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    Development of Calanus euxinus during spring cold homothermy in the Black Sea
    (Inter-Research, 2009) Svetlichny, Leonid S.; Yuneva, Tatyana V.; Hubareva, Elena S.; Schepkina, Alla M.; Besiktepe, Sengul; Kideys, Ahmet E.; Bat, Levent
    In copepodites and adults of Calanus euxinus abundance, body length and weight, chemical composition and respiration rate in relation to age were studied during the cruise of R/V 'Knorr' in April 2003 in the southwestern Black Sea and in laboratory experiments. Data on morphology and physiology of C. euxinus collected during other seasons were also used in comparative analyses. At high concentrations of the diatom Proboscia alata during spring homothermy (6.8 to 8.5 degrees C) C. euxinus did not undertake diel vertical migrations to the oxygen minimum zone (OMZ). The majority of the population was located above the OMZ, feeding on phytoplankton during nighttime and daytime whilst nearly 10%, of copepodite stages IV and V (CIV and CV) and adults remained constantly in the OMZ. Although a diapausing stock of the population began to form in the OMZ, the majority of CV developed without diapause. The development times of copepodite stages at 8 C were determined on the basis of field observations of ontogenetic changes in carbon content and calculated absolute growth rates. Development time from CI to CV amounted to 22 d. In CV the time for lipid deposition from 0.008 +/- 0.007 mm(3) in postmolts up to a maximum volume of 0.165 +/- 0.054 mm(3) in intermolts constituted 26 d. The total generation time from eggs to adults is not less than about 66 d.
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    Population dynamics and ecology of the invasive veined rapa whelk, Rapana venosa in the southern Black Sea
    (Academic Press Ltd- Elsevier Science Ltd, 2022) Mutlu, Erhan; Kideys, Ahmet E.; Sahin, Fatih; Erik, Gokhan; Aksu, Hakan; Erdem, Ercan; Karayucel, Sedat
    Spatial and temporal changes in some ecological characteristics (i.e. biomass, abundance, morphometrics, sex composition, growth parameters and population dynamics) of the invasive veined rapa whelk (Rapana venosa) were studied off Sinop Bay, in the southern Black Sea. The whelk specimens were sampled from three depths (15 m, 25 m and 35 m) at monthly intervals between November 2005 and October 2007. Custom-made pots were deployed for the capture of R. venosa individuals. Monthly distributions in whelk biomass and abundance peaked in summer (June/July) and mid-autumn (October) and displayed no differences between 2006 and 2007. With the exception of gut weight, all morphometric variables produced three peak periods (January, June and September, respectively) over one year. Densities, morphometrics and sex composition were dictated significantly by bottom depth and monthly variation. Two stages were defined in the ovary and testis index maxima denoting longer spawning and recruitments periods starting as early as in March which is a different finding compared to previous studies from the Black Sea. For the estimation of population growth parameters, of the five morphometric variables analysed, siphon width was the best variable to produce clear size cohorts. Whelk growth in terms of shell length and width oscillated seasonally and ceased during February-March. Maximum age of the veined rapa whelk in the southern Black Sea was determined as 3.5 years corresponding to 7 cohorts. Among the environmental parameters, dissolved oxygen, temperature and salinity appeared to affect whelk densities. Results obtained here are important for better management of the whelk fishery in the Black Sea.
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    Öğe
    The qualitative and quantitative distribution in phytoplankton and zooplankton of southern Black Sea of cape Sinop, Turkey in 1999-2000
    (Ieee, 2007) Bat, Levent; Sahin, Fatih; Ustun, Funda; Kideys, Ahmet E.; Satilmis, Hasan H.
    In the present study, seasonality and composition of phytoplankton and zooplankton were comparatively studied at two stations (one inshore and one offshore) off Sinop, in southern Black Sea during January-May 1999 and March -October 2000. A total 76 genera including 149 species and varieties were identified, of which 46% were dinoflagellates and 34% were diatoms in phytoplankton. Abundance of the genera Emiliana (in January-May 1999), Pseudosolenia and Ceratium (in March-October 2000) were higher than that of the other genera in almost every sampling period. Increased dinoflagellate to diatom ratio reflects more fertile conditions in the southern Black Sea. Abundance and biomass of the total fodder zooplankton the highest values were recorded in February 1999; March 2000. Cladocera and Appendicularia abundance and biomass values were higher in 1999 than 2000. Noctiluca scintillans was the most abundant of zooplankton group with a share of 43% (maximum: 416,925 ind.m(-2) in May) in 1999. The second abundant group was Copepoda with 42% (172,981 ind.m(-2) in February).Copepods with 78% of abundance and 73% of biomass (maximum: 372,330 ind.m(-2) and 15,253 mg.m(-2) in March) were the dominant group in 2000. They were followed by the dinoflagellate Noctiluca scintillans with 4.8% (maximum: 24,500 ind.m(-2) in June).