Lessepsian migration

The term lessepsian, is derived from Ferdinand De Lesseps who designed and led the team that built the Suez Canal, thus linking the Red Sea with the Mediterranean. Lessepsian migration refers to species which have entered the Mediterranean, from the Red Sea, through the Suez Canal. Some of these introductions seem to be permanent, some short-lived.

For those of you interested in exotic introductions to the Mediterranean, there is a website CIESM Atlas of Exotic Species in the Mediterranean Sea which has a list of introduced molluscs, including quite a few opisthobranchs. There is a comprehensive page on each species.

Use the SEARCH facility on the Forum [type 'lessepsian'] to get a current list of lessepsian migrants reported here.

Authorship details
Rudman, W.B., 2002 (January 13) Lessepsian migration. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/lessep

Related messages

Re: CIESM Atlas of exotic species - bureaucratic madness!

October 5, 2009
From: Bill Rudman

Concerning message #22069:


I have posted a message today [#22678] about another lessepsian migrant into the Mediterranean, which caused me to check the CIESM website which I refer to above. I was pleasantly surprised to find I can now enter it without being asked to pay a petty charge. As I received no response from the various officials I complained to last year I am not sure whether the decision to allow the rest of the world to enter the site for free is a result of my urgings or not.

Whatever the reason, Thank you officialdom. I am glad that sanity has prevailed! It has enabled me to let you know - free of charge - that Chromodoris annulata needs to be added to your list.

Bill Rudman.

Rudman, W.B., 2009 (Oct 5) Re: CIESM Atlas of exotic species - bureaucratic madness!. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22680

CIESM Atlas of exotic species - bureaucratic madness!

November 20, 2008
From: Bill Rudman

Earlier this year I raised the question of access to this Atlas [message #21469]. Today I have received another message [#22066 ] which brings up the access question again:

On the Lessesian migration Fact Sheet I have a link to the Mediterranean Science Commission's CIESM Atlas of Exotic Species in the Mediterranean Sea. In the past I have used this site to check earlier records of exotic opisthobranchs in the Mediterranean. Earlier this year I discovered I could not access the site because I was not a citizen of a 'Member State':

"You have requested access to CIESM products that are delivered free of charge only to the Member States of our Commission that support our activities. For all other visitors like you, downloading from Australia, a participation fee (1.50 €) is applied for this product."

I thought the point of such websites was to spread information widely for the good of us all. What is particularly galling is that this site makes full use of the freely available results produced by scientists worldwide to produce their database. They have made extensive use of the Sea Slug Forum in the past and I am sure they will continue to do so. They have never asked for permission or offered to pay for this information so why should they expect me to pay to look at my own records when all I am trying to do is to further their aims. 1.50 € may seem a trifling amount so why do I complain? The whole purpose of such databases is to provide up to date information - so to use them properly they need to be checked regularly - so every time I do this I will have to pay another 1.50 € and bank charges etc. What is the point in this government body charging? It will hardly generate enough funds to buy a bureaucrat a fancy chair! Government bodies such as CIESM should be encouraging the public to support their activities - which have already been paid for by the member governments. Surely the governing committee just by looking at the contributions to their site must realise that the expertise they need is to be found all around the world, not just in their member countries. After all, the 'exotic species' being recorded will by definition be from outside Europe and so be better known by scientists from outside the 'Member States".

Petty imposts like this completely destroy the aim of the internet to be a means for the fast and free exchange of information worldwide. Today's question demonstrates the pettiness of this charge: To study the background of today's question, I as a non-member, would need to pay 1.50 € to answer a question from a citizen of a member state, who pays nothing. I would like to thank those participants from member states, with free access, who have offered to check things on the Atlas for me - but it is not the same as being able to personally browse.  

I have just written to the CIESM Editorial Board. If anyone else would like to ask then to rethink this charge here are their email addresses:

Frédéric Briand,  Director General, CIESM   fbriand@ciesm.org
Ferdinando Boero   boero@caspur.unile.it
Maria Grazia Mazzocchi   grazia@alpha.szn.it
Costas Papaconstantinou   pap@posidon.ncmr.ariadne-t.gr
Giulio Relini   sibmzool@unige.it
Helmut Zibrowius   hzibrowi@com.univ-mrs.fr

Bill Rudman

Rudman, W.B., 2008 (Nov 20) CIESM Atlas of exotic species - bureaucratic madness!. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22069

Re: Lessepsian migration, need of a separate term?

February 28, 2005
From: Cynthia Trowbridge

Dear Bill and Jim,
Hi! Interesting question [#13233] that Jim (and Nishina) have brought up. As a marine biologist working on introduced species, I would suggest that we not create more site-specific terms.

When Por coined the term "Lessepsian Migration", the phenomenon of introduced species was not widely recognized so the phrase was extremely useful. Now we are inundated with introduced species from many vectors (canals, container vessels, aquaculture, etc.) so site-specific terms are not particularly useful.

In a global review chapter of introduced macroalgae that I wrote for "Seaweed Resources of the World", there are numerous canal systems that have become invasion corridors to introduced species (despite any freshwater locks) including:

1. Suez Canal
2. Volga-Don Canal
3. Panama Canal
4. St. Lawrence Seaway

Here are a few *annotated* excerpts from my chapter:

The Suez Canal, connecting the eastern Mediterranean Sea and the Red Sea, was opened in 1869. Since then there has been dispersal of marine species through the canal, almost exclusively from the Red Sea to the Mediterranean; this movement of species has been termed "Lessepsian Migration" (Por 1978). Although the species' dispersal is natural (due to currents, etc.), human activities removed the geographic barrier separating the two biogeographical provinces; thus, these migrating species are considered introduced species.

The construction of numerous canals in Eastern Europe has permitted the spread of many invertebrates and fishes. For example, the construction of the Volga-Don Canal enabled species to move into the brackish Caspian Sea. This 101 km long canal with 13 shipping locks interconnected the Volga River (attached to the Black Sea) to the Don River (attached to the Caspian Sea). Many species have appeared in the Caspian Sea since the canal was opened in 1952.

The Panama Canal is another anthropogenic corridor through which Pacific and Atlantic species could move. Andrew Cohen and colleagues are currently surveying exotic marine species on the Pacific and Atlantic coasts in the vicinity of the canal to determine the importance of the corridor between biogeographic regions.

The St. Lawrence Seaway in eastern North America is a complex system of waterways, canals and locks linking the Great Lakes between Canada and the U.S. to the Atlantic Ocean. The seaway system is inter-connected by six short canals and nineteen shipping locks. There is a variety of species that have entered the Great Lakes from shipping (ballast water and/or hull fouling).

  • Por, F.D. (1978) Lessepsian migration - the influx of Red Sea biota into the Mediterranean by way of the Suez Canal. Berlin: Springer Verlag.

Thank you for considering my plea for no more site-specific terms.



Trowbridge, C.D., 2005 (Feb 28) Re: Lessepsian migration, need of a separate term?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13240

Dear Cynthia,
I couldn't agree more
Best wishes,
Bill Rudman

Re:Lessepsian migration

February 28, 2005
From: Lindsay Warren

Dear Bill
I have just been reading the latest message about Lessepsian migration [#13233] and followed the leads in your earlier note to the CIESM Atlas of Exotic species. Their species list now does have links to photos for most species along with additional information. Pity is that they have only used B&W photos or illustrations but better than nothing. Makes very interesting reading.

all the best


Warren, L.C.R., 2005 (Feb 28) Re:Lessepsian migration. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13246

Thanks Lindsay,
It's certainly more useful with the photos - I'll have to change my comment on the Fact Sheet. I am glad they have included at least some references from the Forum
Best wishes,
Bill Rudman

Rudman, W.B., 2005 (Feb 28). Comment on Re:Lessepsian migration by Lindsay Warren. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13246

Lessepsian migration, need of a separate term?

February 25, 2005
From: Jim Lyle

Dr. Rudman,

Following the recent message [#13226] on Glossodoris sedna:

Hyselodoris infucata is an Indian Ocean branch that is now found in the Mediterranean having made its way through the Suez Canal. The term "Leseppsian migrant" is given to such species, named for Ferdinand de Lesepps, the builder of the Canal.

Glossodoris sedna, a Pacific Ocean species, is now found in the Atlantic Ocean off Florida and in the Caribbean and was likely introduced via the Panama Canal. Is it correct to refer to G. sedna as a Leseppsian migrant, or is there another term for those species migrating via the Panama Canal?

An argument could be made to call both species Lessepsian migrants as Lesepps was involved in both canals, planning the Panama Canal for the French after finishing the Suez. But the French abandoned their efforts in Panama and it was the U.S. Corps of Engineers that finished the project. Further, the term Lessepsian migrant does not differentiate between the two.

If no separate term exists for migrants via the Panama Canal, several choices exist; they could be named after Lucien Wyse or Godin de Lepinay, Frenchmen who first proposed a lock/dam canal; or named after John Wallace, John Stevens or George Goethels, American engineers who supervised the construction of the canal.

My vote would be for "Stevensian migrant" after John Stevens who is given the most credit for the successful completion.

Jim Lyle


Lyle, J.L., 2005 (Feb 25) Lessepsian migration, need of a separate term?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13233

Dear Jim,
I have a page - if brief - on Lessepsian migrants, and a couple of years ago Nishina Masayoshi raised the same question [message #6321]. I guess the basic difference is that the Panama Canal has a system of freshwater locks, which I presume deters transport of organisms from one side to the other directly in the water. Of course this does not stop ship's ballast water being transported from one side to the other or aquariists dumping unwanted organisms in the wrong ocean, but it is 'migration' of quite a different nature.


Rudman, W.B., 2005 (Feb 25). Comment on Lessepsian migration, need of a separate term? by Jim Lyle. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13233

the term 'lessepsian' and the Panama Canal

March 9, 2002
From: Nishina Masayoshi

Dear Bill,
I found the term lessepsian in your site. I am interested in this fact. Is there any word like this for Panama Canal?
Best Regards,
Nishina Masayoshi


Masayoshi, N., 2002 (Mar 9) the term 'lessepsian' and the Panama Canal. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6321

Dear Nishina,
I am not aware of such a name. The situation with the Panama Canal is rather different to that of the Suez Canal because in Panama there are a series of higher level freshwater lakes which effectively prevent marine larvae from travelling from one side to the other. Interestingly Ferdinand de Lesseps, who built the Suez Canal, was in charge of the first attempt to build the Panama Canal but engineering and disease problems sent his company bankrupt. His design was for a sea-level canal and if he had succeeded then there could indeed have been migration from the Pacific to the Caribbean - but would it have been Lessepsian as well?
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Mar 9). Comment on the term 'lessepsian' and the Panama Canal by Nishina Masayoshi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6321