No abstract

No abstract

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 environmentalparameters indicated low salinity, oxic and anoxic conditions, high nutrient levels and intensive phytoplankton growth. A total of 69 protozoan specieswere 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 protozoangroups showed clearly different spatial patterns in both composition and abundance: whereas amoebozoans and non-tintinnid ciliates were dominant in themore polluted areas (sites IV and V), tintinnids dominated in the less polluted areas (sites, I, II and III). Several pollution indicators wererecorded: 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

The spatial pattern of zooplankton communities at Damietta coast, southeastern Mediterranean was studied to assess the impact of human activities on the abundance and community structure. Twenty-five stations from five different stressed sites were sampled in June-July 2014. Thirty-four zooplankton taxa were recorded, in addition to the larvae of copepods and meroplankton. Copepoda was the most abundant group among which, Oithona nana, Euterpina acutifrons, and Parvocalanus cirrostratus were the most frequent. The calanoid copepod Pseudodiaptomus trihamatus is a new record for the Mediterranean Sea that may have been introduced via ballast water. Multivariate/Univariate analyses demonstrated that 1) the environmental variables and zooplankton communities represented significant differences among five sites; 2) the spatial variations of community structure were undoubtedly due to land-based effluents; and 3) among all environmental variables, salinity and phytoplankton biomass had the major determining effects on the spatial patterns of zooplankton categories. The results indicates that not only the discharged water makes the Damietta coast at risk, but also the ballast water is not less dangerous. Hence, we emphasize the need for activation of the ballast water management to reduce the risk of future species invasions.

The objective of this study is to reveal the spatial and temporal variations of surface water quality in this part of the River Nile with respect to heavy metals pioneerution. Seventeen parameters in total were monitored at seven sites on a monthly basis from October 2013 to September 2014. The dataset was treated using the tools of univariate and multivariate statistical analyses. Cluster analysis showed three different groups of similarity between the sampling sites reflecting the variability in physicochemical characteristics and pollution levels of the study area. Six PCs factors were identified as responsible for the data structure explaining 91 % of the total variance. These were eutrophication factor (23.2 %), physicochemical factor (20.6 %), nutrients (16.3 %) and three additional factors, affected by alkalinity and heavy metals, recorded variance less than 15 % each. Also, the heavy metals pollution index (HPI) revealed that most of the calculated values were below the critical index limit of 100. However, two higher values (124.89 and 133.11) were calculated at sites V and VI during summer due to the temperature and increased run-off in the river system.

No abstract

The physical characteristics (temperature, salinity, pH and dissolved oxygen), turbidity, phytoplankton biomass (Chlorophyll-a) and nutrients in the coastal waters of a stressed area of the Nile Delta were studied biweekly from January to December 2007. The results indicated that the discharged waste waters caused pronounced changes in the water quality. The surface salinity recorded a minimum of 0.3 ‰ at site IV and a maximum of 38.1 ‰ at site I. pH ranged from 7.25 at site V to 8.55 at site II, while dissolved oxygen attained the lowest concentration (0.5 mg/l) at sites IV and V, and the highest concentration (10.82 mg/l) at site II. The water turbidity demonstrated wide fluctuation between 0.2 NTU at site II and 117 NTU at site III. The nutrient salts experienced great variation throughout the area of study as well as on the time scale; nitrate showed a range of 3-1682 µg/l, nitrite: 0.42-1106.2 µg/l, ammonia displayed undetectable level as well as high concentration (1646.6 µg/l), while the total phosphorus fall within a range of 10-8260 µg/l and silicate of 40-40800 µg/l. High phytoplankton biomass was recorded over the whole area (chl. a: 0.4-197.4 µg/l). The trophic state of the study area calculated by trophic index (TRIX) appeared to be widely different, reflecting degraded and very high trophic water, except at site I which contained moderate quality and high trophic water in significant part of the year.

Authors' Contribution WSE-T designed the study, drafted the main text and prepared figures. RRH helped in the manuscript preparation and editing. WSE-T and NEMAA did field investigations and sampling .