Ayhan Dede

Biodiversity of the northern Aegean Sea and southern part of the Sea of Marmara, Turkey

Two marine areas (the northern Aegean Sea and southern part of the Sea of Marmara, Turkey) which have different trophic and hydrodynamic characteristics were compared regarding diversities of bacteria, phytoplankton, zooplankton, benthos, fish and cetaceans. During the study period (2006–2007), a total of 27 taxa of aerobic heterotrophic mesophilic bacteria including ten bacterial classes were reported for the first time from both seas. A total of 103 taxa from seven algal classes were determined. Copepod species in the northern Aegean Sea and southern part of the Sea of Marmara were recorded as 44 and 27, respectively. A total of 523 underwater photographs were taken at ten stations and the benthic organism diversity were examined for the first time using the photo-quadrat technique. A total of 72 fish belonging to 36 families, were determined. During the study, a total of 1548 nautical miles of survey effort were conducted for cetacean observation. Living individuals of the Stenella coeruleoalba (striped dolphin) were recorded for the first time. This study is intended to be the first detailed description of the diversity of bacteria, phytoplankton, zooplankton, benthos, fish and cetaceans and comparison of two different marine environments in order to put forth the situation of the ecosystem as it is today.

Stomach contents of by-caught striped dolphins ( Stenella coeruleoalba ) in the eastern Mediterranean Sea

Stomach contents of six striped dolphins taken as by-catch in the swordfish fishery in the eastern Mediterranean Sea off the Turkish coast were examined. In total, 29 taxa were identified to species or family and 1777 individual food items (1394 bony fishes, 289 cephalopods, 94 crustaceans) were counted. Diaphus spp. and Ceratoscopelus maderensis were the most remarkable ones, as they accounted for 70.45% of the total number of fishes. Onychoteuthis banksii , on the other hand, was the only cephalopod species found in all stomach content analyses and represented 38.06% of the total number of cephalopods. Bony fish species: Myctophum punctatum, Notoscopelus elongatus, Electrona risso, Sudis hyalina, Moridae sp., Phycidae sp., Sternoptychidae sp. and cephalopods: Pterygioteuthis giardi and Chtenopteryx sicula were reported the first time in the stomach contents of striped dolphin in the Mediterranean Sea.

Acoustic discrimination between harbor porpoises and delphinids by using a simple two-band comparison.

A simple discrimination method between Delphinidae and Phocoenidae based on the comparison of the intensity ratios of two band frequencies (130 and 70 kHz) is proposed. Biosonar signals were recorded at the Istanbul Strait (Bosphorus) in Turkey. Simultaneously, the presence of the species was confirmed by visual observation. Two types of thresholds of two-band intensity ratios, fixed and dynamic threshold, were tested for identification. The correct detection and false alarm rates for porpoises were 0.55 and 0.06 by using the fixed threshold and 0.74 and 0.08 by using the dynamic threshold, respectively. When the dynamic threshold was employed, the appropriate threshold changed depending on the mix ratio of recorded sounds from both Delphinidae and Phocoenidae. Even under biased mix ratios from 26% to 82%, the dynamic threshold worked with >0.80 correct detection and <0.20 false alarm rates, whereas the fixed threshold did not. The proposed method is simple but quantitative, which can be applicable for any broadband recording system, including a single hydrophone with two frequency band detectors.

Stranding of a Green Turtle, Chelonia mydas (Linnaeus, 1758), in the Turkish Black Sea

& SIMMONS 1980, GLUTZ VON BLOTZHEIM & BAUER 1989), and other parts of Transcaucasia. Georgia has an estimated 10-50 breeding pairs, where a small colony was discovered on Javakheti Plateau (GÁLVEZ et. al. 2005). No recent breeding record is known for Armenia (ANANIAN, pers. comm.), although ADAMIAN & KLEM (1999) listed the species as a rare breeding species. I assume that this breeding occurs irregularly in Azerbaijan and in low numbers, and may have been overlooked in the past because of the low density of observers.

The stomach content of a Mediterranean Monk Seal (Monachus monachus): finding of Green Turtle (Chelonia mydas) remains

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.

Is there a distinct harbor porpoise subpopulation in the Marmara Sea

Abstract Genetic population structure of geographically isolated endangered Black Sea harbor porpoise (Phocoena phocoena relicta) is little known in Turkish waters, especially in the Turkish Straits System (TSS- Marmara Sea, Bosphorus and Dardanelles), which connects the Black Sea and the Aegean Sea. Mitochondrial DNA sequences of 70 new individuals sampled in the Turkish Black Sea, TSS and Aegean Sea, revealed five new haplotypes from the Black Sea. The findings support the idea that harbor porpoises from the Black Sea dispersed into the Aegean through the TSS. Considering signatures of population expansion, all subpopulations showed a signature of population expansion. The network data and the Фst calculations indicated that the Marmara Sea subpopulation was significantly differentiated from all of the other subpopulations, and supports the notion of its isolated. The finding of a potential management unit (MU) within an already heavily impacted subpopulation as a whole suggests that the individuals of P. p. relicta inhabiting the Marmara Sea require a very rigorous conservation strategy to ensure the survival of this subpopulation, represented by its unique haplotype.

Differences in Biosonar Sound Characteristics between Cetacean Species in the Istanbul Strait

Previous visual observation suggested there is a possibility of difference in habitat use between harbor porpoise (Phocoena phocoena) and bottlenose dolphin (Tursiops truncatus) in the Istanbul Strait (Bosphorus). However, no direct evidence of difference was recorded, except for the number and area of sightings so far. From 12 April to 1 June 2012, passive acoustic monitoring was conducted with visual observation. The click trains with visual confirmation of species were extracted to compare the difference of inter-click intervals between harbor porpoise and bottlenose dolphins. In the results, the inter-click intervals showed multimodal distribution, which had one peak around 40-50 ms and the other around 100-130 ms in bottlenose dolphins. On the other hand, harbor porpoises showed only one peak around 10-20 ms. These results suggest that two species are using biosonar for different sensing distances even in the same area.

Preliminary study of acoustic identification of odontocetes in the Istanbul Strait, Turkey

In the Istanbul Strait, three odontocetes species are observed; the harbor porpoise which belongs to Phocoenidae and the common dolphin and the bottlenose dolphin which belong to Delphinidae. Previous visual observation conducted in the middle of this Strait showed, Phocoenidae appeared frequently in March and April, whereas Delphinidae appeared throughout the year. However, visual observation can only occur during daytime. On the other hand, acoustic observation can be used all day long, but is not suitable to identify and distinguish different species. In this study, we examined whether a two band acoustic comparison of biosonar sounds can identify family or species of odontocetes. We compared the sound intensity ratio of two frequency bands at 70 kHz and 130 kHz. Narrow-band sounds, with dominant frequency around 130 kHz, correspond to a large ratio of two band intensities, possibly originating from Phocoenidae. In contrast, broad-band sounds provide similar intensities at both frequencies, which possibly originating from Delphinidae. The results show Phocoenidae appeared frequently in March and April, whereas Delphinidae appeared during all months. These findings are consistent with previous visual observations and suggest that two band acoustic monitoring of small odontocetes could be useful for the identification of harbor porpoises from Delphinidae species in a long term study.

Study of cetaceans in Istanbul Strait using passive acoustic method

The Istanbul Strait connects to the Aegean Sea and the Black Sea. Three cetaceans appear in this Strait, harbor porpoise (Phocoena phocoena relicta), common dolphin (Delphinus delphis ponticus), bottlenose dolphin (Tursiops truncatus ponticus). We used stereo passive acoustic monitoring system (A-tag) to monitor the moving pattern of these cetaceans from July 2009 to September 2010. This system enables to record the sound source direction calculated by the sound arrival time difference between two hydrophones. They have different frequency sensitivity, which enable to distinguish Phocoenidae from Delphinidae. Phocoenidae and Delphinidae were detected most frequently in April. They stay near the A-tag in March and April than in August. Acoustic sensing distance, which is proportional to the inter-click-interval of the sonar signals, was short in the same months. This was more clear in Phocoenidae. Dominant behavior pattern of both species was staying rather than moving in all seasons. However, Phocoenidae ...