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Improving Existing Article: Lessepsian Migration
link to article: Lessepsian migration

WHY?

 * I want to improve this existing article because I did a lot of research on the bio-invasion of Indo-Pacific species into the Mediterranean through the Suez Canal for my fisheries management class.
 * This article mentions this bio-invasion, but doesn't give any of the repercussions of this, and I would like to add the aspect of how the introduction of these invasive species are impacting native species biological responses & interactions, and how this has impacted/will impact local fisheries. Furthermore, based off my literature review, I would like to add the past and current management systems in place to reduce species invasions and provide future management programs and methods to reduce the effects of this Lessepsian Migration.
 * As far as what is already in place, I would like to add on to the section with sub-header "Red Sea to Mediterranean", to go more in depth about the invasive species that are infiltrating, and also go more into the reasons why this is occurring, and at an exponential rate.

Lead Section
This migration of invasive species through the Suez Canal from the Indo-Pacific region has been facilitated by many factors, both abiotic and anthropogenic, and has strong implications on the ecosystem and local fisheries of the Eastern Mediterranean.

The phenomenon that has occurred from this Canal, however detrimental, has given scientists the opportunity to study the impact and processes of species invasions on a large scale, which usually occurs over long periods of time, but in this case, mere decades.

Red Sea to Mediterranean

 * Within the first paragraph:

Constructed in 1869 in order to provide a quick trade route from Europe to India to the Far East, this canal extends 162.5 km with a depth of 10-15 meters and a width of 200-300 meters.

The Red Sea is a highly abundant, tropical environment apart of the eastern Indo-Pacific Region, while on the other hand the Mediterranean is a temperate region with significantly low productivity; two systems extremely different in terms of structure and ecology. This connection became the main pathway of the introduction of invasive species into the Eastern Mediterranean, having zoogeographic and ecological consequences far beyond what the designers could foresee. The Lessepsian migration triggered biogeographic changes comparable to those generated by continental drift- hundreds of Red Sea and Indo-Pacific species have colonized and secured themselves in the Eastern Mediterranean system

2.1 Out competition of Natives
2.1.1 Native A. regius vs. Invasive S. commerson 

A native meagre in the Eastern Mediterranean, A. regius, was one of the most common commercial fish in Israel. However, this species has since disappeared from local catches, while interestingly, the Lessepsian migrant mackerel S. commersonhas has dramatically increased in population. Studies have been done on this occurrence, and it has been theorized 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

2.1.2 Native M. kerathurus vs Invasive Prawns

Eight species of invasive prawns from the Erythrean Sea have been recorded in the Eastern Mediterranean. These prawns are considered highly prized to the Levantine fisheries, and compose most of the prawn catch off the Mediterranean coast of Egypt, being 6% of total Egyptian landings. However, this high abundance of invasive prawns has lead to the decline of a native penaeid prawn M. kerathurus, which supported a commercial Israeli fishery throughout the 1950s. Due to out competition and its habitat being overrun by these migrants, this native species has since disappeared, having a detrimental impact on the commercial fishery.

2.2 Species Displacement
The goldband goatfish, Upeneus moluccensis, was first recorded in the eastern Mediterranean in the 1930’s and has since established an abundant population. Following a warm winter of 1954-1955, it increased to 83% of the Israeli catch, replacing the native red mullet, which also effected the Egyptian fishery, being 3% of their total landings. 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 this opened niche. Native mullet have since been displaced into deeper, cooler waters, where it has been found that Lessepsian migrants consist of only 20% of the catch, whereas in shallower, warmer waters, these invasives take up a staggering 87% of the catch. From this data, it is apparent that the Lessepsian migrants have not adapted to the more temperate environment of the deeper areas of the basin, but have established dominant populations in the habitats most similar to the tropical sea habitats from which they came.

2.3 Food Web Phase Shift
Indigenous Red Sea species S. ribulatus and Siganus luridus were first recorded off the coast of Israel in 1924. In only a few decades, these schooling, herbivorous fish were able to settle in a range of habitats forming abundant populations, to the extent where George and Athanassiou in a paper published in 1967 reported that: "The millions of young abound over rocky outcropping grazing on the relatively abundant early summer algal cover". By 2004, a study on these species of rabbitfish found that they comprise 80% of the abundance of herbivorous fish in the shallow coastal sites of the Lebanon. They have been able to create marked phase shifts within the food web on multiple levels. Prior to the arrival of these Lessepsian migrants, the herbivores filled a small ecological role within the Eastern Mediterranean system. Therefore, with such a high influx of herbivorous species in a small period of time, it has been found that this phenomenon has normalized the food web, increasing the rate at which algae is consumed and serving as a major prey item for large predators. This increased rate of grazing has in turn proliferated the settlement and colonization of a non indigenous species of mussel from the Indo-Pacific that is now able to attach to rocky substrate that was once covered with algae. This mussel, which has a thicker shell than that of the native mussel, has created a change in predation patterns as well, since they are more difficult to consume. Not only are these Red Sea migrants having a huge impact on this ecosystem, they are effecting fisheries as well, outcompeting native fish of high commercial value, such as Boops boops.

3. Factors Facilitating Lessepsian Migrant Colonization and Expansion
Anthropogenic Stressors: Aswan Dam

Impact of Lessepsian migrants on system may be heavier due to a major anthropogenic factor: the construction of the Aswan Dam. Before construction, the Nile River was able to deeply influence the marine environment of the Eastern Mediterranean, discharging high tonnage of nutrient rich water. This resulted in a high abundance of phytoplankton in the delta which had a beneficial influence on the productivity in the surrounding sea, and attracted large schools of sardines, resulting in a highly lucrative commercial fishery. After the dam’s completion in 1964, this productivity diminished, resulting in the cessation of nutrients in the Mediterranean, leading to a sharp decrease in fish populations, namely sardines, which ultimately lead to the collapse of the sardine fishery. As a result the Egyptian purse seine fishing industry today takes only 10% of the pre-dam catch This all may have been due to the influence of dispersion of the Red Sea invasives. The fresh-water discharge of the Nile could have been a natural barrier for some of the migrants in their movement through the Eastern Mediterranean.

Natural Stressors: Climate Change

With climate change and the warming of sea-water temperature, the thermophilic Lessepsian migrants will find it easier to reproduce, grow, and survive and will give them a distinct advantage over native temperate Mediterranean taxa. Both processes, global warming and the influx of Lessepsian migrants, may impact the already teetering fisheries by displacing commercially important native species, causing a phase shift in coastal ecosystems and changing seascape patterns. Furthermore, deepening of the warm surface layer is causing massive mortalities of organisms that do not tolerate high temperatures. Through various studies, it has been shown that species are now restricted to deeper levels and thrive for shorter periods than in the past. Climate change is also one of the reasons for another stressor on this system, the decline of natural barriers that were once in place to prevent many Red Sea natives to migrate to the Mediterranean. Due to global warming, the eastern Mediterranean is experiencing an increase in temperature and salinity, which is decreasing the hydrological barrier between the two seas, favoring the migrants from the tropic Indo-Pacific which have a warm-water affinity and causing mortality in the temperate eastern Mediterranean natives. The Bitter lakes created a natural salinity barrier within the Suez Canal due to their high deposits of salt, preventing many species from migrating. However, due to the freshening of these lakes, this natural barrier is weakening, allowing a higher mitigation of invasive species.