Egypt
http://hdl.handle.net/1834/999
2024-03-29T00:47:01ZGrowth, mortalities and yield per recruit of the shrimp fish scad Alepes djedaba (Forskal) (F. Carangidae), from Abu Qir Bay, Eastern Alexandria, Egypt
http://hdl.handle.net/1834/4995
Growth, mortalities and yield per recruit of the shrimp fish scad Alepes djedaba (Forskal) (F. Carangidae), from Abu Qir Bay, Eastern Alexandria, Egypt
El-Sayed, H.Kh.A.
Growth and population dynamics parameters of Alepes djedaba as an exotic carangid fish species from Red Sea into the Levant Basin of the Mediterranean Sea, were investigated. Fish samples were obtained from purse-seiners operating during the day time from Jan. to Dec. 2003 in Abu Qir Bay, Eastern Alexandria. The results obtained show that back-calculated lengths (based upon otolith readings) for the first; second and third age groups were 10.38; 15.4 and 19.32 cm TL respectively, the estimated Bertalanffy growth parameters were L∞=33.29 cm, K=0.2473 and t0= -0.51. The Length-weight relationship was represented by the formula: Log W=-1.9245+2.9762 Log L. Total mortality (Z), natural mortality (M) and fishing mortality (F) were 1.85; 0.62 and 1.23 respectively. The exploitation rate (E) was found to be 56%. A Beverton and Holt yield per recruit model indicated that the maximium sustainable yield could 20.20 g at fishing mortality F= 1.6, while the current yield per recruit was 20.10 g at fishing mortality 1.23. The results proved that the purse-seine fishery of A. diedaba is over exploited in Abu-Qir Bay and requires to be managed.
2005-01-01T00:00:00ZCell culture from two red sea benthic invertebrates: a case study on the soft octocorals dendronephthya klunzingeri and anthelia glauca
http://hdl.handle.net/1834/2218
Cell culture from two red sea benthic invertebrates: a case study on the soft octocorals dendronephthya klunzingeri and anthelia glauca
Ammar, M.S.A.; Emara, A.M.; Perovic, S.; Wiens, M.; Billinghurst, Z.; Müller, I.M.; Müller, W.E.G.
Primmorphs were obtained from single cells of both coral species Dendronephthya klunzingeri and Anthelia glauca following incubation for three or four days during 2001. Both ultraviolet light (UVB; peak of emission of 320 nm) and visible light (wavelength between 400 and 520 nm with a maximum at 480 nm) were applied to the primmorphs as stressors. The following incubation probes have been isolated from D. klunzingeri and were used to monitor the expression of the respective genes in the homologous cell system; the heat-shock protein HSP90 (to monitor general stress responses), the histone H4cDNA (to monitor the cell cycle/proliferation) and the UVS-related protein (response to ultraviolet light) from D. klunzingeri. The data show that the steady state level of HSP90 expression is only upregulated at low level of exposure to UVB (30 J/cm2), while at stronger irradiation the expression level decreases. The expression of the histone H4 gene is blocked following exposure to UVS. Interestingly, in the absence of UVB no transcripts of UVS-related protein can be visualized. However, after exposure of the primmorphs with 30 to 300 J/cm2 a strong upregulation of the expression of the UVS-related gene is seen. The response of the primmorphs to visible light is distinct to that following exposure to UVB. The expression of the gene for histone H4 is significantly upregulated following exposure to UVB, while no expression of the gene UVS-related protein can be detected. It is concluded that, the primmorph system is useful to assess potential nature and anthropogenic disturbances on coral cells.
2007-01-01T00:00:00ZInfluence of salinity variations on zooplankton community in el-mex bay, alexandria, egypt
http://hdl.handle.net/1834/2211
Influence of salinity variations on zooplankton community in el-mex bay, alexandria, egypt
Zakaria, H.Y.; Radwan, A.A.; Said, M.A.
El-Mex Bay receives a heavy load of waste waters (7×109 m3/year) both directly from industrial outfalls and indirectly from Lake Maryuit via El-Mex Pumping Station. Zooplankton samples were collected bimonthly from seven stations during the period March 2005 to January 2006 to illustrate the influence of salinity variations on the abundance and community structure of zooplankton in El-Mex Bay waters. Based on the salinity values, four water types are identified: the mixed land drainage (L) of salinity < 10ppt, mixed water (M) of salinity range 10 to 30ppt, diluted sea water (D) of salinity range 30 to 38.5 ppt and Mediterranean Sea water (S) of salinity > 38.5. The highest zooplankton standing crop (106.6×103 ind/m3) was recorded in the mixed land drainage water type (L); while the lowest counts (5.9×103 ind/m3) was found in the Mediterranean Sea water type (S). Rotifera were the most dominant zooplankton groups in water type (L) constituting about 86% to the total zooplankton and represented by 19 species belonging to 10 genera. Brachionus urceolaris and Filinia longiseta dominate Rotifera population. Protozoa was the second important group in this water type contributing 9.23% to the total zooplankton crop. In water type (M), Rotifera, Protozoa and Copepoda were the most dominant groups constituting 57.87%, 21.32% and 13.45% to the total zooplankton counts respectively. In water type (D), Copepoda and their larval stages were the most dominant zooplankton groups constituting about 51% to the total zooplankton. Protozoa was the second important group constituting 37.20%, while Rotifera represented only 4.20%. In the Mediterranean water type (S), Copepoda and their larvae were the most dominant zooplankton group, forming 49.46% of the total zooplankton. Oithona nana, Acartia clausi and Paracalanus parvus dominated copepod population. Cirriped larvae occupied the second order of abundance at this water type with a percentage frequency of 19.17% to the total zooplankton crop.
2007-01-01T00:00:00ZInfluence of barley straw and submerged macrophytes on fishpond wastewater quality
http://hdl.handle.net/1834/2210
Influence of barley straw and submerged macrophytes on fishpond wastewater quality
Ghobrial, M.G.; Okbah, M.A.; Gharib, S.M.; Soliman, A.M.
Barley straw has received, recently, considerable attention as an algicide, which could be used to control algal growth in fishponds. It is regarded as cost-effective, user friendly and environmentally sounds. On the other hand, the submerged wetland macrophytes are crucial for the stabilization of clear water state in shallow lakes, by their active production of anti-algal compounds (allelochemicals) through allelopathy. Microcosm experiments using barley straw and the submerged macrophytes: Najas marina L., Potamogeton pectinatus L. and Ceratophyllum demersum L. in culture media with fishpond water were carried out outdoors to simulate the situation as natural as possible. Nutrients concentrations were measured beside the analysis of phytoplankton and zooplankton communities were analyzed during nineteen days incubation period. Nitrogen and phosphorus elements were determined in the tissues of used aquatic macrophytes at the beginning and by the end of the experiment. Multivariate statistical assessment using matrix correlation and principal components analysis was applied for interpretation of the experimental data. Principal component PC1 in barley straw medium accounted for about 47% of the total variance with strong correlation between selected parameters and a positive coefficient (r = 0.94 and 0.84) for diatoms – PO4 and diatoms – SiO4 respectively. On the other hand, PC1 in the status of N. marina and C. demersum contributed to 46% and 58% of the total variance, respectively with high positive loading between diatoms and green algae, while in case of P. pectinatus PC1 accounted for 62% of the variance with positive loading for chlorophyll – a, green algae and rotifers. Thus, rotted barley straw stimulated the growth and dominance of diatoms, rather than the green algae, throughout the incubation period. In the mean time, the macrophytes had allelopathic impact on the diatoms community, particularly Najas, while stimulated growth of the green algae. Zooplankton community was dominated by rotifers in all macrophytes media, while protozoan dominated barley straw medium. Complete depletion of nutrients was detected after few days in all media, while oxygen sustained acceptable levels. Phytoplankton assemblages shifting from green algae dominance to diatoms in barley straw medium is recommended as an invention to provide an integrated bioremediative product with readyto-use. Active biological compounds (algicides) derived from barley straw were more reliable than allelochemicals from aquatic macrophytes. Through their beneficial effects they would render aquatic environments such as, ponds, lagoons, aquaria, aquaculture systems, wastewater treatment, holding or conveying systems more aesthetically pleasing, efficient in aquatic animal production, and less susceptible to algae and other undesirable aquatic plants. They would thus require less maintenance. It is a tentative suggestion to use barley straw for field manipulation experiments.
2007-01-01T00:00:00Z