Convenors: John Boyle (University of Liverpool, UK) and John Anderson (University of Loughborough, UK)

This theme draws together recent research activities which quantify either drivers of aquatic ecosystem change (primarily climate, ontogeny and land-use change) or the chemicophysical status of terrestrial-limnic ecosystems (vegetation dynamics, nutrient budget or fluxes, soil paludification and erosion) through the Holocene. New quantitative ecosystem models and methodological developments in biogeochemistry may allow greater understanding of past organic and inorganic material fluxes to lakes, and the impact of these on lake functioning.

A particular emphasis will be on natural (landscape ontogeny) versus anthropogenic influences (land-use change) on carbon and nutrient fluxes and their effect on lake productivity and biological structure, including the development of heterotrophy in lakes, which is a major focus in limnology but has received little attention by palaeolimnologists.

Keynote: Dan Engstrom
Science Museum of Minnesota

S15-KN Paleo-productivity, the Elusive Grail – Integrating the effects of nutrient and DOC loading on lakes over millennial timescales

One of the enduring themes in paleolimnology is the long-term trophic development of lakes – as a consequence of natural or anthropogenic changes in material export from the terrestrial catchment. While we’ve become reasonably proficient at reconstructing material fluxes (nutrients, major ions, sediment) associated with human disturbance, progress on the effects of natural forcing (climate, fire, vegetation and soil development) is more limited largely because of the comparative subtlety of the signals and the complexity of the catchment processes involved. And trophic reconstruction itself has been a particularly elusive grail, owing to the fact that we have no reliable proxy for total ecosystem productivity and because heterotrophic and autotrophic production cannot at present be de-convolved in the sediment record. This presentation will review concepts of lake productivity from a paleo- and neo-limnological perspective and efforts to reconstruct trophic change and its linkages to the transfer of both organic carbon and nutrients from the terrestrial system. Nutrient export, particularly that associated with human activities, has received the greatest attention in our discipline, owing to its obvious effects on autotrophic productivity. However, organic carbon subsidies, which reflect long-term-catchment vegetation succession and soil process, have equally profound effects on biological structure and trophic interactions in aquatic systems. This talk will thus consider the contrasting trajectories and drivers of heterotrophic and autotrophic production in the context of postglacial landscape development, land-use disturbance, and climate change.

List of oral presentations:

• S15-01 John Boyle Long-term dynamics of phosphorus in deglaciated landscapes: combining Holocene lake sediment records with process modelling
• S15-02 Richard Chiverrell Farming, mining and extreme flows: impacts of accelerated sediment flux to Bassenthwaite Lake
• S15-03 Phuong Doan Can sedimentary pigments be used to track ecosystem response to climate change and anthropogenic impacts in Australian lakes? A case study from Tower Hill, Victoria, Australia.
• S15-04 Xuhui Dong Carbon burial by shallow lakes on the Yangtze floodplain and its relevance to regional carbon sequestration

List of poster presentations:

• S15-P-01 Agata Marzecova Paleolimnological perspective on the lake response to anthropogenic impact: multi-proxy analysis of sediment from Lake Lohja, North Estonia
• S15-P-02 Michal Miroslaw Local environmental response of climate change in the Trzechowskie paleolake in northern Poland, during the late glacial and early Holocene
• S15-P-03 Jiang Qingfeng Holocene climate changes in central Asia reflected by multi-proxy records from Sayram Lake, northern Xinjiang, China
• S15-P-04 Izabela Zawiska Lake environment changes as a response to variable climate condition in Preboreal period
• S15-P-05 Jianbao Liu Mineral magnetic study of lacustrine sediments from Gonghai Lake, North China, and its paleoenvironmental significance since the last deglaciation
• S15-P-06 Grzegorz Kowalewski Structuring role of floating islands in floating mat development and shoreline changes in peatland lakes (Tuchola Forest, Poland)
• S15-P-07 Krystyna Milecka Spatial-temporal dynamics of overgrowing of peatland lakes influenced by natural and anthropogenic factors.
• S15-P-08 Samanta Skulmowska The early-Holocene history of Lilla Öresjön
• S15-P-09 Daniela Valentova Sedimentological and geochemical study of the lacustrine deposits of the former Komořany Lake