Tonay A.M.,Istanbul University |
Tonay A.M.,Turkish Marine Research Foundation
Journal of the Marine Biological Association of the United Kingdom | Year: 2016
This is the first study estimating cetacean by-catch in the Turkish western Black Sea turbot fishery. One turbot fishing boat was observed during two fishing seasons, from April through July 2007 and April through mid-September 2008. During this time, 24 harbour porpoises and one bottlenose dolphin were caught in turbot trammel nets. The by-catch rate was found to be 0.18 for harbour porpoise and 0.01 for bottlenose dolphin individuals per kilometre in 2007, and 0.19 for harbour porpoise individuals in 2008. It is estimated that the total numbers of harbour porpoises killed in the Turkish western Black Sea during the legal fishing period (April and July) were 167 ± 153 (CV: 0.92) in 2007 and 329 ± 220 (CV: 0.67) in 2008, and the number killed during both legal and illegal periods of turbot fishing were 2011 ± 742 (CV: 0.37) in 2007 and 2294 ± 806 (CV: 0.35) in 2008. The estimated range of harbour porpoise by-catch in the turbot fishery on the Turkish western Black Sea coast is between these two estimates. The by-caught harbour porpoises were between 1-8 years of age. About half of them were within the age range of 4 (26%) and 5 (21%) years old, and 78% were physically immature individuals. Turbot fishing carried out with bottom nets, especially in May and June, when turbot fishing is banned, is a threat to the sustainability of harbour porpoise stocks. © Marine Biological Association of the United Kingdom 2016.
Belivermis M.,Istanbul University |
Kilic O.,Istanbul University |
Cotuk Y.,Istanbul University |
Topcuoglu S.,Turkish Marine Research Foundation
Environmental Monitoring and Assessment | Year: 2010
The inventory of gamma-emitting radionuclides was determined in soil samples collected at six depth levels, from 15 locations in Istanbul metropolis. The activity concentrations of 232Th, 238U, 40K were measured by means of gamma spectrometry. The average activity concentrations of 232Th, 238U, 40K in the 30-cm depth soil were found as 32.1, 27.4, 393.1 Bq kg-1, respectively. The mean value of the absorbed dose rate (D), annual effective dose equivalent (AEDE) from the outdoor terrestrial gamma radiation, Ra equivalent activity (Raeq), and the external hazard index (H ex) were calculated as 48.7 nGy h-1, 59.7 μSv, 104.1 Bq kg-1, and 0.28, respectively. The effects of organic matter content, textural properties, and pH value of soil samples on the natural radionuclide levels were also investigated. The relations between natural radionuclide level and the physical and chemical properties of studied soil samples were mainly clarified with cluster analysis and Pearson correlation. © 2009 Springer Science+Business Media B.V.
Composition and abundance of octocorals in the Sea of Marmara, where the Mediterranean meets the Black sea [Composición y abundancia de especies de octocorales en el mar de Mármara, donde el Mediterráneo confluye con el mar Negro]
Topcu E.N.,Istanbul University |
Topcu E.N.,Turkish Marine Research Foundation |
Ozturk B.,Istanbul University |
Ozturk B.,Turkish Marine Research Foundation
Scientia Marina | Year: 2015
Species composition and abundance of octocoral assemblages were investigated in the Sea of Marmara, which forms the connection between the Mediterranean and the Black Seas, two semi-enclosed seas with peculiar oceanographic conditions. Fourteen octocoral species were collected in the saline layer of the Marmara Sea (20-40 m), with a mean coral abundance of 5.21±5.11 colonies m-2 (mean ± SD) calculated from a total of 1390 colonies counted in transects. In spite of severe anthropogenic disturbances, dense assemblages of corals/gorgonians were observed during this study. The coralligenous communities—one of the most valuable structures of the Mediterranean Sea—harbored either Eunicella cavolini or Paramuricea macrospina as the dominant gorgonian in the Marmara Sea. Furthermore, the gorgonian assemblages of the Marmara Sea differed from those of the Mediterranean in their high abundance of P. macrospina and Spinimuricea klavereni, two species rarely encountered in the Mediterranean Sea at the studied depth range. The factors behind the observed differences are discussed in regard to the particular oceanographic conditions of the Marmara Sea. Finally, we revised the main threats to corals/gorgonians in the Marmara Sea and provided some insights on management recommendations for coral conservation in this area. © 2015 CSIC.
Bas A.A.,Istanbul University |
Bas A.A.,Turkish Marine Research Foundation |
Amaha Ozturk A.,Istanbul University |
Amaha Ozturk A.,Turkish Marine Research Foundation |
And 2 more authors.
Marine Mammal Science | Year: 2015
Marine traffic is a significant source of disturbance to the bottlenose dolphin population in the Istanbul Strait, Turkey. To determine the importance of this threat, behavioral data together with sighting data of both dolphins and marine vessels were assessed for 2012. The current study suggests that the Istanbul Strait is used mostly as a foraging ground for bottlenose dolphins. Nonetheless, in the same area there is intense marine traffic as well as increase of industrial fishing activities in autumn. The findings of this study indicated that high-speed ferries and high-speed boats were the most significant source of disturbance. Moreover, increased densities of fishing vessels resulted in a drastic decline of dolphin sightings. This study highlights that vessel type, speed, distance, and density have a cumulative negative effect on dolphins. In order to mitigate the impacts of vessels, it is necessary to establish managed areas in the Istanbul Strait. Such proposed areas should limit speed and density of marine traffic and have specific restrictions on vessel routes. We propose three different seasonal managed areas according to their values as critical habitat for bottlenose dolphins in the strait. © 2014 Society for Marine Mammalogy.
Tonay A.M.,Istanbul University |
Tonay A.M.,Turkish Marine Research Foundation |
Danyer E.,Turkish Marine Research Foundation |
Danyer E.,Istanbul University |
And 6 more authors.
Zoology in the Middle East | Year: 2016
The stomach contents of an adult Mediterranean Monk Seal (Monachus monachus) found stranded on the Turkish eastern Mediterranean coast near Antalya in May 2013 were analysed. In total, 69 individual food items were counted and nine taxa were identified to species or family level. Of the identified taxa, Sparidae was the most highly represented family of prey fish, and one cephalopod species, Octopus vulgaris, was found. Ariosoma balearicum and Argyrosomus regius were encountered for the first time in the diet of a Monk Seal in the Mediterranean. Several body parts (three heads, six forelimbs, neck bones and fractured upper forelimb bones) of Green Turtles (Chelonia mydas) were also identified, which is the first record of this species in the Monk Seal’s diet. © 2016 Taylor & Francis