Lessepsian migration
When the canal was completed in 1869, fish, crustaceans, mollusks, and other marine animals and plants were exposed to an artificial passage between the two naturally separate bodies of water, and cross-contamination was made possible between formerly isolated ecosystems.
[1] The migration of invasive species through the Suez Canal from the Indo-Pacific region has been facilitated by many factors, both abiotic and anthropogenic, and presents significant implications for the ecological health and economic stability of the contaminated areas; of particular concern is the fisheries industry in the Eastern Mediterranean.
Despite these threats, the phenomenon has allowed scientists to study an invasive event on a large scale in a short period of time, which usually takes hundreds of years in natural conditions.
[2] The Suez Canal quickly became the main pathway for the introduction of invasive species into the Eastern Mediterranean, having zoogeographic and ecological consequences far beyond what the designers foresaw.
The Lessepsian migration includes hundreds of Red Sea and Indo-Pacific species that have colonized and established themselves in the Eastern Mediterranean system, causing biogeographic changes without precedent in human memory.
It has since disappeared from local catches, while the narrow-barred Spanish mackerel Scomberomorus commerson, a known Lessepsian migrant, has dramatically increased in population.
Studies performed on this occurrence conclude that, due to similar life histories and diets, this may be an example of an invasive migrant outcompeting a native species and occupying its niche.
In addition, parasites originating in the Red Sea have shown an ability to use related native Mediterranean fish species as alternative hosts; e.g. the copepod Nipergasilus bora was known to parasitise the grey mullets Mugil cephalus and Liza carinata in the Red Sea, both taxa having been recorded as Lessepsian migrants, and was subsequently found parasitising the native Mediterranean mullets Chelon aurata and Chelon labrosus.
For example, the Indo-Pacific swimming crab Charybdis longicollis was first recorded in the Mediterranean in the mid-1950s and became dominant in silty and sandy substrates off the coast of Israel, making up to 70% of the total biomass in these habitats.
Following the warm winter of 1954–1955, it increased to 83% of the Israeli catch, replacing the native red mullet, which affected the Egyptian fishery, being 3% of their total landings.
[12] The high water temperatures of this unusually warm winter may have resulted in the poor survival of red mullet juveniles, which may have allowed the goatfish population to expand into the opened niche.
The population of Caesio varilineata (a fusilier fish, Caesionidae), recently reported from the eastern Mediterranean Sea,[13] may develop in a similar fashion.
Therefore, with such a high influx of herbivorous species in a small period of time, this phenomenon has normalised the food web, increasing the rate at which algae are consumed and serving as a major prey item for large predators.
[16] Among the fish species that have been confirmed as anti-Lessepsian migrants are peacock blenny (Salaria pavo),[17] Solea aegyptiaca, Mediterranean moray (Muraena helena), the rock goby (Gobius paganellus),[18] the meagre (Argyrosomus regius),[19] the comber (Serranus cabrilla),[20] European seabass (Dicentrarchus labrax), and spotted seabass (Dicentrarchus punctatus).
[22] The alewife (Alosa pseudoharengus), a species of shad from the Western Atlantic, invaded the Great Lakes by using the Welland Canal to bypass Niagara Falls.
