The Bottom of the Suez Canal
69
bottoms: a light brown mud, a dark reductive mud, dayey mud mixed with
gypsum and sandy muds.
It is evident that the bottoms below 9-10 m have suffered and are perhaps still
suffering locally from periods of lack of oxygen. This may be due in the first
instance to conditions of saline stratification in the Bitter Lake. Even under the
present circumstances of relatively lowered and homogenous salinities, pycnodines hindering circulation can still occur locally and temporarily.
Older information regarding the shallow bottoms of the lake, the "zone vivante" ofGruvel, is more than patchy. According to Tillier the eastern shores are
muddy, covered with sand and overgrown with very scattered patches of algae.
The LittIe Bitter Lake has, according to this author, bottoms of much harder
consistency. Fox (1926) gives only little information about the shallow bottoms of
the Lakes. He indicates the presence of H alophila-covered sand bottoms between
1-3 m depth. Gruvel (1936) gives a good map of the Great Bitter Lake and its
bottoms. According to hirn the shallowest are sheIl-admixed sands and around
5 m gepth there are muddy sands. Gruvel states that it is rare to find living specimes
of animals and plants below 6-7 m depth, although the sandy muds descend to
8-9 m depth before being replaced by the gypsiferous muds (see Fig. 26).
The most complete information is supplied by Beets (1953) who dredged the
bottoms of the Great Bitter Lake. His 47 stations cover the whole lake with a
most satisfactory grid. According to Beets, there are three types of "Plant Zones"
characterizing the shallow bottoms down to 10 m depth, the depth of the ''fouled''
bottoms. Plant Zone 2 is, according to Beets, covered with "Sargassum prob.crispum". In fact, there are probably three species of dominant algae there: Sargassum
dentifolium, S. subrepandum as weIl as Cystoseira myrica (Lipkin, 1972a). The upper
limit of the Sargassum zone is about 2-4 m. This type of algal association was
found by Beets along the western and most probably the southern and southeastern shore. In Beets' opinion there is a connection between the presence of distinct
plant zones along the western and southern shores and the prevailing northerly
winds.
Plant Zone 1 of Beets occupies the shallows of the western and northern
shores. It seems to this author probable that the zone is present with some
interruptions all around the Great Bitter Lake. The leading plant in this zone is
the sea-grass Halophila stipulacea, alm ost exdusive in Beets' words. According to
Lipkin (1972a) Halophila is intermingled to some extent with another sea-grass,
Halodule uninervis and with the alga Caulerpa racemosa. Plant Zone 1 extends
fromjust below waterlevel [usually 25 cm depth, Lipkin (1972b)] down to 2-4 m
and the Sargassum zone on the western and southern(?) shores. On the eastern
shore the Halophila meadows form the only subtidal vegetal association.
Beets' Plant Zone 3 is rather undefmed and formed of very shallow patchy
algal cover. It is probably similar to the patches of Cladophora species growing
according to Lipkin on very shallow sands, in fact attached to the protruding
shells of M actra olorina and other lamellibranchs and gastropods. The alga Acetabularia calyculus appears in the spring, growing on shells admixed to the shallow-water sand (Lipkin, 1972a).
The different plant associations grow on sandy-to-muddy bottoms. The bottom of the eastern shore is much shallower and less steep: here transition from
69
bottoms: a light brown mud, a dark reductive mud, dayey mud mixed with
gypsum and sandy muds.
It is evident that the bottoms below 9-10 m have suffered and are perhaps still
suffering locally from periods of lack of oxygen. This may be due in the first
instance to conditions of saline stratification in the Bitter Lake. Even under the
present circumstances of relatively lowered and homogenous salinities, pycnodines hindering circulation can still occur locally and temporarily.
Older information regarding the shallow bottoms of the lake, the "zone vivante" ofGruvel, is more than patchy. According to Tillier the eastern shores are
muddy, covered with sand and overgrown with very scattered patches of algae.
The LittIe Bitter Lake has, according to this author, bottoms of much harder
consistency. Fox (1926) gives only little information about the shallow bottoms of
the Lakes. He indicates the presence of H alophila-covered sand bottoms between
1-3 m depth. Gruvel (1936) gives a good map of the Great Bitter Lake and its
bottoms. According to hirn the shallowest are sheIl-admixed sands and around
5 m gepth there are muddy sands. Gruvel states that it is rare to find living specimes
of animals and plants below 6-7 m depth, although the sandy muds descend to
8-9 m depth before being replaced by the gypsiferous muds (see Fig. 26).
The most complete information is supplied by Beets (1953) who dredged the
bottoms of the Great Bitter Lake. His 47 stations cover the whole lake with a
most satisfactory grid. According to Beets, there are three types of "Plant Zones"
characterizing the shallow bottoms down to 10 m depth, the depth of the ''fouled''
bottoms. Plant Zone 2 is, according to Beets, covered with "Sargassum prob.crispum". In fact, there are probably three species of dominant algae there: Sargassum
dentifolium, S. subrepandum as weIl as Cystoseira myrica (Lipkin, 1972a). The upper
limit of the Sargassum zone is about 2-4 m. This type of algal association was
found by Beets along the western and most probably the southern and southeastern shore. In Beets' opinion there is a connection between the presence of distinct
plant zones along the western and southern shores and the prevailing northerly
winds.
Plant Zone 1 of Beets occupies the shallows of the western and northern
shores. It seems to this author probable that the zone is present with some
interruptions all around the Great Bitter Lake. The leading plant in this zone is
the sea-grass Halophila stipulacea, alm ost exdusive in Beets' words. According to
Lipkin (1972a) Halophila is intermingled to some extent with another sea-grass,
Halodule uninervis and with the alga Caulerpa racemosa. Plant Zone 1 extends
fromjust below waterlevel [usually 25 cm depth, Lipkin (1972b)] down to 2-4 m
and the Sargassum zone on the western and southern(?) shores. On the eastern
shore the Halophila meadows form the only subtidal vegetal association.
Beets' Plant Zone 3 is rather undefmed and formed of very shallow patchy
algal cover. It is probably similar to the patches of Cladophora species growing
according to Lipkin on very shallow sands, in fact attached to the protruding
shells of M actra olorina and other lamellibranchs and gastropods. The alga Acetabularia calyculus appears in the spring, growing on shells admixed to the shallow-water sand (Lipkin, 1972a).
The different plant associations grow on sandy-to-muddy bottoms. The bottom of the eastern shore is much shallower and less steep: here transition from