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Reproductive biology of Penaeus kerathurus (Forskål, 1775) (Decapoda: Penaeidae) in the Sea of Marmara, Turkey

Ihsanoglu Mukadder Arslan, Daban Ismail Burak, Işmen Ali, Cabbar Koray, Yığin Cahide Çiğdem

Oceanological and Hydrobiological Studies

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2021

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Vol. 50, No. 1

33--37

EN

One of the economically important species is Penaeus kerathurus (Forskål, 1755), which is widespread in the Mediterranean ecosystem. This paper presents results of research on reproductive biology of Penaeus kerathurus in the Sea of Marmara. A total of 1404 specimens were dissected to determine the maturity stages, reproduction time, and length at first reproduction. The female-to-male ratio was 1:0.9. A high percentage of mature females was determined in April, May and July. Moreover, the value of the gonadosomatic index (GSI) decreased after July. The spawning period was observed between April and July, and its intensity increased in July. The carapace length at first sexual maturity was determined to be 39 mm.

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Growth pattern, mortality and reproductive biology of common sole, Solea solea (Linneaus, 1758), in the Sea of Marmara, Turkey

Kahraman Abdullah Ekrem, Yıldız Taner, Uzer Uğur, Çanak Özgür

Oceanological and Hydrobiological Studies

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2021

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Vol. 50, No. 4

398--410

EN

The study deals with the growth pattern, mortality, and reproduction of common sole, Solea solea (Linneaus, 1758), from the Sea of Marmara (Turkey). A total of 580 fish specimens were sampled monthly from October 2017 to September 2018. The total length of all sampled individuals ranged from 11.1 to 29.5 cm, corresponding to ages from 1 to 3 years. The length–weight relationship was expressed as W = 0.022 TL2.6838, where the slope indicated negative allometric growth. Growth parameters were L∞ = 33.7 cm, k = 0.48, and t0 = −0.18 for all samples. A seasonally oscillating growth model, indicating the amplitude of oscillations, revealed an important seasonal growth pattern. Total, natural, and fishing mortality rates were calculated as 1.42, 0.47, and 1.01, respectively. The exploitation ratio (E = 0.68) indicates that the fishing pressure on the common sole in the Sea of Marmara was high. The sex ratio (♀/♂) was 1.18. The gonadosomatic index (GSI) for females showed that two main spawning seasons were observed: one in spring (May) and one in autumn (September–October). Sizes at the onset of sexual maturity were estimated for both females and males at 21.6 and 18.6 cm, respectively.

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Mollusk fauna associated with Cystoseira barbata (Stockhouse) C. Agardh, 1820 in the Sea of Marmara (Turkey)

Bitlis Banu

Oceanological and Hydrobiological Studies

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2019

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Vol. 48, No. 2

174--183

EN

Mollusk species associated with Cystoseira barbata were examined in the Sea of Marmara in 2012 at 14 sampling sites with a depth ranging from 0.2 to 0.5 m. A total of 18 468 specimens belonging to three classes (Polyplacophora, Gastropoda and Bivalvia) and 30 species were identified. Alvania mamillata Risso, 1826 is a new record for the marine mollusk fauna of the Sea of Marmara. The number of species at the sampling sites varied from 2 to 11 (400 cm–2), the density ranged between 758 and 63 083 ind. m–2, and wet weight between 0.4 and 34.3 g m–2. Gastropoda were the richest class, represented by 22 species and 7611 individuals. The families Rissoidae, Mytilidae and Pyramidellidae were represented by the largest number of species. The most dominant mollusk species in C. barbata facies were Mytilaster minimus (Poli, 1795) (37.77%), Rissoa splendida Eichwald, 1830 (27.20%), Mytilaster lineatus (Gmelin, 1791) (18.69%) and Bittium reticulatum (da Costa, 1778) (6.89%). However, the mollusks R. splendida (86%), M. lineatus (71%), M. minimus (69%) and Steromphala adansonii (Payraudeau, 1826) (67%) were characterized by the highest values of the frequency index. Canonical correspondence analysis showed that the main factors affecting the assemblages of mollusks were the content of total nitrogen, the maximum thallus height, algal wet weight and temperature.

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Distribution of antibiotic resistance and the presence of vancomycin-resistance genes (vanA and vanB) in Enterobacteriaceae isolated from the Sea of Marmara, the Canakkale Strait and the Istanbul Strait, Turkey

Çardak M., Altuğ G., Ayad M., Erol Ő.

Oceanological and Hydrobiological Studies

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2016

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Vol. 45, No. 2

182--190

EN

We investigated the frequency of antibiotic resistance of Enterobacteriaceae and the presence of vancomycinresistance genes in samples taken from the Sea of Marmara, and the Istanbul and Canakkale Straits, Turkey. Different colony-forming bacteria were isolated and identiffed with the VITEK 2 Compact 30 system. The antibiotic resistance of the isolates was determined by the disc diffusion method. The isolates were tested against amoxicillin, ampicillin, aztreonam, ce azidime, cefotaxime, cefuroxime, o oxacin, vancomycin, tetracycline, kanamycin and gentamycin. e presence of vancomycin-resistance genes (vanA and vanB) was also investigated. the level of Enterobacteriaceae species was higher in the Sea of Marmara than in the Istanbul Strait and the Canakkale Strait. Isolates showing resistance to the greatest number of antibiotics were identiffed from E. coli isolates. the resistance of the selected bacterial isolates were as follows: kanamycin (82%), vancomycin (78%) and ampicillin (60%). Some intermediately vancomycin-resistant Enterobacteriaceae isolates had the vanA gene. This study provides evidence of widespread bacterial resistance to clinically relevant antibiotics in marine environments. It also contributes to the knowledge on the distribution of antibiotic resistance among Enterobacteriaceae and indicates the importance of control measures in domestic water treatment.

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Red tides of the dinoflagellate Noctiluca scintillans associated with eutrophication in the Sea of Marmara (the Dardanelles, Turkey)

Turkoglu M.

Oceanologia

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2013

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No. 55 (3)

709--732

EN

This investigation focused on weekly variations in cell density and volume of the dinoflagellate Noctiluca scintillans between March 2001 and January 2004 in the Dardanelles. March-June and October-December periods were excessive bloom periods. During the bloom periods the density of N. scintillans reached 2.20 × 105 cells L-1 with a volume of 1.32 × 1012 µm3 L-1. In addition to the high surface density, there was an increase in subsurface waters during the blooms. The bloom of N. scintillans, like that of diatom and other dinoflagellate blooms, was associated not only with eutrophication, but also with stable temperatures and salinities.