Seminar Room 1, Geographical Sciences
This BRIDGE seminar will consist of two short talks as outlined below.
Please note this event is only open to University of Bristol staff and students.
Diksha Bista - A Sr isotope record of the Early Pleistocene Caspian Sea: Implications for the Caspian-Arctic connectivity
The Caspian Sea, together with the Black Sea, was once part of the Eastern Paratethys Sea until continental uplift during the late Miocene restricted and fragmented the Eastern Paratethys Sea into individual subbasins. Since the fragmentation, the Caspian Sea has been an isolated basin with periodic reconnection to the Mediterranean Sea and Open Ocean via the Black Sea. As a result, these basins have developed a unique biodiversity that has Paratethyan, open marine as well as freshwater ancestry. In addition, Caspian Sea also harbours some species that has Arctic origin. The Arctic element in the Caspian Sea is resultant from a connection between the Arctic Ocean and the Caspian Sea during the Pliocene ? Pleistocene time, however, the exact timing for this connection is uncertain. Here I will present Sr isotopic ratios measured on fossil ostracods collected from the marginal Caspian Sea section together with the salinity estimates deduced from the paleontological data to explore the link between the Caspian Sea, Black Sea and the Arctic Ocean between 2.6 and 1.9 Ma.
Charuni Pathmeswaran -Impact of extreme weather events on coconut productivity in three climatic zones of Sri Lanka
Coconut is a major plantation crop in Sri Lanka, a tropical island in the Indian Ocean. The highest coconut production is found in Gampaha, Kurunegala and Puttalam districts which belong to the wet, intermediate and dry zones respectively. An increase in the frequency of extreme weather events has been observed during the recent past. This study, the first of its kind, was undertaken to assess the impact of extreme events on coconut productivity. Meteorological and coconut productivity data were obtained for the period 1995-2015 from six estates, two estates representing each of the above-mentioned districts. Extreme events were defined using maximum daily temperature (Tmax) and daily rainfall. The 90th percentiles of the daily distribution of rainfall and Tmax in the reference period were used to define high rainfall and high temperature days respectively. The days with their rainfall below the 10th percentile were defined as low rainfall days. Regression analyses between coconut productivity and the number of extreme events during the first four months after flowering were performed. In the dry zone the number of high rainfall and high Tmax days during the said period had a negative influence on productivity and the mean rainfall had a positive influence on productivity. In the intermediate zone the number of high rainfall events and the mean Tmax of the same period had a negative impact on coconut productivity. In the wet zone, while the number of extreme weather events had no influence on the coconut productivity, the mean Tmax during the first four months since flowering had a negative impact on coconut productivity.