Ecosystem functioning along gradients of increasing hypoxia and changing soft-sediment community types
Artikel i vetenskaplig tidskrift, 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.

Macrofauna

Ecosystem functioning

Structural community changes

Hypoxia

Nutrient cycling

Meiofauna

Författare

Joanna Norkko

Tvärminne Zoological Station

Conrad A. Pilditch

University of Waikato

Johanna Gammal

Tvärminne Zoological Station

Rutger Rosenberg

Göteborgs universitet

A. Enemar

Göteborgs universitet

Marina Magnusson

Marine Monitoring AB

Maria E. Granberg

IVL Svenska Miljöinstitutet

Fredrik Lindgren

Chalmers, Mekanik och maritima vetenskaper, Maritima studier, Maritim miljövetenskap

Stefan Agrenius

Göteborgs universitet

Alf Norkko

Tvärminne Zoological Station

Stockholms universitet

Journal of Sea Research

1385-1101 (ISSN)

Vol. 153 101781

Ämneskategorier

Ekologi

Oceanografi, hydrologi, vattenresurser

Miljövetenskap

DOI

10.1016/j.seares.2019.101781

Mer information

Senast uppdaterat

2019-11-08