Turkish Marine Research Foundation

İstanbul, Turkey

Turkish Marine Research Foundation

İstanbul, Turkey
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Bas A.A.,Istanbul University | Bas A.A.,Turkish Marine Research Foundation | Bas A.A.,Marine Mammals Research Association | Christiansen F.,Murdoch University | And 5 more authors.
PLoS ONE | Year: 2017

Marine traffic is threatening cetaceans on a local and global scale. The Istanbul Strait is one of the busiest waterways, with up to 2,500 vessels present daily. This is the first study to assess the magnitude of short- and long-term behavioural changes of the endangered Black Sea harbour porpoises (Phocoena phocoena relicta) in the presence of marine vessels within the Istanbul Strait. Markov chains were used to investigate the effect of vessel presence on the transition probability between behavioural states (diving, surface-feeding and travelling), and to quantify the effect on the behavioural budget and bout length (duration of time spent in a given state) of porpoises. Further, the changes on swimming directions of porpoises in relation to vessel speed and distance was investigated using generalized linear models. In vessel presence, porpoises were less likely to remain in a given behavioural state and instead more likely to switch to another state. Because of this, the bout length of all three behavioural states decreased significantly in the presence of vessels. The vessel effect was sufficiently large to alter the behavioural budget, with surface-feeding decreasing significantly in the presence of vessels. However, when taking into account the proportion of time that porpoises were exposed to vessels (i.e. 50%), the measured effect size was not large enough to significantly alter the animals' cumulative (diurnal) behavioural budget. Additionally, vessel speed and distance had a significant effect on the probability of porpoises showing a response in their swimming directions. The southern and middle sections of the Istanbul Strait, which have the heaviest marine traffic pressure, had the lowest porpoise sightings throughout the year. Conversely, northern sections that were exposed to a lesser degree of marine traffic hold the highest porpoise sightings. The effect shown in this study in combination with increasing human impacts within the northern sections should be considered carefully and species-specific conservation actions, including establishment of protected areas, should be put in place to prevent the long-term consequences of marine traffic on the Black Sea harbour porpoise population. © 2017 Akkaya Bas et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Bas A.A.,Istanbul University | Bas A.A.,Turkish Marine Research Foundation | Bas A.A.,Marine Mammals Research Association | Christiansen F.,Murdoch University | And 7 more authors.
Endangered Species Research | Year: 2017

The non-lethal impacts of marine vessels on cetaceans are now a globally recognised threat. This study is the first to investigate the effect of marine traffic on the behaviour of bottlenose dolphins Tursiops truncatus in the Istanbul Strait, Turkey. The Istanbul Strait (also known as the Bosphorus) is one of the busiest international waterways in the world and is exposed to dense marine traffic. The effect of marine traffic, location and season on the behavioural transitions was investigated through general log-linear analysis. Further, the changes on the behavioural budget and bout duration were assessed using Markov chains. Results showed that marine vessels were the main driving force for the behavioural transitions. These changes in transitions between behaviours led to significant changes in behavioural budget and bout durations (average time in each behavioural state). Surface-feeding, resting and socialising behaviour significantly de creased in the control budget, while diving showed an increase in the presence of vessels. Moreover, dolphins spent less time surface-feeding, resting, socialising and diving once disrupted. Furthermore, the current level of vessel-dolphin interaction (51%) in the Istanbul Strait was sufficiently high to alter the dolphins' cumulative behavioural budget significantly. Finally, speed and distance of vessels played a considerable role in the directional responses of dolphins. These results raise concerns on the potential biological consequences of the observed behavioural changes, considering that the population is already classified 'at risk' and is still lacking species-specific conservation plans. The results of the study must be considered immediately to create protected zones in order to mitigate the vessel-dolphin interactions. © The authors 2017.

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.

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.

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

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.

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.

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