Blue Resources for Aquaculture, Environment and Society DevelopmentEgyptian Journal for Aquaculture2090-78778220180501Isolation, identification and antibiotic resistance of Vibrio alginolyticus isolated from Mugil seheli - Suez Governorate, Egypt1163622910.21608/eja.2018.36229ENJournal Article20190621<em>Vibrio alginolyticus</em> was isolated from <em>Mugile seheli</em> collected from private farm in Suez Governorate. Clinically examined fish exhibited dark colouration, erosions and haemorrhages of body parts. The target organs for isolation were kidney (52%), liver (48%) and spleen (15%). Isolates were biochemically and molecularly identified using species specific primers targeting collagenase gene and tdh gene. Investigation revealed that, 17 isolates were identified as <em>V.alginolyticus</em> which detected at 737 bp fragment, and only one positive amplicon for tdh gene that was detected at 373bp fragment. The sequence results of <em>V.alginolyticus</em> isolate showed 99% identity with the reference strain <em>V.alginolyticus</em> reported on Gene Bank with accession number (<strong>MG271844</strong>). The antibiotic sensitivity test of virulent strain of <em>V. alginolyticus</em> showed that, the bacterium was highly resistant to lincomycin 2µg, streptomycin 10µg, ampicillin10µg, trimethoprim 5µg and ampicillin/ sulbactam combination, and intermediate sensitivity to Naldixic acid 30µg, polymyxin B 300u, erythromycin 15µg, Tobramycin 10µg, ciprofloxacin 5µg, kanamycin 30µg and chloramphenicol 30µg. It was also found that, the bacterium was highly sensitive to imipenem 10µg, Oxolonic acid 2µg, oxytetracyclin 30µg, gentamycin 10µg, gatifloxacin 5µg and piperacillin/ tazobactam combination.Blue Resources for Aquaculture, Environment and Society DevelopmentEgyptian Journal for Aquaculture2090-78778220180501Genetic Study of Some Egyptian Crabs Species in the Fisheries Grounds17283622710.21608/eja.2018.36227ENJournal Article20190621The Random Amplification of Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) analyses were applied for studying 7 Egyptian populations of crab species. The genetic distance (GD) among close collection sites was small among location 1, 2, 3, 4, 6 and 7, but those between location 5 and 8 were much larger (0.666 and 0.833, respectively). These values between the populations of<strong> Lake Timsah</strong>, <strong>Bitter Lakes</strong>, <strong>Suez, Attaka, Al-Tur,</strong> <strong>Port said</strong>, <strong>Domietta</strong>, <strong>Rashid</strong> and <strong>Abo-Qir </strong>showed that<strong>, AL-Tur</strong> population was distantly related from both <strong>Lake Timsah</strong>, <strong>Bitter Lakes</strong>, <strong>Suez, Attaka, Port-Said</strong>, <strong>Domietta</strong>, <strong>Rashid</strong> and <strong>Abo-Qir </strong>populations.
Average of similarity index (SI) values among the studied populations based on RAPD analysis were 0.646, 0.229, 0.32, 0.328, 0.222 and 0.338 in respective arrangement between each pair of the populations; S<em>.T.z</em> with E<em>.T.z</em>, S<em>.T.z</em> with S<em>.O.au</em>, S<em>.T.z</em> with E<em>.O.au</em>, E<em>.T.z</em> with S<em>.O.au, </em>E.<em>T</em>.<em>z</em> with E.<em>O</em>.<em>au</em> and S.<em>O</em>.<em>au</em> with E.<em>O</em>.<em>au</em>.<strong> Lake Timsah</strong>, <strong>Bitter Lakes</strong>, <strong>Suez, Attaka, Al-Tur,</strong> <strong>Port-Said</strong>, <strong>Domietta</strong>, <strong>Rashid</strong> and <strong>Abo-Qir</strong>.
It was stated that the lowest SI value (0.2) was calculated between <strong>Rashid</strong> and <strong>Lake Timsah</strong> populations and the highest similarity value (1.00) was calculated between <strong>Domietta</strong>, <strong>Port-Said and Bitter Lakes</strong>. However, lower SI values were obtained between <strong>Al-Tur</strong> and the other studied crab populations. It was emphasized that this population appeared with a unique molecular character. Where, there is low migration rate between <strong>Al-Tur</strong> population and the other studied crab populations. Moreover, the genetic relationships analysis clustered all populations together except <strong>Al-Tur</strong> population which was distant from the other populations.Blue Resources for Aquaculture, Environment and Society DevelopmentEgyptian Journal for Aquaculture2090-78778220180501Water Quality and Bacterial Load of Water and Tilapia Organs from Edku Lake29563623010.21608/eja.2018.36230ENJournal Article20190621Lakes are very important part of the aquatic ecosystem in Egypt. Edku Lake is one of the northern coastal lakes in Egypt which is the third largest wetland area in it. Edku Lake receives huge amounts of drainage water from four main drains, namely, Edku, El Bousily, El Khairy and Bersik which effect on its ecosystem. This study was carried out four seasons of 2017 where twenty-four surface water samples and fish samples were collected from sex stations in the lake. The results of water quality indicated that temperature, pH, dissolved oxygen and phosphorus were indicated in suitable range at all study stations. While, ammonia and nitrite were indicated in stress range for fish, but nitrate results were lied as desirable results. Results of lake water bacterial load (TC& CF) are exceed the permissible values mentioned by EC, 1998 and Ministry of Health, Egypt, 1996. Also, the bacterial loads (Total bacterial count, TC& Coliform group, CF) found in this study for Nile tilapia organs (skin & muscle) was beyond the standard value (FAO, 1979 and ICMSF, 1982), which indicate their unacceptability as food from public health point of view which may be cause human health risk due to consumption of tilapia collected.Blue Resources for Aquaculture, Environment and Society DevelopmentEgyptian Journal for Aquaculture2090-78778220180501The use of coated and uncoated oral inactivated Aeromonas hydrophila vaccine on the immune response of Nile Tilapia (Oreochromis niloticus)57693623210.21608/eja.2018.36232ENJournal Article20190621Coated and uncoated formalized killed vaccine of <em>Aeromonas hydrophila</em> (bacterin) were used in the immunization of Nile tilapia against Motile Aeromonad septicemia. Vaccination was conducted via oral route.Fish were fed on oral initial dose followed by 2 booster doses every 2 weeks at 2<sup>nd</sup> and 4<sup>th</sup>week . Blood samples were taken at zero day to get the pre-immune serum and every two weeks 2, 4 and 6 weeks post immunization from the initial dose and at 8<sup>th</sup> week post challenge for antibody titration in the fish sera. The humoral antibody response of vaccinated Nile tilapia <em>(Oreochromis niloticus) </em>was determined by direct agglutination titer test. Moreover, lysozyme activity was assayed for non-specific immunity. Experimental challenge infection with the virulent strain of <em>Aeromonas hydrophila </em>was done and daily mortality was recorded for 14 days to estimate the cumulative mortality and relative percent survival (RPS) of the fish in both control and vaccinated groups. The results of the group that fed on coated formalized killed vaccine gave the highest Antibody titers, lysozyme values, and RPS percent.