The Mediterranean Sea during the Pleistocene - bivalve shells and their potential to reconstruct decadal and seasonal climate signals of the past

Master Thesis subject (30 ECTS)
Understanding the climate of the past is essential for anticipating future climate change and its impact on marine ecosystems. Palaeoclimatic archives are the key to the past, but few marine archives (including tropical corals) combine long recording times (decades to centuries) with high temporal resolution (intra-annual). The bivalve Arctica islandica is a particularly unique bio-archive owing to its wide distribution throughout the North Atlantic and its extreme longevity (up to 500 years). This master project will focus on fossil A. islandica shells derived from the Pleistocene (1.78-0.8 million years ago) Stirone River (Mediterranean Sea, Italy) location. The main objective will be to utilize the full potential of these shell archives to answer palaeo-environmental and palaeo-climatic questions from a seasonal to multi-year perspective. There are three particular tasks: (i) reconstruction of the seasonal water temperature amplitude, (ii) identification of decadal patterns in shell growth, (iii) establishment of a shell growth model. The first part of the project will focus on the preservation of the shell material (by means of confocal Raman microscopy) and the reconstruction of the seasonal water temperature amplitude, which will be derived from stable oxygen isotope (δ18O) measurements (micro-milling and Isotope Ratio Mass Spectrometry). For the second part of the project (tasks (ii) and (iii)), the widths of the annual shell growth increments will be used to create individual shell chronologies. Statistical methods (such as singular spectrum analysis, Multitaper method and wavelet transformation) will then be used to identify potential multi-year signals, such as the North Atlantic Oscillation (NAO). Shell growth models will be established by means of standard approaches from population dynamics. The findings will then be considered within a bigger (global) picture and used to answer specific scientific questions from a regional scale (e.g., ecology) to a larger scale (e.g., ocean-atmosphere phenomena).
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Prof. Dr. Thomas Brey
Reference Number: RP-35262