Professor of Statistics and Mathematical Ecology at the same university, can guarantee better catches of fish. In recent decades when Greek fishermen have recorded large losses, Mr. Kokkoris along with researcher Sylvain Giakoumi have proposed the creation of a network of protected marine coastal areas that will operate as free hatcheries for local fish populations. “The fishermen react because they are afraid, while politicians never have the courage to impose a decision” says Mr. Kokkoris, referring to their proposed integrated plan for the creation of such areas in the Southern Cyclades.
For as long as a decisive intergovernmental agreement doesn’t appear on the horizon, such local actions, although unable on their own to resolve the problem of invasion of Lessepsian immigrants, have the potential to offer some protection to endemic populations in the Mediterranean. “From Minoan frescoes we observe that the fauna of the Mediterranean has remained the same for 5,000 years” says Mr. Eleftheriou. “But I am afraid that with this new situation, we will start seeing big changes.”
Written by ASPASIA DASKALOPOULOU and translated from Greek by GEORGE DEODATIS, Professor at Columbia University.