الفهرس 
ACKNOWLEDGEMENTS
Identification key for the collected taxa and speciesOnly 14 pages are availabe for public view
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Abstract
The present investigation was designed to study the effects of nitrate concentration on soil macroinvertebrates with special reference to their taxonomy and ecology at El-Minia governorate. To carry out the above mentioned aims, six sites were chosen for this study and the macroinvertebrates in these sites were surveyed. Samples of soil and macroinvertebrates were collected monthly during a period of one year extended from December 2013 till November 2014 using pitfall traps. Nitrate concentrations in both soil samples and isopod bodies were determined and compared. The study revealed the occurrence of twenty six taxa in the investigated sites. The density of each taxon obviously varied in each site according to season. The majority of collected macroinvertebrates could be assigned to phylum Arthropoda and divided into ten orders: Araneae, Orthoptera, Isopoda, Dermaptera, Lepidoptera, Coleoptera, Geophilomorpha, Dictyopetra, Hymenoptera and Hemiptera. In addition, one taxon belonged to phylum Annelida (Haplotaxida). The most dominant species at all sites belonged to order Isopoda then Orthoptera. Higher density of macroinvertebrates was recorded during spring and summer compared with their relevant numbers during winter and autumn. All collected macroinvertebrates exhibited negative correlation with nitrate concentration of soil in their habitat especially isopods that showed strong significant negative correlation. Based on the model equations; temperature was observed to be the most ecological factor affecting taxa densities. Based on laboratory experiment and using isopod Porcellio laevis as a model; the isopod was subjected to different concentrations of nitrate; 30, 60 and 90 ppm in food diet to study the effects of NO3 on the food consumption rate, growth efficiency rate, bioconcentration (BCF) and biomagnification (BMF) factors for the three treated groups. P. laevis showed changes in the rates of food consumption, growth efficiency, bioconcentration and biomagnification factors according to nitrate concentration in the food diet. Concerning food consumption and growth efficiency, P. laevis exhibited decline in these rates especially in the 90 ppm treated group. However, the patterns of nitrate accumulation (BMF) and (BCF) in P. laevis appeared to be dependent on metals concentrations in both soil and diet. The biomagnification factor (BMF) showed a highly significant difference between untreated and treated groups. While the (BCF) of nitrate revealed a significant difference among sites in winter, spring and autumn, however there was no significant difference among sites in summer. The hepatopancreas is the major metabolic organ in crustaceans. It has an important function in the assimilation of nutrients and structurally includes two types of cells (B and S). This study also investigated the negative effects of nitrate on the hepatopancreas of the terrestrial isopod P. laevis. The study revealed that histopathological changes resulted from exposure to different concentrations of nitrate. The hepatopancreatic epithelium of the exposed isopods displayed numerous pathological changes varied from destruction of the apical cell membrane with the appearance of deeply stained cytoplasm to complete disintegration of B cells especially in 90 ppm treated group. In the present study; five histochemical stains were used to stain the hepatopancreatic sections of the control and treated groups of P. laevis where each stain method was used to give a different histochemical structure. These stains included Hematoxylin and Eosin (H&E), Bromophenol blue, Periodic acid-Schiff (PAS) technique, Alcian blue/ PAS combined staining method and Alcian blue method (1.0 pH). The histochemical changes of protein, neutral mucopolysaccharides, acidic and sulphated mucopolysaccharides in hepatopancreatic epithelium were observed. The results showed different pattern of positive staining ranged between weak, moderate and strong reaction. In control and treated groups, the stains were concentrated mostly in the cells apices, basal lamina of the hepatopancreatic sections. Quantifying changes of the histological structure in the hepatopancreas of P. laevis were assessed using image analysis software for cellular area determination, it indicated that the presence of dose-related changes in the area of the hepatopancreatic cells, nuclei and lumen. Finally, from our study, it could be recommend that: Egypt should formulate agricultural policies and recommendations to encourage farmers to reduce their fertilization rates by improving the balance of supplied nutrients in the fields. It is necessary to control the quantity of nitrogen applied to the soil with fertilizers. It is recommended to focus the effortsrtts concerning the importance of soil fauna.