Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 October 2021 | 13(12): 19860–19863
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.7603.13.12.19860-19863
#7603 | Received 03 August 2021 | Final
received 31 August 2021 | Finally accepted 10 September 2021
Are the uplifted reef beds in
North Andaman letting nesting Olive Ridley Sea Turtle Lepidochelys
olivacea stranded?
Nehru Prabakaran
1 , Anoop Raj Singh 2 &
Vedagiri Thirumurugan
3
1–3 Wildlife Institute of India, Chandrabani, Post Box 18, Chandrabani,
Dehradun 248001, India.
1 nehrumcc@gmail.com (corresponding
author), 2 anooprajsingh23@gmail.com, 3 thirumurugan771@gmail.com
Editor: Raju Vyas,
Vadodara, Gujarat, India. Date of
publication: 26 October 2021 (online & print)
Citation: Prabakaran,
N., A.R. Singh & V. Thirumurugan (2021). Are the uplifted reef beds in
North Andaman letting nesting Olive Ridley Sea Turtle Lepidochelys
olivacea stranded? Journal of Threatened Taxa 13(12): 19860–19863. https://doi.org/10.11609/jott.7603.13.12.19860-19863
Copyright: © Prabakaran
et al. 2021. Creative Commons Attribution
4.0 International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: The Department
of Science and Technology under the INSPIRE Faculty scheme
[DST/INSPIRE/04/2018/001071]; Rufford Small Grant
[ID:32387-1].
Competing interests: The authors
declare no competing interests.
Acknowledgements: We are thankful to the
DST-INSPIRE program (DST/INSPIRE/04/2018/001071) for funding the study. We are
indebted to the Department of Environment & Forests, Andaman and Nicobar
Islands for permission and facilitating the fieldwork.
Andaman & Nicobar Islands have nesting of four
marine turtle species—Olive Ridley Turtle Lepidochelys
olivacea (Eschscholtz,
1829), Leatherback Turtle Dermochelys coriacea (Vandelli, 1761),
Hawksbill Turtle Eretmochelys imbricate (Linnaeus,
1766), and Green Sea Turtle Chelonia mydas (Linnaeus, 1758)—of which Olive Ridley Turtle is
reported to exhibit mass nesting (Bhaskar & Whitaker 1983; Namboothri et al. 2012). With major nesting and foraging
grounds, North Andaman is among the vital conservation zones for all the four
sea turtles (Murugan 2004; Andrews et al. 2006;
Sridhar et al. 2019). For example, Interview Island is one of the largest green
turtle nesting sites in North Andaman (Namboothri et
al. 2012) and an earlier study suggested that the northwestern coast of the
North Andaman Island should be conserved as Hawksbill Turtle sanctuary as it
provides a potential nesting and feeding ground for this species (Bhaskar &
Andrews 1993).
The 2004 Sumatra-Andaman
earthquake and the subsequent tsunami have severely affected the entire coastal
ecosystems across the Andaman & Nicobar Islands (Andrews & Vaughan
2005; Prabakaran & Paramasivam
2014). The tectonic uplift in the west coast of North Andaman has especially
resulted in a huge landmass of coral reefs being exposed, and the altered
hydrology resulted in a loss of more than 90% of the mangrove forest (Andrews
et al. 2006; Ramakrishnan et al. 2020). Additionally, beaches used by many sea
turtles as nesting ground were drastically affected by the mega-disaster (Murugan 2005; Andrews et al. 2006). The high intensity
tsunami waves not only resulted in heavy deposition of sand and sediment at the
shore, but it also brought a huge pile of sea debris such as plastic, wood, and
polyethylene (Murugan 2005; Ramachandran et al. 2005;
Rajendran et al. 2013). The turtle
nesting across the Andaman Islands
severely declined in the subsequent years following the disaster owing
to the altered coastal lines (Murugan 2005; Namboothri et al. 2015). Though many turtle nesting beaches
were affected by the uplift, the new beaches formed after the tsunami provided
some hope for turtle nesting in the North Andaman (Murugan
2005; Namboothri et al. 2015).
During our survey to understand
vegetation colonization, focused on mangroves, in the uplifted reef beds near
the Radhanagar creek in North Andaman on 10 February
2021 (13.411N & 92.849E), we came across four carcasses of Olive Ridley
Turtles within a 500-m transect (Image 1). The carcasses were probably a week
old and are characterized by the presence of degenerating flesh and foul smell.
Incidentally, the North and
Middle Andaman is known to have some critical nesting beaches of marine
turtles, of which the Cuthbert Bay is known to have mass nesting of Olive
Ridley Turtles. Mass nesting usually occurs during the third quarter phase of
the lunar cycle that coincides with the neap tide phase of the ocean (Forest
Department, pers. comm. February 12, 2021).
As per the local reports, the mass nesting of Olive Ridley peaked in the
middle of the first week (1–7) February 2021 at the Cuthbert Bay, and our
observations happened roughly a week later. Olive Ridley Turtles are likely to
nest all across the Andaman Islands and during this peak-nesting season, the
observed turtles could have approached the coastal line searching for the
potential nesting beach but instead
ended up stranded in the exposed reef bed. The site has exposed reef
beds that are 100–300 m wide, and at some places, it is up to 500 m wide. Most
of these uplifted reef beds are partially inundated through the complex water
channels in the reef beds during high tides and are often fully exposed during
low tides, except for some puddles.
Interestingly, a report that
reviewed all the research work on the turtle nesting beaches in the Andaman
& Nicobar Islands doesn’t record nesting of Olive Ridley Turtles in the
west coast of North Andaman (Namboothri et al. 2012).
However, many sites especially in the east coast namely Cuthbert Bay, Harguna beach, Rutland Island, Ross & Smith islands, Ramnagar beach of North Andaman, exhibit frequent nesting
of Olive Ridley Turtles (Andrews et al. 2006; Namboothri
et al. 2012, 2015; Sridhar et al. 2019). Many of such sites were notified
as wildlife sanctuaries to exclusively
conserve and protect the sea turtles in North Andaman Island.
Most of the Olive Ridley nesting
sites are from the east coast of Andaman Islands due to the upheaval of reef
flats that resulted in beaches becoming inaccessible for nesting in the west
coast of North Andaman (Andrews et al. 2006). Our observation suggests that the
nesting turtles are either stranded in the reef beds, or there may be other
factors contributing to such mortality. Note that the observation pertains to
just one site in the otherwise long coast line that is usually uninhabited by
humans and with a high potential for turtle nesting. In addition, utilization
of the uplifted reef beds and the adjacent beaches by the nesting marine
turtles is largely unknown. Therefore, a focused survey on turtle stranding in
the uplifted reef beds across the North Andaman during the peak-nesting season
may provide better insights on the turtle mortality incidences.
References
Andrews, H.
& A. Vaughan (2005). Ecological impact assessment in the Andaman islands and observations in
the Nicobar islands. The ground beneath the waves: Post-tsunami impact
assessment of wildlife and their habitats in India. New Delhi: Wildlife Trust
of India, 2, 78–103pp.
Andrews,
H.V., A. Tripathy, S. Aghue,
S. Glen, S. John & K. Naveen (2006). The status of sea turtle
populations in the Andaman and Nicobar Islands of India. Towards an
integrated and collaborative sea turtle conservation programme
in India: a UNEP/CMS-IOSEA Project Report, 92pp.
Bhaskar, S.
& H.V. Andrews (1993). Action plan for sea turtles in the Andaman and Nicobar Islands, India. Marine
Turtle Newsletter 60: 23. http://www.seaturtle.org/mtn/archives/mtn60/mtn60p23.shtml
Bhaskar, S.
& R. Whitaker (1983). Sea turtle resources in the Andamans. Bulletin of the Central
Marine Fisheries Research Institute 34: 94–97. https://core.ac.uk/download/pdf/33011239.pdf#page=113
Bhaskar, S.
(1993). The status
and ecology of sea turtles in the Andaman and Nicobar Islands. Centre for
Herpetology. Publication No. ST 1/93: 1–37.
Murugan, A. (2004). Sea turtles and their
conservation in Andaman and Nicobar Islands. Proceedings of the
International Symposium on SEASTAR 2000 and Bio-logging Science (The 5th
SEASTAR 2000 Workshop). http://hdl.handle.net/2433/44095
Murugan, A. (2005). The effect of tsunami on sea
turtle nesting beaches along the coast of India. Proceedings of the 2nd
International symposium on SEASTAR 2000 and Asian Bio-logging Science (The 6th
SEASTAR 2000 Workshop). https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/44088/1/6thSEASTAR_75.pdf
Namboothri, N., A. Swaminathan & K. Shanker (2012). A compilation of data from
Satish Bhaskar’s sea turtle surveys of the Andaman and Nicobar Islands. Indian
Ocean Turtle Newsletter 16: 4–13. https://www.iotn.org/iotn17-03-a-compilation-of-data-from-satish-bhaskars-sea-turtle-surveys-of-the-andaman-and-nicobar-islands/
Namboothri, N., A. Swaminathan & K. Shanker (2015). Olive ridley
mass-nesting at Cuthbert Bay wildlife sanctuary, Middle Andaman Island. Indian
Ocean Turtle Newsletter 21: 7–9. https://www.iotn.org/wp-content/uploads/2015/09/21-4-Olive-ridley-mass-nesting-at-Cuthbert-bay-wildlife-sanctuary-Middle-Andaman-island.pdf
Prabakaran, N. & B. Paramasivam
(2014). Recovery
rate of vegetation in the tsunami impacted littoral forest of Nicobar Islands,
India. Forest Ecology and Management 313: 243–253. https://doi.org/10.1016/j.foreco.2013.11.023
Rajendran,
C.P., K. Rajendran, V. Andrade & S. Srinivasalu
(2013). Ages and
relative sizes of pre-2004 tsunamis in the Bay of Bengal inferred from geologic
evidence in the Andaman and Nicobar Islands. Journal of Geophysical
Research: Solid Earth 118(4): 1345–1362. https://doi.org/10.1002/jgrb.50122
Ramachandran,
S., S. Anitha, V. Balamurugan, K. Dharanirajan,
K.E. Vendhan, M.I.P. Divien,
A.S. Vel, I.S. Hussain & A. Udayaraj
(2005). Ecological
impact of tsunami on Nicobar islands (Camorta, Katchal, Nancowry and Trinkat). Current Science 89(1): 195–200.
Ramakrishnan,
R., Y. Gladston, N.L. Kumar, P. Rajput, R.M. Murali
& A.S. Rajawat (2020). Impact of 2004 co-seismic
coastal uplift on the mangrove cover along the North Andaman Islands. Regional
Environmental Change 20(1): 1–12. https://doi.org/10.1007/s10113-020-01608-7
Sridhar, R.,
V. Sachithanandam, T. Mageswaran,
M. Mahapatra, K.O. Badarees, R. Purvaja
& R. Ramesh (2019). Small island management: a case study of the Smith Island, North
Andaman, India. Environment, Development and Sustainability 22: 8211–8228.
https://doi.org/10.1007/s10668-019-00553-8