Bioturbation-driven release of sediment-associated contaminants in the Baltic Sea mediated by the invading polychaete Marenzelleria neglecta

• Baltic Sea sediments are among the world’s most polluted regarding eutrophication and contamination. Eutrophicationinduced hypoxia hascauseddepletion of bioturbatingmacrofauna in vast areas, producing laminated sediments. We investigated if reoxygenation and colonization by the invading deepburrowing polychaete Marenzelleria neglecta may cause an augmented contaminant release from Baltic Sea sediments. Intact laminated sediment cores were exposed either to in situ hypoxia, reoxygenation, or reoxygenation combined with bioturbating M. neglecta. The release fluxes of particleassociated (NPart) and dissolved (NDiss) PCBs and chlorinated pesticide residues (POPs) were quantified (GC-ECD) after 85 d along with contaminant concentrations in sediment and biota. Lavoisier-based mass transfer coefficients (Kf) were calculated from NDiss. Sediment contaminant concentrations were high (ΣPCB7: 42–52 ng gsediment -1 dw) due to emissions from Stockholm. NDiss always exceeded NPart by an order of magnitude. Bioturbation enhanced NDiss and Kf from hypoxic sediments 0.7 – 3 times while reoxygenation alone had no significant effect. M. neglecta accumulated low amounts of contaminants but significantly stimulated aquatic release of bioavailable sequestered contaminants. Bioturbation should be included in aquatic contaminant fate models. We advise to consider quiescent pollutant sources and possible ecological shiftswhenaimingtorestoreeutrophicatedaquaticenvironments.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

sediment

ecotoxicology

invading species

baltic sea

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