Abstract:
Out of the seven sea turtle species, five species come to Sri Lankan coastal belt for nesting.
Southern coast of Sri Lanka comprises most of the known marine turtle rookeries,
due to the availability of foraging and nesting grounds. But the threats to nesting turtles
are very high in these areas due to various human, animal, and physical factors that
affect negatively. Coastal erosion can be considered as one of the most severe physical
threats. This study was carried out to identify shoreline changes in selected turtle nesting
sites in southern coast namely Kosgoda, Habaraduwa, Mirissa, Rekawa, Kalamatiya,
Ussangoda, Uraniya in Bundala and between Mahaseelawa and Patatupana in Yala.
Google Earth high resolution satellite images were used to extract the instantaneous
shoreline over a period of 15 years. Shorelines were digitized referring to wet dry margin
and saved as KML file format. KML file was converted in to layer file by Arc GIS
10.8 software. Transects were casted using manually created baseline. Shoreline change
statistics such as Net Shoreline Movement (NSM) and End Point Rate (EPR) were
calculated. Results respectively for the above-mentioned sites are NSM values (m) of
3.51, 2.67,−2.26, −20.88, 15.72, 5.79, 19.79 and 7.19 and EPR values (m/yr) of 0.57,0.43,
−0.41, −3.96, 3.12, 1.15, 2.81 and 1.23. That indicated Mirissa and Rekawa beaches are
eroded while other sites are accreted. It may be due to development activities, sand
mining, destruction of coastal vegetation and coral reef, etc. Especially Rekawa being
one of the main sea turtle rookeries, these long-term trends can be very important to
study further. Furthermore, seasonal erosion and accretion cycles play a key role in
maintaining the quality of nesting environment. Therefore, in situ nest monitoring and
turtle conservation projects supported by data on long term and seasonal erosion and
accretion cycles are needed to protect them.
