Conference program and abstracts - Coastal-Change.Org
Conference program and abstracts - Coastal-Change.Org Conference program and abstracts - Coastal-Change.Org
Wetland Ecosystem of Mahanadi Delta, India: A palynological perspective Shilpa Singh Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow, 226007 India ABSTRACT Wetland habitats exhibit different ecological diversities and environmental variations. These habitats help in flood storage, sediment trapping, reduce erosion forces and associated menace. Under the Convention of Wetlands, the Chilka Lagoon is the largest saltwater lagoon in Asia and is also an internationally important ecosystem with rich ecobio-diversity and sustainability. The present communication deals with mangrove dynamics of the Chilka Lagoon during the Holocene using pollen data. Mangroves are highly susceptible to climatic changes and sea-level fluctuations. The development of mangroves is controlled by land-sea interaction and their expansion is determined by the topography of the sediment surface. Pollen investigation of sediments indicate existence of a brackish water estuarine mangrove swamp forest in the lagoon during the Middle Holocene. High sedimentation rate and delta progradation probably resulted in the loss of mangrove habitats during Late Holocene as evidenced by the pollen records. These records indicate an expansion of fresh water elements and contraction of the mangrove area. It is also observed that mangroves reappeared for a short span of time during Late Holocene at the study site with return of estuarine environment, which, however, later gradually degraded from the area. This degradation is attributed due to climatic changes, relative sea-level fall and probably got further accelerated by anthropogenic activities. The Fourth IGCP 588: PREPARING FOR COASTAL CHANGE 21
Holocene environmental changes inferred from a sediment record in Nan’Ao Island, Southeastern China Bishan Chen 1 , Zhuo Zheng 1 , Fengling Yu 2 , Adam D. Switzer 2 , Kangyou Huang 1 , Huanhuan Peng 1 , Bingjie Yang 1 1 Department of Earth Sciences, Sun Yat-sen University, Xingangxi Rd., Guangzhou, 510275 China 2 Earth Observatory of Singapore, Nanyang Technological University, 639798, Singapore ABSTRACT Qing’ao Bay is located in the northeast of Nan’Ao Island, Guangdong Province. The flat plain of the bay formed since the late Pleistocene has more than 10m thick Quaternary sediment, which contains abundant information of environmental changes. A core (NA9) has been collected in the middle of the coastal plain of Qing’ao Bay of the Island. The core length is 12.84m, reaching at the bottom the granite weathering bedrock. This paper uses combined methods including pollen analysis, grain size, ignition loss, foraminifer for revealing local sedimentary environment, terrestrial ecosystem and climate changes during the Holocene. According to the age model, marine transgression invaded to this coast at about 8300 cal a B.P, creating a set of transgression-regression cycle with sediment thickness of about 12m. Based on lithology and grain-size analysis, there is following succession of sedimentary facies in the Holocene: subtidal - intertidal -supratidal and lagoon facies. Pollen record demonstrates that the Holocene primary vegetation is a type of south subtropical monsoonal evergreen broad-leaved forest, comparable with modern flora. The marine indicative pollen such as mangrove can testify the local community changes in coastal plain, which is closely related to the changes of sedimentary environment. The detail environmental succession can be described as follow: (1) The sea-level rise approached to the study site at the early Holocene (8277-5703cal a B.P.). The highest sea-level with abundant foraminifer is only found between 7903 and 6018cal a B.P. The sediment of this period consists of marine shells and conchs. Some intact shells has been identified as Rhinoclavis articulate which occurs usually in a marine condition of >10m water depth. The foraminifera in the sediment is mostly Ammonia becearii vars. (2) The coarse particle sediment characterize the Middle Holocene period between 5703 and 3013cal a BP. The reconstructed sedimentary environment is intertidal facies. The terrestrial runoff became more important with frequent exchanges between land and ocean. Pollen and charcoal concentration and the LOI550℃ organic carbon display their lowest values of the entire section, confirming the existence of intertidal bay environment. The flat flooding plains started to form in the coastal area. (3) Local formation of mangrove is in the early stage of late Holocene (3013-1353cal a B.P.). The sediment consists of organic matter and plant debris. Pollen of Gramineae, Cyperaceae, Chenopodiaceae, Compositae and fern spore increased, associated with high amount of 22 The Fourth IGCP 588: PREPARING FOR COASTAL CHANGE
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- Page 20 and 21: Coastal resilience on microbial pol
- Page 22 and 23: Hazard Line Mapping Of Mahadi Delta
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Wetl<strong>and</strong> Ecosystem of Mahanadi Delta, India: A<br />
palynological perspective<br />
Shilpa Singh<br />
Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow,<br />
226007 India<br />
ABSTRACT<br />
Wetl<strong>and</strong> habitats exhibit different ecological diversities <strong>and</strong><br />
environmental variations. These habitats help in flood storage, sediment<br />
trapping, reduce erosion forces <strong>and</strong> associated menace. Under the<br />
Convention of Wetl<strong>and</strong>s, the Chilka Lagoon is the largest saltwater lagoon<br />
in Asia <strong>and</strong> is also an internationally important ecosystem with rich ecobio-diversity<br />
<strong>and</strong> sustainability. The present communication deals with<br />
mangrove dynamics of the Chilka Lagoon during the Holocene using<br />
pollen data. Mangroves are highly susceptible to climatic changes <strong>and</strong><br />
sea-level fluctuations. The development of mangroves is controlled by<br />
l<strong>and</strong>-sea interaction <strong>and</strong> their expansion is determined by the<br />
topography of the sediment surface. Pollen investigation of sediments<br />
indicate existence of a brackish water estuarine mangrove swamp forest<br />
in the lagoon during the Middle Holocene. High sedimentation rate <strong>and</strong><br />
delta progradation probably resulted in the loss of mangrove habitats<br />
during Late Holocene as evidenced by the pollen records. These records<br />
indicate an expansion of fresh water elements <strong>and</strong> contraction of the<br />
mangrove area. It is also observed that mangroves reappeared for a<br />
short span of time during Late Holocene at the study site with return of<br />
estuarine environment, which, however, later gradually degraded from<br />
the area. This degradation is attributed due to climatic changes, relative<br />
sea-level fall <strong>and</strong> probably got further accelerated by anthropogenic<br />
activities.<br />
The Fourth IGCP 588: PREPARING FOR COASTAL CHANGE 21
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