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Synopsis of the Biological Data on the Leatherback Sea Turtle (Dermochelys Coriacea) (Paperback)
Loot Price: R571
Discovery Miles 5 710
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Synopsis of the Biological Data on the Leatherback Sea Turtle (Dermochelys Coriacea) (Paperback)
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Loot Price R571
Discovery Miles 5 710
Expected to ship within 10 - 15 working days
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The leatherback sea turtle (Dermochelys coriacea; leatherback) is
the largest and most migratory of the world's turtles, with the
most extensive geographic range of any living reptile. This highly
specialized turtle is the only living member of the family
Dermochelyidae. It exhibits reduced external keratinous structures:
scales are temporary, disappearing within the first few months and
leaving the entire body covered by smooth black skin. Dorsal keels
streamline a tapered form. The species has a shallow genealogy and
strong population structure worldwide, supporting a natal homing
hypothesis. Gravid females arrive seasonally at preferred nesting
grounds in tropical and subtropical latitudes, with the largest
colonies concentrated in the southern Caribbean region and central
West Africa. Non-breeding adults and sub-adults journey into
temperate and subarctic zones seeking oceanic jellyfish and other
soft-bodied invertebrates. Long-distance movements are not random
in timing or location, with turtles potentially possessing an
innate awareness of profitable foraging opportunities. The basis
for high seas orientation and navigation is poorly understood.
Studies of metabolic rate demonstrate marked differences between
leatherbacks and other sea turtles: the "marathon" strategy of
leatherbacks is characterized by relatively lower sustained active
metabolic rates. Metabolic rates during terrestrial activities are
well-studied compared with metabolic rates associated with activity
at sea. The species faces two major thermoregulatory challenges:
maintaining a high core temperature in cold waters of high
latitudes and/or great depths, and avoiding overheating in some
waters and latitudes, especially while on land during nesting. The
primary means of physiological osmoregulation are the lachrymal
glands, which eliminate excess salt from the body. The leatherback
was re-classified in 2000 by the International Union for the
Conservation of Nature (IUCN) Red List of Threatened Species as
Critically Endangered. It remains vulnerable to a wide range of
threats, including bycatch, ingestion of and entanglement in marine
debris, take of turtles and eggs, and loss of nesting habitat to
coastal processes and beachfront development. There is no evidence
of significant current declines at the largest of the Western
Atlantic nesting grounds, but Eastern Atlantic populations face
serious threats and Pacific populations have been decimated.
Incidental mortality in fisheries, implicated in the collapse of
the Eastern Pacific population, is a largely unaddressed problem
worldwide. Although sea turtles were among the first marine species
to benefit from legal protection and concerted conservation effort
around the world, management of contemporary threats often falls
short of what is necessary to prevent further population declines
and ensure the species' survival throughout its range. Successes
include regional agreements that emphasize unified management
approaches, national legislation that protects large juveniles and
breeding-age adults, and community-based conservation efforts that
offer viable alternatives to unsustainable patterns of
exploitation. Future priorities should include the identification
of critical habitat and priority conservation areas, including
corridors that span multiple national jurisdictions and the high
seas, the creation of marine management regimes at ecologically
relevant scales and the forging of new governance patterns,
reducing or eliminating causal factors in population declines
(e.g., over-exploitation, bycatch), and improving management
capacity at all levels.
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