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Title [en]
Response and recovery of benthic biodiversity and ecosystem functions to chemical pollution and eutrophication
Abstract [en]
Society and ecological health depend on ecological processes and functions, the so-called ecosystem functions. These functions are essential for all levels of organisms and a result of their interactions with the environment. Benthic habitats, some of the most productive and diverse ecosystems on Earth, are of global importance for biogeochemical cycles. Each of the three major benthic communities, macrofauna, meiofauna and microorganisms, have key roles in these processes. Currently, the anthropogenic pressures from nutrient overloading with oxygen depletion and pollution by heavy metals are potent threats to the diversity and functioning of these communities in the Baltic Sea and ultimately on the provision of ecosystem goods and services, that affect human wellbeing of societies in this region. Crucial, unanswered questions within Baltic Sea ecology are how anthropogenic pressure affects benthic community structure and how interactions between macrofauna, meiofana and microbial community mediate sediment ecosystem functions under different environmental conditions. To bridge these knowledge gaps, this project will examine how Baltic Sea sediment meiofauna, the most diverse and abundant metazoans in aquatic sediment, and microbial diversity interact and are structured by double exposure to two important stressors, hypoxia and cadmium exposure. The project will investigate how and to what extent this affects important benthic ecosystem functions relevant to sediment nitrogen cycling. Taking advantage of the multidisciplinary range of expertise of the three candidates, analyses will combine ecological, ecotoxicological, biogeochemical methods and environmental genomics approaches. Drawing on insurance and resilience theory this project will investigate if the loss of diversity in the sediment communities reduces the resilience and recovery of benthic ecosystems processes. Outcomes will directly relate to the directives initiated by the European community, the Water Framework Directive and the Marine Strategy Framework Directive and the Baltic Sea Action Plan that address diversity of bioindicators, chemical status and quality of the marine environment to achieve Good Environmental Status in regards to qualitative descriptors, including biological diversity, eutrophication and contaminants.
Publications (6 of 6) Show all publications
Abdelgadir, M., Alharbi, R., AlRashidi, M., Alatawi, A. S., Sjöling, S. & Dinnétz, P. (2023). Distribution of denitrifiers predicted by correlative niche modeling of changing environmental conditions and future climatic scenarios across the Baltic Sea. Ecological Informatics, 78, Article ID 102346.
Open this publication in new window or tab >>Distribution of denitrifiers predicted by correlative niche modeling of changing environmental conditions and future climatic scenarios across the Baltic Sea
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2023 (English)In: Ecological Informatics, ISSN 1574-9541, E-ISSN 1878-0512, Vol. 78, article id 102346Article in journal (Refereed) Published
Abstract [en]

Denitrifying microbial communities provide an important ecosystem function in aquatic systems. Yet, knowledge on predictive and modeling of these complex and changing communities is limited. The emergently challenging question of how the geographical distribution of denitrifiers responds to ongoing and future environmental change is not yet fully understood. In our study we use metadata-based correlative niche modeling to analyze the geographical distribution of selected putative denitrifiers in the genus Sphingomonas, Mycoplana, Shewanella, and Alteromonas at different predicted environmental conditions and future climatic scenarios across the Baltic Sea. Using the predictive power of an ensemble modeling approach and eight different machine-learning algorithms, habitat suitability and the distribution of the selected denitrifiers were evaluated using geophysical and bioclimatic variables, benthic conditions, and four Representative Concentration Pathway (RCP) trajectories of future global warming scenarios. All algorithms provided successful prediction capabilities both for variable importance, and for habitat suitability with Area Under the Curve (AUC) values between 0.89 and 1.00. Model findings revealed that salinity and nitrate concentrations significantly explained the variation in distribution of the selected denitrifiers. Rising temperatures of 0.8 to 1.8 °C at future RCP60–2050 trajectories are predicted to diminish or eliminate the bioclimatic suitable habitats for denitrifier distributions across the Baltic Sea. Multi-collated terrestrial and marine environmental variables contributed to the successful prediction of denitrifier distributions within the study area. The correlative niche modeling approach with high AUC values presented in the study allowed for accurate projections of the future distributions of the selected denitrifiers. The modeling approach can be used to improve our understanding of how ongoing and predicted future environmental changes may affect habitat suitability for organisms with denitrification capacity across the Baltic Sea.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Climate change, Benthic conditions, Ensemble modeling, Habitat suitability, Machine-learning, Multi-collated variables
National Category
Environmental Sciences
Research subject
Environmental Studies; Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-52629 (URN)10.1016/j.ecoinf.2023.102346 (DOI)001109366700001 ()2-s2.0-85176443244 (Scopus ID)
Funder
The Foundation for Baltic and East European Studies, 77/2017
Available from: 2023-11-07 Created: 2023-11-07 Last updated: 2023-12-18Bibliographically approved
Broman, E., Abdelgadir, M., Bonaglia, S., Forsberg, S. C., Wikström, J., Gunnarsson, J. S., . . . Sjöling, S. (2023). Long-Term Pollution Does Not Inhibit Denitrification and DNRA by Adapted Benthic Microbial Communities. Microbial Ecology, 86, 2357-2372
Open this publication in new window or tab >>Long-Term Pollution Does Not Inhibit Denitrification and DNRA by Adapted Benthic Microbial Communities
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2023 (English)In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 86, p. 2357-2372Article in journal (Refereed) Published
Abstract [en]

Denitrification in sediments is a key microbial process that removes excess fixed nitrogen, while dissimilatory nitrate reduction to ammonium (DNRA) converts nitrate to ammonium. Although microorganisms are responsible for essential nitrogen (N) cycling, it is not yet fully understood how these microbially mediated processes respond to toxic hydrophobic organic compounds (HOCs) and metals. In this study, we sampled long-term polluted sediment from the outer harbor of Oskarshamn (Baltic Sea), measured denitrification and DNRA rates, and analyzed taxonomic structure and N-cycling genes of microbial communities using metagenomics. Results showed that denitrification and DNRA rates were within the range of a national reference site and other unpolluted sites in the Baltic Sea, indicating that long-term pollution did not significantly affect these processes. Furthermore, our results indicate an adaptation to metal pollution by the N-cycling microbial community. These findings suggest that denitrification and DNRA rates are affected more by eutrophication and organic enrichment than by historic pollution of metals and organic contaminants.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Baltic Sea, Chlorinated dibenzofurans, Dioxins, Metagenome, Nitrogen cycling, Sediment
National Category
Microbiology
Research subject
Environmental Studies; Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-51571 (URN)10.1007/s00248-023-02241-7 (DOI)000994100600004 ()37222807 (PubMedID)2-s2.0-85160251009 (Scopus ID)
Funder
The Foundation for Baltic and East European Studies, 77/2017Swedish Environmental Protection Agency, 2020–0002Swedish Geotechnical Institute, 1.1–1602-0106
Available from: 2023-06-01 Created: 2023-06-01 Last updated: 2023-11-24Bibliographically approved
Albert, S., Hedberg, P., Motwani, N. H., Sjöling, S., Winder, M. & Nascimento, F. J. (2021). Phytoplankton settling quality has a subtle but significant effect on sediment microeukaryotic and bacterial communities. Scientific Reports, 11(1), Article ID 24033.
Open this publication in new window or tab >>Phytoplankton settling quality has a subtle but significant effect on sediment microeukaryotic and bacterial communities
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2021 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, no 1, article id 24033Article in journal (Refereed) Published
Abstract [en]

In coastal aphotic sediments, organic matter (OM) input from phytoplankton is the primary food resource for benthic organisms. Current observations from temperate ecosystems like the Baltic Sea report a decline in spring bloom diatoms, while summer cyanobacteria blooms are becoming more frequent and intense. These climate-driven changes in phytoplankton communities may in turn have important consequences for benthic biodiversity and ecosystem functions, but such questions are not yet sufficiently explored experimentally. Here, in a 4-week experiment, we investigated the response of microeukaryotic and bacterial communities to different types of OM inputs comprising five ratios of two common phytoplankton species in the Baltic Sea, the diatom Skeletonema marinoi and filamentous cyanobacterium Nodularia spumigena. Metabarcoding analyses on 16S and 18S ribosomal RNA (rRNA) at the experiment termination revealed subtle but significant changes in diversity and community composition of microeukaryotes in response to settling OM quality. Sediment bacteria were less affected, although we observed a clear effect on denitrification gene expression (nirS and nosZ), which was positively correlated with increasing proportions of cyanobacteria. Altogether, these results suggest that future changes in OM input to the seafloor may have important effects on both the composition and function of microbenthic communities.

Place, publisher, year, edition, pages
Springer Nature, 2021
National Category
Ecology
Research subject
Environmental Studies; Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-47894 (URN)10.1038/s41598-021-03303-x (DOI)000730739800052 ()34911983 (PubMedID)2-s2.0-85121378825 (Scopus ID)
Funder
Swedish Research Council Formas, 2016-00804Swedish Research Council Formas, 2015-1320The Foundation for Baltic and East European Studies, 77/2017
Available from: 2021-12-21 Created: 2021-12-21 Last updated: 2022-09-15Bibliographically approved
Broman, E., Motwani, N. H., Bonaglia, S., Landberg, T., Nascimento, F. J. & Sjöling, S. (2019). Denitrification responses to increasing cadmium exposure in Baltic Sea sediments. Aquatic Toxicology, 217, Article ID 105328.
Open this publication in new window or tab >>Denitrification responses to increasing cadmium exposure in Baltic Sea sediments
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2019 (English)In: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 217, article id 105328Article in journal (Refereed) Published
Abstract [en]

Benthic ecosystems have come under intense pressure, due to eutrophication-driven oxygen decline and industrial metal contamination. One of the most toxic metals is Cadmium (Cd), which is lethal to many aquatic organisms already at low concentrations. Denitrification by facultative anaerobic microorganisms is an essential process to transform, but also to remove, excess nitrate in eutrophied systems. Cd has been shown to decrease denitrification and sequester free sulfide, which is available when oxygen is scarce and generally inhibits complete denitrification (i.e. N2O to N2). In polluted sediments, an interaction between oxygen and Cd may influence denitrification and this relationship has not been studied. For example, in the Baltic Sea some sediments are double exposed to both Cd and hypoxia. In this study, we examined how the double exposure of Cd and fluctuations in oxygen affects denitrification in Baltic Sea sediment. Results show that oxygen largely regulated N2O and N2 production after 21 days of exposure to Cd (ranging from 0 to 500 μg/L, 5 different treatments, measured by the isotope pairing technique (IPT)). In the high Cd treatment (500 μg/L) the variation in N2 production increased compared to the other treatments. Increases in N2 production are suggested to be an effect of 1) enhanced nitrification that increases NO3 − availability thus stimulating denitrification, and 2) Cd successfully sequestrating sulfide (yielding CdS), which allows for full denitrification to N2. The in situ field sediment contained initially high Cd concentrations in the pore water (∼10 μg/L) and microbial communities might already have been adapted to metal stress, making the effect of low Cd levels negligible. Here we show that high levels of cadmium pollution might increase N2 production and influence nitrogen cycling in marine sediments. © 2019 The Authors

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Baltic Sea, Benthos, Denitrification, Hypoxia, Oxygen, Pollution, Sediment
National Category
Environmental Sciences
Research subject
Environmental Studies; Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-39283 (URN)10.1016/j.aquatox.2019.105328 (DOI)000501413700002 ()31629202 (PubMedID)2-s2.0-85073170054 (Scopus ID)3150-3.1.1-2017 (Local ID)3150-3.1.1-2017 (Archive number)3150-3.1.1-2017 (OAI)
Funder
The Foundation for Baltic and East European Studies, 77/2017
Available from: 2019-10-31 Created: 2019-10-31 Last updated: 2023-06-01Bibliographically approved
Sommer, C., Hu, Y., Nascimento, F., Gunnarsson, J., Dinnétz, P. & Sjöling, S. (2019). Reduced large-scale beta-diversity and changes in metapopulation patterns of sediment bacterial communities following a major inflow into the Baltic Sea. Environmental Microbiology
Open this publication in new window or tab >>Reduced large-scale beta-diversity and changes in metapopulation patterns of sediment bacterial communities following a major inflow into the Baltic Sea
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2019 (English)In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920Article in journal (Other academic) Submitted
Abstract [en]

The Baltic Sea is heavily affected by eutrophication caused by nutrient overload, climate, and infrequency in major inflow events, resulting in widespread areas of oxygen depleted waters and sediments. A Major Baltic Inflow event (MBI) brings saline and oxygenated Atlantic Ocean water into the Baltic Sea, as occurred in 2014. Using a theoretical framework based on metapopulation and metacommunity theory we predicted a transition of the sediment bacterial community after the MBI, from a more heterogeneous community pattern driven by local colonisation-extinction dynamics towards a more pronounced environmental gradient but with reduced beta-diversities. Community diversity patterns before and after the MBI were investigated by 16S rRNA gene sequencing of samples from 42 Baltic Sea environmental monitoring stations. Results showed strong metapopulation dynamics with many satellite and few core taxa. NMDS-ordination showed distinct geographical clustering. After the MBI, alpha-diversity increased, beta-diversity decreased and a significant distance-decay relationship developed. Changes in community composition correlated significantly with changes in oxygen and salinity from 2010 to 2015. Our results indicate strong metapopulation and metacommunity structuring of sediment bacterial diversity and composition in the Baltic Sea and how movements of large-scale water bodies affect bacterial communities through changes in large-scale environmental gradients and dispersal patterns.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
aquatic microbiology, bacterial diversity, 16S rRNA gene, high-throughput sequencing, biogeography, Major Baltic Inflow, monitoring, oxygen decline, sediment, DADA2
National Category
Microbiology
Research subject
Environmental Studies; Baltic and East European studies
Identifiers
urn:nbn:se:sh:diva-39748 (URN)
Funder
The Foundation for Baltic and East European Studies, 3150-3.1.1-2017Swedish Research Council Formas, 2016-00804
Note

As manuscript in dissertation.

Available from: 2020-01-09 Created: 2020-01-09 Last updated: 2020-01-09Bibliographically approved
Sjöling, S., van Elsas, J. D., Andreote, F. D. & Rodrigues, J. L. (2019). Soil Metagenomics: deceiphering the soil microbial gene pool (3ed.). In: JD van Elsas, JT Trevors, As Rosado, P Nannipieri (Ed.), Modern Soil Microbiology: (pp. 227-243). Boca Raton: CRC Press
Open this publication in new window or tab >>Soil Metagenomics: deceiphering the soil microbial gene pool
2019 (English)In: Modern Soil Microbiology / [ed] JD van Elsas, JT Trevors, As Rosado, P Nannipieri, Boca Raton: CRC Press, 2019, 3, p. 227-243Chapter in book (Refereed)
Place, publisher, year, edition, pages
Boca Raton: CRC Press, 2019 Edition: 3
Keywords
microbial ecology, metagenomics, environmental microbiology, environmental science, mikrobiell ekologi, metagenomik, miljömikrobiologi, miljövetenskap
National Category
Biological Sciences
Research subject
Environmental Studies
Identifiers
urn:nbn:se:sh:diva-39807 (URN)10.1201/9780429059186-14 (DOI)2-s2.0-85146407893 (Scopus ID)9781498763530 (ISBN)9780429059186 (ISBN)
Available from: 2020-01-13 Created: 2020-01-13 Last updated: 2024-01-10Bibliographically approved
Principal InvestigatorSjöling, Sara
Co-InvestigatorNascimento, Francisco
Co-InvestigatorBonaglia, Stefano
Co-InvestigatorBroman, Elias
Co-InvestigatorMotwani, Nisha H.
Coordinating organisation
Södertörn University
Funder
Period
2018-01-01 - 2020-12-31
Keywords [sv]
Östersjö- och Östeuropaforskning
Keywords [en]
Baltic and East European studies
National Category
Environmental SciencesBiochemistry and Molecular Biology
Identifiers
DiVA, id: project:1848Project, id: 77/2017_OSS

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