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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
    Seasonal variation and taxonomic composition of mesozooplankton in the southern Black Sea (off Sinop) between 2005 and 2009
    (Tubitak Scientific & Technological Research Council Turkey, 2018) Ustun, Funda; Bat, Levent; Mutlu, Erhan
    The monthly and long-term fluctuations of mesozooplankton abundance, biomass, and taxonomic composition in the Sinop inner harbor (southern Black Sea) between 2005 and 2009 are presented in the present study. In total, 31 mesozooplankton taxa were identified during the study. The recorded average mesozooplankton abundance and biomass were 34,323 +/- 7580 ind. m(-2) and 1208 +/- 460 mg m(-2) in 2005, 95,063 +/- 31,434 ind m(-2) and 1787 +/- 604 mg m(-2) in 2006, 97,626 +/- 12,141 ind m(-2 )and 1034 +/- 20 mg m(-2) in 2007, 91,918 +/- 10,476 ind m(-2) and 775 +/- 121 mg m(-2) in 2008, and 146,918 +/- 19,671 ind m(-2) and 1955 +/- 437 mg m(-2) in 2009, respectively. The highest abundance values of mesozooplankton were encountered in March 2006 (299,110 ind m(-2)) with the contribution of Copepoda nauplii (167,000 ind m(-2)) particularly. Meanwhile, the mesozooplankton biomass was highest in October 2005 (5852 mg m(-2)), due to Parasagitta setosa (3695 mg m(-2)). The heterotrophic dinoflagellate Noctiluca scintillans was a major component of plankton samples in the Sinop region, presenting its highest values in April 2005. Mesozooplankton abundance values showed significant differences (except 2007-2009 and 2008-2009) during the 5-year sampling period. Since the middle of 2006, an increase in abundance, biomass, and biodiversity of mesozooplankton has been detected. Many mesozooplanktonic species/groups showed seasonality in the study (especially Cladocera species). This seasonality was determined to be based on temperature changes.
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    Öğe
    Spatial geochemical structure of soft sediment on shallow littoral of the Gulf of Antalya, the eastern Mediterranean Sea
    (Pergamon-Elsevier Science Ltd, 2023) Yalcin, Mustafa Gurhan; Mutlu, Erhan; Olguner, Cansu; Atakoglu, Ozge Ozer; Bat, Levent; Ozkan, Ebru Yesim
    The concentrations of heavy metals in soft sediments of the Manavgat and Lara regions in Antalya, Turkiye were investigated to assess contamination levels and their potential sources, followed by multivariate statistical analysis and generation of spatial distribution maps. Results showed low contamination levels for As, Zn, and Cu, moderate contamination for Pb, Ni, and Mn, and very high accumulation for Co and Cr. Geoaccumulation index (Igeo) and contamination factor (CF) analyses revealed moderate enrichment for Mn and low enrichment for As, indicating no human-induced contamination in Cu, Pb, Zn, Mn, and As, while Ni, Co, and Cr originated mainly from agriculture. The maximum modified degree of contamination (mCd) value was at an extreme high level, with an average mCd of 4.12 indicating high contamination. Maximum pollution load index (PLI) value was 3.13, indicating high-grade pollution and an average value of 1.7 indicating moderate pollution.