Benthic contribution to whole-lake production in southwest Greenland: A palaeoecological perspective

• Main Author: Keechy Akkerman
• Format: Thesis
• Language: unknown
• Published: 2022
• Subjects: Earth Sciences not elsewhere classified; Palaeoecology; Diatoms; Lakes; Arctic; Greenland; Production
• Online Access: https://doi.org/10.26174/thesis.lboro.19799230.v1; https://figshare.com/articles/thesis/Benthic_contribution_to_whole-lake_production_in_southwest_Greenland_A_palaeoecological_perspective/19799230

Arctic aquatic ecosystems are typically strongly nutrient-limited and are sensitive to change over a range of timescales. These systems are recognised as being increasingly affected by recent environmental and climatic changes, both in terms of primary productivity and whole ecosystem function. Biological (primary producers, such as diatoms) and geochemical proxy data from sedimentary archives can be used as valuable tools to infer past ecological response to environmental and climate changes at high temporal resolution and give insight into how these critical ecosystems might respond in the future. Sediment cores are usually taken from the deepest part of the lake, where sediment focussing leads to greater sediment accumulation. However, due to uneven sediment redistribution, this often leads to quantitative and qualitative underrepresentation of the littoral communities. This has major implications for the interpretation of diatom records based on a single, central sediment core, especially since nutrient-poor conditions and high water transparency in many Arctic lakes result in a relatively high contribution of benthic primary production to whole-lake productivity. Therefore, this thesis criticises the representativeness of using one sediment core for whole-lake diatom production reconstructions in the Arctic. This thesis provides a bridge between contemporary research on algal habitat variability in the Arctic and how this is represented in the sedimentary archive as a means to improve our understanding of both recent and longer-term ecological change in Arctic lakes. For this, the spatial distribution of periphytic diatoms was analysed, as well as the diatom assemblage in surface sediments and multiple (3-5) sediment cores in three lakes in southwest Greenland. Furthermore, a correction was calculated for benthic, planktonic and total whole-lake diatom productivity, as well as for relative abundances of individual taxa, and these improved inferences were used to separate local from regional drivers of lake ...