Phytoplankton Variability in the Eastern Harbour Alexandria (Egypt)

Abstract

T he present study was conducted during August 1997-August 99 to investigate the Eastern Harbour (eutrophic marine basin) environments and the corresponding phytoplankton communi ty structure, species composition and blooming of different causative organisms that are known to be inherently continuously variable. Anthropogenic eutrophication and geographical dispersion from neighbouring areas into the harbour strongly influenced such variability, and hinder any particular seasonal trends. Yet, the pronounced late winter-spring increasing population and other blooming pulses in summer and autumn caused by less than a dozen species (mainly of diatoms, eutrophication symptom) were predominant characteristics of the production cycle in the harbour, Discharge water into the harbour created rich spectra for algal growth, not necessarily for its nutrient content, but ultimately for the stabilisation of the water column, salinity fluctuation was a crucial factor limiting the phytoplankton variability. Pyramimonas and Micromonas species culminated at maximum abundance in spring with the initiation of thermo-haline stratification of the water column, and it also seems sensitive to the inter-annual variations in temperature. Dinoflagellates predominated at intermittent periods in summer well stabilized the water column, with low nitrate, and relatively high phosphate concentrations. The species-specific patterns include aspects as; the cyclic abundance of the centric diatom Skeletonema costatum', the episodic blooms of mdegenous species that normally do not show blooming in the harbour {Cyclotella narta, Leptocylindrus minimus and Lithodesmfum unduhtum); the reappearance of endogenous dinoflagellate species that were not so far recorded during the last decades (Gyrnnodinum sanguineum and Gonyaulax spinifera); and the seasonal shift in predominance and 76 Wagdy Labib trends (increasing-decreasing abundance and disappearance) of the major dinoflagellate species {Prorocenirum iriestinum, Gymnodinium caienatum and Scrippsiella trochoidea).

Potential effects of abiotic factors on the abundance and distribution of the plankton in the Western Harbour, south-eastern Mediterranean Sea, Egypt

“…No harmful bloom of Eutreptiella has been seen on Egyptian coastal waters before. It was previously recorded as a rare form in the Eastern Harbour southeastern Mediterranean Sea during 1997-1999(Labib, 2002. The species was possibly new in the Mediterranean Sea, and so may have been introduced via ballast water.…”

Biological indicators as tools for monitoring water quality of a hot spot area on the Egyptian Mediterranean Coast

“…As all marine coastal areas, Mediophyceae (previously included in the diatoms group in the preceding classification) demonstrated the most effective contribution to the total phytoplankton count. They are perennial forms with short generation time (Goma et al 2005), usually producing great successive blooming pulses (Labib 2002). The prevalence of Mediophyceae might be due to their ability to adapt quickly to changes in hydrographical conditions (Rajesh et al 2001) or attributed to the expected high silicate content in the outlet of El-Umoum drain (Dorgham et al 1987).…”

Factors controlling marine fouling in some Alexandria Harbours, Egypt

“…Thus, harbour (B) represents a mesotrophic basin, with the minimum concentrations of all nutrient salts (Table 4) and almost without an industrial source of pollution has the highest diversity indices (with monthly average of H=1.39, d=0.6), although due to water circulation the harbour may be subjected to additional amount of municipal wastewater from the main sewer of alexandria (Kayet Bey), located in its western vicinity (laBiB, 2002). Meanwhile, harbour (C) representing a eutrophic, polluted, semiclosed basin, with the highest concentrations of nitrite, total nitrogen, phosphate, zinc, lead and chromium (Tables 4 and 5), has intermediate values of diversity indices (with monthly average of H=1.23, d=0.6).…”