66
The Suez Canal
lives on these muddy bottoms. On the other hand, Fox reports grey sandy mud
from the center of the lake with abundant ophiuroids and leucosiid crabs. Black
mud with ophiuroids appears also at another station in the middle of the lake. It
appears thus that the dredged bottoms of Lake Timsah present difficult conditions for benthic animals, though still suitable for some species.
The natural undredged bottoms of the lake, at an average of 6 m depth, as weIl
as the many shallow lagoons are covered with mud at depths exceeding 2-3 m;
however, this mud is already rich in fauna. These bottoms are characterized as
grey muds by Gruvel.
Gradually this oxygenated mud is covered with a layer of sand and around 25 m meadows of the flowering plant Halophila stipulacea appear. The shallows of
the lagoons are pure sand (Tortonese, 1952)-the lagoons ofthe western shore are
already covered with fresh w~ter and overgrown with Ceratophyllum. In the eastern lagoons Halophila is found even on the shallowest sands.
Lake Timsah is given by various authors as a textbook case (following Fox,
1926) for the presence of oxygen on the bottom despite saline stratification. Since
the water is clear, water plants and algae provide abundant oxygen supply,
probably down to some 3-4 m depth.
The bottoms of the Bitter Lakes are much better known. Gruvel (1936)
(Fig.26) and Beets (1953) give bathymetric and sediment maps of the Bitter Lakes.
Arecent transect sampled in 1973 by Y. Etam (personal communication) also
gives interesting information.
The problem of the so-called "gelatinous mud" and the gradual dissolution of
the salt bank have already been discussed in a previous chapter.
.
Here is the relevant place to present the description of the basin of the Bitter
Lakes before the flooding by the Canal waters, as given by Aillaud (1868). The
basin was a typical "sabkha": a salt marsh like many others around the Red Sea
and Persian Gulf and the Sabkhat el Bardawil (mentioned above as the Sirbonic
Lagoon) (Fig.27). Aillaud speaks of the thiekets of Tamarix on the east shore as
being inhabited by a rich avifauna counting among others such water fowl as
pelicans, flamingoes, ducks, and geese. These are frequent on the sandy shoals
which emerge from the water-filled depression which surrounds the salt bank. As
far as one kilometer from the central salt dome there were big puddIes of very
clear water. The bottom around was muddy and contained many moIlusc shells.
At the time of Tillier, the Bitter Lakes were filled up and had sandy shallows
around the central deep. Fox's sampIes came mostly from the Little Bitter Lake:
sam pIes of black anoxic mud, one sam pIe of grey muddy sand at 11-12 m depth
with a fairly rieh fauna, and two shallow sampIes from bottoms covered with the
sea-grasses Halophila or Diplanthera (Halodule).
Gruvel indicates that the whole central part of the Great Bitter Lake is covered by a gypsum-admixed mud. This is an anaerobic bottom: a "zone morte"
where only a few specimens of Murex tribulus and Gastrochaena live.
Beets (1953) did not investigate the deepest bottoms of ± 15 m. However, from
the central shipping lane he reports at 10.80 m and 11.30 m depth, clay or sandy
clay devoid ofvegetation. The bottoms below 9 mare, according to this author,
fouled by a combination of stagnancy and the exhaust products (see also previous
chapter). Etam in 1973 (pers. comm.) reports from 10-16 m depth a variety of
The Suez Canal
lives on these muddy bottoms. On the other hand, Fox reports grey sandy mud
from the center of the lake with abundant ophiuroids and leucosiid crabs. Black
mud with ophiuroids appears also at another station in the middle of the lake. It
appears thus that the dredged bottoms of Lake Timsah present difficult conditions for benthic animals, though still suitable for some species.
The natural undredged bottoms of the lake, at an average of 6 m depth, as weIl
as the many shallow lagoons are covered with mud at depths exceeding 2-3 m;
however, this mud is already rich in fauna. These bottoms are characterized as
grey muds by Gruvel.
Gradually this oxygenated mud is covered with a layer of sand and around 25 m meadows of the flowering plant Halophila stipulacea appear. The shallows of
the lagoons are pure sand (Tortonese, 1952)-the lagoons ofthe western shore are
already covered with fresh w~ter and overgrown with Ceratophyllum. In the eastern lagoons Halophila is found even on the shallowest sands.
Lake Timsah is given by various authors as a textbook case (following Fox,
1926) for the presence of oxygen on the bottom despite saline stratification. Since
the water is clear, water plants and algae provide abundant oxygen supply,
probably down to some 3-4 m depth.
The bottoms of the Bitter Lakes are much better known. Gruvel (1936)
(Fig.26) and Beets (1953) give bathymetric and sediment maps of the Bitter Lakes.
Arecent transect sampled in 1973 by Y. Etam (personal communication) also
gives interesting information.
The problem of the so-called "gelatinous mud" and the gradual dissolution of
the salt bank have already been discussed in a previous chapter.
.
Here is the relevant place to present the description of the basin of the Bitter
Lakes before the flooding by the Canal waters, as given by Aillaud (1868). The
basin was a typical "sabkha": a salt marsh like many others around the Red Sea
and Persian Gulf and the Sabkhat el Bardawil (mentioned above as the Sirbonic
Lagoon) (Fig.27). Aillaud speaks of the thiekets of Tamarix on the east shore as
being inhabited by a rich avifauna counting among others such water fowl as
pelicans, flamingoes, ducks, and geese. These are frequent on the sandy shoals
which emerge from the water-filled depression which surrounds the salt bank. As
far as one kilometer from the central salt dome there were big puddIes of very
clear water. The bottom around was muddy and contained many moIlusc shells.
At the time of Tillier, the Bitter Lakes were filled up and had sandy shallows
around the central deep. Fox's sampIes came mostly from the Little Bitter Lake:
sam pIes of black anoxic mud, one sam pIe of grey muddy sand at 11-12 m depth
with a fairly rieh fauna, and two shallow sampIes from bottoms covered with the
sea-grasses Halophila or Diplanthera (Halodule).
Gruvel indicates that the whole central part of the Great Bitter Lake is covered by a gypsum-admixed mud. This is an anaerobic bottom: a "zone morte"
where only a few specimens of Murex tribulus and Gastrochaena live.
Beets (1953) did not investigate the deepest bottoms of ± 15 m. However, from
the central shipping lane he reports at 10.80 m and 11.30 m depth, clay or sandy
clay devoid ofvegetation. The bottoms below 9 mare, according to this author,
fouled by a combination of stagnancy and the exhaust products (see also previous
chapter). Etam in 1973 (pers. comm.) reports from 10-16 m depth a variety of