Studies on the embryology, ecology and evolution of sea turtles in the Eastern Mediterranean

Kaska, Yakup (1998) Studies on the embryology, ecology and evolution of sea turtles in the Eastern Mediterranean. PhD thesis, University of Glasgow.

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Printed Thesis Information: https://eleanor.lib.gla.ac.uk/record=b1710599

Abstract

1-) The temperature of sea turtle nests in the Eastern Mediterranean was between 24 and
35 "C and rose by up to 10 "C during incubation.
2-) The mean incubation temperature can be used for estimating the incubation period
but provides a poor prediction of sex ratio.
3-) The mean temperature during the middle third of the incubation period was closely
correlated with the percent sex ratio.
4-) There was a female dominated sex ratio among the 22 nests and only one loggerhead
turtle nest showed less than a 50 % female sex ratio.
5-) There was a consistent temperature difference within the nest with top eggs warmer,
bottom eggs cooler and middle ones intermediate. Therefore the majority of hatchlings
11'0111 [he top level in nests were females and those from the bottom level were
predominantly males.
6-) Temperature differences within the nest also influenced the rate of development; the
greater the difference in temperature between top and bottom the longer the time
required to complete hatching of all embryos of the nest. The hatching intervals of green
turtle nests were shorter than those at loggerhead turtle nests. Temperature variation
between top and bottom of nests was low within green turtle nests. In general, a 1 "C
temperature difference within the clutch caused a 4 day range in both hatching and
emergence of hatchlings.
7-) Since the temperature within the nest and between the nests was so variable, sand air
or sea water temperatures gave a poor prediction of the temperature of a nest and
therefore the sex ratio.
8-) Although the predation pattern of sea turtle nests varied in relation to nest age, this
predation can be reduced by screening the nest with mesh grids.9-) lnundation was one of the main abiotic factors lowering the hatching success on the
beaches. Hatching success can be increased by relocating the nests to a safer area on the
night of laying
10-) The mean grain sizes of sand ranged from 0.49 to 2.20 phi(<!»on 10 beaches but
hatching success was not related to mean grain size of sand on the beaches.
11-) Simple embryonic staging of Mediterranean sea turtles was developed after
measuring Cl set of selected morphological characteristics. The frequency of gross
abnormalities among the samples was also calculated. Most common abnormalities were
supernumerary and subnumerary scutes, albinos, head and jaw abnormalities and
twinning
l2-) The heavy metal concentrations III the tissues (yolk, liver and eggshell) of
loggerhead turtle eggs and hatchlings were analysed. The concentrations of mercury,
cadmium, lead, iron and copper were highest in the liver, while zinc concentrations were
highest in the yolk. The concentrations of metals were similar on different beaches,
except for lead concentrations in the eggshells, which varied between sites.
13 -) The genetic structure of loggerhead turtle samples from Cyprus exhibited haplotype
B and green turtle samples haplotype XIII. No additional haplotypes were found. The
presence of only single haplotypes suggests little variation in genetics within the
Mediterranean and that these population were recently established by a small number of
immigrants from the Atlantic.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QL Zoology
Colleges/Schools: College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Supervisor's Name: Furness, Dr. R.W.
Date of Award: 1998
Depositing User: Ms Dawn Pike
Unique ID: glathesis:1998-5321
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 26 Jun 2014 10:37
Last Modified: 10 Oct 2014 09:53
URI: http://theses.gla.ac.uk/id/eprint/5321

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