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Seasonal changes in the biochemical components of Pseudonereis anomala (Polychaeta, Nereididae) from the Alexandria coast, Egypt

Dorgham M.M., Hamdy R., Al-Rashidy H. H., Atta M. M.

Oceanologia

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2014

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No. 56 (4)

881--887

EN

The biochemical composition (carbohydrates, protein, lipids, fatty acids and amino acids) of the nereid polychaete Pseudonereis anomala Gravier 1901, from a shallow part of the Alexandria coast (Egypt), was studied seasonally. The results revealed that P. anomala had a lower water content, higher carbohydrates and protein, but approximately similar or higher lipid levels than several other polychaetes. Fatty acids appeared to be dominated by unsaturated acids, constituting seasonally 49.6-81%, while saturated acids reached high amounts in winter and spring (23.3 and 38.3% respectively). C20:5n-3 was the major polyunsaturated fatty acid, accompanied by small amounts of C18:4n-3, C20:4n-6, C16:1n-7 and C20:1n-9. C18:0 dominated the saturated fatty acids for most of the year, except in autumn when C16:0 was the major one.

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Biometry and reproductive biology of Pseudonereis anomala Gravier 1901 (Polychaeta: Nereididae) on the Alexandria coast, Egypt

Hamdy R., Dorgham M.M., El-Rashidy H. H., Atta M. M.

Oceanologia

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2014

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No. 56 (1)

41--58

EN

The biometric characteristics and reproductive biology of the nereid polychaete Pseudonereis anomala were studied monthly from August 2009 to July 2010 at two ecologically different sites (Abu-Qir and El-Mex) on the Alexandria coast, south-eastern Mediterranean Sea. The maximum body length and weight showed different values at the two sites: 9.8 and 11.9 cm, and 0.77 and 1.3 g respectively. The formula of the length-weight relationship indicated allometric growth, whereas the regression equation between length to the 6th segment and weight reflected isometric growth. Immature individuals were the major component of the worm population at the two sites, making up 69.1% at Abu Qir and 66.9% at El Mex; the respective percentages of males and females at these sites were 5.8-8.1% and 22.8-27.3%. Spawning was observed all the year round with female fecundity conspicuously lower at Abu-Qir (annual average: 26556 ± 999 eggs per female) than at El-Mex (annual average: 47955 ± 2916 eggs per female). However, oocyte size was greater at Abu Qir (diameter: up to 250 µm) than at El Mex (diameter: up to 220 µm).

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Protozoa in a stressed area of the Egyptian Mediterranean coast of Damietta, Egypt

Dorgham M. M., El-Tohamy W. S., Abdel-Aziz N. E., El-Ghobashi A., Qin J. G.

Oceanologia

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2013

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No. 55 (3)

733--750

EN

The Damietta coast is part of the Egyptian Mediterranean coast off the Nile Delta and has recently been polluted as a result of intensive human activities. The environmental parameters and protozoan community in the area were studied biweekly from January to December 2007. The results of the environmental parameters indicated low salinity, oxic and anoxic conditions, high nutrient levels and intensive phytoplankton growth. A total of 69 protozoan species were identified, belonging to Amoebozoa (8 species), Foraminifera (12 species), non-tintinnid ciliates (22 species) and tintinnids (27 species). The numerical density of protozoans was high over the whole area, with annual averages between 8.2 × 103 cells m-3 and 51.4 × 103 cells m-3. Spring was the most productive season for protozoans, but several distinct peaks were observed during the year at the sampling sites. The protozoan groups showed clearly different spatial patterns in both composition and abundance: whereas amoebozoans and non-tintinnid ciliates were dominant in the more polluted areas (sites IV and V), tintinnids dominated in the less polluted areas (sites, I, II and III). Several pollution indicators were recorded: amoebozoans - Centropyxis aculeata, Centropyxis sp., Cochliopodium sp., Difflugia sp.; non-tintinnids - Bursaridium sp., Frontonia atra, Holophrya sp., Paramecium sp., Paramecium bursaria, Vasicola ciliata, Vorticella sp., Strombidium sp.; tintinnids - Favella ehrenbergii, Helicostomella subulata, Leprotintinnus nordgvisti, Tintinnopsis beroidea, Stenosemella ventricosa, Tintinnopsis campanula, T. cylindrica, T. lobiancoi, Eutintinnus lusus-undae.

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First records of polychaetes new to Egyptian Mediterranean waters

Dorgham M.M., Hamdy R., El-Rashidy H. H., Atta M. M.

Oceanologia

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2013

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No. 55 (1)

235-267

EN

Nineteen benthic polychaete species were recorded for the first time in the intertidal zone of the Alexandria coast, south-eastern Mediterranean Sea. They belong to Syllidae (7 species), Hesionidae (3 species), Serpulidae (2 species) and 7 other families (one species each). Of these species Eunice miurai Carrera-Parra & Salazar-Vallejo 1998 appears to be new to the Mediterranean Sea, while four of the alien species earlier recorded in the Mediterranean were found for the first time in Egyptian waters: Opisthosyllis brunnea Langerhans 1879, Loimia medusa Savigny 1822, Syllis schulzi Hartmann-Schröder 1960, Phyllodoce longifrons Ben-Eliahu 1972. The newly recorded species demonstrated markedly different patterns of frequency of occurrence and numerical abundance. Spirobranchus triqueter Linnaeus 1758, S. schulzi, L. medusa and Salvatoria clavata Clapare`de 1863 were permanent and abundant species in fouling samples along the Alexandria coast. Saccocirrus papillocercus Bobretzky 1872 persisted in the sediments at two sites, with a much higher count at the stressed one, while Protodrilus sp. inhabited sediments at two other sites throughout the year, sometimes in very high numbers. In addition, the alien species found earlier, Brania arminii Langerhans 1881, Odontosyllis fulgurans Audouin & Milne-Edwards 1833 and O. brunnea Langerhans 1879, were frequently observed along the Alexandria coast.

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Vertical distribution of zooplankton in the epipelagic zone off Sharm El-Sheikh, Red Sea, Egypt

Dorgham M.M., Elsherbiny M. M., Hanafi M. H.

Oceanologia

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2012

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No. 54 (3)

473-489

EN

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 a trial 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.

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Eutrophication problems in the Western Harbour of Alexandria, Egypt

Dorgham M. M., Abdel-Aziz N. E., El-Deeb K. Z., Okbah M. A.

Oceanologia

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2004

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No. 46 (1)

25-44

EN

Eutrophication-related problems in the Western Harbour of Alexandria 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 of variations. Nutrient salts varied widely, often occurring in high concentrations, with ranges of 0.12-5.7 and 0.06-2.6 žM at the surface and the bottom respectively for phosphate, 0.21-20.46 and 0.25-18.12 žM for nitrate, 0.29-3.3 and 0.23-1.66 žM for nitrite, 0.56-57.46 and 2.32-43.73 žM for ammonia and 0.3-36.3 and 0.48-38.4 žM for silicate. As a result of nutrient enrichment, phytoplankton growth was very intensive, reflected by an abnormally high concentration of chlorophyll a (annual average: 33.82 žg l-1). At the same time the death of large numbers of phytoplankton cells could be inferred from the relatively large amount of phaeopigment (annual average: 10.39 žg l-1). The high levels of nutrient salts and phytoplankton biomass together serve as a good indicator of high 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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Ecological indices as a tool for assessing pollution in El-Dekhaila Harbour (Alexandria, Egypt)

Ismael A. A., Dorgham M. M.

Oceanologia

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2003

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No. 45 (1)

121-131

EN

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 1 and 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).