الفهرس 
Numerical taxonomicalOnly 14 pages are availabe for public view
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Abstract
V - SUMMARY
Freshwnter invertebrates have a great economic importance either as a source
of protein for man (as cn~stacea) or as a source of food for fishes and edible
Crustacea (as zooplankton and other invertebrates). Furthermore some these
freshwater invertebrates are parasites which cause diseases for several aquatic
animals either vertebrates or invertebrates. Also, other species act as intermediate . .
hosts for parasites infecting man, wild and domestic animals, birds and fishes.
In spite of the above mentioned economic importance, the taxonomical and
morphological studies on the Egyptian freshuiater invertebrate fauna are
insufficient and covers only very small parts of the taxa, and Therefore this thesis
was planned in an attempt to fill this shortage. The study is divided into two main
parts. The first part contains a detailed taxonomical investigation of freshwater
invertebrate fauna inhabiting some water bodies in Gharbia and Menoufia
governorats. Keys and descriptions of the recorded specces as well as
redescriptions were submitted with the aid of scanning eletron microscope. The
second part includs some ecological observation on the recorded taxa including
dominancy population density and seasonal distribution. . .
The sa~nples were collected monthly from each of four sites in Delta
provience (Two sites in Gharbia governorate and two sites in Menoufia
govcrnorate) through n period of two years extending from December 1988 till
November 1900. Each sample consisted of a single vertical net haul at the
sampling site. Meanwhile, with each collection, temperature of water and air were
measured. Other sites of collecrion were taken once either to search for large
Crustacea as shrimp and crab (Rahr Shebin Canal) or to determine the density of
freshwater invertebrate fauna in polluted area (drain behind the ice factory in
Tan t a).
The large samples such as leeches, Molluses and decapods which are
attached to stones, plants stems and floating leaves were hand-picked for the
investigation.
The main results of this study could be summarized as follow : -
1 - Taxonomy :
The recorded species were 27 in number belonging to seven phyla. Among
these, 14 species are large and hand - picked. These species are Barbronia
assiuti; Salijb perspicax; Helobdella conifera (Nirudinea : Annelida); Neritina
nilotica; Viviparn utzicolm-, Lanistes boltetzi; Cleopatra bulitnoides; Lytnlnaeu
tnitzcat~rla; Bulitz~is trwzcatus; Bio~npl~daria alexatzdritza; plzysa acuta; Sphueriutn
sitnile (Molluscs) atzd Potarnotzautes tziloticus (Crustacea). The other 13 species
are planktonic ind collected by the net. These are Hydra viridis; Hydra vulgaris
(Hydrozoa : Cnidar-ia); Mesostoma orabiensis (Turbellaria : Platyhelminthes),
Brachion~is ~irceolaris (Rotifera), Dorylainzus fecundus (Nematoda); Pristina
sp., Nais sp. (Oligochaeta : Annelida), Ceriodaphnia reticulata, Sitnoceplzalus
exspitlosus, Si11zoceplza1~i.s ver~ilus (Brnnchiopoda : Crustacea). Cypretta bilicis,
Cl~lutnydotlzeca texasiensis (Ostracoda : Crustacea) and Cyclops vernalis
(Copepoda : Crustacea). Among detected sample 8 species are firstly recorded in
Egyptian freshwater. These species are H. viridis, H. vulgris, D. fecundus,
Pristina sp. Nais sp., Cypretta bilicis, C. texasiensis and C. vernalis .
2. Ecology :
It has been found from the data, that the species of Copepoda and Cladocera . .
are the most domitiant members in all sites of collection while the species of
Ostracoda and Turbellxia are the least dominant members. The relatively low
densities of Kotifera recorded here might be due to the cleaning of the investigated
water bodies during late sping and early summer in both years of investigation.
The species of Rotifera, B. ~irceolnris, was found to be dominant at sites 2 and 4.
On the other hand, the species of Copepoda (C. vernalis ) and Nematoda (D.
fec~rndi~s ) weie’found to be dominant at all sites of collection except at site 4.
Moreover, the turbellarian species and Nais sp. were found to be subdominant in
- all the investigated sites. The ostracode species, C. texasiensis was found to be
subrecedent at site 3. The ecological parameters used have reveale that the species
composition of the invertebrate zooplankton community at the studied sites was
more or less similar. This may be due to the close similarity of the prevailing
anvironmentnl factors during this study.
The effect of silt, clay, mud and salinity on the susceptibility of Nais sp. and
Physa aclltcl to Cd C12 concentrations was also studied. The applied solutions
were changed every 24 hours. The volume of the solution depended upon the
number and size of the animals i.e. 1 ml and 2 ml of solution for each
individual of Nais sp. and P. acuta, respectively. The concentrations of Cd C12
used were 1, 1.5, 2.5, 5 and 10 ppm and the quantities of silt, clay or mud used
. in the experiments were 0.2, 0.4, 0.6, 0.8 and 1 gm.
The present data demonstrate that Nais sp. shows an obvious resistant
against the different concentrations of Cd C12 or no obvious effect on the
mortality of these worms at low levels of cadmium and there is no significant
difference between the doses 1 and 1.5 ppm. Moreover, the results showed that
silt amount of 0.6 gm was accompanied by higher mortalities within the first
seven days of treatment after which the higher mortalities were restricted the lower
quantity of silt. The statistical analysis showed a tendency to decrease the
mortality as the concentration of CdC12 increased which may be produced as a
result of the adsorption effect of the silt. On the other hand, there is no significant
difference between the control group and any of the various quantities of clay or
mud. Therefore, mortalities caused by using mud or clay with Cd C12 could be
referred to the effect of Cd C12 alone. This gives indication to the importance of
clay or mud in adsorbing Cd cations as a heavy metal and hence enhancing the
survival of this species.
The present results showed that a decrease in salinity caused an increase in
the lethality of cadmium for these womx.
On the other hand, the data demonstrated that the snail P. acuta is very
resistant to all the concentrations of Cd C12 below 10 ppm, while 10 ppm caused
death for more or less half of the tested snails at 24 hours. Moresover, Silt, Clay
and mud proved no significant effect in adsorbing cadmium and hence did not
influence the survival of’the snail.