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Eva Ehrnsten, foto: Niklas Björling/SU

Eva Ehrnsten

Doktorand

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Arbetar vid Stockholms universitets Östersjöcentrum
E-post eva.ehrnsten@su.se
Besöksadress Svante Arrhenius väg 20 F, plan 5
Postadress Stockholms universitets Östersjöcentrum 106 91 Stockholm

Om mig

I am a PhD student in marine ecology working jointly at Tvärminne Zoological Station, University of Helsinki and the Baltic Sea Centre of Stockholm University.

In my thesis, I study ecosystem dynamics of the Baltic Sea focusing on bottom-living invertebrate animals and plants in the coastal zone. I also look at how the joint effects of climate change and human-induced pressures such as nutrient loads might change functioning of the benthic system and the ecosystem services it provides.

Previously I have worked with mapping underwater nature and management of coastal habitats (VELMU and NANNUT projects), as well as minimizing the ecological effects of oil spills in coastal areas (OILRISK project).

Publikationer

I urval från Stockholms universitets publikationsdatabas
  • 2019. Eva Ehrnsten (et al.). Journal of Marine Systems 196, 36-47

    Benthic macrofauna is an important component linking pelagic and benthic ecosystems, especially in productive coastal areas. Through their metabolism and behaviour, benthic animals affect biogeochemical fluxes between the sediment and water column. Mechanistic models that quantify these benthic-pelagic links are imperative to understand the functioning of coastal ecosystems. In this study, we develop a dynamic model of benthic macrofauna to quantify the relationship between organic matter input and benthic macrofaunal biomass in the coastal zone. The model simulates the carbon dynamics of three functional groups of benthic macrofauna and their sediment food sources and is forced by a hydrodynamic-biogeochemical model simulating pelagic physical and biological dynamics. The model reproduces measured time-series of macrofaunal biomass from two coastal sites with contrasting sedimentation in the Baltic Sea in 1993-2005 with comparatively high accuracy, including a major increase at one of the sites dominated by the bivalve Limecola (Macoma) balthica. This shift in community composition suggests altered pathways of organic matter degradation: 39% of simulated sedimentation was mineralised by macrofauna in 2005 compared to 10% in 1995. From the early 2000s onward macrofaunal biomass seems to be food-limited, as ca 80% of organic carbon sedimentation was processed by the deposit-feeding macrofauna at both sites. This model is a first step to help quantify the role of macrofauna in marine coastal ecosystem functioning and biogeochemical cycles and build predictive capacity of the effects of anthropogenic stressors, such as eutrophication and climate change, on coastal ecosystems.

  • 2019. Eva Ehrnsten, Barbara Bauer, Bo G. Gustafsson. Frontiers in Marine Science 6

    The responses of food webs to simultaneous changes in several environmental drivers are still poorly understood. As a contribution to filling this knowledge gap, we investigated the major pathways through which two interlinked environmental drivers, eutrophication and climate, affect the biomass and community composition of fish and benthic macrofauna. For this aim, we conducted a systematic sensitivity analysis using two models simulating the dynamics of benthic and pelagic food webs in the Baltic Sea. We varied environmental forcing representing primary productivity, oxygen conditions and water temperature in all possible combinations, over a range representative of expected changes during the 21st century. Both models indicated that increased primary productivity leads to biomass increase in all parts of the system, however, counteracted by expanding hypoxia. Effects of temperature were complex, but generally small compared to the other drivers. Similarities across models give confidence in the main results, but we also found differences due to different representations of the food web in the two models. While both models predicted a shift in benthic community composition toward an increased abundance of Limecola (Macoma) balthica with increasing productivity, the effects on deposit-feeding and predatory benthic groups depended on the presence of fish predators in the model. The model results indicate that nutrient loads are a stronger driver of change for ecosystem functions in the Baltic Sea than climate change, but it is important to consider the combined effects of these drivers for proper management of the marine environment.

Visa alla publikationer av Eva Ehrnsten vid Stockholms universitet

Senast uppdaterad: 17 januari 2020

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