History of the Population of the Canal
71
funnel, a corridor through which animals pass like ships from one sea to the other,
it is evident that the 162 km could not be passed in one attempt, even by swift
swimmers. Keller (1882) spoke of an advance of the biota like "caravans" making
stop-overs from time to time; Tillier (1902) separates "especes ftxes" among the
ftsh of the Suez Canal; Gruvel (1936) speaks of the necessity for the species to ftnd
"zones de stabulation" in the Canal. The authors, and most recently Thorson
unpublished, 1971) never completely ruled out the possibility of planktonic
larvae being transported through the Canal by currents during one life-cycle step,
i.e. being hatched in the open waters of the Red Sea and reaching metamorphosis
and settling down in the open Mediterranean. This hypothesis was, however,
never supported by any fmding in the fteld.
Lipkin (1972a), when he opposes my "step by step" advance through the
Canal (por, 1971 b) and emphasizes the "one-jump" possibility, refers only to
passive transport by ship. H. Steinitz (1968) accepts as "rare incidents" only, cases
in which one individual passed the whole length of the route from one sea to the
other.
Therefore, Lessepsian migration cannot be understood without an analysis of
the living world of the Suez Canal wh ich acts as a filtrating funnel. EIsewhere
(Por, 1971 b, 1973b), I have postulated that the best and perhaps the only proof
that an Indo-Pacmc species found in the Mediterranean is a Lessepsian migrant,
is the fact that it is living in the Suez Canal. Only those animals able to survive in
the Suez Canal environments for some periods or generations, eventually become
Lessepsian migrants.
The discussion ofthe biota of the Suez Canal has every right to be considered
a subject for a monographie study. I shall conftne myself in the following sentences only to those aspects necessary for the understanding of Lessepsian migration, i.e. the zoogeographical end-product of a successful crossing of the Suez
Canal.
One more reservation is necessary. Most of the knowledge concerning the
living world of the Suez Canal relates to the Bitter Lakes. Since 85% of the water
volume of the Suez Canal is contained in the Bitter Lakes, this circumstance is
welcome. However, the lack of information, especially concerning Lake Timsah,
is very regrettable.
The following discussion will be brought under three main topics: (1) history
of colonization; (2) aspects of floral and faunal diversity; (3) zoogeographical
analysis of the Canal population.
2.6 History of the Population of the Canal
Nothing is known about the animal and vegetal populations of the very ftrst
years of the Canal. Only Tillier (1902) remarks briefly that during a crossing of the
Suez Canal in June 1871 Qess than two years after its opening) the waters were
rich in fish, especially Sciaena aquila. Since this fish feeds on mullets, Tillier
assumes that Mugilidae were also present at that date.
According to this same author, even the shallow service channel of two to
three m in depth built in 1863 southward from Port Said already contained fish.
71
funnel, a corridor through which animals pass like ships from one sea to the other,
it is evident that the 162 km could not be passed in one attempt, even by swift
swimmers. Keller (1882) spoke of an advance of the biota like "caravans" making
stop-overs from time to time; Tillier (1902) separates "especes ftxes" among the
ftsh of the Suez Canal; Gruvel (1936) speaks of the necessity for the species to ftnd
"zones de stabulation" in the Canal. The authors, and most recently Thorson
unpublished, 1971) never completely ruled out the possibility of planktonic
larvae being transported through the Canal by currents during one life-cycle step,
i.e. being hatched in the open waters of the Red Sea and reaching metamorphosis
and settling down in the open Mediterranean. This hypothesis was, however,
never supported by any fmding in the fteld.
Lipkin (1972a), when he opposes my "step by step" advance through the
Canal (por, 1971 b) and emphasizes the "one-jump" possibility, refers only to
passive transport by ship. H. Steinitz (1968) accepts as "rare incidents" only, cases
in which one individual passed the whole length of the route from one sea to the
other.
Therefore, Lessepsian migration cannot be understood without an analysis of
the living world of the Suez Canal wh ich acts as a filtrating funnel. EIsewhere
(Por, 1971 b, 1973b), I have postulated that the best and perhaps the only proof
that an Indo-Pacmc species found in the Mediterranean is a Lessepsian migrant,
is the fact that it is living in the Suez Canal. Only those animals able to survive in
the Suez Canal environments for some periods or generations, eventually become
Lessepsian migrants.
The discussion ofthe biota of the Suez Canal has every right to be considered
a subject for a monographie study. I shall conftne myself in the following sentences only to those aspects necessary for the understanding of Lessepsian migration, i.e. the zoogeographical end-product of a successful crossing of the Suez
Canal.
One more reservation is necessary. Most of the knowledge concerning the
living world of the Suez Canal relates to the Bitter Lakes. Since 85% of the water
volume of the Suez Canal is contained in the Bitter Lakes, this circumstance is
welcome. However, the lack of information, especially concerning Lake Timsah,
is very regrettable.
The following discussion will be brought under three main topics: (1) history
of colonization; (2) aspects of floral and faunal diversity; (3) zoogeographical
analysis of the Canal population.
2.6 History of the Population of the Canal
Nothing is known about the animal and vegetal populations of the very ftrst
years of the Canal. Only Tillier (1902) remarks briefly that during a crossing of the
Suez Canal in June 1871 Qess than two years after its opening) the waters were
rich in fish, especially Sciaena aquila. Since this fish feeds on mullets, Tillier
assumes that Mugilidae were also present at that date.
According to this same author, even the shallow service channel of two to
three m in depth built in 1863 southward from Port Said already contained fish.