A record of late Holocene sea level and human impacts from the southeastern Coast of Sri Lanka

Abstract

AMS radiocarbon-dated palynological evidence from Embilikala Lagoon in Bundala National Park (one of the Ramsar wetland sites) on the southeast coast of Sri Lanka indicates palaeoenvironmental changes during the last 2,700 years. The persistence of fewer mangroves (eg Rhizophoraceae taxa) suggests that sea level low stands occurred between 2,700 and 1750 cal yr BP. From the later age, the relative sea level rose, and reached the present sea level at 950 cal yr BP as indicated by the mangrove maximum. At 2,250, 700–400 and 200–150 cal yr BP, the sudden increase in marine dinoflagellate cysts (eg Spiniferites mirabilis) and foraminifera (Globigerinoides ruber) suggests increased marine influence. This is consistent with a decrease in mangrove habitats. Between 2,700 and 950 cal yr BP, severely degraded dry monsoon forests and minimal levels mangrove suggest human and marine influences were the critical drivers for changing the major vegetation types along the southeastern coast. Vegetation changes have been drastic over the last millennia.

Keywords:

• Holocene
• lagoon
• mangrove
• pollen
• sea level
• sediment
• Sri Lanka

Acknowledgments

The authors thank Prof. Sudantha Liyange, the former Vice Chancellor, and Prof. Pathmalal Manage, the present Vice-Chancellor and the former the Dean of the Faculty of Graduate Studies and the Chairperson of the Research Council of the University of Sri Jayewardenepura for the funding to conduct this research (Research Grant No ASP/01/RE/HSS/2019/05). In addition, the authors appreciate the help received in administrative and scientific contexts from the Department of Wildlife Conservation and Geological Survey and Mines Bureau staff, Colombo. We would also like to thank Mr. Prasad Sirinivasa, French Institute of Pondicherry, India, and Mrs. Nuwanprabha Kapugeekiyana Whittall for their valuable comments. Finally, the valuable support extended by the staff of the Bundala National Park and the team headed by Dr. Oshan Wedage, Senior Lecturer, Department of Archaeology, University of Sri Jayawardenapura and Dr. Dilantha Dharmagunawardene for the smooth conduction of fieldwork and sample collection is highly appreciated.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was funded by Faculty of Graduate Studies and the Chairperson of the Research Council of the University of Sri Jayewardenepura (Research Grant No ASP/01/RE/HSS/2019/05).

Notes on contributors

Rathnasiri Premathilake

RATHNASIRI PREMATHILAKE is a senior lecturer at the Postgraduate Institute of Archaeology, University of Kelaniya, Sri Lanka, whose research focuses on climate and environmental change, sea-level fluctuations, and the understanding of human impact on landscape using the application of sequence stratigraphy. Premathilake currently has research projects on the Paleohome, consequences of geographic places or habitats over long time spans in the Palaeolithic and the development of phytolith proxies for palaeovegetation reconstruction from Pleistocene deposits, and biotic responses to environmental change. Premathilake has contributed to developing multi-proxy approaches on several international projects (eg MANDU Project and Indo-French Archaeological Mission) to understand ecological change during the Holocene.

Jayani Herath

JAYANI HERATH is a PhD researcher at the Queensland University of Technology, Australia, working on the impacts of sea-level rise on land use dynamics in the southern coastal region of Sri Lanka which will contribute to the literature on climate change adaptation. Other research interests include pollen and physical geography, land use analysis and planning.