The Egyptian Journal of Aquatic Research, Mar 1, 2020
Abstract The present study aims to document the diversity and density of benthic fauna in Great B... more Abstract The present study aims to document the diversity and density of benthic fauna in Great Bitter Lakes through their spatial and temporal changes in this important area from spring 2016 to winter 2017. Eleven sampling stations representing most of the area of the Great Bitter Lakes were selected. The results showed that there was 41 species and an annual density of 104,680 organisms/m2 of macro-benthic fauna belonging to five phyla in the studied area. Eighteen species from polychaetes, 12 molluscs, 7 species from crustaceans, 3 echinoderms and one species belonging to cephalochordate were recorded. With the exception of the most dominant species of the lakes, Modiolus auriculatus, which was represented by an annual average of 6822.91 organisms/m2, the onshore stations were the highest in density and diversity than offshore stations (35 and 28 species with an annual density of 18,873 and 10,755 organisms/m2, respectively). The value of heavy metals in surface water was within the following sequence; Fe > Zn > Cu > Pb > Mn > Cd. While in the sediments were arranged as follows: Fe > Mn > Zn > Cu > Ni > Pb > Cd. In the studied area, the medium sediments (O2+O3) recorded the highest percentage (61.34%) of the total percentage of sediment.
Alginates are one of the most important compounds of brown seaweeds. These compounds are employed... more Alginates are one of the most important compounds of brown seaweeds. These compounds are employed in the food area, because of their important rheological properties, such as viscosity, gelling, and stabilizing features and as dietary fiber source. In this study, five species of dominant brown seaweeds were collected in the Red Sea (Padina boergesenii, Turbinaria triquetra, Hormophysa cuneiformis, Dictyota ciliolata, and Sargassum aquifolium) so as to characterize the alginate yield and its properties. The analysis demonstrated differences in the alginate yield among the seaweeds. The highest yield of alginate was recorded in the species T. triquetra (22.2 ± 0.56% DW), while the lowest content was observed in H. cuneiformis (13.3 ± 0.52% DW). The viscosity from the alginates varied greatly between the species, whereas the pH varied slightly. The alginate exhibited a moisture content between 6.4 and 13.1%, the ash content ranged between 12.3 and 20% DW, the protein reached values fro...
International Journal of Ecotoxicology and Ecobiology, 2018
Heavy metals incorporation within the hard skeletons of 16 hard coral species collected from the ... more Heavy metals incorporation within the hard skeletons of 16 hard coral species collected from the tidal flats off five wadis along the eastern side the of Gulf of Suez and western side of Aqaba Gulf were measured using Atomic Absorption Spectrophotometer (AAS). The selected wadis were intensively affected by the temporary intensive flashfloods. The highest averages of Fe, Mn, Cu, Ni, Co and Cd were recorded in the skeleton of Acropora forskali (2211.93; 57.85, 35.32 and 55.15, 4.70 and 1.72 µg/g respectively) at W. Isla in the eastern bank of Suez Gulf meanwhile the lowest averages of Fe, Mn, Cu were observed in Acropora yongei (142.59; 2.70 and 0.02µg/g) at W. Muqebla and the lowest Ni (2.85µg/g) was recorded at W. Watir in the western side of Aqaba Gulf. Stylophora pistillata showed the highest average of Zn (108.63µg/g) at W. Gharandel in the eastern side of Suez Gulf and the lowest value was recorded in Acropora pharaonis (2.17µg/g) at W. Muqebla. Pb showed the highest average in Acropora variables (32.88µg/g) at W. Kid at the western part of Aqaba Gulf and it was not detected in Montipora sp. at W. Isla and Porites sp. at W. Kid. The hard coral skeletons showed significantly high concentrations of (Fe, Mn, Cu, Pb, Ni, Co and Cd) at W. Isla and W. Gharandel along the eastern side of Suez Gulf. It is obvious that the studied coral species have variable tendencies to accumulate the heavy metals within their skeletons. In general, the coral species collected from Gulf of Suez wadis recorded high to significantly high bio-accumulation tendencies indicating to remarkable contributions of the land based activities (mining and oil exploration activities). The recorded heavy metals along Aqaba Gulf were significantly attributed to the flashfloods. The differential abilities of coral species showed that; S. pistillata at W. Gharandel along the eastern side of Suez Gulf has the highest bioaccumulation tendencies toward Zn (2.12), Pb (3.94), Ni (35), Co (1.60) and Cd (5.47) but Platygyra sp. has the highest bio-accumulation tendency towards Ni (3.53). The Gulf of Aqaba wadis showed the minimized bioaccumulation tendencies for the different coral species relative to the investigated coral species at Suez Gulf wadis except Acropora variables at W. Kid (1.22) for Pb and Acropora digitifera at W. Watir (1.25) for Ni.
Mangrove swamps have unique biogeochemical interaction between the plant and the underlying sedim... more Mangrove swamps have unique biogeochemical interaction between the plant and the underlying sediments. The bioactive heavy metals; Zn, Cu, Fe, Mn, Pb, Ni, Cd and Co were measured using Atomic Absorption Spectrophotometer (AAS) in the bulk sediment samples and the fine fractions; 125µ, 63µ and <63µ and slack water as well as different parts of the Avicennia marina mangrove (fruits, leaves and roots) collected from 9 mangrove swamps at the nearshore zone of the Red Sea. The average percentage of the fine sediment group (125µ + 63µ + <63µ) was varied between 18.78% and 51.22% from the total sediments with recognized occurrences for the fractions 125µ and 63µ. The bulk sediments recorded the highest averages of the bioactive Zn (69.91µg/g), Mn (186.91µg/g) and Ni (19.49µg/g), the fraction 125µ recorded the highest average of Pb (16.92 µg/g), while <63µ fraction showed the highest averages of Cu and Fe (26.45 and 2744.84µg/g). In the mangrove stands, the highest averages of Zn and Cu were recorded in fruits (Avs. ≈116.41 and 15.20 µg/g), Mn in leaves (Av. ≈ 43.72 µg/g) and the highest Pb was recorded in roots (Av. ≈ 30.14 µg/g). The bio-accumulation sequence of heavy metals in the fruits and roots was Fe>Zn>Pb>Cu>Mn>Ni and in leaves was Fe>Zn>Mn>Pb>Cu>Ni. The low contents heavy metals recorded in the slack water of the mangrove swamps attributed to the reducing nature of the underlying sediments that accumulate the heavy metals in insoluble sulphide forms. The effects of the elevated metal contents in the fruits, leaves and the roots of A. marina were at the studied forests were reflected in the ramified and shorten roots, pale yellowish colour and reduction the leaves number in many of the mangrove stands.
Macro-benthic fauna are considered the good bio-indicators for the environmental changes of any a... more Macro-benthic fauna are considered the good bio-indicators for the environmental changes of any aquatic ecosystems. Samples of macro-benthos, sediments and surface water were collected from 13 stations representing different conditions in the Western Lagoon (10 stations) and Timsah Lake (3 stations) from autumn 2014 to summer 2015. Macro-benthic density and diversity in Timsah Lake were higher than those in the Western Lagoon; the density at Timsah Lake encompassed 167,649 individual/m 2 representing 42 species from the total of 46 species recorded in the investigated area. While species density in the Western Lagoon constituted 12,008 individ-ual/m 2 presenting only 16 species. Winter recorded the highest density (74,854 individual/m 2); the highest dominance (CDI = 0.858) and the lowest Equitability (0.293) due to the dominance of the opportunistic species. Spring harvested both the highest diversity (28 species) and species richness (SR = 2.917). While autumn and summer procured both the lowest density and diversity (34,021 and 29,544 individual/m 2 and 23 and 25 species respectively). The equitability index (E 0) showed its highest values within the Western Lagoon (>0.90) owing to the species poorness relative to Timsah Lake. The water quality data showed that the Western Lagoon and Timsah Lake had significant high oxygen influx in spring (11.00 and 9.35 mg/l, respectively) and oxygen depletion in summer (1.00 and 3.00 mg/l, respectively). Reactive phosphorus and ammonia in the Western Lagoon exceeded the world averages. Timsah Lake sediments were highly affected by the sediment drifts from the Western Lagoon. The highest influx of the fine sediment group (FSG) was estimated during spring with an average of 62.77% and 61.18% in Timsah Lake and Western Lagoon, respectively. Total organic matter (TOM) in Western Lagoon recorded the highest average of 17.05% in spring accompanied with the high biological productivities.
Cette étude est axée sur le comportement alimentaire sélectif et le rôle écologique des principal... more Cette étude est axée sur le comportement alimentaire sélectif et le rôle écologique des principales espèces d’holothuries — Holothuria atra, Holothuria hawaiiensis et Bohadschia vitiensis — vivant sur les platiers découverts à marée basse et les eaux peu profondes de la mer Rouge à Hurghada, en Égypte. Les sédiments retrouvés dans l’appareil digestif de ces trois espèces varient beaucoup en fonction du poids total de l’animal. Les individus ayant un poids moyen ont besoin de consommer d’importantes quantités d’aliments pour grandir et développer leurs gonades, et il s’est avéré qu’ils absorbent davantage de gravier que les holothuries ayant un poids élevé ou faible. Ce comportement sélectif des holothuries permet d’expliquer pourquoi les graviers et le sable grossier constituent les principaux sédiments retrouvés dans l’appareil digestif de l’animal au cours des différentes saisons. Pendant la période de reproduction (début de l’été jusqu’à l’automne), les individus tendent à assimiler plus de sédiments fins que de sédiments grossiers, peut-être parce qu’ils ont davantage besoin de matières organiques. Le remaniement sédimentaire par les différentes espèces varie au cours de l’année et dépend du nombre d’individus, de la disponibilité des aliments, de la taille des individus et des conditions locales. Les effets de l’alimentation de ces trois espèces d’holothuries sur le remaniement sédimentaire ont été le plus marqués en juillet (été) et en novembre (automne) pour H. atra, en automne et en hiver (septembre et décembre) pour H. hawaiiensis, et principalement en été (mai à août) pour B. vitiensis. Il a été observé que le remaniement s’étale de la fin du printemps à la fin de l’automne, période pendant laquelle deux phases importantes de la reproduction des holothuries se déroulent: la maturation et la ponte.
The mobile forms of heavy metals are the exchangeable phases of these metals that represent the b... more The mobile forms of heavy metals are the exchangeable phases of these metals that represent the bioavailable toxic hazards in the marine environment. The exchangeable forms of Fe, Zn, Cu, Mn, and Pb were measured using atomic absorption spectrophotometry in the inshore sediments at five locations along the Red Sea coast in areas under natural and anthropogenic discharges. The fine sediment group (FSG) reached the average of 51.29 % representing the controlling and vital factor in the different geochemical processes that occur in seabed sediments. Hamrawin Bay recorded the highest averages of Mn (283.55 μg/g), Zn (99.63 μg/g), and Pb (73.35 μg/g). Abu Dabab recorded the highest average of Fe (1336.41 μg/g), Shalateen exhibited the highest Cu average (35.62 μg/g) and the lowest averages of Mn, Zn, and Pb (50.18, 24.28, and 18.44 μg/g), and Qula’an showed the lowest averages of Fe and Cu (944.61 and 17.39 μg/g). The estimated results indicated that the exchanges from one phase to another were active in all locations due to the continuous reworking processes in the surface sediments. Under the oxic conditions, oxides, hydroxides, and carbonates of Fe, Mn, and Zn were expected to be the dominant metal forms associated with the sand fraction at the different locations. Under the reducing environments (anoxic conditions), sulfide forms of Fe, Pb, Mn, and Cu were associated with fine sediment fractions (very fine sand, silt, and mud) were dominant. Ionic exchanges were active in the near bottom and the interstitial water during the transformation operations from one phase to another at the different locations. The continuity of the forms transformation in the marine ecosystem at the studied locations provide the favorable environment for benthos growing up.
The heavy metal contents of Cu, Zn, Pb, Mn and Cd were measured using AAS in the fine sediment fr... more The heavy metal contents of Cu, Zn, Pb, Mn and Cd were measured using AAS in the fine sediment fractions (Ø3, Ø4 and Ø5) and the seawater at six sites represent the main land-based activities at Hurghada, Safaga and Hamrawin along the Red Sea coast. The fine sediment group (Ø3 + Ø4 + Ø5) was varied between 24.61 and 88.88 % from the total sediment percentage, whereas Ø3 was the most abundant fraction with average percentages between 14.92 % at site III and 28.3 % at Site IV followed by Ø4 with average between 8.04 % at site III and 57.46 % at site II; therefore Ø3 and Ø4 were considered the essential pollutant bearing fractions. Cu recorded the highest average content (248.69 µg/g) at site I, Zn (746.24 µg/g) at site V, Pb (215.86 µg/g) at site III, Mn (407.66 µg/g) at site IV and Cd recorded the highest average (28.47 µg/g) at site VI. Site II showed the lowest average contents of the different metals that may attribute to the continuous leaching of the metal bearing fractions by the longshore currents and waves. In the seawater, site IV recorded the highest Cu average (10.49 μg/l), site III showed the highest averages of Zn and Pb (63.02 and 42.49 μg/l) whilst site VI recorded the highest averages of Mn and Cd (17.78 and 1.13 μg/l, respectively). Zn, Pb, Mn and Cd showed significant correlation relationships to each other in sediments at Hurghada indicated that they tend to accumulate in the same form. The insignificant correlations of Cu and other metals at Safaga and Hamrawin indicated the accumulation in multiple forms under variable local conditions. The different sites were classified between slightly and highly polluted with heavy metals. The obtained results illustrated that the land-based activities at the different localities have serious threatening on the near-shore environment and Safaga marine area was more polluted than Hurghada and Hamrawin.
The granulometric characteristics, the bio-available heavy metals and the natural radionuclide ac... more The granulometric characteristics, the bio-available heavy metals and the natural radionuclide activities in the surface sediments were investigated semi-annually in Timsah Lake at the middle district of the Suez Canal, Egypt. The average percentages of mud and fine grained sediments recorded in summer were (4.17% and 33.89%) much higher than in winter (1.43% and 22.70%) attributed to the relatively high dispersing of the fine sediment fractions in winter by wave action and the fine sediments drifting towards Suez Canal. The average carbonate percentage was 19.72% in summer increased to 22.71% in winter, inversely, the average total organic matter (TOM) in summer was 7.52% decreased to 6.32% in winter. The highest averages of the bio-available heavy metals; Zn, Cu, Pb, Cd, Mn, Co, Ni and Fe were; 65.51, 18.06, 27.76, 0.78, 260.64, 4.10, 17.16 and 2087.71μg/g were recorded summer and the highest average activities of 238U, 232Th and 40K were 23.79, 23.72and 221.35Bqkg-1 were recorded in winter. The recoded heavy metals and radionuclides were attributed to multi anthropogenic sources; untreated wastewater drains, agriculture drains, industrial runoff and shipyards. The high values of TOM and bioavailable heavy metals in summer are related to the highest fine sediment percentages, while the radionuclides may tend to associate with the coarse sediments. The significant positive correlations of TOM and Fe with heavy metals and radionuclides indicated to two essential metal phases, one with organic matter in the highly reducing conditions and the other associated and/or adsorbed by Fe-oxides and hydroxide particles in addition to the other independent metal phases. The recorded bioavailable metals are lower than the excepted because of suspended matters and water drift toward Suez Canal dilute the metal accumulation in the lake sediments.
The distribution patterns, the index of geoaccumulations
(MIgeo), and the enrichment ratios (ERn... more The distribution patterns, the index of geoaccumulations
(MIgeo), and the enrichment ratios (ERn) of the
contaminantmetals: Fe,Mn, Zn, Cu, Pb, and Ni were studied in
gravel, sand, mud, coarse, medium, and fine sediment fractions
of the uppermost layer of the bottom sediments collected from
12 stations covering the northern part of Safaga Bay. The
distribution levels of these metals were increasing with grain
size decreasing toward the central axis of the bay that extends
NE–SWand southward to Safaga Harbour indicating that these
metals concentrated mainly in the fine, very fine, and particulate
fractions of sediments and to many anthropogenic sources. The
geo-accumulation factor of Zn was more significant (MIgeo≈
0.62–4.23) relative to the other metals. The bay was classified
as moderately to strongly polluted by Zn while it is unpolluted
to moderately polluted with the other metals with accumulation
sequence of: Zn>Ni>Cu>Mn≥Pb. Zn and Ni recorded the highest
enrichment ratios (average ERZn≈3.07 to 8.89; average
ERNi≈0.84 to 3.63) in the different sediment fractions relative
the other metals. These enrichment ratios classified the bay as
minimal enrichment, suggestive of no or minimal pollution, to
significant enrichment, suggestive of a significant pollution
signals with metals sequence of: Zn>Ni>Cu>Pb>Mn.
The natural radioisotopes 238U, 231Th and 40K as well as the artificial radioisotopes 137Cs, 238P... more The natural radioisotopes 238U, 231Th and 40K as well as the artificial radioisotopes 137Cs, 238P and 90Sr were measured using high resolution -spectrometry in some living corals in tidal flat areas of Hurghada, Safaga and Shlateen along the Red Sea coast. Stylophora sp. recorded the highest 238U activity (25.20Bqkg-1dw), Favia lacuna recorded the highest 231Th activity (16.20Bqkg-1dw), while the highest 40K activity was recorded in Platygyra crosslanda (996.00Bqkg-1dw). The artificial radioisotopes recorded very low activities relative to the marine sediments; 90Sr recorded the highest activity in the hydrocoral Millipora dechtoma (5.57Bqkg-1dw), 238P observed only in some massive species at Hurghada and shlateen (Av ≈ 0.03±0.00 and 0.12±0.06Bqkg-1dw respectively) and 137Cs activities were insignificant in all coral species (<0.1Bqkg-1dw). Safaga locality shows the highest average contents for; 238U (15.26±6.14Bqkg-1dw), 231Th (9.52±3.89Bqkg-1dw); 40K (677.18±284.71Bqkg-1dw) and 90Sr (2.02±1.59Bqkg-1dw) while Shalteen recorded the highest average of 238P indicating that the natural radioisotope accumulations in coral reefs is highly affected by the phosphate inputs from mining, grinding and shipping operations and other terrestrial inputs while the artificial radioisotopes may accumulated from the planktonic particulates from the sea. The interspecific variations of the radioisotopes in the coral skeletons were controlled by the changes of carbonate ion content of the seawater, salinity and alkalinity influences, pH, seasonal influences, the substitution mechanism based on substitution of Ca2+, the amounts of particulates in the water column and influence of temperature. In addition to some other biological factors as; the growth rate of the coral skeletons, the exposing surface area, skeleton bulk densities and the organic matrices thickness. The natural and artificial radioisotopes may be mineralized as ionic forms with skeleton formation and/or included as independent particulates inside the aragonitic skeletal frameworks.
The skeletons of 15 coral species were investigated in three localities along the Red Sea coast, ... more The skeletons of 15 coral species were investigated in three localities along the Red Sea coast, two of them have coral species under stress while the third locality was used as control area. Total phosphorous (TP) and the trace metal contents were measured in the skeletons these coral species. The recorded data was amazing and reflects very high ability of the corals to resist and survive in the polluted environment but with different degrees of acclimation for these conditions. TP, Fe, Mn and Zn recorded high accumulation rates in the stressed areas much more than those in the control one while the other trace metals such as Cu, Ni, Co, Cd and Pb have not any signs of pollution in the three localities. Also, this study illustrates that a great variation between the coral species to assimilate the dissolved metal ions and the particulate materials from the water column and precipitating them inside their own skeletons. The non-scleractinian corals show very high ability to assimilate the largest quantities of pollutants more than the scleractinian ones and they can be used as effective biomonitors in the monitoring programs in the polluted areas.
The total phosphorous that affects on the mangrove trees was studied in the fine three fractions;... more The total phosphorous that affects on the mangrove trees was studied in the fine three fractions; fine sand(Ø3), very fine sand (Ø4), and mud (Ø5) of the underlying sediments in three mangrove forests in the northwestern Red Sea coast. A total of 26 samples collected during December 2002, were sieved and 78 sub-samples were taken for total phosphorous (TP) analyses. Phosphorous concentrations in the Abu Minqar and Safaga islands have anthropogenic origin. At Wadi Abu Hamra downstream, phosphorous accumulation appear to be naturally loaded from the land throughout longterm accumulation and from the sea through the accretion processes. Despite the high amounts of phosphorous present, it was useless to the overlying flora due to the high inactive apatite content.
Sediment reworking processes in the tidal flat areas are very important in order to provide the f... more Sediment reworking processes in the tidal flat areas are very important in order to provide the favorable environment for the other living fauna and flora. These processes change the underlying sediment facies and help the other oceanographic factors to work on these sediments. the gut contents of six holothurian species, the amount of sediment consumed per day and the annual reworking rates are studied in details. this study appears that the holothurians are the most efficacious benthos in the tidal flat zones and if missed, the other benthos as the coral reefs will really threaten.
Nineteen species belonging to four coral forms of the recent coral reefs were identified and stud... more Nineteen species belonging to four coral forms of the recent coral reefs were identified and studied in an area of high sedimentation stress. The trace metal contents were measured in the hard skeleton of the different species. The massive forms recorded the highest content of Cu, Fe, Mn and Ni, while the branching forms recorded the highest content of Pb and Zn relative to their relative abundance. The highest Fe, Mn and Pb contents in the different species are strongly attributed to the landfilling and the different anthropogenic impacts in the locality. The mechanism of the heavy metals bioaccumulation within the structure lattice of the coral skeletons is attributed to the biominerlization process and the residual oxides inside the pore spaces of the coral frameworks.
The artificial radionuclides of 238Pu and 239+240Pu were measured in the shallow water sediments ... more The artificial radionuclides of 238Pu and 239+240Pu were measured in the shallow water sediments along the Red Sea coast in 9 stations between Hurghada and Safaga using the α-analyst spectrometer. 4 stations recorded high 238Pu and 239+240Pu; NIOF (0.053Bq/Kg dw, 0.041Bq/Kg dw), Magawesh (0.10Bq/Kg dw, 0.065Bq/Kg dw), Coral Beach (0.060Bq/Kg dw, 0.098Bq/Kg dw), Dishet-Edaba (0.052Bq/Kg dw, 0.083Bq/Kg dw) respectively. Two stations recorded high 239+240Pu only; Abu Minqar (0.15±0.03Bq/Kg dw) and Safaga Bay (0.165±0.03Bq/Kg dw), while the other stations recorded low measurement of these artificial radioelements. The recorded radionuclide concentrations in the different stations indicated that these artificial radioelements are coming from the sea mainly from NE direction belonging to the general wind trend in the locality (NE-SW). The estimated measurements are lower than the recorded averages in many localities around the world which deal to that the average concentrations of the man-made radionuclides along the Egyptian Red Sea coasts are still in the safe limits. No significant source can be impeached as the main source of the artificial radionuclides in the shallow water areas of the Red Sea but they might be accumulated from many sources; atmospheric testing of the nuclear weapons, atmospheric fallout and nuclear wastes discharges in the deep waters of the Red Sea are not away from the arraigning.
The radionuclide activities of 238U, 232Th, 40K and 137Cs were measured using
high resolution gam... more The radionuclide activities of 238U, 232Th, 40K and 137Cs were measured using high resolution gamma spectrometry system. The total organic matter (TOM) and carbonate contents were also measured in the surface sediments of three valleys downstream at the southern Egyptian Red Sea coast. These localities are characterized by the presence of mangrove swamps with dense aerobic roots that provide calm conditions for particulate and fine sediments settlement. 238U and 232Th recorded almost equal activity values in the studied localities and their occurrence in the localities indicated that the metal accumulation are due to the complex and multiple processes that characterize the mangrove environments including accumulation in particulate form with the fine sediments, absorption on iron and manganese oxides and hydroxides from the sea water, incorporation inside the carbonate frameworks and as detrital phase. 40K showed obvious radioactivity in the three localities indicating the presence of terrestrial radionuclide. 137Cs concentrations were not evident in the studied localities which may indicate non-significant artificial source of radionuclide activity.
The Egyptian Journal of Aquatic Research, Mar 1, 2020
Abstract The present study aims to document the diversity and density of benthic fauna in Great B... more Abstract The present study aims to document the diversity and density of benthic fauna in Great Bitter Lakes through their spatial and temporal changes in this important area from spring 2016 to winter 2017. Eleven sampling stations representing most of the area of the Great Bitter Lakes were selected. The results showed that there was 41 species and an annual density of 104,680 organisms/m2 of macro-benthic fauna belonging to five phyla in the studied area. Eighteen species from polychaetes, 12 molluscs, 7 species from crustaceans, 3 echinoderms and one species belonging to cephalochordate were recorded. With the exception of the most dominant species of the lakes, Modiolus auriculatus, which was represented by an annual average of 6822.91 organisms/m2, the onshore stations were the highest in density and diversity than offshore stations (35 and 28 species with an annual density of 18,873 and 10,755 organisms/m2, respectively). The value of heavy metals in surface water was within the following sequence; Fe > Zn > Cu > Pb > Mn > Cd. While in the sediments were arranged as follows: Fe > Mn > Zn > Cu > Ni > Pb > Cd. In the studied area, the medium sediments (O2+O3) recorded the highest percentage (61.34%) of the total percentage of sediment.
Alginates are one of the most important compounds of brown seaweeds. These compounds are employed... more Alginates are one of the most important compounds of brown seaweeds. These compounds are employed in the food area, because of their important rheological properties, such as viscosity, gelling, and stabilizing features and as dietary fiber source. In this study, five species of dominant brown seaweeds were collected in the Red Sea (Padina boergesenii, Turbinaria triquetra, Hormophysa cuneiformis, Dictyota ciliolata, and Sargassum aquifolium) so as to characterize the alginate yield and its properties. The analysis demonstrated differences in the alginate yield among the seaweeds. The highest yield of alginate was recorded in the species T. triquetra (22.2 ± 0.56% DW), while the lowest content was observed in H. cuneiformis (13.3 ± 0.52% DW). The viscosity from the alginates varied greatly between the species, whereas the pH varied slightly. The alginate exhibited a moisture content between 6.4 and 13.1%, the ash content ranged between 12.3 and 20% DW, the protein reached values fro...
International Journal of Ecotoxicology and Ecobiology, 2018
Heavy metals incorporation within the hard skeletons of 16 hard coral species collected from the ... more Heavy metals incorporation within the hard skeletons of 16 hard coral species collected from the tidal flats off five wadis along the eastern side the of Gulf of Suez and western side of Aqaba Gulf were measured using Atomic Absorption Spectrophotometer (AAS). The selected wadis were intensively affected by the temporary intensive flashfloods. The highest averages of Fe, Mn, Cu, Ni, Co and Cd were recorded in the skeleton of Acropora forskali (2211.93; 57.85, 35.32 and 55.15, 4.70 and 1.72 µg/g respectively) at W. Isla in the eastern bank of Suez Gulf meanwhile the lowest averages of Fe, Mn, Cu were observed in Acropora yongei (142.59; 2.70 and 0.02µg/g) at W. Muqebla and the lowest Ni (2.85µg/g) was recorded at W. Watir in the western side of Aqaba Gulf. Stylophora pistillata showed the highest average of Zn (108.63µg/g) at W. Gharandel in the eastern side of Suez Gulf and the lowest value was recorded in Acropora pharaonis (2.17µg/g) at W. Muqebla. Pb showed the highest average in Acropora variables (32.88µg/g) at W. Kid at the western part of Aqaba Gulf and it was not detected in Montipora sp. at W. Isla and Porites sp. at W. Kid. The hard coral skeletons showed significantly high concentrations of (Fe, Mn, Cu, Pb, Ni, Co and Cd) at W. Isla and W. Gharandel along the eastern side of Suez Gulf. It is obvious that the studied coral species have variable tendencies to accumulate the heavy metals within their skeletons. In general, the coral species collected from Gulf of Suez wadis recorded high to significantly high bio-accumulation tendencies indicating to remarkable contributions of the land based activities (mining and oil exploration activities). The recorded heavy metals along Aqaba Gulf were significantly attributed to the flashfloods. The differential abilities of coral species showed that; S. pistillata at W. Gharandel along the eastern side of Suez Gulf has the highest bioaccumulation tendencies toward Zn (2.12), Pb (3.94), Ni (35), Co (1.60) and Cd (5.47) but Platygyra sp. has the highest bio-accumulation tendency towards Ni (3.53). The Gulf of Aqaba wadis showed the minimized bioaccumulation tendencies for the different coral species relative to the investigated coral species at Suez Gulf wadis except Acropora variables at W. Kid (1.22) for Pb and Acropora digitifera at W. Watir (1.25) for Ni.
Mangrove swamps have unique biogeochemical interaction between the plant and the underlying sedim... more Mangrove swamps have unique biogeochemical interaction between the plant and the underlying sediments. The bioactive heavy metals; Zn, Cu, Fe, Mn, Pb, Ni, Cd and Co were measured using Atomic Absorption Spectrophotometer (AAS) in the bulk sediment samples and the fine fractions; 125µ, 63µ and <63µ and slack water as well as different parts of the Avicennia marina mangrove (fruits, leaves and roots) collected from 9 mangrove swamps at the nearshore zone of the Red Sea. The average percentage of the fine sediment group (125µ + 63µ + <63µ) was varied between 18.78% and 51.22% from the total sediments with recognized occurrences for the fractions 125µ and 63µ. The bulk sediments recorded the highest averages of the bioactive Zn (69.91µg/g), Mn (186.91µg/g) and Ni (19.49µg/g), the fraction 125µ recorded the highest average of Pb (16.92 µg/g), while <63µ fraction showed the highest averages of Cu and Fe (26.45 and 2744.84µg/g). In the mangrove stands, the highest averages of Zn and Cu were recorded in fruits (Avs. ≈116.41 and 15.20 µg/g), Mn in leaves (Av. ≈ 43.72 µg/g) and the highest Pb was recorded in roots (Av. ≈ 30.14 µg/g). The bio-accumulation sequence of heavy metals in the fruits and roots was Fe>Zn>Pb>Cu>Mn>Ni and in leaves was Fe>Zn>Mn>Pb>Cu>Ni. The low contents heavy metals recorded in the slack water of the mangrove swamps attributed to the reducing nature of the underlying sediments that accumulate the heavy metals in insoluble sulphide forms. The effects of the elevated metal contents in the fruits, leaves and the roots of A. marina were at the studied forests were reflected in the ramified and shorten roots, pale yellowish colour and reduction the leaves number in many of the mangrove stands.
Macro-benthic fauna are considered the good bio-indicators for the environmental changes of any a... more Macro-benthic fauna are considered the good bio-indicators for the environmental changes of any aquatic ecosystems. Samples of macro-benthos, sediments and surface water were collected from 13 stations representing different conditions in the Western Lagoon (10 stations) and Timsah Lake (3 stations) from autumn 2014 to summer 2015. Macro-benthic density and diversity in Timsah Lake were higher than those in the Western Lagoon; the density at Timsah Lake encompassed 167,649 individual/m 2 representing 42 species from the total of 46 species recorded in the investigated area. While species density in the Western Lagoon constituted 12,008 individ-ual/m 2 presenting only 16 species. Winter recorded the highest density (74,854 individual/m 2); the highest dominance (CDI = 0.858) and the lowest Equitability (0.293) due to the dominance of the opportunistic species. Spring harvested both the highest diversity (28 species) and species richness (SR = 2.917). While autumn and summer procured both the lowest density and diversity (34,021 and 29,544 individual/m 2 and 23 and 25 species respectively). The equitability index (E 0) showed its highest values within the Western Lagoon (>0.90) owing to the species poorness relative to Timsah Lake. The water quality data showed that the Western Lagoon and Timsah Lake had significant high oxygen influx in spring (11.00 and 9.35 mg/l, respectively) and oxygen depletion in summer (1.00 and 3.00 mg/l, respectively). Reactive phosphorus and ammonia in the Western Lagoon exceeded the world averages. Timsah Lake sediments were highly affected by the sediment drifts from the Western Lagoon. The highest influx of the fine sediment group (FSG) was estimated during spring with an average of 62.77% and 61.18% in Timsah Lake and Western Lagoon, respectively. Total organic matter (TOM) in Western Lagoon recorded the highest average of 17.05% in spring accompanied with the high biological productivities.
Cette étude est axée sur le comportement alimentaire sélectif et le rôle écologique des principal... more Cette étude est axée sur le comportement alimentaire sélectif et le rôle écologique des principales espèces d’holothuries — Holothuria atra, Holothuria hawaiiensis et Bohadschia vitiensis — vivant sur les platiers découverts à marée basse et les eaux peu profondes de la mer Rouge à Hurghada, en Égypte. Les sédiments retrouvés dans l’appareil digestif de ces trois espèces varient beaucoup en fonction du poids total de l’animal. Les individus ayant un poids moyen ont besoin de consommer d’importantes quantités d’aliments pour grandir et développer leurs gonades, et il s’est avéré qu’ils absorbent davantage de gravier que les holothuries ayant un poids élevé ou faible. Ce comportement sélectif des holothuries permet d’expliquer pourquoi les graviers et le sable grossier constituent les principaux sédiments retrouvés dans l’appareil digestif de l’animal au cours des différentes saisons. Pendant la période de reproduction (début de l’été jusqu’à l’automne), les individus tendent à assimiler plus de sédiments fins que de sédiments grossiers, peut-être parce qu’ils ont davantage besoin de matières organiques. Le remaniement sédimentaire par les différentes espèces varie au cours de l’année et dépend du nombre d’individus, de la disponibilité des aliments, de la taille des individus et des conditions locales. Les effets de l’alimentation de ces trois espèces d’holothuries sur le remaniement sédimentaire ont été le plus marqués en juillet (été) et en novembre (automne) pour H. atra, en automne et en hiver (septembre et décembre) pour H. hawaiiensis, et principalement en été (mai à août) pour B. vitiensis. Il a été observé que le remaniement s’étale de la fin du printemps à la fin de l’automne, période pendant laquelle deux phases importantes de la reproduction des holothuries se déroulent: la maturation et la ponte.
The mobile forms of heavy metals are the exchangeable phases of these metals that represent the b... more The mobile forms of heavy metals are the exchangeable phases of these metals that represent the bioavailable toxic hazards in the marine environment. The exchangeable forms of Fe, Zn, Cu, Mn, and Pb were measured using atomic absorption spectrophotometry in the inshore sediments at five locations along the Red Sea coast in areas under natural and anthropogenic discharges. The fine sediment group (FSG) reached the average of 51.29 % representing the controlling and vital factor in the different geochemical processes that occur in seabed sediments. Hamrawin Bay recorded the highest averages of Mn (283.55 μg/g), Zn (99.63 μg/g), and Pb (73.35 μg/g). Abu Dabab recorded the highest average of Fe (1336.41 μg/g), Shalateen exhibited the highest Cu average (35.62 μg/g) and the lowest averages of Mn, Zn, and Pb (50.18, 24.28, and 18.44 μg/g), and Qula’an showed the lowest averages of Fe and Cu (944.61 and 17.39 μg/g). The estimated results indicated that the exchanges from one phase to another were active in all locations due to the continuous reworking processes in the surface sediments. Under the oxic conditions, oxides, hydroxides, and carbonates of Fe, Mn, and Zn were expected to be the dominant metal forms associated with the sand fraction at the different locations. Under the reducing environments (anoxic conditions), sulfide forms of Fe, Pb, Mn, and Cu were associated with fine sediment fractions (very fine sand, silt, and mud) were dominant. Ionic exchanges were active in the near bottom and the interstitial water during the transformation operations from one phase to another at the different locations. The continuity of the forms transformation in the marine ecosystem at the studied locations provide the favorable environment for benthos growing up.
The heavy metal contents of Cu, Zn, Pb, Mn and Cd were measured using AAS in the fine sediment fr... more The heavy metal contents of Cu, Zn, Pb, Mn and Cd were measured using AAS in the fine sediment fractions (Ø3, Ø4 and Ø5) and the seawater at six sites represent the main land-based activities at Hurghada, Safaga and Hamrawin along the Red Sea coast. The fine sediment group (Ø3 + Ø4 + Ø5) was varied between 24.61 and 88.88 % from the total sediment percentage, whereas Ø3 was the most abundant fraction with average percentages between 14.92 % at site III and 28.3 % at Site IV followed by Ø4 with average between 8.04 % at site III and 57.46 % at site II; therefore Ø3 and Ø4 were considered the essential pollutant bearing fractions. Cu recorded the highest average content (248.69 µg/g) at site I, Zn (746.24 µg/g) at site V, Pb (215.86 µg/g) at site III, Mn (407.66 µg/g) at site IV and Cd recorded the highest average (28.47 µg/g) at site VI. Site II showed the lowest average contents of the different metals that may attribute to the continuous leaching of the metal bearing fractions by the longshore currents and waves. In the seawater, site IV recorded the highest Cu average (10.49 μg/l), site III showed the highest averages of Zn and Pb (63.02 and 42.49 μg/l) whilst site VI recorded the highest averages of Mn and Cd (17.78 and 1.13 μg/l, respectively). Zn, Pb, Mn and Cd showed significant correlation relationships to each other in sediments at Hurghada indicated that they tend to accumulate in the same form. The insignificant correlations of Cu and other metals at Safaga and Hamrawin indicated the accumulation in multiple forms under variable local conditions. The different sites were classified between slightly and highly polluted with heavy metals. The obtained results illustrated that the land-based activities at the different localities have serious threatening on the near-shore environment and Safaga marine area was more polluted than Hurghada and Hamrawin.
The granulometric characteristics, the bio-available heavy metals and the natural radionuclide ac... more The granulometric characteristics, the bio-available heavy metals and the natural radionuclide activities in the surface sediments were investigated semi-annually in Timsah Lake at the middle district of the Suez Canal, Egypt. The average percentages of mud and fine grained sediments recorded in summer were (4.17% and 33.89%) much higher than in winter (1.43% and 22.70%) attributed to the relatively high dispersing of the fine sediment fractions in winter by wave action and the fine sediments drifting towards Suez Canal. The average carbonate percentage was 19.72% in summer increased to 22.71% in winter, inversely, the average total organic matter (TOM) in summer was 7.52% decreased to 6.32% in winter. The highest averages of the bio-available heavy metals; Zn, Cu, Pb, Cd, Mn, Co, Ni and Fe were; 65.51, 18.06, 27.76, 0.78, 260.64, 4.10, 17.16 and 2087.71μg/g were recorded summer and the highest average activities of 238U, 232Th and 40K were 23.79, 23.72and 221.35Bqkg-1 were recorded in winter. The recoded heavy metals and radionuclides were attributed to multi anthropogenic sources; untreated wastewater drains, agriculture drains, industrial runoff and shipyards. The high values of TOM and bioavailable heavy metals in summer are related to the highest fine sediment percentages, while the radionuclides may tend to associate with the coarse sediments. The significant positive correlations of TOM and Fe with heavy metals and radionuclides indicated to two essential metal phases, one with organic matter in the highly reducing conditions and the other associated and/or adsorbed by Fe-oxides and hydroxide particles in addition to the other independent metal phases. The recorded bioavailable metals are lower than the excepted because of suspended matters and water drift toward Suez Canal dilute the metal accumulation in the lake sediments.
The distribution patterns, the index of geoaccumulations
(MIgeo), and the enrichment ratios (ERn... more The distribution patterns, the index of geoaccumulations
(MIgeo), and the enrichment ratios (ERn) of the
contaminantmetals: Fe,Mn, Zn, Cu, Pb, and Ni were studied in
gravel, sand, mud, coarse, medium, and fine sediment fractions
of the uppermost layer of the bottom sediments collected from
12 stations covering the northern part of Safaga Bay. The
distribution levels of these metals were increasing with grain
size decreasing toward the central axis of the bay that extends
NE–SWand southward to Safaga Harbour indicating that these
metals concentrated mainly in the fine, very fine, and particulate
fractions of sediments and to many anthropogenic sources. The
geo-accumulation factor of Zn was more significant (MIgeo≈
0.62–4.23) relative to the other metals. The bay was classified
as moderately to strongly polluted by Zn while it is unpolluted
to moderately polluted with the other metals with accumulation
sequence of: Zn>Ni>Cu>Mn≥Pb. Zn and Ni recorded the highest
enrichment ratios (average ERZn≈3.07 to 8.89; average
ERNi≈0.84 to 3.63) in the different sediment fractions relative
the other metals. These enrichment ratios classified the bay as
minimal enrichment, suggestive of no or minimal pollution, to
significant enrichment, suggestive of a significant pollution
signals with metals sequence of: Zn>Ni>Cu>Pb>Mn.
The natural radioisotopes 238U, 231Th and 40K as well as the artificial radioisotopes 137Cs, 238P... more The natural radioisotopes 238U, 231Th and 40K as well as the artificial radioisotopes 137Cs, 238P and 90Sr were measured using high resolution -spectrometry in some living corals in tidal flat areas of Hurghada, Safaga and Shlateen along the Red Sea coast. Stylophora sp. recorded the highest 238U activity (25.20Bqkg-1dw), Favia lacuna recorded the highest 231Th activity (16.20Bqkg-1dw), while the highest 40K activity was recorded in Platygyra crosslanda (996.00Bqkg-1dw). The artificial radioisotopes recorded very low activities relative to the marine sediments; 90Sr recorded the highest activity in the hydrocoral Millipora dechtoma (5.57Bqkg-1dw), 238P observed only in some massive species at Hurghada and shlateen (Av ≈ 0.03±0.00 and 0.12±0.06Bqkg-1dw respectively) and 137Cs activities were insignificant in all coral species (<0.1Bqkg-1dw). Safaga locality shows the highest average contents for; 238U (15.26±6.14Bqkg-1dw), 231Th (9.52±3.89Bqkg-1dw); 40K (677.18±284.71Bqkg-1dw) and 90Sr (2.02±1.59Bqkg-1dw) while Shalteen recorded the highest average of 238P indicating that the natural radioisotope accumulations in coral reefs is highly affected by the phosphate inputs from mining, grinding and shipping operations and other terrestrial inputs while the artificial radioisotopes may accumulated from the planktonic particulates from the sea. The interspecific variations of the radioisotopes in the coral skeletons were controlled by the changes of carbonate ion content of the seawater, salinity and alkalinity influences, pH, seasonal influences, the substitution mechanism based on substitution of Ca2+, the amounts of particulates in the water column and influence of temperature. In addition to some other biological factors as; the growth rate of the coral skeletons, the exposing surface area, skeleton bulk densities and the organic matrices thickness. The natural and artificial radioisotopes may be mineralized as ionic forms with skeleton formation and/or included as independent particulates inside the aragonitic skeletal frameworks.
The skeletons of 15 coral species were investigated in three localities along the Red Sea coast, ... more The skeletons of 15 coral species were investigated in three localities along the Red Sea coast, two of them have coral species under stress while the third locality was used as control area. Total phosphorous (TP) and the trace metal contents were measured in the skeletons these coral species. The recorded data was amazing and reflects very high ability of the corals to resist and survive in the polluted environment but with different degrees of acclimation for these conditions. TP, Fe, Mn and Zn recorded high accumulation rates in the stressed areas much more than those in the control one while the other trace metals such as Cu, Ni, Co, Cd and Pb have not any signs of pollution in the three localities. Also, this study illustrates that a great variation between the coral species to assimilate the dissolved metal ions and the particulate materials from the water column and precipitating them inside their own skeletons. The non-scleractinian corals show very high ability to assimilate the largest quantities of pollutants more than the scleractinian ones and they can be used as effective biomonitors in the monitoring programs in the polluted areas.
The total phosphorous that affects on the mangrove trees was studied in the fine three fractions;... more The total phosphorous that affects on the mangrove trees was studied in the fine three fractions; fine sand(Ø3), very fine sand (Ø4), and mud (Ø5) of the underlying sediments in three mangrove forests in the northwestern Red Sea coast. A total of 26 samples collected during December 2002, were sieved and 78 sub-samples were taken for total phosphorous (TP) analyses. Phosphorous concentrations in the Abu Minqar and Safaga islands have anthropogenic origin. At Wadi Abu Hamra downstream, phosphorous accumulation appear to be naturally loaded from the land throughout longterm accumulation and from the sea through the accretion processes. Despite the high amounts of phosphorous present, it was useless to the overlying flora due to the high inactive apatite content.
Sediment reworking processes in the tidal flat areas are very important in order to provide the f... more Sediment reworking processes in the tidal flat areas are very important in order to provide the favorable environment for the other living fauna and flora. These processes change the underlying sediment facies and help the other oceanographic factors to work on these sediments. the gut contents of six holothurian species, the amount of sediment consumed per day and the annual reworking rates are studied in details. this study appears that the holothurians are the most efficacious benthos in the tidal flat zones and if missed, the other benthos as the coral reefs will really threaten.
Nineteen species belonging to four coral forms of the recent coral reefs were identified and stud... more Nineteen species belonging to four coral forms of the recent coral reefs were identified and studied in an area of high sedimentation stress. The trace metal contents were measured in the hard skeleton of the different species. The massive forms recorded the highest content of Cu, Fe, Mn and Ni, while the branching forms recorded the highest content of Pb and Zn relative to their relative abundance. The highest Fe, Mn and Pb contents in the different species are strongly attributed to the landfilling and the different anthropogenic impacts in the locality. The mechanism of the heavy metals bioaccumulation within the structure lattice of the coral skeletons is attributed to the biominerlization process and the residual oxides inside the pore spaces of the coral frameworks.
The artificial radionuclides of 238Pu and 239+240Pu were measured in the shallow water sediments ... more The artificial radionuclides of 238Pu and 239+240Pu were measured in the shallow water sediments along the Red Sea coast in 9 stations between Hurghada and Safaga using the α-analyst spectrometer. 4 stations recorded high 238Pu and 239+240Pu; NIOF (0.053Bq/Kg dw, 0.041Bq/Kg dw), Magawesh (0.10Bq/Kg dw, 0.065Bq/Kg dw), Coral Beach (0.060Bq/Kg dw, 0.098Bq/Kg dw), Dishet-Edaba (0.052Bq/Kg dw, 0.083Bq/Kg dw) respectively. Two stations recorded high 239+240Pu only; Abu Minqar (0.15±0.03Bq/Kg dw) and Safaga Bay (0.165±0.03Bq/Kg dw), while the other stations recorded low measurement of these artificial radioelements. The recorded radionuclide concentrations in the different stations indicated that these artificial radioelements are coming from the sea mainly from NE direction belonging to the general wind trend in the locality (NE-SW). The estimated measurements are lower than the recorded averages in many localities around the world which deal to that the average concentrations of the man-made radionuclides along the Egyptian Red Sea coasts are still in the safe limits. No significant source can be impeached as the main source of the artificial radionuclides in the shallow water areas of the Red Sea but they might be accumulated from many sources; atmospheric testing of the nuclear weapons, atmospheric fallout and nuclear wastes discharges in the deep waters of the Red Sea are not away from the arraigning.
The radionuclide activities of 238U, 232Th, 40K and 137Cs were measured using
high resolution gam... more The radionuclide activities of 238U, 232Th, 40K and 137Cs were measured using high resolution gamma spectrometry system. The total organic matter (TOM) and carbonate contents were also measured in the surface sediments of three valleys downstream at the southern Egyptian Red Sea coast. These localities are characterized by the presence of mangrove swamps with dense aerobic roots that provide calm conditions for particulate and fine sediments settlement. 238U and 232Th recorded almost equal activity values in the studied localities and their occurrence in the localities indicated that the metal accumulation are due to the complex and multiple processes that characterize the mangrove environments including accumulation in particulate form with the fine sediments, absorption on iron and manganese oxides and hydroxides from the sea water, incorporation inside the carbonate frameworks and as detrital phase. 40K showed obvious radioactivity in the three localities indicating the presence of terrestrial radionuclide. 137Cs concentrations were not evident in the studied localities which may indicate non-significant artificial source of radionuclide activity.
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— Holothuria atra, Holothuria hawaiiensis et Bohadschia vitiensis — vivant sur les platiers découverts à marée basse et
les eaux peu profondes de la mer Rouge à Hurghada, en Égypte. Les sédiments retrouvés dans l’appareil digestif de
ces trois espèces varient beaucoup en fonction du poids total de l’animal. Les individus ayant un poids moyen ont besoin
de consommer d’importantes quantités d’aliments pour grandir et développer leurs gonades, et il s’est avéré qu’ils
absorbent davantage de gravier que les holothuries ayant un poids élevé ou faible. Ce comportement sélectif des holothuries
permet d’expliquer pourquoi les graviers et le sable grossier constituent les principaux sédiments retrouvés
dans l’appareil digestif de l’animal au cours des différentes saisons. Pendant la période de reproduction (début de l’été
jusqu’à l’automne), les individus tendent à assimiler plus de sédiments fins que de sédiments grossiers, peut-être parce
qu’ils ont davantage besoin de matières organiques.
Le remaniement sédimentaire par les différentes espèces varie au cours de l’année et dépend du nombre d’individus, de
la disponibilité des aliments, de la taille des individus et des conditions locales. Les effets de l’alimentation de ces trois espèces
d’holothuries sur le remaniement sédimentaire ont été le plus marqués en juillet (été) et en novembre (automne)
pour H. atra, en automne et en hiver (septembre et décembre) pour H. hawaiiensis, et principalement en été (mai à août)
pour B. vitiensis. Il a été observé que le remaniement s’étale de la fin du printemps à la fin de l’automne, période pendant
laquelle deux phases importantes de la reproduction des holothuries se déroulent: la maturation et la ponte.
(MIgeo), and the enrichment ratios (ERn) of the
contaminantmetals: Fe,Mn, Zn, Cu, Pb, and Ni were studied in
gravel, sand, mud, coarse, medium, and fine sediment fractions
of the uppermost layer of the bottom sediments collected from
12 stations covering the northern part of Safaga Bay. The
distribution levels of these metals were increasing with grain
size decreasing toward the central axis of the bay that extends
NE–SWand southward to Safaga Harbour indicating that these
metals concentrated mainly in the fine, very fine, and particulate
fractions of sediments and to many anthropogenic sources. The
geo-accumulation factor of Zn was more significant (MIgeo≈
0.62–4.23) relative to the other metals. The bay was classified
as moderately to strongly polluted by Zn while it is unpolluted
to moderately polluted with the other metals with accumulation
sequence of: Zn>Ni>Cu>Mn≥Pb. Zn and Ni recorded the highest
enrichment ratios (average ERZn≈3.07 to 8.89; average
ERNi≈0.84 to 3.63) in the different sediment fractions relative
the other metals. These enrichment ratios classified the bay as
minimal enrichment, suggestive of no or minimal pollution, to
significant enrichment, suggestive of a significant pollution
signals with metals sequence of: Zn>Ni>Cu>Pb>Mn.
The interspecific variations of the radioisotopes in the coral skeletons were controlled by the changes of carbonate ion content of the seawater, salinity and alkalinity influences, pH, seasonal influences, the substitution mechanism based on substitution of Ca2+, the amounts of particulates in the water column and influence of temperature. In addition to some other biological factors as; the growth rate of the coral skeletons, the exposing surface area, skeleton bulk densities and the organic matrices thickness. The natural and artificial radioisotopes may be mineralized as ionic forms with skeleton formation and/or included as independent particulates inside the aragonitic skeletal frameworks.
Also, this study illustrates that a great variation between the coral species to assimilate the dissolved metal ions and the particulate materials from the water column and precipitating them inside their own skeletons. The non-scleractinian corals show very high ability to assimilate the largest quantities of pollutants more than the scleractinian ones and they can be used as effective biomonitors in the monitoring programs in the polluted areas.
The estimated measurements are lower than the recorded averages in many localities around the world which deal to that the average concentrations of the man-made radionuclides along the Egyptian Red Sea coasts are still in the safe limits. No significant source can be impeached as the main source of the artificial radionuclides in the shallow water areas of the Red Sea but they might be accumulated from many sources; atmospheric testing of the nuclear weapons, atmospheric fallout and nuclear wastes discharges in the deep waters of the Red Sea are not away from the arraigning.
high resolution gamma spectrometry system. The total organic matter (TOM) and
carbonate contents were also measured in the surface sediments of three valleys
downstream at the southern Egyptian Red Sea coast. These localities are
characterized by the presence of mangrove swamps with dense aerobic roots that
provide calm conditions for particulate and fine sediments settlement. 238U and
232Th recorded almost equal activity values in the studied localities and their occurrence in the localities indicated that the metal accumulation are due to the
complex and multiple processes that characterize the mangrove environments
including accumulation in particulate form with the fine sediments, absorption on
iron and manganese oxides and hydroxides from the sea water, incorporation
inside the carbonate frameworks and as detrital phase. 40K showed obvious
radioactivity in the three localities indicating the presence of terrestrial
radionuclide. 137Cs concentrations were not evident in the studied localities which
may indicate non-significant artificial source of radionuclide activity.
— Holothuria atra, Holothuria hawaiiensis et Bohadschia vitiensis — vivant sur les platiers découverts à marée basse et
les eaux peu profondes de la mer Rouge à Hurghada, en Égypte. Les sédiments retrouvés dans l’appareil digestif de
ces trois espèces varient beaucoup en fonction du poids total de l’animal. Les individus ayant un poids moyen ont besoin
de consommer d’importantes quantités d’aliments pour grandir et développer leurs gonades, et il s’est avéré qu’ils
absorbent davantage de gravier que les holothuries ayant un poids élevé ou faible. Ce comportement sélectif des holothuries
permet d’expliquer pourquoi les graviers et le sable grossier constituent les principaux sédiments retrouvés
dans l’appareil digestif de l’animal au cours des différentes saisons. Pendant la période de reproduction (début de l’été
jusqu’à l’automne), les individus tendent à assimiler plus de sédiments fins que de sédiments grossiers, peut-être parce
qu’ils ont davantage besoin de matières organiques.
Le remaniement sédimentaire par les différentes espèces varie au cours de l’année et dépend du nombre d’individus, de
la disponibilité des aliments, de la taille des individus et des conditions locales. Les effets de l’alimentation de ces trois espèces
d’holothuries sur le remaniement sédimentaire ont été le plus marqués en juillet (été) et en novembre (automne)
pour H. atra, en automne et en hiver (septembre et décembre) pour H. hawaiiensis, et principalement en été (mai à août)
pour B. vitiensis. Il a été observé que le remaniement s’étale de la fin du printemps à la fin de l’automne, période pendant
laquelle deux phases importantes de la reproduction des holothuries se déroulent: la maturation et la ponte.
(MIgeo), and the enrichment ratios (ERn) of the
contaminantmetals: Fe,Mn, Zn, Cu, Pb, and Ni were studied in
gravel, sand, mud, coarse, medium, and fine sediment fractions
of the uppermost layer of the bottom sediments collected from
12 stations covering the northern part of Safaga Bay. The
distribution levels of these metals were increasing with grain
size decreasing toward the central axis of the bay that extends
NE–SWand southward to Safaga Harbour indicating that these
metals concentrated mainly in the fine, very fine, and particulate
fractions of sediments and to many anthropogenic sources. The
geo-accumulation factor of Zn was more significant (MIgeo≈
0.62–4.23) relative to the other metals. The bay was classified
as moderately to strongly polluted by Zn while it is unpolluted
to moderately polluted with the other metals with accumulation
sequence of: Zn>Ni>Cu>Mn≥Pb. Zn and Ni recorded the highest
enrichment ratios (average ERZn≈3.07 to 8.89; average
ERNi≈0.84 to 3.63) in the different sediment fractions relative
the other metals. These enrichment ratios classified the bay as
minimal enrichment, suggestive of no or minimal pollution, to
significant enrichment, suggestive of a significant pollution
signals with metals sequence of: Zn>Ni>Cu>Pb>Mn.
The interspecific variations of the radioisotopes in the coral skeletons were controlled by the changes of carbonate ion content of the seawater, salinity and alkalinity influences, pH, seasonal influences, the substitution mechanism based on substitution of Ca2+, the amounts of particulates in the water column and influence of temperature. In addition to some other biological factors as; the growth rate of the coral skeletons, the exposing surface area, skeleton bulk densities and the organic matrices thickness. The natural and artificial radioisotopes may be mineralized as ionic forms with skeleton formation and/or included as independent particulates inside the aragonitic skeletal frameworks.
Also, this study illustrates that a great variation between the coral species to assimilate the dissolved metal ions and the particulate materials from the water column and precipitating them inside their own skeletons. The non-scleractinian corals show very high ability to assimilate the largest quantities of pollutants more than the scleractinian ones and they can be used as effective biomonitors in the monitoring programs in the polluted areas.
The estimated measurements are lower than the recorded averages in many localities around the world which deal to that the average concentrations of the man-made radionuclides along the Egyptian Red Sea coasts are still in the safe limits. No significant source can be impeached as the main source of the artificial radionuclides in the shallow water areas of the Red Sea but they might be accumulated from many sources; atmospheric testing of the nuclear weapons, atmospheric fallout and nuclear wastes discharges in the deep waters of the Red Sea are not away from the arraigning.
high resolution gamma spectrometry system. The total organic matter (TOM) and
carbonate contents were also measured in the surface sediments of three valleys
downstream at the southern Egyptian Red Sea coast. These localities are
characterized by the presence of mangrove swamps with dense aerobic roots that
provide calm conditions for particulate and fine sediments settlement. 238U and
232Th recorded almost equal activity values in the studied localities and their occurrence in the localities indicated that the metal accumulation are due to the
complex and multiple processes that characterize the mangrove environments
including accumulation in particulate form with the fine sediments, absorption on
iron and manganese oxides and hydroxides from the sea water, incorporation
inside the carbonate frameworks and as detrital phase. 40K showed obvious
radioactivity in the three localities indicating the presence of terrestrial
radionuclide. 137Cs concentrations were not evident in the studied localities which
may indicate non-significant artificial source of radionuclide activity.