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Effect of replacement of fish meal protein with boiled full fat soybean seeds and dried algae on growth performance, nutrient utilization and some blood parameters of Nile tilapia (Oreochromis niloticus)ABSTRACT ixture of boiled full fat soybean seeds and dried algae (Dunaliella spp.) at mixing level of 1:1 was tested to replace fish meal protein at 50% (soybean); 50% mixture ; 75% mixture ; 100% mixture and 100% soybean, on Nile tilapia fry of initial weight 1.2 ± 0.05 g. Results obtained are summarized as follows : 1-Incorporation of the mixture of soybean seeds with dried algae in diets of Nile tilapia fry at 50 and 75% levels released no significant effects on final weight average weight gain, daily gain and survival rates, compared to the control groups, while the same parameters were decreased significantly in the other treatment groups. 2-Replacing fish meal protein with the mixture of soybean seeds plus dried algae (1:1) at 50% level had insignificant effects on feed conversion and protein efficiency ratios compared to the control groups, while the same parameters were negatively affected in the other group.

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ex Bay, west of Alexandria (Egypt) is a large, shallow and turbid coastal plain estuary of socioeconomic importance. Along its salinity gradient (3.30 to 39.64), seven sampling stations were chosen to cover the different habitats. Regionally, four water masses could be defined; the Mediterranean water mass of salinity >38.5, mixed Mediterranean of 30 to 38.5, diluted of 10 to 30 and drain water mass of salinity <10. Phytoplankton species were grouped into three major types: freshwater, coastal low salinity and euryhaline species. A massive spring bloom characterized the annual production cycle and attributed to Skeletonema costatum. Salinity shares in shaping the structure of diatomdominated communities, and its levels between 30 and 35 seem suitable ecological condition for their growth. A boundary of salinity 3.3-5.1 identified as a critical region for certain freshwater species, mostly cyanophytes. Dinoflagellates existed with salinity above 14.8. Chlorophyll a (average 14.39 µg l-1) reached its maximum in mid summer. Chlorophyll a for cells <20 µm contributed over 65% of the biomass. During the phytoplankton blooms, the > 20 µm cells dominated (62.73% of total Chl. a) in May, both fraction size (50.1% and 49.9%, respectively) in July, and the <20 µm cells in September (67.52 %). No significant correlation was found between any chlorophyll a size fraction and abundances of diatoms, euglenophytes, chlorophytes, and cyanophytes, except for the >20 µm size with dinoflagellate abundances. The distribution patterns of biomass showed relatively high Chl. a (average 15.68 µg l-1 , 83.73% <20 µm) at salinity <10; 26.24 µg l-1 , 58.76 % <20 µm at salinity 10-30; and decreased values (6.16 µg l-1 , 58.5 % <20 µm) and 0.99 µg l-1 , 66.06% <20 µm at salinity between 30-38.5, and > 38.5, respectively. Values of the diversity index fluctuated between 0.34 nats (May) and 2.24 nats (September), linked with species diversity and blooming.

Temperature, salinity and light duration dependence on the growth and cellular carbon and nitrogen contents of the epiphytic diatom, Achnanthes longipes Agardh