62
The Suez Canal
were above 60%0. From these data we may deduce that the sampies were collected
in the August-October period; this is however not by any means certain. In
October 1895 the "Pola" found no decrease in salinity and at Km 60 the value was
51.2%0 (Natterer, 1898). It can eventually be assumed that in the first period of
Canal history, the salinity was so high that the diluting influence was not felt so
much, or conversely that the current regime in the northern Canal was then
different (see above).
Tillier (1902) is again the first author to mention the connection between the
summer current regime and the appearance of low salinity waters in the northern
Canal. Wüst (1934) gave the classical presentation ofthe phenomenon.
Morcos (1960) reports for September 195433.15%0 at the Canal entrance and
36.29%0 near Lake Timsah. The respective values for September 1964 were
32.25%0 and 34.83%0. These are, however, surface values since in September 1964
at the Canal entrance the salinity at only 5 m depth was already 39.02%0.
After the cessation of the Nile flow through the closure of the Aswan Dam, in
October 1966 the "Chain" measured salinities between 40-43%0 in the northern
Canal, whereas in the Bitter Lakes it was 47%0. It seems therefore that in the late
summer period there is no marked decrease in salinity in the northern Canal.
Several authors assumed that the late summer period with the southward
current and lowered salinity is-or rather was---especially propitious for the
influx of Mediterranean species into the Canal. However, in the season when
salinity is at its lowest in the northern Canal, maximum seasonal salinities are
found in the Bitter Lake area. In September 1954, for instance-. the salinity range
from north to south reached 14.6%0 and in September 1964 even 15.6%0. On the
other hand in April of the respective years the salinity variations along the whole
Canal system were restricted to only 2%0.
One may eventually ass urne that after the closure of the Aswan Dam in 1966
some advantage resulted for the southward migrating animals since in the period
in which a southward current moves into the Canal, there are no more of the
sharp changes in salinity which the organisms had to face before.
Pollution. Little is known about pollution in this highly navigated waterway.
One can accept apriori that the Canal system suffered much from pollution and
that the whole environment was comparable to that of a big harbor. There are no
data concerning the restricting influence of pollution on the Canal biota.
The only data found in literature are those of Fonselius (1966, 1967) who
found unusually high values of zinc and copper in the Bitter Lake. Strangely,
Fonselius attributed this to some sort of influence from the Northern Red Sea, in
which the values of these ions were also high. Morcos (1970) however, rightly
assurnes that these concentrations may be due to pollution.
Oil pollution due to leaks and bilges is probably high. In' the littoral of the
Bitter Lake near Deversoir in 1969, I saw considerable amounts of oil and tar
mixed with the beachrock and the sandy conglomerate (Por, 1971 b). Considerable oil pollution is reported from Suez where big oil refineries are situated west
of the harbor of Port Ibrahim. Pollution there was already considerable in the
thirties when Gruvel (1934) considered the area as "literalement empoisonnee par
le petrole, le mazout ou leurs d6chets de fabrication".
The Suez Canal
were above 60%0. From these data we may deduce that the sampies were collected
in the August-October period; this is however not by any means certain. In
October 1895 the "Pola" found no decrease in salinity and at Km 60 the value was
51.2%0 (Natterer, 1898). It can eventually be assumed that in the first period of
Canal history, the salinity was so high that the diluting influence was not felt so
much, or conversely that the current regime in the northern Canal was then
different (see above).
Tillier (1902) is again the first author to mention the connection between the
summer current regime and the appearance of low salinity waters in the northern
Canal. Wüst (1934) gave the classical presentation ofthe phenomenon.
Morcos (1960) reports for September 195433.15%0 at the Canal entrance and
36.29%0 near Lake Timsah. The respective values for September 1964 were
32.25%0 and 34.83%0. These are, however, surface values since in September 1964
at the Canal entrance the salinity at only 5 m depth was already 39.02%0.
After the cessation of the Nile flow through the closure of the Aswan Dam, in
October 1966 the "Chain" measured salinities between 40-43%0 in the northern
Canal, whereas in the Bitter Lakes it was 47%0. It seems therefore that in the late
summer period there is no marked decrease in salinity in the northern Canal.
Several authors assumed that the late summer period with the southward
current and lowered salinity is-or rather was---especially propitious for the
influx of Mediterranean species into the Canal. However, in the season when
salinity is at its lowest in the northern Canal, maximum seasonal salinities are
found in the Bitter Lake area. In September 1954, for instance-. the salinity range
from north to south reached 14.6%0 and in September 1964 even 15.6%0. On the
other hand in April of the respective years the salinity variations along the whole
Canal system were restricted to only 2%0.
One may eventually ass urne that after the closure of the Aswan Dam in 1966
some advantage resulted for the southward migrating animals since in the period
in which a southward current moves into the Canal, there are no more of the
sharp changes in salinity which the organisms had to face before.
Pollution. Little is known about pollution in this highly navigated waterway.
One can accept apriori that the Canal system suffered much from pollution and
that the whole environment was comparable to that of a big harbor. There are no
data concerning the restricting influence of pollution on the Canal biota.
The only data found in literature are those of Fonselius (1966, 1967) who
found unusually high values of zinc and copper in the Bitter Lake. Strangely,
Fonselius attributed this to some sort of influence from the Northern Red Sea, in
which the values of these ions were also high. Morcos (1970) however, rightly
assurnes that these concentrations may be due to pollution.
Oil pollution due to leaks and bilges is probably high. In' the littoral of the
Bitter Lake near Deversoir in 1969, I saw considerable amounts of oil and tar
mixed with the beachrock and the sandy conglomerate (Por, 1971 b). Considerable oil pollution is reported from Suez where big oil refineries are situated west
of the harbor of Port Ibrahim. Pollution there was already considerable in the
thirties when Gruvel (1934) considered the area as "literalement empoisonnee par
le petrole, le mazout ou leurs d6chets de fabrication".