College of Science Postgraduate Seminar Series 17th June 2014

College of Science Postgraduate Seminar Series - Spring 2014 17th June 2014 - 1pm - Zoology Museum (Wallace)

Speaker 1

THE DEGLACIATION OF SOUTHEAST GREENLAND: SYNCHRONICITY AND DRIVING MECHANISMS.

Laurence Dyke

(PhD student, Swansea University, UK)

Laurence is a PhD student as a part of the Glaciology Group, interested in reconstructions of past glacial extent and behaviour, primarily from the late Quaternary. Supervised by Tavi Murray, John Hiemstra and Anna Hughes (Bergen), he came to Swansea in 2005 to study for a BSc in Geography, a field trip to the Austrian mountains kindled a passion for glaciers and he returned in 2010 to start a PhD researching the glacial history of southeast Greenland.

The Greenland ice sheet contains enough freshwater to raise global sea-level by around 7 metres. Recent observations of rapid changes in the marine-terminating sectors of the ice sheet have prompted concerns about its future stability. Long-term records of ice sheet behaviour are required to assess the magnitude of current change and may help resolve the mechanisms driving deglaciation. 

We use cosmogenic isotope exposure dating to reconstruct the timing of deglaciation in southeast Greenland. We develop retreat chronologies for two large fjord systems and compare them with existing work from the centre of the sector to examine the timing and style of deglaciation at a regional-scale. 

Deglaciation occurred at Kangerdlugssuaq Fjord at 11.8 ka at the end of the Younger Dryas (12.8-11.6 ka). Retreat coincides with incursion of the warm Irminger Current onto the continental shelf; this is inferred to have initiated retreat. Deglaciation occurred around 1 ka later in the south of the sector at Sermilik and Bernstorffs Fjords; retreat here was driven by dramatic climatic amelioration at the termination of the Younger Dryas stadial. 

We suggest the disparate timing of deglaciation across the SE region may be explained primarily by the varying influence of the warm Irminger Current; glaciers in southern SE Greenland were isolated from warm Atlantic waters during the Younger Dryas by complex shelf bathymetry. Once initiated retreat was rapid and persistent in all fjord systems. 

Speaker 2

The Early life at sea of juveniles albatrosses and petrels

Sophie De Grissac

(PhD student, Chizé Centre for Biological Studies)

Sophie graduated in Marine Ecology (2009) after a 6 month internship with the CEBC Chizé (Centre d’Etude Biologiques de Chizé) were she worked on the impact of wind pattern changes on wandering albatrosses foraging ecology. Between 2010 and 2013 she was a field worker for the CEBC Chizé “Marine top predators” team and for the French Subantarctic Islands Natural Reserve.

In September 2013, Sophie started a PhD entitled “At sea ecology of albatross juveniles” as part of the ERC granted Early Life program lead by Henri Weimerskich at Centre d’Etudes Biologiques de Chizé.

Sophie proposes to talk in two parts. 1) A rapid presentation of the ERC Early Life project leaded by Henri Weimerskirch and 2) A presentation of the first part of my PhD (within Early Life), first results and perspectives.

In long lived species, juveniles and immatures, represent up to 50% of the total population. Therefore, in order to understand the dynamics of those populations, it is essential to better understand their foraging ecology that remains, until recently, poorly known. We tracked the juveniles of nine species of Procellariiformes in the Southern Ocean during their first month at sea in order to examine how their foraging strategy differ from that of adults, and how they differ between species  whose adults show contrasted foraging habits. (1) We use analyze trajectory parameters in order to characterise and compare the different foraging strategies. Within species, birth colony and sex can affect individual strategy and foraging zones. (2) We find that species differ extensively from dispersive to true migratory behaviour. Most juveniles of each species follow, the migration or dispersion patterns of non-breeding adults, showing,an innate ability for navigation toward preferred foraging places. However, for two species we observe a clear contrast between foraging strategies of adult and juveniles. Important sex specific differences also occur for some species. We discuss the implication of these results in terms of the evolution of the foraging behavioir of naïve individuals.