The extent of sea-ice and its interactions with biological and physical processes in the Southern Ocean play a key role in regulating atmospheric greenhouse gases, such as carbon dioxide, over glacial-interglacial timescales. Understanding how sea-ice influences these processes is essential for our understanding of recent climate change and for modelling of future climates. Much of our insight into past climates originates from the use of geochemical proxies, which relate to environmental parameters such· as temperature, salinity, pH and carbonate chemistry. The stable isotope and trace metal compositions of foraminiferal calcite are widely used, and of diatom opal to a lesser extent, as palaeothermometers and palaeonutrient indicators. However, these geochemical proxies are complex and exhibit multiple controls, resulting in apparently conflicting interpretations. In particular, we need to improve our understanding of the influence of sea-ice and low temperatures on these microalgae. The objective of this thesis is to investigate the impact of seasonal sea-ice on trace metals and geochemical proxies as part of a larger, three year field campaign of water and sediment sampling off the West Antarctic Peninsula. This thesis demonstrates tl1e key roles played by the Southern Ocean sea-ice environment in the availability of trace metals over a range of timescales. On a seasonal timescale, changes in populations during the intense high latitude summer blooms influence algal trace metal requirements and uptake. On annual and interannual timescales, sea-ice influences stable isotop.e and trace metal uptake by foraminifera and diatoms. Finally, processes within meltwater zones significantly influence past nutrient and freshwater budgets from centennial to glacial-interglacial timescales.