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Kristina Sundbäck

About Kristina Sundbäck

Benthic ecology, microbenthos, microbial ecology, multiple stressors My research deals with the benthic ecology of shallow-water, illuminated sediments, particularly the role of microbenthic communities (microalgae, bacteria and microscopic fauna) in the carbon and nutrient cycling. The response and recovery of these shallow-water ecosystems when exposed to anthropogenic impacts, such as changed nutrient load, raised temperature due to climate change, physical disturbance, and toxicants, alone or in combination, are assessed.

Current projects

Nutrient COCktails in COAstal zones of the Baltic Sea (COCOA) The BONUS project COCOA is a multidisciplinary project aiming at studying the role of the coastal zone as a ”filter” between land and sea. Nutrients are transformed and removed in a complex mosaic of processes by microbial communities, plants and animals with environmental conditions modulating the process rates.Together with professor Stefan Hulth (Dept of Chemistry and molecular Biology), we lead a work package that studies specifically the role of plants in the coastal filter and their influence on the biogeochemical processes at the sediment–water interface. Dr. Karl Norling and Dr. Christian Alsterberg are co-workers (Dept of Biological and Environmental Sciences). Different types of coastal areas are considered (river-dominated estuaries, lagoons, embayments and archipelagos) along the Baltic coast and the results will be used to improve the process description in current coastal models. In COCOA, 14 institutes from 8 countries are participating and the project is co-ordinated by the University of Århus in Denmark. Consequences of a potential loss of coastal nutrient retention will affect nutrient reduction targets in the Baltic Sea Action Plan required to establish HELCOM´s ecological objectives.

Response of shallow-water illuminated sediments to single and multiple stressors, including global change Within this project, funded by FORMAS, we have focused on the sensitivity of shallow-water sediments to local, regional and global environmental changes. The emphasis is on the role of microbially mediated key ecological functions and characters (primary production, trophic status, mineralization, nutrient cycling, nitrogen retention and removal, as well as the biodiversity of the benthic communities). In this experimental work, natural intact sediments are manipulated in flow-through mesocosms, under natural variation of light and temperature. Stressors include changed nutrient load, toxicants, hypoxia increased sedimentation, warming and acidification. I appears that benthic microalgae play an important role in the recovery of the sediment system after temporary disturbance events, thereby contributing to the resilience of the shallow-water sediment system and a general buffering against environmental changes. This function appears to be related to the resistance of benthic diatoms to e.g. hypoxia and anoxia, and to their rapid re-oxygenation of the sediment surface. Funding is manily from FORMAS and research has been done in collaboration with Department of Chemistry at GU, and NERI in Denmark

Role of shallow-water sediments as sinks and sources of nitrogen in the coastal zone Shallow-water illuminated sediments constitute an important functional part of the "coastal filter" where nutrients are transformed, retained and removed by processes mainly driven by autotrophic and heterotrophic microorganisms. The trophic state of the sediment (balance between oxygen production and consumption) largely decides whether the sediment functions as a sink or source of nitrogen. Focus is on the biogeochemistry and microbially mediated processes of the sediment system and their response to environmental changes, such and warming in combination with regional stressors. The role of dissolved organic nitrogen (DON) in the N-turnover and as a nitrogen source for benthic microalgae has also been studied. Dissolved free amino acids can constitute an important N source for benthic microalgae when the availability of dissolved inorganic nitrogen is limited. In co-operation with the County administration of Västra Götaland, management issues related to shallow coastal bays are approached. In a recent study, the balance between nitrogen fixation of N2 by benthic microbial mats (mainly cyanobacteria) and nitrogen removal by denitrification is studied to better understand the effect of managing nutrient loads to shallow bays.

Current collaborations:

Professor Stefan Hulth GU Dr Christian Alsterberg GU

Professor Sara Hallin SLU

Lars Gamfeldt GU