Department of Biology
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Item Diatoms diversity and dynamics in a southern Mediterranean lagoon (Mellah, Algeria)(2019-06-18) Draredja, M. A; Barour, C; Frihi, H; Boualleg, C; Laabir, M.The composition and distribution of diatoms were studied using a biweekly sampling performed in three representative stations in the Mellah Lagoon (South Western Mediterranean, Algeria), during 2016. In total, 160 diatoms species - belonging to centric species (52 species) and pennate species (108 species) - were inventoried. The relative abundance of the pennate forms (67.50%) is clearly higher compared to the centric forms (32.50%). The blooms of diatoms are represented by 3 species: Chaetoceros constrictus Gran, 1897 with up to 15000 cells.L-1 (end of May), Chaetoceros sp. with up to 178320 cells.L-1 (early October), and Nitzschia longissima (Brébisson) Ralfs, 1861 with up to 200640 cells.L-1 (early September). Proliferations of three potentially toxic species: Pseudo-nitzschia group delicatissima (Cleve) Heiden, 1928 (2500 cells.L-1), Pseudo-nitzschia group seriata (Cleve) H. Peragallo, 1899 (700 cells.L-1) and Thalassionema nitzschoides (Grunow) Mereschkowsky, 1902 (210 cells.L-1), requires regular monitoring of this ecosystem where the exploitation of the shells is practiced. The diatom populations seem to be structured showing diversity (H’) and equitability (J’) indices reaching 4.56 bits.cell and 0.98 respectively, with the exception of springsummer and summer-autumn transition periodsItem Study of some biological parameters of Cyprinus carpio from Foum El-khanga Dam, Souk-Ahras, Algeria(2017-07-04) Sahtout, F; Boualleg, C; Khelifi, N; Kaouachi,N; Boufekane,Bi; Brahmia, S; Mouaissia, W; Bensouilah, M.Cyprinus carpio (Linnaeus, 1758) is a wide-world freshwater fish, and is among the top important aquaculture species of the world. Since there are no available data on the growth pattern of this species in Foum El-Khanga Dam Souk-Ahras, Algeria, this study was carried out to determine the condition factor, length-weight relationship, age and growth. A total of 347 specimens of C. carpio were collected from Foum El-Khanga Dam (Souk-Ahras, Algeria) by monthly sampling from March 2015 to February 2016. Significant differences were noticed between the mean length of females (33.44±0.38) and males (30.88±0.31). The age of the examined fishes ranged from 2- to 7-year-old, meanwhile the dominant age group was 3-year-old. The size frequency distributions and the growth parameters were analyzed according to ELEFAN method, using FISAT II software. The Von Bertalanffy growth parameters were found as asymptotic length, L∞ = 58.28 cm, asymptotic weight, W∞ = 2019.76 g, growth coefficient, K = 0.30 year-1, to = -0.47 year for both combined sexes, asymptotic length, L∞ = 48.83 cm, asymptotic weight, W∞ = 1148.56 g, growth coefficient, K = 0.49 year-1, to = -0.29 year for males, and asymptotic length, L∞ = 58.28 cm, asymptotic weight, W∞ = 2049.84 g, growth coefficient, K = 0.41 year-1, to = -0.34 year for females. Also, the results indicated that L∞ and W∞ values of females were higher than those of males. The growth performance index was estimated as Φ́́́́ = 3.008 for combined sexes, Φ́́́́ = 3.068 for males, and Φ́́́́ = 3.144 for females. The condition factor indicates good conditions of the C. carpio fish. Moreover, the length-weight relationship was estimated as W = 0.0181 × Lt2.859 (the coefficient of determination, R2 = 0.963) for both sexes. Statistical analyses showed that the b coefficient is significantly lower than 3 (negative allometry) for separated and combined sexes (t-test, p < 0.05), as well as the relationship between the length and the weight exhibited a high correlation.