Eutrophication problems in the Western Harbour of Alexandria, Egypt

• Autorzy: Dorgham M.M. , Abdel-Aziz N.E. , El-Deeb K.Z. , Okbah M.A.
• Języki publikacji: EN

Abstrakty

EN

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).

Słowa kluczowe

EN

biomass; nutrient; water quality; Alexandria Western Harbour; plankton; salinity; Egypt; eutrophication

• Wydawca: -
• Czasopismo: Oceanologia
• Rocznik: 2004
• Tom: 46
• Numer: 1
• Opis fizyczny: p.25-44,fig.,ref.

Twórcy

autor

Dorgham M.M.

• Alexandria University, EG-21511 Alexandria, Egypt

autor

Abdel-Aziz N.E.

autor

El-Deeb K.Z.

autor

Okbah M.A.

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