Phytoplankton community structure, photophysiology and primary production in the Atlantic Arctic

• Main Author: Jackson, T
• Other Authors: Bouman, H, Sathyendranath, S, Tilstone, G
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: Geobiology; Biological Oceanography; Biodiversity; Polar; Arctic; Arctic Ocean; Greenland; Atlantic Arctic; Atlantic-Arctic; Climate change; Greenland Sea; Phytoplankton; Sea ice
• Online Access: https://ora.ox.ac.uk/objects/uuid:a4de300a-992d-4f22-bb7e-16a1225fc810

The Arctic is a region undergoing unprecedented and unequivocal climate change. The seas of this extreme region form a major component of the oceanic thermohaline conveyor and natural carbon cycle. Using a combination of recent and historical datasets this study examines the distribution, diversity, photophysiology and primary productivity of phytoplankton in the Atlantic sector of the Arctic Ocean. CHEMTAX analysis reveals a diverse phytoplankton community structure in the Greenland Sea comprising six main phytoplankton groups. The influence of sea-ice and water column stratification are key factors in the presence or absence of groups such as haptophytes and prasinophytes. Group-specific differences are observed in spectral absorption and photophysiological parameters. However, the influence of environmental factors has a stronger influence than taxonomic composition on photophysiology. A clear division between the photoacclimatory response of algal communities beneath sea-ice and those of open-ocean stations is predominantly due to ‘Ek independent’ photoacclimation beneath sea-ice. This occurs due to the combined effect of sea-ice decreasing irradiance entering the water column and a positive correlation between Pm B and temperature. This variation in photophysiology is important for primary production models as a sensitivity analysis shows that errors in these parameters propagate to give the largest final errors in primary production values. The importance of other model parameters varies with the level of biomass in the water column and the presence or absence of sea ice. Accelerated ice-melt and an increase in open water due to climate change are likely to increase primary production in the Atlantic Arctic alongside an altered distribution of phytoplankton groups, with an increase in the importance of prasinophytes or haptophytes.