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1
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Ecological indices as a tool for assessing pollution in El-Dekhaila Harbour (Alexandria, Egypt)

100%
Ismael A. A., Dorgham M. M.
Oceanologia
|
2003
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tom 45
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nr 1
Statistical analyses of data concerning the phytoplankton standing crop and biomass were applied as a tool for assessing pollution in El-Dekhaila Harbour. Univariate and multivariate analysis showed a succession of three clusters associated with salinity and temperature variations. The first and third clusters comprised mainly diatoms and dinoflagellates. The second cluster, richer in species, was dominated by brackish water cyanophytes, chlorophytes and euglenophytes. The diversity index ranged from 0.08 to 2.41. A high diversity was associated with high evenness, reflecting the multidominance pattern of cluster (2). On the other hand, multiple correlations between salinity and standing crop, richness and evenness, were negative and significant, but positive with the diversity index. The ABC curve showed that the k-dominance curve for numerical abundance extends above that for the biomass when clusters 1an d 3 are dominant. Both curves coincide more or less for another segment of the curve but when cluster 2 becomes dominant the numerical abundance curve runs below that of the biomass. Such a pattern may indicate unpolluted or moderate to heavily polluted conditions in El-Dekhaila Harbour. The present study reveals that the combination of univariate and multivariate analysis with the ABC curve provides a promising tool for the characterization of phytoplankton dynamics under stress conditions. On the other hand, the phytoplankton community in El-Dekhaila Harbour is stressed not by the inflow of brackish water but rather by the inflow of sea water. This is indicated by the higher diversity and evenness, and by the ABC curve during the dominance of cluster (2).
2
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Seasonal changes in the biochemical components of Pseudonereis anomala (Polychaeta, Nereididae) from the Alexandria coast, Egypt

81%
Dorgham M. M., Hamdy R., Al-Rashidy H. H., Atta M. M.
Oceanologia
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2014
|
tom 56
|
nr 4
3
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Vertical distribution of zooplankton in the epipelagic zone off Sharm El-Sheikh, Red Sea, Egypt

81%
Dorgham M. M., Elsherbiny M. M., Hanafi M. H.
Oceanologia
|
2012
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tom 54
|
nr 3
The purpose of the present study was to track the seasonal vertical distribution of zooplankton abundance in the epipelagic zone off Sharm El-Sheikh, Red Sea. Zooplankton samples were collected seasonally within the depth ranges of 0–25, 25–50, 50–75, 75–100 m at a single station off Sharm El-Sheikh City. The present study is an attempt to expand knowledge about the structure as well as the vertical distribution of the epipelagic zooplankton community in the Gulf of Aqaba in general and in its southern part in particular. The results indicate the occurrence of 52 copepod species and several species of other planktonic groups in the study area; the zooplankton standing crop fluctuated between 1124 and 4952 organisms m−3. Copepods appeared to be the predominant component, forming an average of 86.5% of the total zooplankton count, and with other groups demonstrated a markedly different seasonal vertical distribution. Twelve bathypelagic copepod species were reported during the present study, and five species were new to the area, having migrated northwards from the main basin of the Red Sea.
4
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Biometry and reproductive biology of Pseudonereis anomala Gravier 1901 (Polychaeta: Nereididae) on the Alexandria coast, Egypt

81%
Hamdy R., Dorgham M. M., El-Rashidy H. H., Atta M. M.
Oceanologia
|
2014
|
tom 56
|
nr 1
5
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First records of polychaetes new to Egyptian Mediterranean waters

81%
Dorgham M. M., Hamdy R., El-Rashidy H. H., Atta M. M.
Oceanologia
|
2013
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tom 55
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nr 1
6
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
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Eutrophication problems in the Western Harbour of Alexandria, Egypt

81%
Dorgham M. M., Abdel-Aziz N. E., El-Deeb K. Z., Okbah M. A.
Oceanologia
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2004
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tom 46
|
nr 1
Eutrophication-related problems in the Western Harbour ofA lexandria were studied monthly from April 1999 to March 2000. Variation in salinity appeared to be the key to all changes in water quality and plankton abundance in the harbour. Both at the surface and near the bottom the salinity was lower (annual average: 35.1 and 38.3 PSU respectively) than in the open sea (39 PSU). Dissolved oxygen levels indicated poor aeration conditions along the water column (2.3–3.98 mg l−1). Average pH values were approximately similar in the two layers (8.1 and 8 respectively) but exhibited different ranges ofv ariations. Nutrient salts varied widely, often occurring in high concentrations, with ranges of 0.12–5.7 and 0.06–2.6 μM at the surface and the bottom respectively for phosphate, 0.21–20.46 and 0.25–18.12 μM for nitrate, 0.29–3.3 and 0.23–1.66 μM f or nitrite, 0.56–57.46 and 2.32–43.73 μM for ammonia and 0.3–36.3 and 0.48–38.4 μM for silicate. As a result ofn utrient enrichment, phytoplankton growth was very intensive, reflected by an abnormally high concentration ofc hlorophyll a (annual average: 33.82 μg l−1). At the same time the death ofl arge numbers ofp hytoplankton cells could be inferred from the relatively large amount of phaeopigment (annual average: 10.39 μg l−1). The high levels ofn utrient salts and phytoplankton biomass together serve as a good indicator ofhig h eutrophication levels in the Western Harbour throughout the year. These conditions clearly affected the zooplankton stock, which varied between 5.8–93.6×103 indiv. m−3, although for most of the time values remained at a low level (annual average: 26 728 indiv. m−3).
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Protozoa in a stressed area of the Egyptian Mediterranean coast of Damietta, Egypt

71%
Dorgham M. M., El-Tohamy W. S., Abdel-Aziz N. E., El-Ghobashi A., Qin J. G.
Oceanologia
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2013
|
tom 55
|
nr 3
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