38
The HistoricaI Background
over 90%0, a marine cyc1opoid N eocyclops salinarum meets two euryhaline harpacticoids of continental origins, N itocra lacustris and Cletocamptus conjluens. It
is of considerable interest that 12 of the 15 species are also known from the Suez
Canal and its surroundings. Six species are of Red Sea origin and one or two
additional species, although possibly circumtropical, also came by way of the
Canal (Por, 1973a).
No other group ofthe zoobenthos has been analyzed in detail. There are two
euryhaline ostracods (Cyprideis torosa and Aglaiella sp.), many nematodes, a watermite, and one or two species of mysids. The larva of the chironomide Cricotopus mediterraneus reaches predominance at high salinities (around 60-70%0) and is
an important food basis for some fishes (Ben-Tuvia and Herman, 1972).
The macrobenthos is excessively poor. The only macrophyte is the flowering
plant Ruppia ovalis. On the plants are rich epiphytic growths of Cladophora sp.
(Lipkin, unpublished). This last species developed especially during the high salinity years of the c10sure of the openings (Ben Tuvia and Herman, 1972). Only five
species of mollusc are reported, namely Cerithium scabridum, Pirenella conica (or
P. cailliaudi), Cerastoderma glaucum, M actra olorina, and Brachidontes variabilis.
The first four species live on level bottoms, B. variabilis on wooden piers and
poles. It is interesting to note that this litde mussel can be found even at a salinity
of70%0.
An unidentified hydrozoan and the sabelIid polychaete Augeneriella lagunari
live on the Ruppia sterns. Balanus amphitrite accompanies Brachidontes on the
wooden structures. A Sphaeroma sp. seems to be the only type of isopod present.
The migratory element, reproducing in the open sea and entering the lagoon
for a certain period, is represented among decapods and fishes. The shrimp M etapeneus stebbingi is a widespread species, but according to Tendler (1972) in the
high salinity year of 1970 it was relatively rare at 60%0. The swimming crab
Charybdis sp. was also reported.
A total of 41 species of fish have been reported from the lagoon by Ben-Tuvia
and Herman (1972). This number increased to 65 (Ben-Tuvia, 1975b). Only Aphanius dispar reproduces in the lagoon and survives at salinities over 70%0. The other
species probably only feed in the lagoon. The most important commercial fish,
Sparus aurata, was introduced from the Lagoon of Venice by Italian fishermen
(Ben-Tuvia, personal communication). The estuarine fishes predorninate: Dicentrarchus labrax and D. punctatus, six species of grey mullet, among them the Red
Sea Liza carinata, the atherinids Atherina mochon (Mediterranean) and Pranesus
pinguis (Red Sea), the Mediterranean goby Pomatoschistus marmoratus, the Red
Sea Sparidae Crenidens crenidens, etc. It is interesting to note that the fishes of
Red Sea origin constitute 25% of the species in the Sirbonis, whereas in the open
Mediterranean they constitute only 10% (Ben-Tuvia, 1975b).
In conc1usion, the relevance ofthe study ofthe Sirbonic Lagoon (or Bardawil
Lagoon) for the Lessepsian migration, can be summarized as folIows:
1. The flora and fauna of the Sirbonis may serve as a model for an Isthmian,
pre-Lessepsian saline waterbody, especially in its periods of isolation from the sea.
2. The wide range ofhigh salinities in the lagoon, once renewed contact to the
sea is established, give excellent opportunities for a model of the first stages of the
invasion of the Suez Canal when salinity was still high.
The HistoricaI Background
over 90%0, a marine cyc1opoid N eocyclops salinarum meets two euryhaline harpacticoids of continental origins, N itocra lacustris and Cletocamptus conjluens. It
is of considerable interest that 12 of the 15 species are also known from the Suez
Canal and its surroundings. Six species are of Red Sea origin and one or two
additional species, although possibly circumtropical, also came by way of the
Canal (Por, 1973a).
No other group ofthe zoobenthos has been analyzed in detail. There are two
euryhaline ostracods (Cyprideis torosa and Aglaiella sp.), many nematodes, a watermite, and one or two species of mysids. The larva of the chironomide Cricotopus mediterraneus reaches predominance at high salinities (around 60-70%0) and is
an important food basis for some fishes (Ben-Tuvia and Herman, 1972).
The macrobenthos is excessively poor. The only macrophyte is the flowering
plant Ruppia ovalis. On the plants are rich epiphytic growths of Cladophora sp.
(Lipkin, unpublished). This last species developed especially during the high salinity years of the c10sure of the openings (Ben Tuvia and Herman, 1972). Only five
species of mollusc are reported, namely Cerithium scabridum, Pirenella conica (or
P. cailliaudi), Cerastoderma glaucum, M actra olorina, and Brachidontes variabilis.
The first four species live on level bottoms, B. variabilis on wooden piers and
poles. It is interesting to note that this litde mussel can be found even at a salinity
of70%0.
An unidentified hydrozoan and the sabelIid polychaete Augeneriella lagunari
live on the Ruppia sterns. Balanus amphitrite accompanies Brachidontes on the
wooden structures. A Sphaeroma sp. seems to be the only type of isopod present.
The migratory element, reproducing in the open sea and entering the lagoon
for a certain period, is represented among decapods and fishes. The shrimp M etapeneus stebbingi is a widespread species, but according to Tendler (1972) in the
high salinity year of 1970 it was relatively rare at 60%0. The swimming crab
Charybdis sp. was also reported.
A total of 41 species of fish have been reported from the lagoon by Ben-Tuvia
and Herman (1972). This number increased to 65 (Ben-Tuvia, 1975b). Only Aphanius dispar reproduces in the lagoon and survives at salinities over 70%0. The other
species probably only feed in the lagoon. The most important commercial fish,
Sparus aurata, was introduced from the Lagoon of Venice by Italian fishermen
(Ben-Tuvia, personal communication). The estuarine fishes predorninate: Dicentrarchus labrax and D. punctatus, six species of grey mullet, among them the Red
Sea Liza carinata, the atherinids Atherina mochon (Mediterranean) and Pranesus
pinguis (Red Sea), the Mediterranean goby Pomatoschistus marmoratus, the Red
Sea Sparidae Crenidens crenidens, etc. It is interesting to note that the fishes of
Red Sea origin constitute 25% of the species in the Sirbonis, whereas in the open
Mediterranean they constitute only 10% (Ben-Tuvia, 1975b).
In conc1usion, the relevance ofthe study ofthe Sirbonic Lagoon (or Bardawil
Lagoon) for the Lessepsian migration, can be summarized as folIows:
1. The flora and fauna of the Sirbonis may serve as a model for an Isthmian,
pre-Lessepsian saline waterbody, especially in its periods of isolation from the sea.
2. The wide range ofhigh salinities in the lagoon, once renewed contact to the
sea is established, give excellent opportunities for a model of the first stages of the
invasion of the Suez Canal when salinity was still high.