Impact of pollution on phytoplankton structure and bacteria in some Alexandria beaches, Egypt

The hydrographic, phytoplankton and bacteria data were collected monthly during 1995 from nine selected beaches of Alexandria, as an attempt to classify Alexandria recreational areas. The results showed a distinct difference between the water quality of Eastern and western parts of beaches in all parameters. Generally, relatively high values of water salinity, low concentration of nutrient salts particularly ammonia, nitrite and silicate as well as low oxidizable organic matter are considered as indicators of improvement in the water quality. The phytoplankton standing crop displayed wide variation, from 9 x 103 to 20.5 x 106 unit.L-1 chlorophyll-a content from 0.01 to 12.7 mg.m-3, Coliform bacteria from 0.0 to 2600 per 100 ml and diversity from 0.09 nats to 2.57 nats. The phytoplankton comprised 102 taxa belonging to a wide ecological habitat, extending from fresh water forms [33 species] to typical marine forms [69 species] often found side by side. However, few of them were responsible for the bulk of the community; namely, Skeletonema costatum, Rhizosolenia fragilissima, R. delicatula, R. hebetata, Nitzschia seriata, Chaetoceros socialis and Euglena granulata. The highest distribution of phytoplankton standing crop, chlorophyll-a and bacteria counts as well as low diversity values were recorded at a highly eutrophic area, Shatby and Anfoushi beaches. Monthly variation showed the highest outstanding peak in summer months. Several phytoplankton species were recorded as indicators of eutrophication. The correlation between phytoplankton standing crop, chlorophyll-a content, diversity, bacteria counts and the environmental conditions at each beach were computed and discussed

Phytoplankton role in waste water treatment by stabilization ponds system

In developing countries, oxidation pond system is considered now as a valid means of wastewater treatment, and the effluent can be reused for fish aquaculture or on agricultural land for crop irrigation. Since oxidation ponds require large areas, land should be available at low cost. This could be applied successfully in aired areas affected by water shortage and protein deficiencies. Maturation pond showed their best performance during spring season and at lower detention times in summer and autumn. It was noticed that high temperature, high intensity of light and longer detention times decreased the efficiency of the pond instead of increasing it as a result of the formation of algal mats on the surface. Although algae produce an additional organic load during hot seasons, yet their merits are as follows: [1] They constitute valuable source of oxygen in facultative and maturation ponds, leading to an acceleration in the aerobic degradation of organic compounds. [2] They remove appreciable amounts of nitrogen and phosphorus from the final effluent. [3] They play an important role in raising the pH which acts as a bactericidal factor. [4] Finally, algae serve as food source for the fish Tilapia nilotica in the aquacultural pond. Phytoplankton diversity was found to maintain high values in the maturation ponds confirming successful performance of the system in wastewater treatment

Comparative study of phytoplankton production, composition and diversity index in the eutrophic eastern harbour of Alexandria, Egypt

The process of eutrophication, which has been in progress for some decades in the :oastal waters of Alexandria, Eastern Harbour [E. H.], shows mainly cyclic seasonal features. In autumn and summer large blooms of diatoms usually occur, while in spring, blooms of dinoflagellates cause red tides. Low salinity and high nutrient loads carried with the Nile water and sewaqe outfalls favour the production of these blooms. The two episodes of red tides that Occurred during spring of both 1987 and 1992 taw caused fish, mortality and affected the Regional tourist industry Phytoplankton diversity indices are used to characterize the effect of eutrophication in the Eastern Harbour. Generally, the phytoplankton density was always higher in the surface water than the near bottom layer. Surface phytoplankton standing crop increased irom one year to the other. Thus, it ranged from 0.2x10[6] to 19x10[6] unit.l[-1] during, 1986-87, from 0.04x10[6] to 23.5x10[6] unit.l[-1] in 1990-91 and from 0.03x10[6] to 77x10[6] to unit.l[-1] during 1991-92 addition, changes in the dominant species were revealed. In 1986-87, Chaetoceros affinis, Cyclolella meneghiniana, Amphichrysis compressa [new record] and Alexandrium minutum dominated. During 1990-91, Anabaena sp., Skeletonema costatum and Rhizosolina spp. Prevailed, in 1991-92, different dominant species were recorded; namely, Prorocentrum triestinum and Skeletonema costatum. The Shannon diversity indices reflect an inverse relationship to the degree of dominance of the main species and the magnitude of phytoplankton standing crop rather than to the species richness. A simple mathematical regression equation describing the dependence of diversity on the species dominance variations for this area is given. The correlation between standing crop, diversity and the major environmental parameters and their regression equations are discussed

Eutrophication syndrome in the western harbour of Alexandria, Egypt

Considerable amounts of untreated domestic, industrial and agricultural waters are discharged daily into the western harbour, and affect markedly the physical, chemical and biological properties. Hydrographic and phytoplankton data were collected bimonthly during 1989 from the surface and bottom water at selected eight stations representing the different habitats in the harbour. The Secchi-disc transparency was low, it averaged 1.8 m. the pH of the water lies mostly between 7.6 and 8.9. the surface values were slightly higher than that of the bottom. The surface water salinity was greatly affected by inland discharge the minimum value of 28.965% was recorded in February. The most striking features are low oxygen content in the surface water which coincided with relatively high values of oxidizable organic matter, nutrient salts and total phytoplankton counts. The P:N ratio of 1:16 which is similar to the oceanic ratio. The phytoplankton standing crop averaged 6.7 x 10[6] celle. L[1] in the surface water, which is higher than the records of the open sea. Strong positive correlation was obtained between pH value and chlorophy ll-a in summer, and between phosphate and diophyceae during February. Also strong negative correlations were obtained between secchi-disc transparency and each of the water temperature, organic matter and water salinity as well as between salinity and reactive silicate

Phytoplankton flora and its dynamics in the Eastern Harbour of Alexandria

Phytoplankton communities of the Eastern Harbour were collected monthly from August 1986 to July 1987. Seventy seven species were recorded, belonging to Bacillariophyceae [48], Dinophyceae [13], Chlorophyceae [7], Cyanophyceae [6], Euglenophyceae [2] and one Chrysophyceae. Although numerous species were encountered, yet very few of them formed the main bulk of the community: Chaetoceros affinis, Cyclotella meneghiniana, Amphicrysis compressa and Alexandrium minutum. The mean phytoplankton crop varied from 0.2x10[6] to 19x10[6] cells L[-1] in surface water and was lower in bottom layer. In the last few years the quantitative cycle of the standing crop density did not follow the previously observed seasonal trend. This is the result of increasing eutrophication which also causes a decrease in cell dimensions for most recorded species

Water characteristics, chlorophyll-a and zooplankton population at Kait Bey Region[Alexandria]

More than 0.5x10[6]m[3] of domestic waste water are discharged daily at Kait Bey area and affecting markedly the physical, chemical and biological properties of the echo-system. Hydrographic and biological data collected monthly during the period from August, 1987 to August, 1988 showed both horizontal and vertical variations in the physico-chemical parameters of the sea water. The pH of water lies mostly between 7.8 and 8.2 which are less alkaline than the open water. Sewage wastes diluted the sea water and salinity values dropped to reach its minimum of 22.5%. in September. The most striking features are the poorly oxygenated surface water accompanied with relatively high content of oxidizable organic matter, particularly during summer months. The concentration of chlorophyll A in the surface water reached its highest averages in these warm months [3.8-4.8 mg/m[3]]. The maximum persistence of zooplankton was also in summer [June - August] and early autumn [October]. The bottom layer harboured high density of the zooplankton with annual average of 181x10[3] organisms/m[3]. This value decreased to 67x10[3] organisms/m[3] at the surface water. The community composition of zooplankton at both the two layers was nearly similar and it consisted mainly of copepods [69% and 70% by number of the total population in the two layers, respectively] and ciliates [24% and 17%]. Appendicular and larval stages of both cirripeds and polychaets were also frequently recorded