The Levant Shore-the Core Area ofthe Lessepsian Immigration
123
Prior to the opening of the Canal there were practically no species specifically
restricted to the Levant Basin. Perhaps the only positive traits can be found in the
quantitative increase in the populations of some species typical for warm and
saline waters. Parker (1958), far instance, notes the considerable increase in the
numbers of the planktonic forrniniferan Globigerinoides ruber in the Eastern
Mediterranean. Here it represents 41-77% ofthe planktonic F oraminiferida, while
in the Western Mediterranean it constitutes only 1-25% of the total. Peres (1967)
emphasizes the exceptionally rich development along the Levant coast of the
facies-building mollusc Vermetus triqueter, rare in the West. Peres also emphasizes
the rich development of the soft bottom meadows of the green al ga Caulerpa
prolifera accompanied by Caulerpa scalpelliformis (considered by Peres to be a
Red Sea immigrant, but known also from the Canary Islands).
A few words must be said about the so-called "Levantine nannism"-the
smallness of the specimens in the Levant Basin, especially apparent in groups
such as Sipuncula (Stephen, 1958) and Porifera (Levi, 1957). Remarked already by
Forbes far the Aegean Sea and by Le Danois (1925) for the East Mediterranean
fishes, it is later accepted as a general phenomenon by Tortonese (1951). Such
small-sized individuals indicate sub optimal environmental conditions, The
smaller biomasses of an irnpoverished fauna is the general rule for biota of the
Levant Basin. Peres (1967) concludes his study on the Mediterranean benthos
with the words: "It appears that certain Mediterranean biocoenoses, above all
those in the infralittoral zone, are under a kind of disequilibrium which is a
consequence of the non-utilization of a certain fraction of their production"-a
statement more applicable specifically to the Levant Basin.
The Lessepsian migrants may be considered, in a figurative sense, "welcome
guests" in the impoverished, subtropical cul-de-sac of the Atlanto-Mediterranean
world.
3.3 The Levant Shorethe Core Area of the Lessepsian Immigration
Most of the Lessepsian immigrants are to be found along the shores of Sinai,
Israel, Lebanon and Syria, thus necessitating a more detailed description of the
Levant shelf area, an integral part of the Levant Basin (see Map 2, p. 85).
The Levant shore is dorninated by a relatively broad shelf built up by sediments deposited by the Nile. The majority of the 100-130 million tons of silt
carried yearly by the Nile (Hammerton, 1972) was deposited to the East of the
Delta, by the counter-clockwise Coriolis current. At depths of 30-75 m (Oren,
unpublished data) the outrunners of the Atlantic current also contributed to
the transport.
The shelf of the Levant shore, from Port Said to the surroundings of Haifa, is
relatively wide. According to Gorgy (1966) it reaches a maximum width of75 km
in the Gulf of Pelusium (Gulf of Tina), then narr9ws to 29 km off the Sirbonic
Lagoon (Bardawil), broadens to 40 km at EI Arish, and narrows gradually along
the Israel shores from 30 km at Rubin to 10 km near Haifa (Emery and Bentor,
1960). Near the Lebanese barder, the shelf is very narrow, some 3 km wide, and it
123
Prior to the opening of the Canal there were practically no species specifically
restricted to the Levant Basin. Perhaps the only positive traits can be found in the
quantitative increase in the populations of some species typical for warm and
saline waters. Parker (1958), far instance, notes the considerable increase in the
numbers of the planktonic forrniniferan Globigerinoides ruber in the Eastern
Mediterranean. Here it represents 41-77% ofthe planktonic F oraminiferida, while
in the Western Mediterranean it constitutes only 1-25% of the total. Peres (1967)
emphasizes the exceptionally rich development along the Levant coast of the
facies-building mollusc Vermetus triqueter, rare in the West. Peres also emphasizes
the rich development of the soft bottom meadows of the green al ga Caulerpa
prolifera accompanied by Caulerpa scalpelliformis (considered by Peres to be a
Red Sea immigrant, but known also from the Canary Islands).
A few words must be said about the so-called "Levantine nannism"-the
smallness of the specimens in the Levant Basin, especially apparent in groups
such as Sipuncula (Stephen, 1958) and Porifera (Levi, 1957). Remarked already by
Forbes far the Aegean Sea and by Le Danois (1925) for the East Mediterranean
fishes, it is later accepted as a general phenomenon by Tortonese (1951). Such
small-sized individuals indicate sub optimal environmental conditions, The
smaller biomasses of an irnpoverished fauna is the general rule for biota of the
Levant Basin. Peres (1967) concludes his study on the Mediterranean benthos
with the words: "It appears that certain Mediterranean biocoenoses, above all
those in the infralittoral zone, are under a kind of disequilibrium which is a
consequence of the non-utilization of a certain fraction of their production"-a
statement more applicable specifically to the Levant Basin.
The Lessepsian migrants may be considered, in a figurative sense, "welcome
guests" in the impoverished, subtropical cul-de-sac of the Atlanto-Mediterranean
world.
3.3 The Levant Shorethe Core Area of the Lessepsian Immigration
Most of the Lessepsian immigrants are to be found along the shores of Sinai,
Israel, Lebanon and Syria, thus necessitating a more detailed description of the
Levant shelf area, an integral part of the Levant Basin (see Map 2, p. 85).
The Levant shore is dorninated by a relatively broad shelf built up by sediments deposited by the Nile. The majority of the 100-130 million tons of silt
carried yearly by the Nile (Hammerton, 1972) was deposited to the East of the
Delta, by the counter-clockwise Coriolis current. At depths of 30-75 m (Oren,
unpublished data) the outrunners of the Atlantic current also contributed to
the transport.
The shelf of the Levant shore, from Port Said to the surroundings of Haifa, is
relatively wide. According to Gorgy (1966) it reaches a maximum width of75 km
in the Gulf of Pelusium (Gulf of Tina), then narr9ws to 29 km off the Sirbonic
Lagoon (Bardawil), broadens to 40 km at EI Arish, and narrows gradually along
the Israel shores from 30 km at Rubin to 10 km near Haifa (Emery and Bentor,
1960). Near the Lebanese barder, the shelf is very narrow, some 3 km wide, and it