Paleolandscape and paleoenvironmental interpretation of spring-deposited sediments in Dakhleh Oasis,Western Desert of Egypt

Iron-rich sediments in Dakhleh Oasis, Western Desert of Egypt, have been recognized as spring mounds and as archaeological sites where Paleolithic materials have been recovered. Detailed sedimentologic investigation and mapping of these features reveal that spring mound sediments were deposited in a shallow vegetated wetland formed by the discharge of iron-rich Nubian Aquifer waters along the southern margin of the oasis, controlled largely by localized faulting and the variable paleotopography of the basin floor. The spring sediments represent peri-lacustrine or lake independent features and can be differentiated from fully lacustrine deposits on the basis of their sedimentary characteristics as well as the presence of goethite and jarosite in a region where authigenic deposition during Pleistocene pluvial activity principally resulted in tufas and lacustrine marls. Spring mound formation incorporated sediment through the ponding of surface water, aeolian entrapment by local vegetation, and the formation of iron precipitates in a low-energy, oxidative and acidic environment that was not dependent upon surface water inputs into the Dakhleh basin. The potentially interpluvial nature of this water resource makes it an important sedimentary archive for archaeological investigations in the basin. The Dakhleh spring mounds record a unique groundwater controlled paleoenvironment, providing the first evidence of a bog iron in Egypt and one of the few occurrences of iron-rich wetland remnants in the modern Sahara.     

Production Economics of Nile Tilapia (Oreochromis niloticus) Pond Culture in El-Fayum Governorate,Egypt

Econometric techniques were used to estimate a production function for tilapia pond culture in El-Fayum Governorate, Egypt, utilizing cross-sectional field data. Explanatory variables were feed, initial stocking weight, and pond size. The function was used to examine returns to scale, estimate the productivity of feed and initial stocking weight, and estimate the profit maximizing demand equations for feed and fingerlings. Diminishing returns to scale seem to exist for tilapia pond culture. Optimal economic stocking and feeding rates, yield, and profits for the whole sample were estimated at prevailing prices. Results indicated that producers were using stocking rates greater than the optimal by 36% to 115% and using insufficient feed by 8% to 22%. Investigation of the effects of changes in tilapia selling price and feed price on optimal stocking and feeding rates, yield, and profits showed that a change in tilapia selling price has greater effect on profits, yield, stocking, and feeding rates than a proportional change in feed price. Profits, feeding, and stocking rates are more sensitive than yield to changes in selling price, while feeding rate is more sensitive than stocking rate, yield, and profits to changes in feed price.     

不同基因型、环境和收获时间对埃及中上部地区甘蔗产量的影响

[目的]了解在埃及两个不同地区种植的4个有潜力甘蔗品种的最佳收获期.[方法]于2009~2010、2010~2011年度分别在埃及卢克索省El-Mattana研究站(上埃及)和米尼亚省Mallawi研究站(中埃及)进行了两个田间试验,采用裂区设计,3个重复,对4个有潜力的甘蔗品种G95-21、G98-28、G99-160和G99-103的新植蔗分别在不同时间,即(植后)10、11、12和13个月收获,并分别调查农艺性状、甘蔗产量和糖产量.[结果]在(植后)13个月收获时,甘蔗品种G99-103和G95-21的茎高、茎径、茎重、蔗糖分、蔗汁纯度、出糖率、蔗产量以及糖产量最高,且以在卢克索省种植的甘蔗大部分农艺性状表现更优.品种、收获期和种植地点的第一和第二交互顺序显著影响所有甘蔗的农艺性状.[结论]在埃及中上部地区种植甘蔗品种G99-103和G95-2,且在12和13个月株龄时收获,可以获得最高的蔗茎产量和糖产量.     

Do camels (<Emphasis Type="Italic">Camelus dromedarius</Emphasis>) play an epidemiological role in the spread of Shiga Toxin producing <Emphasis Type="Italic">Escherichia coli</Emphasis> (STEC) infection?

In the present work, faecal and serum samples from 400 camels were investigated for the presence of Shiga Toxin producing E.coli (STEC) and Anti-Shiga Toxin (Anti-Stx) antibodies, respectively. The used samples were obtained from adult male camels of five east African countries (Egypt, Somalia, Djibouti, Kenya and Sudan) between the years 2002-2004. One E.coli isolate per camel was randomly selected to be cultured on Gassner, Chromocult and sorbit agar for the detection of O157:H7 strains. In the same time, a Stx-specific PCR screening was performed for the isolates using the shiga toxin specific primers Mk1-Mk2. Vero cells were also used for shiga toxin neutralization assay. None of the investigated isolates reacted positively with the Stx-specific primers. Also, none of the studied sera could neutralize the Stx on tissue culture. The obtained results indicate that camels do not play any significant epidemiological role in STEC infection and transmission. The possible reasons for the absence of STEC in the investigated samples are discussed in brief.     

Experimental sponge fishery in Egypt during recovery from sponge disease

• 1. A survey was undertaken (1995) on the Mediterranean coast of Egypt that investigated four sponge fishing grounds. These fishing banks suffered from sponge disease between 1987 and 1990, causing a mass mortality of commercial sponges in the eastern and central Mediterranean.
• 2. Adult commercial sponges (length >10 cm) were harvested by divers in the infralittoral zone (depth range 17–36 m). The substratum at most of the sampling stations was hard, consisting mainly of plaques, rocks and heavy stones, sometimes covered by Posidonia oceanica.
• 3. Two commercial sponge species were detected, Hippospongia communis and Spongia cfr zimocca; the former was more prevalent and abundant. Light penetration in the area surveyed was high. The two commercial sponge species detected seemed to be well adapted to these conditions, as indicated by the colour of their external membranes, which were almost black due to enhanced pigment formation. The absence of Spongia officinalis, in the area surveyed may also be related to light penetration, since S. officinalis is a more sciaphilous species.
• 4. The shape of H. communis was almost spherical, and the average dimensions (length, width, height, circumference) increased with increasing depth of the fishing grounds. At shallower depths (<30 m), adult H. communis occurred in lower densities, whereas young commercial sponges were abundant. No signs of sponge disease were found.
• 5. It is concluded that the recovery of the four sponge fishing grounds was in progress, and that the repopulation of commercial sponges in the infralittoral zone showed a gradient from deeper to shallower waters. It is recommended to prohibit destructive fishing methods in the deeper waters in order to protect the population and its ability to regenerate.

Copyright © 2005 John Wiley & Sons, Ltd.