64
The Suez CanaI
at least the last 50 years, from the Cambridge Expedition of 1924 ti11 1972, when it
still was widespread. The lancelet needs fairly clean sandy bottoms, so that the
much-repeated talk ab out the progressive silting of the canal bottom is not supported by facts. Gohar (1954) speaks, for instance, of the fact that "during the first
years after the opening of the Canal the deposition of mud had not gone so far as
to impede the settlement of plants and animals ... Thus it is highly probable that,
during those years, the passage of the faunas ... was more active than it is now".
There are, however, no indications that the migration was more active in the first
years after the opening of the Canal.
There are likewise no data regarding a gradual silting up of the canal bottom.
As early as 1858 Schleiden expressed fears that an artificial canalleading through
the desert would soon be shoaled up by sands, as in the Sirbonic Lagoon. In the
different war periods in which the Canal was not subjected to maintenance and
especia11y during the last seven years of inactivity (1967-1974), fears were expressed that large stretches would have to be litera11y dug out again from und er
sand. This, however, was not the case for the several months of inactivity in 1956
[see Thorson in his letter exchange with Steinitz (1972)]. No dredges were used to
open the Canal in 1974 and the only problem mentioned as hindering the opening
to navigation were the mines, other war remnants and ship wrecks.
It is apparent that the currents in the Canal stretches are strong enough to
sweep away mud and sand deposits. This does not, however, mean that the Canal
bottom is a suitable substrate for a slowly developing population of sedentary
animals. Branchiostoma is the best example of an animal wh ich lives buried in a
current-swept substrate, capable of adjusting itself quickly and by adroit movements to the shifting ofthe substrate.
Most of the Canal banks are plated with stone and concrete slabs. The covering with stone started near the end ofthe 19th Century and is mentioned by Tillier
(1902). To this, one must add the ever-increasing surfaces of piers, pontoons,
buoys and, for some periods, ships wrecked or sunken in the Canal. Therefore, at
the surface of the Canal there is no dearth of hard substrate for a few species of
hardy intertidal organisms to settle. This circumstance was overseen in one of my
previous papers (Por, 1971 b), where I stated that hard substrates are rare along
the Canal. The stone banks are settled by some very hardy intertidal organisms.
However, in Lake Timsah and the Bitter Lakes, the shores are sandy, with only
restricted hard bottoms of beach-rock type.
If the lakes contain nearly 90% of the waters found in the canal, they offer also
the great majority of the bottoms available to the organisms entering the Canal.
Most of the lake bottom is natural and has never been dredged out. Therefore,
soon after the flooding, normal sedimentological processes started and similarly
also im undisturbed buildup of benthic communities began. The fact that the
bottoms of the lakes are almost exclusively sedimentary is of crucial importance
for the type of population which inhabits the Canal.
Our knowledge of the bottom of Lake Timsah (Fig.25) is based on Ti11ier
(1902), Fox (1926), Gruvel (1936), and on Tortonese (1952). According to Tillier
only some 75 ha have been dredged and dug out. To this one must add, according
to the same author, dumping places of out-dredged material, "bancs de vidage",
which at that time covered some 60 ha. Those dumping pi aces have no doubt
The Suez CanaI
at least the last 50 years, from the Cambridge Expedition of 1924 ti11 1972, when it
still was widespread. The lancelet needs fairly clean sandy bottoms, so that the
much-repeated talk ab out the progressive silting of the canal bottom is not supported by facts. Gohar (1954) speaks, for instance, of the fact that "during the first
years after the opening of the Canal the deposition of mud had not gone so far as
to impede the settlement of plants and animals ... Thus it is highly probable that,
during those years, the passage of the faunas ... was more active than it is now".
There are, however, no indications that the migration was more active in the first
years after the opening of the Canal.
There are likewise no data regarding a gradual silting up of the canal bottom.
As early as 1858 Schleiden expressed fears that an artificial canalleading through
the desert would soon be shoaled up by sands, as in the Sirbonic Lagoon. In the
different war periods in which the Canal was not subjected to maintenance and
especia11y during the last seven years of inactivity (1967-1974), fears were expressed that large stretches would have to be litera11y dug out again from und er
sand. This, however, was not the case for the several months of inactivity in 1956
[see Thorson in his letter exchange with Steinitz (1972)]. No dredges were used to
open the Canal in 1974 and the only problem mentioned as hindering the opening
to navigation were the mines, other war remnants and ship wrecks.
It is apparent that the currents in the Canal stretches are strong enough to
sweep away mud and sand deposits. This does not, however, mean that the Canal
bottom is a suitable substrate for a slowly developing population of sedentary
animals. Branchiostoma is the best example of an animal wh ich lives buried in a
current-swept substrate, capable of adjusting itself quickly and by adroit movements to the shifting ofthe substrate.
Most of the Canal banks are plated with stone and concrete slabs. The covering with stone started near the end ofthe 19th Century and is mentioned by Tillier
(1902). To this, one must add the ever-increasing surfaces of piers, pontoons,
buoys and, for some periods, ships wrecked or sunken in the Canal. Therefore, at
the surface of the Canal there is no dearth of hard substrate for a few species of
hardy intertidal organisms to settle. This circumstance was overseen in one of my
previous papers (Por, 1971 b), where I stated that hard substrates are rare along
the Canal. The stone banks are settled by some very hardy intertidal organisms.
However, in Lake Timsah and the Bitter Lakes, the shores are sandy, with only
restricted hard bottoms of beach-rock type.
If the lakes contain nearly 90% of the waters found in the canal, they offer also
the great majority of the bottoms available to the organisms entering the Canal.
Most of the lake bottom is natural and has never been dredged out. Therefore,
soon after the flooding, normal sedimentological processes started and similarly
also im undisturbed buildup of benthic communities began. The fact that the
bottoms of the lakes are almost exclusively sedimentary is of crucial importance
for the type of population which inhabits the Canal.
Our knowledge of the bottom of Lake Timsah (Fig.25) is based on Ti11ier
(1902), Fox (1926), Gruvel (1936), and on Tortonese (1952). According to Tillier
only some 75 ha have been dredged and dug out. To this one must add, according
to the same author, dumping places of out-dredged material, "bancs de vidage",
which at that time covered some 60 ha. Those dumping pi aces have no doubt