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Search command : Author="Γιαννουλάκη"
And Author="Μαριάννα"
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| Identifier |
000426438 |
| Title |
Ιστολογική ανάλυση ωοθηκών των μεσοπελαγικών ψαριών Maurolicus muelleri Gmelin , 1789), Argyrop elecus hemigymnus Cocco , 1829, Ceratoscopelus maderensis Lowe , 1839), Hygophum benoiti Cocco , 1838) και Myctophum punctatum Rafinesque , 1810 |
| Alternative Title |
Ovarian histological analysis of mesopelagic species Maurolicus muelleri Gmelin , 1789), Argyrop elecus hemigymnus Cocco , 1829, Ceratoscopelus maderensis Lowe , 1839), Hygophum benoiti Cocco , 1838) και Myctophum punctatum Rafinesque , 1810 |
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Author
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Χατζηαποστόλου, Αναστασία Β.
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Thesis advisor
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Κουμουνδούρος, Γεώργιος
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Reviewer
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Σωμαράκης, Στυλιανός
Γιαννουλάκη, Μαριάννα
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| Abstract |
Mesopelagic fish play a key role in deep-sea, pelagic ecosystems. In the Mediterranean Sea, their biology has been poorly studied and knowledge on their reproductive traits is almost absent. In the present study, we collected samples of mesopelagic fish in the Korinthiakos gulf (central Greece) with the aim to study some aspects of their reproductive biology. Two sampling cruises were carried out in November 2018 and April 2019 using the research vessel ‘PHILIA’. Five species were selected for the study, i.e., two species of the family Sternoptychidae (Maurolicus muelleri, Argyropececus hemigymnus) and three species of the family Myctophidae (Ceratoscopelus maderensis, Hygophum benoiti, Myctophum punctatum). During the first cruise (autumn), an effort was made to fix the fish gonads onboard the research vessel. This proved a time consuming and inefficient method due to the small body size of mesopelagic fish. In spring 2019, whole fish rather than gonads were fixed and subsequently analyzed in the laboratory. Ovaries were subjected to histological analysis and the characteristics of different oocyte stages as well as ovarian stages are described. The pattern of oocyte development was asynchronous in all species and many active ovaries contained markers of recent spawning (postovulatory follicles and residual eggs). These findings imply that the examined species are multiple spawners. In autumn, C. maderensis and M. punctatum were reproductively inactive whereas a high percentage of A. hemigymnus had ovaries with massive oocyte atresia. In spring, all species were mature/active expect for a number of fish belonging to the species C. maderensis and H. benoiti with ovaries in early stages of maturation. Sex ratios were male-biased in all species and seasons. In A. hemigymnus, smaller fish were caught in deeper waters whereas in C. maderensis and M. muelleri larger fish were caught in deeper layers. In species/seasons in which more than one sample were collected and a sufficiently wide size range was available, many cases of sexual size dimorphism were revealed with increased portion of females in larger size classes (e.g., M. muelleri and C. maderensis in spring).
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| Language |
Greek |
| Issue date |
2019-11-29 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
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Type of Work--Post-graduate theses
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| Permanent Link |
https://elocus.lib.uoc.gr//dlib/e/7/6/metadata-dlib-1575283158-972512-18538.tkl
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| Views |
325 |
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