Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Istanbul University, Deniz Bilimleri Ve İşletmeciliği Enstitüsü, Deniz Bilimleri Ve İşletmeciliği Bölümü, Turkey
Approval Date: 2020
Thesis Language: Turkish
Student: Güzin Gül
Principal Supervisor (For Co-Supervisor Theses): Nazlı Demirel
Abstract:
In this study, the feeding behavior and trophic levels
of Elasmobranchii species obtained on a seasonal basis from the Sea of Marmara
between December 2017 and December 2018, was determined using stable carbon and
nitrogen isotopes with stomach content analysis. While Crustacea is the main
prey item for Mustelus mustelus and Mustelus asterias, Teleostei group was
determined as the main prey item for S.
acanthias, S. canicula, D. pastinaca, T. marmorata, and R. clavata. M. aquila which mainly feeds on Mollusca has the lowest Levins
niche breadth and is determined as a specialist predator species. According to
results of stable isotope analysis and stomach content analysis, S. acanthias
is a generalist predator species, and feeds on Teleostei among the short and
long timescale. The Pianka index was showed that, the high niche overlap
between M. mustelus to M. asterias. Also, according to the results of the
isotopic niche overlap; the hight niche overlap was found between Scyliorhinus canicula and juvenile Raja clavata and Squalus acanthias species. With the exception of Myliobatis aquila and Mustelus asterias, the Levins niche breadth
of the other species were found to be quite similar. Apart from these two
species, other species have been determined as generalist predator species. According
to the stomach content analysis results, the highest trophic level was S. acanthias, while the lowest one was M. asterias. However, the species with
the highest trophic level was determined as Oxynotus
centrina by stable isotope analysis.