Ecosystem functioning along gradients of increasing hypoxia and changing soft-sediment community types
Journal article, 2019

Marine ecosystems world-wide are threatened by oxygen deficiency, with potential serious consequences for ecosystem functioning and the goods and services they provide. While the effects of hypoxia on benthic species diversity are well documented, the effects on ecosystem function have only rarely been assessed in real-world settings. To better understand the links between structural changes in macro- and meiofaunal communities, hypoxic stress and benthic ecosystem function (benthic nutrient fluxes, community metabolism), we sampled a total of 11 sites in Havstensfjord and Askeröfjord (Swedish west coast) in late summer, coinciding with the largest extent and severity of seasonal hypoxia in the area. The sites spanned oxic to anoxic bottom water, and a corresponding gradient in faunal diversity. Intact sediment cores were incubated to measure fluxes of oxygen and nutrients (NO3−, NO2−, NH4+, PO43−, SiO4) across the sediment-water interface. Sediment profile imaging (SPI) footage was obtained from all sites to assess structural elements and the bioturbation depth, and additional samples were collected to characterise sediment properties and macro- and meiofaunal community composition. Bottom-water O2 concentration was the main driver of macrofauna communities, with highest abundance and biomass, as well as variability, at the sites with intermediate O2 concentration. Meiofauna on the other hand was less sensitive to bottom-water O2 concentration. Oxygen was the main driver of nutrient fluxes too, but macrofauna as well meiofauna were also significant predictors; DistLM analyses indicated that O2 concentration, macrofaunal abundance or biomass, and meiofaunal abundance collectively explained 63%, 30% and 28% of the variation in sediment O2 consumption, NH4+flux and PO43− flux, respectively. The study provides a step towards a more realistic understanding of the link between benthic fauna and ecosystem functioning, and the influence of disturbance on this relationship, which is important for management decisions aimed at protecting the dwindling biodiversity in the coastal zones around the world.


Ecosystem functioning

Structural community changes


Nutrient cycling



Joanna Norkko

Tvärminne Zoological Station

Conrad A. Pilditch

University of Waikato

Johanna Gammal

Tvärminne Zoological Station

Rutger Rosenberg

University of Gothenburg

A. Enemar

University of Gothenburg

Marina Magnusson

Marine Monitoring AB

Maria E. Granberg

IVL Swedish Environmental Research Institute

Fredrik Lindgren

Chalmers, Mechanics and Maritime Sciences, Maritime Studies, Maritime Environmental Sciences

Stefan Agrenius

University of Gothenburg

Alf Norkko

Tvärminne Zoological Station

Stockholm University

Journal of Sea Research

1385-1101 (ISSN)

Vol. 153 101781

Subject Categories


Oceanography, Hydrology, Water Resources

Environmental Sciences



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