Download 4. Movement Patterns - Sustainable Initiatives

Preliminary Feasibility Study for using DNA Mapping for determining
Migration Patterns of Green Turtles Nesting in the
Sandspit/Hawksbay Beaches
1. Objective of the Study
The objective of the study is to determine the preliminary technical and
institutional feasibility for using DNA mapping for determining migration
patterns of green turtles nesting in the Sandspit/Hawksbay beaches and evolve
baseline strategies for initiating this process.
2. Study Methodology
The study would assess global trends and practices in using DNA
mapping/analysis for promoting turtle conservation. Some case studies would be
identified that explore the various possibilities offered by this technique for
investigating turtle behavior, in particular, the migration patterns.
A review would then be made of the techniques and practices presently being
applied to investigate green turtle migration trends in Pakistan by the Sindh
Wildlife Department and the World Wildlife Fund.
Based on the evaluation of the work presently being carried out and the options
available for enhancing the research, a baseline strategic assessment would be
made on the feasibility of using the technology of DNA mapping to increase our
knowledge on the migration patterns and behavior of green turtles nesting in the
Sandspit/Hawksbay beaches.
3. Sea Turtles-Distribution and Habitat
Sea turtles are found in the waters off
every continent except Antarctica.
Now scientists recognize eight species
of the sea turtles. These include
Greens, Blacks (probably a subspecies of
the Greens) Hawksbill, Kemp’s Ridley,
Olive Ridley, Loggerhead, Flatback
and Leatherback. The Loggerhead sea
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
Green Turtles Nesting in the Sandspit/Hawksbay Beaches
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turtle is listed as threatened, the Flatback is listed as vulnerable and all other
species are listed as endangered. The Olive Ridley continues to ply the high seas in
the tropics of the Pacific, Atlantic, and Indian Oceans. The Kemp’s Ridley takes
to the shallows of the Gulf of Mexico and North American Atlantic. The
Leatherback adapts to both Arctic and tropical waters while making the longest
seasonal migration of any sea turtle. The Loggerhead populates the world’s
subtropics, and coral reefs attract the Hawksbill. The Green Turtle grazes the sea
grasses in the tropics. The East Pacific Black turtle, perhaps a subspecies of the
green, ranges from Baja California to the Galapagos. Only the Australian Flatback
is not found in the Western Hemisphere.
3.1. Green Turtles – Distribution and Habitat
Green Sea Turtles are distributed throughout the world’s oceans between
35 degrees north-south latitude. They are found in the eastern and western
hemispheres and nest on beaches throughout the Atlantic, Pacific and
Indian Oceans. Green Sea Turtles enjoy warm, tropical and sub-tropical,
shallow waters near continental coasts and around islands where the sea is
plentiful.
Green Turtles occupy three habitat types:
 High energy oceanic beaches
 Convergence zones in the pelagic habitat
 Benthic feeding grounds in relatively shallow, protected waters
Females deposit egg clutches on high energy beaches, usually on islands,
where a deep nest cavity can be dug above the high water line. Hatchlings
leave the beach and apparently move into convergence zones in the open
ocean where they spend an undetermined length of time. When the turtles
reach a carapace length of approximately 20 to 25 cm, they leave the
pelagic habitat and enter benthic feeding grounds. Most commonly, these
foraging habitats are pastures of sea grasses and/or algae, but small green
turtles can also be found over coral reefs, warm reefs and rocky bottoms.
Coral reefs or rocky outcrops near feeding pastures are often used as
resting areas, both at night and during the day.
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
Green Turtles Nesting in the Sandspit/Hawksbay Beaches
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4. Movement Patterns
The navigation feats of the green turtles are well known but poorly understood.
We know that hatchlings and adult females on the nesting beaches orient towards
the ocean using light cues. For a long time, no one knew what cues were
employed in pelagic movements, in movements among foraging grounds, or in
migrations between foraging grounds and nesting beaches. Recently conducted
research however suggests that the earth’s magnetic field plays a role in these
feats.
Because green turtles feed in marine pastures in quiet, low-energy areas, but nest
on high energy beaches, their feeding and nesting habitats, are, of necessity,
located some distance apart. For instance, green turtles that nests on Ascension
Island forage along the coast of Brazil, some 1000 km away.
It is generally accepted that green turtles return to nest on the beach where they
were born. Green turtles do exhibit strong site fidelity in successive nesting
seasons and they also exhibit strong site fidelity for their foraging grounds.
5. Understanding Sea Turtle Migration Trends
Sea turtles are elusive and secretive
animals spending most of their lives in
the sea, mostly migrating between their
foraging and nesting area. The male sea
turtles don’t leave the sea at all, while the
female sea turtles only do so when
nesting. Yet, all eight species are
endangered or threatened. They are
killed for meat and leather; their eggs are
taken for food and aphrodisiacs. Their
nesting sites go for development. They
are ground up by dredges, run over by
pleasure boats, poisoned by pollution, strangled by trash, and drowned by fish line
and net. And we hardly know them. Scientists and researchers have long known
that mysteries surrounding the living patterns and behavior of sea turtles cannot
be solved unless knowledge is gained about their time spent in the sea that
includes identifying their migration patterns to better understand their life cycle.
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
Green Turtles Nesting in the Sandspit/Hawksbay Beaches
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The long distance migrations of sea turtles involve some of the most remarkable
feats of orientation and navigation in the animal kingdom. As hatchlings, the
turtles that have never before been in the ocean establish unerring courses
towards the open sea as soon as they enter the water and then maintain their
headings after swimming beyond sight of land. Adult turtles of several species
migrate across hundreds or thousands of kilometers of open ocean to nest on
their natal beaches, which are often isolated stretches of continental shores or
tiny, remote islands. Such impressive feats are all the more astonishing in view of
the fact that they are accomplished in an open ocean environment devoid of
visual landmarks and by marine animals whose poor eyesight above water
precludes the use of star patterns and other celestial clues.
The management of populations of migratory species requires knowledge of the
distribution of each population, identification of the jurisdictions (range states)
through which the population passes, and cooperation among range states for
regional management plans so that the geographic range over which management
policies must be integrated can be properly defined. These are difficult but at the
same time important to achieve for sea turtles with their extensive and largely
obscure migration patterns.
Research into investigating the sea turtle migration trends has only recently begun.
It was only in 1954 that the father of sea turtle research, a visionary herpetologist,
the late Archie Carr, set up camp on the beach at Totuguero, Costa Rica, the
largest green turtle rookery in the Caribbean. Green turtle populations had
plummeted, and Carr wanted to learn how to protect them. Today, one man on
the beach has grown into an international army of biologists and volunteers trying
to understand the ways of sea turtles and save them from extinction.
Though there remains much to be learnt, there are some signs of progress.
Studies done in the East coast of Florida on Loggerhead turtles reveal that
hatchlings from the East coast of Florida migrate into the Gulf Stream current
and the North Atlantic gyre. As the turtles grow, they remain in the gyre for a
period of years, eventually returning to the southeastern Unites States coast. Later,
as adults, the females migrate back to their natal beaches to nest. The initial
offshore migration, in which hatchlings swim from the east coast of Florida to the
Gulf Stream current, has provided a convenient starting point for investigating
orientation mechanisms in sea turtles. The investigations suggest that sea turtles
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
Green Turtles Nesting in the Sandspit/Hawksbay Beaches
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use features of the earth’s magnetic field in global position finding and perhaps in
navigation.
It has been found that Loggerhead sea turtles emerge from underground nests in
the night, scramble to the sea and begin a trans-oceanic migration by swimming
away from their natal beach and into the open ocean. Evidence suggests that
hatchlings use three different sets of cues to maintain orientation during their
initial migration offshore. While on the beach, the hatchlings find the ocean by
crawling towards the lower, brighter seaward horizon and away from the dark,
elevated silhouettes of vegetation and dunes. Upon entering the ocean, turtles
initially orient seawards by swimming into waves, which can be detected as orbital
movements from under water.
Laboratory experiments have demonstrated that turtles can transfer a course
initiated on the basis of waves or visual cues to a course mediated by a magnetic
compass. Thus, by setting a magnetic course on the basis of near shore cues that
indicate the seaward direction, hatchlings may continue on offshore headings after
entering deep water beyond sight of land. Sea turtles may use earth’s magnetic
field not only as a cue for compass orientation but also as a source of world wide
positional information. Recent experiments have demonstrated that Loggerheads
can detect subtle differences in magnetic field inclination and intensity, two geomagnetic features that vary across the surface of the earth. Because most of the
nesting beaches and oceanic regions are marked by a unique combination of these
features, these findings raise the possibility that adult sea turtles navigate using a
bio-coordinate magnetic map.
6. Methodologies for Tracking Sea Turtle Migration Trends
There are a few standard methods that are used world wide for carrying out
investigation and research into sea turtle migration patterns. The traditional
method of tracking the under sea movement of turtles is manual “Tagging”. The
turtles when they come to nest or are foraging near the coast are tagged on their
flippers. The tags are coded and since this activity is shared by a network of
integrated government and non governmental conservation organizations
worldwide, the information is exchanged and migration routes between various
foraging and nesting areas plotted. In addition, new technologies of DNA
mapping and satellite tracking are beginning to answer questions about behavior
and migration. In the following sections, these new technologies get discussed in
detail:
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6.1. How Satellite Tracking Works: State of the Art Research
The technology of satellite telemetry has advanced to the stage of allowing
researchers to track turtles in the open ocean after attaching Sony
Walkman-sized transmitters to the backs of adult or immature sea turtles.
The transmitters send signals full of information to an orbiting satellite
each time the turtle surfaces for air. The satellite re-transmits the data to a
receiving station on earth, which researchers can access through their
computer and modem. After 8-10 months, the transmitters quit working
and fall safely off the turtle.
The small, low wattage transmitters attached to the turtles are controlled
by a micro-processor which is programmed by a computer before they
were attached. The program tells the microprocessor how to store
information and when to transmit the information to the satellites. There
are 4 polar orbiting satellites that are currently used for tracking animals.
The satellites are operated by the U.S National Oceanic and Atmospheric
Organization (NOAA) and are the same satellites used to monitor global
weather patterns. Attached to these satellites are special instruments
operated by a French company, ARGOS CLS. These special instruments
are designed to listen for transmitters like those we place on turtles and to
determine where those transmitters are located. While such a task would
seem simple, it is not. Each satellite circles the earth every 101 minutes and
so it’s only over one place on the planet for about 10 minutes each. For
the satellite to determine the location of the transmitter it takes about 3-5
minutes, and the transmitter must be on the surface to be detected.
However, turtles rarely remain on the surface for that long, and their
surfacing must coincide with the satellite passing overhead. Thus it is
uncommon to receive a location from a turtle very day.
The data received from the turtles comes in the form of digital codes,
which must be deciphered. The codes allow researchers to determine, with
varying degrees of reliability, the latitude and longitude location of the
turtle, the number of dives taken during the last 24 hours, the duration of
the most recent dive, and the water temperature.
Using computer mapping programs, or by hand plotting the location data,
researchers can then visually see where the turtles are, the route they have
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
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traveled, and how fast they are generally swimming. Depending on the
detail of the map one is using, a researcher can also determine the habitat
characteristics at the turtle’s location.
It should be noted that as with any new technology, the bugs are still being
worked out of the satellite telemetry as a method for tracking marine
turtles. For instance, the batteries in these transmitters can last for 8-10
months, but signals often stop prematurely. Ideas about why this is
occurring range from problems with salt water getting into the device to
turtles knocking the devices off as they wedge themselves under rocks.
When signals do come in, there are also reliability problems with the
location data. Each signal that comes from a turtle carries a code that ranks
the reliability of that particular signal. When the reliability is high, the
latitude and longitude data is usually right on the mark. However, the
locational data can sometimes be a little off. One should be aware of the
plotted turtle movements which represents the best data available;
however, any given plot mark may not be 100% accurate.
This limitation does not really detract from the overall value of the
research. While a particular location point may actually be miles off a given
turtles actual location, the accumulation of data still tells us where the
turtles are generally moving and where their primary foraging areas are
located.
Following are discussed two successful sea turtle tracking projects that
have availed of the technique of satellite tracking:
6.1.1.
Tortuguero Sea Turtle Tracking Project
In late September 2002, the Caribbean Conservation Corporation
(CCC) attached satellite transmitters to the shell of a green sea
turtle named “Miss Junie 2”, after she nested on the beach at
Tortuguero, Costa Rica. After deploying the transmitters, the
turtle was immediately released back into the wild to carry on with
their normal behavior Using state-of-the-art satellite tracking
technology. CCC and other researchers are now monitoring the
movements of these and other turtles. Through CCC’s Turtle
Migration-Tracking Education Program, the public is invited to watch
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along on the Internet as we learn more about these amazing
animals.
6.1.2.
Florida Juvenile Green Turtle Tracking Project
Along the coast of Florida in the U.S.A, an extremely successful
project of satellite tracking has been carried out on the sea turtle
named “Wallace”. Wallace was originally captured in 1996 in the
Indian River Lagoon and has been recapped 3 times since.
Wallace has remained in the same general area, but because the
barrier island is so narrow and the accuracy of the hits are not
exact, researchers have difficulty in telling if she is inside or
outside.
6.2. Reading the Genetic Code: Use of DNA Mapping for Tracking Sea Turtle
Migration Trends
DNA in a cell nucleus is from both mother and father, but the DNA in
cells mitochondria - the bodies that produce the cells energy – is passed
directly from female to offspring. That is the reason why mitochondrial
DNA (mtDNA) is the preferred DNA marker used to mostly to find out
about the fidelity of the turtles to their nesting and foraging sites. If female
turtles are returning to their natal beaches to nest, the turtles on each
beach would have similar and distinctive mitochondrial DNA. For the
most part, they do.
In recent years, genetic markers have provided a valuable tool for
elucidating the distribution of migratory sea turtle populations. Genetic
tags have been used to identify the sources for mixed populations sampled
away from breeding areas. In most species of sea turtles, females return to
nest in the vicinity of their natal beach. The high degree of site fidelity on
the part of the nesting females results in genetically discrete populations
that are distinct demographic (and management) units. When turtles leave the
breeding areas, however, reproductive populations may become mixed on
foraging grounds, and the distinctions among management units are
obscured
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
Green Turtles Nesting in the Sandspit/Hawksbay Beaches
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Following are discussed some projects where DNA mapping is being done
to understand the dynamics behind sea turtle migration behavior and
patterns.
6.2.1.
DNA Mapping of Green Turtles in Inagua Island, Bahamas
The turquoise and emerald shallows surrounding the small
Bahamian Island of Great Inagua are feeding grounds for juvenile
green turtles. Here University of Florida biologists Karen Bjorndal
and Alan Bolten are using DNA to match the turtles with their
native beaches and learn their migration patterns. The mtDNA of
green turtle hatchlings is being collected. The Inagua study shows
that greens born in Florida, Costa Rica, Suriname, and
Venezuela’s Isla Aves are coming here to feed. The scientists are
confident that they now have the mtDNA patterns of most of the
major green turtle rookeries in the Atlantic and now they would
be able to tell where these juveniles come from based on genetics
and would not have to tag 10,000 turtles and wait to catch one.
6.2.2.
Transatlantic Developmental Migrations of Loggerhead Sea
Turtles Demonstrated by mtDNA Sequence Analysis
Molecular markers based on mtDNA control region sequences
were used to test the hypothesis that juvenile loggerhead sea
turtles in pelagic habitats of eastern Atlantic are derived from
nesting populations in the western Atlantic. Scientists compared
mtDNA haplotypes from 131 pelagic juvenile turtles (79 from the
Azores and 52 from Madeira) to mtDNA haplotypes observed in
major nesting colonies of the Atlantic Ocean and Mediterranean
Sea. A subset of 121 pelagic samples (92%) contained haplotypes
that match mtDNA sequences observed in nesting colonies.
Maximum likelihood analysis estimate that 100% of these pelagic
juveniles are from the nesting populations in south eastern United
States and adjacent Yucatan Peninsula, Mexico. The link between
West Atlantic nesting colonies and east Atlantic feeding grounds
provides a more complete scientific basis for assessing the impact
of sub adult mortality in oceanic fisheries.
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7. Tracking Migration Trends of Nesting Green
Hawksbay/Sandspit Beaches – The Present Status
Turtles
on
the
The two main research organizations undertaking sea turtle conservation activities
in the project area – namely, the Sindh Wildlife Department and the World
Wildlife Fund Pakistan have for some time been involved in projects and activities
aimed at investigating the migration trends and behaviors of nesting green turtles
in the Hawksbay/Sandspit area. Following are discussed the details of their work.
7.1. Investigating Green Turtle Migration Trends by Satellite Tracking –
WWF Pakistan
In the year 2001, WWF-Pakistan had initiated a collaborative research and
conservation program with the Environment Research and Wildlife
Agency (ERWDA) on mangroves and marine turtles. ERWDA provided
WWF Pakistan with two satellite transmitters for installation on two of the
nesting green turtles on the Hawksbay/Sandspit beaches. Two experts
from ERWDA, namely, Dr.John Hoolihan and Dr.Himansu Das
conducted satellite tagging on two of the nesting marine turtles at Sandspit,
Karachi coast, in the night of August 1st and 2nd, 2001.
For ensuring accurate
information based on
satellite tracking, the
following procedure
was adopted. Two
green turtles were
captured after they
had
completed
nesting
on
the
Sandspit beach. The
location
of
the
capture of the green
Map – 1
turtles was marked with
the help of Global Positioning System. For identification purposes, the
turtles were named as Chandni I & Chandni II. The captured turtles were
later transported to the WWF’s Wetland Centre and put into a wooden
box with their heads covered by wet towels.
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
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The first scute of the
dorsal side of each of the
green
turtles
was
selected for installation
of
the
satellite
transmitter. The scutes
were rubbed with the
help of sandpaper to
make the surface rough
so that adhesive can
work easily on it.
Map – 2
Elastomer mixture was rubbed on the back of the device and then it was
placed on the scute of the carapace. The device was placed in such a
position that the antenna pointed towards the tail of the turtle. The drying
out of Elastomer took about an hour and thirty minutes. A second
adhesive i.e. marine polyester laminator resin mixed with a catalyst was
applied on the devise by using 1.5 “ * 1.2” strip on either side of the
device. The transmitter was then covered with different layers of fiber
glass strips. Before covering, the visiting cards of ERWDA and WWF
Pakistan were put on the device. A double coating of resins was applied on
the device. Two salt water switches were present at the anterior side and
masking was removed from them to make them operational.
The green turtles were then carried to the same place from where they
were captured. Before releasing them in the sea, a tag was attached on each
front flipper. Location data was later received through ARGOS, a satellite
based system that tracks sea turtles when they surface for air. The data was
transmitted to the station, then to the user. With the help of GIS
Programming, the turtle migration pattern was located. (See Table1/2 for log
sheets of Chandni I& II – and Map 1&2 for Turtle Migration Pattern)
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Table# 1 - Log Sheet of Chandni I
(Transmitter No. 14812 – Tag No. W3090/Left &W9029/Right)
Date
01-08-2001
16-08-2001
28-08-2001
29-08-2001
Time
8:00 pm
10:00 pm
22:45 pm
22:45 pm
No. of Eggs
103
96
Visit (no eggs)
103
Table# 2 - Log Sheet of Chandni II
(Transmitter No. 14810 – Tag No. W9034/Left &W9035/Right)
Date
02-08-2001
17-08-2001
31-08-2001
Time
09:05 pm
09:45 pm
09:10 pm
No. of Eggs
100
76
Visit (no eggs)
7.2. Documenting Green Turtle Migration Trends – Sindh Wildlife
Department
According to the Sindh Wildlife Department figures, from October 1979
to December 1997, 1,531,980 eggs from 17,702 nests were transplanted to
enclosures (three # enclosures, each having a capacity of 300 nests) to protect
them from predators. Of these, 1,453,966 were green turtle eggs from
17,702 nests and 78, 014 were olive ridley eggs from 654 nests (see Chart1).
A total of 3,91,556 hatchlings were released to the sea. Out of these,
3,70,414 were green turtle hatchlings and 21,142 were olive ridley
hatchlings. In addition, 88,108 hatchlings were collected from from outside
the enclosures and were released to the sea. In total, 4,79,664 hatchlings
were released to the sea.
However, only about 5000 turtles have been tagged so far. Adults have
been tagged with Monel Tags (size 19, style 49) on the trailing edge of both
front flippers, as these areas are less frequently damaged. Tags have been
applied after egg laying following methods by Balasingham (1966) and
Bustard (1972). Tag returns have been received from local areas and a few
records of long distance migrations have also been reported
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8. Preliminary Feasibility for using DNA Mapping for determining Migration
Patterns of Green Turtles nesting in the Sandspit/Hawksbay beaches
Discussed below are the various relevant issues related to working out the
preliminary feasibility for using DNA mapping for determining migration patterns
of green turtles nesting in the Sandspit/Hawksbay beaches
8.1. The Technology
When we assess the results of the various methodologies used to track sea
turtle migration trends, then it becomes clear that manual tagging is an
extremely tedious process while the risk factor associated with satellite
tracking of sea turtles is significant with the inherent chances of the sea
turtles getting killed or the transmitter getting unhooked. Where DNA
mapping scores a clear advantage is that it reduces the workload and cuts
down on the risk factor. However, a certain level of technological
advancement is required to make effective use of this technology.
As has been mentioned earlier, greater success of scientific research, when
it comes to sea turtles, lies in an integrated approach. This is because sea
turtles spend most of their lives under the sea, moving between their
foraging and breeding grounds. It is therefore essential to link up the
research work with as many agencies and organizations engaged in sea
turtle conservation efforts as possible, the world over. It is only then that
effective conservation plans are developed that properly addresses the
wide geographical range of sea turtle movement, spread over different
oceans and continents.
In order to achieve harmony and cohesion in scientific research between
different countries, a certain level of similarity in approaches and methods
is required. Manual tagging is a simple process requiring minimum level of
technological input. Use of satellite tracking is gaining ground with
research organizations in the less developed countries making greater use
of this technology to track the movements of their sea turtle populations.
However, DNA mapping is a concept that remains mostly unutilized in
countries such as Pakistan, where the level of technological advancement is
not in anyway comparable to the western and developed world.
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However, where Pakistan is fortunate is that certain centers of excellence
in scientific and medical research have developed through the
contributions and efforts of the private/non governmental sector and local
philanthropists that provide state of the art services, comparable to any of
their counterparts in the developed world. These include among others,
the Aga Khan University Hospital, Karachi and the Hussain Ebrahim
Jamal (HEJ) Research Institute, Karachi. The Aga Khan University
Hospital provides state of the art services in DNA profiling, which though
till now have only been extended to humans. Therefore, a financial
estimation for providing the required facilities for DNA profiling of sea
turtles would need to worked out. However, it is not just a matter of
finding a facility where DNA profiles can be prepared, a substantial effort
is required to build the relevant capacity in the organizations already
involved in sea turtle conservation efforts in the project area to so that
they can make effective use of this technological option. At present, this
desirable level scientific development is found lacking.
8.2. The Institutions
It is logical that the Sindh Wildlife Department and the World Wildlife
Fund, Pakistan be identified as the key organizations to lead the work in
exploring the potential of initiating the process of DNA mapping of the
sea turtles visiting the Sandspit/Hawksbay beaches. However, in order to
extend the scope of this work and facilitate the requirements of applied
scientific research, it is suggested that a scientific institute be identified and
its capacity built to participate in this process. For this purpose, the
Department of Molecular Genetics at the University of Karachi is being
identified.
Linkages would also need to be established with research organizations in
other relevant countries that are undertaking similar research in order to
match and correlate data for understanding migration trends and develop
integrated strategies and projects for sea turtle conservation.
8.3. Geographical Scope of Research
In order to identify countries and organizations with whom collaborative
mechanisms for scientific research can be forge, it is essential first to
investigate possible migratory routes of the turtles visiting the
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
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Sandspit/Hawksbay beaches. As has been mentioned in the earlier
sections, gyres and oceanic currents and wave patterns play a significant
role in determining the sea turtle migration trends. Sea turtle hatchlings
enter the gyre and remain there for years. Wave/current patterns also play
a significant role in determining their movement patterns.
In the following sections, baseline assessment is made of the seawater
circulation patterns and gyre/currents movement along the Karachi coast.
8.3.1.
Seawater Circulation Patterns along the Coast of Karachi
Information about the seawater circulation patterns and oceanic
current movements along the Karachi coast would be helpful in
identifying possible movement and migration patterns of sea
turtles visiting the Sandspit/Hawksbay beaches. The sea water
circulation pattern along the coast of Karachi can be grouped into
three types:
 Clockwise Circulation
 Anti-Clockwise Circulation
 Mixed Circulation
The dominant direction of the seawater flow in the coastal waters
of Karachi is clockwise i.e. the major flux of seawater from
offshore area enters the coastal waters of Karachi at the western
coast area from the southwest. This water then moves along the
coast towards the east and then in southeast direction forming a big
gyre. This pattern is common mostly during mid April to
September period as a consequence of the south west monsoon
winds blowing strongly during this period.
The seawater circulation reverses its direction in response to the
direction of the prevailing northeast monsoon wind direction. The
anti-clockwise circulation of seawater is mostly restricted to the
December-January period - the period of the northeast monsoon
winds in this area. The seawater from the near shore and offshore
Indus Delta enters the coastal waters of Karachi from the southeast
and moves along the coast towards northeast, westward and then at
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the west coast of Karachi, it moves in the south east direction to
the offshore area.
There are transition periods between the southwest and northeast
monsoons period when the direction of the wind changes
frequently. This also results in the complex circulation pattern along
the coast with many clockwise and anti-clockwise gyres which
persist for short periods only. The dominant direction of the
surface circulation during the transition periods depends mostly on
the persistent direction of the prevailing winds. Although the
seawater circulation patterns during the transition periods (i.e.
February-March, October-November) are mixed but there is an
identifiable component of anti-clockwise direction during MarchApril, October-November and clockwise during February. The
detailed directions of the seawater circulation pattern along the near
shore areas of the coastal belt during the transition periods are not
yet mapped and documented.
8.3.2.
Seawater Currents
The predominant direction and speed of the seawater currents for
the South Eastern Karachi coast is given in Table 3. The speed of
the current is generally low, about ½ knots. The speed increases
up to 1 knot during SW monsoon. The direction of the set is
directly related with the prevailing wind system. The set is
generally easterly in the SW monsoon and westerly in the NE
monsoon. The slight difference in direction in the Western and
Eastern part of the Karachi coast is due to circulatory pattern of
the current around gyres that are usually formed at the center of
the sea. There is a clockwise gyre during SW monsoon and an
anti-clockwise gyre during NE monsoon.
Table# 3 – Predominant direction and speed of sea surface currents off South
Eastern Karachi Coast
Seasons
Direction of Set Speed
(Degrees)
North
East W
Monsoon (Dec-Jan)
(Knots)
½
Constancy
in
Direction (%)
Greater than 33
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
Green Turtles Nesting in the Sandspit/Hawksbay Beaches
(16)
Pre-Monsoon (Feb- E-ENE
May)
SW Monsoon (June- E-ENE to ESE
Sep)
Post SW Monsoon E
(Oct-Nov)
½
Greater then 33
½-1
33-36
1/2
Greater then 33
8.4. Potential Migration Routes
Based on the available data and research on documented sea turtle
movements, prevailing seawater circulation and oceanic current
movements, it can be suggested that two possible migration routes for the
sea turtles visiting the Sandspit/Hawksbay beaches could be studied and
investigated using the DNA mapping technique:
8.4.1.
Migration Route#1
It is possible that the movement of the sea turtles, particularly in
the earlier phase of their lives when they are driven by the gyre
movement predominant along the coast, is restricted to the
Northern Arabian Sea, moving back and forth between turtle
nesting/foraging grounds in the vicinity of Oman and Gujrat,
India.
8.4.2.
Migration Route#2
It is possible that the movement of the sea turtles, when they are
driven by the oceanic currents, in particular, the Somali current, is
restricted between the coasts of East Africa and Far Eastern
countries.
9. Collaborative Linkages
It is therefore important that contacts are established with countries like India,
Oman, Malaysia and selected countries in East Africa to explore the possibilities
of joint or coordinated research.
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
Green Turtles Nesting in the Sandspit/Hawksbay Beaches
(17)
A need does exist for utilizing the option of DNA mapping for studying the sea
turtle migration trends. A positive feasibility also exists for exploring in detail the
potential for initiating such a process. However, the financial, technical and
institutional requirements of this option and long term strategies, plans ad
projects would need to be assessed and evaluated in detail prior to
implementation.
_________________
Preliminary Feasibility Study for using DNA Mapping for determining Migration Patterns of
Green Turtles Nesting in the Sandspit/Hawksbay Beaches
(18)
TABLE OF CONTENTS
1.
2.
3.
4.
5.
6.
7.
8.
9.
Objective of the Study .................................................................................................1
Study Methodology......................................................................................................1
Sea Turtles-Distribution and Habitat ...........................................................................1
3.1. Green Turtles – Distribution and Habitat.............................................................2
Movement Patterns .......................................................................................................3
Understanding Sea Turtle Migration Trends ...............................................................3
Methodologies for Tracking Sea Turtle Migration Trends ..........................................5
6.1. How Satellite Tracking Works: State of the Art Research ..................................6
6.1.1. Tortuguero Sea Turtle Tracking Project ......................................................7
6.1.2. Florida Juvenile Green Turtle Tracking Project ..........................................8
6.2. Reading the Genetic Code: Use of DNA Mapping for Tracking
Sea Turtle Migration Trends ................................................................................8
6.2.1. DNA Mapping of Green Turtles in Inagua Island, Bahamas.......................9
6.2.2. Transatlantic Developmental Migrations of Loggerhead
Sea Turtles Demonstrated by mtDNA Sequence Analysis ..............................9
Tracking Migration Trends of Nesting Green Turtles on the
Hawksbay/Sandspit Beaches – The Present Status ....................................................10
7.1. Investigating Green Turtle Migration Trends by Satellite
Tracking – WWF Pakistan .................................................................................10
7.2. Documenting Green Turtle Migration Trends – Sindh Wildlife
Department .........................................................................................................12
Preliminary Feasibility for using DNA Mapping for determining
Migration Patterns of Green Turtles nesting in the
Sandspit/Hawksbay beaches ......................................................................................13
8.1. The Technology .................................................................................................13
8.2. The Institutions ..................................................................................................14
8.3. Geographical Scope of Research .......................................................................14
8.3.1. Seawater Circulation Patterns along the Coast of Karachi ........................15
8.3.2. Seawater Currents ......................................................................................16
8.4. Potential Migration Routes ................................................................................17
8.4.1. Migration Route#1 .....................................................................................17
8.4.2. Migration Route#2 .....................................................................................17
Collaborative Linkages ..............................................................................................17
LIST OF TABLES
Table # 1 — Log Sheet of Chandni I ..............................................................................12
Table # 2 — Log Sheet of Chandni II ..............................................................................12
Table # 3 — Predominant direction and speed of sea surface currents off
South Eastern Karachi Coast .......................................................................17
LIST OF MAPS
Map # 1 — Movement of Chandani I ............................................................................11
Map # 2 — Movement of Chandani II ...........................................................................11
PRELIMINARY FEASIBILITY STUDY FOR USING DNA
MAPPING FOR DETERMINING MIGRATION
PATTERNS OF GREEN TURTLES NESTING
IN THE SANDSPIT/HAWKSBAY BEACHES
(Project — Helping the Turtles Survive)
Submitted by:
Shehri—CBE
(December 2004)
A GEF/SGP Project of UNDP Pakistan