Elisabeth Alve

• Freitas, Thaise Ricardo de; Nomaki, Hidetaka; Hess, Silvia; Renaud, Paul; Ogawa, Nanako O. & Ohkouchi, Naohiko [Vis alle 8 forfattere av denne artikkelen] (2026). Effects of temperature and food availability on Arctic benthic foraminifera: coupling field observations with feeding experiments. Marine Ecology Progress Series. ISSN 0171-8630. doi: 10.3354/meps15237. Fulltekst i vitenarkiv Vis sammendrag

  Climate-driven increases in primary production are expected to alter the organic matter reaching the Arctic seafloor. While polar organisms can respond rapidly to changes in food pulses, there is limited information on how different benthic compartments exhibit distinct physiological and population-level responses. Here, we evaluated the responses of benthic foraminifera to the addition of 13C-labelled algae powder under ambient conditions and a warmer temperature setting. We quantified the species-specific ingestion rates of selected foraminifera taxa from shelf and slope regions characterised by distinct water depths and hydrographic conditions. Our results demonstrated that shelf foraminiferal assemblages had higher uptake than slope assemblages, despite the latter having generally higher abundance. Both suspension feeders and detritivores (e.g., Saccorhiza ramosa and Cribrostomoides subglobosus, respectively) had high feeding rates, indicating that species-specific uptake is related to feeding preferences and strategies. Most taxa did not exhibit increased feeding under warm conditions, except for C. subglobosus and certain calcareous taxa, suggesting that warming effects are secondary and species-specific. Background foraminiferal isotopic signatures (δ13C, δ15N) evidenced trophic plasticity in Arctic benthic foraminifera, as Lagenammina difflugiformis, Elphidium clavatum and Melonis affinis showed varying isotopic values across sites. Our findings indicate that future warming may alter benthic carbon cycling not through generalised metabolic acceleration due to higher water temperature, but through species-specific shifts that should restructure community biodiversity and trophic roles.

• Freitas, Thaise Ricardo de; Hess, Silvia; Renaud, Paul Eric; Appleby, Peter & Alve, Elisabeth (2024). Drivers of organic carbon distribution and accumulation in the northern Barents Sea. Progress in Oceanography. ISSN 0079-6611. 225. doi: 10.1016/j.pocean.2024.103286. Fulltekst i vitenarkiv Vis sammendrag

  Sedimentary properties and accumulation rates on the continental shelf and in the deep sea reflect temporal oceanographic, biological and chemical processes occurring in the water column and the sediment surface. We used the radionuclides 210Pb, 226Ra, and 137Cs activities to estimate sedimentation rates during the last century at nine stations in the northern Barents Sea region. Elemental (C, N) and stable isotopic composition (δ13C, δ15N) were also analysed from the nine stations sampled in August 2018, and, for five other stations sampled in August and December 2019, and in March and May 2021. Sediment accumulation rates varied between 130 and 1 410 g m−2 y−1. The < 63 μm normalized total organic carbon (TOC63) and the total nitrogen from the sediment surface varied between 0.90–2.56 % and 0.13–0.33 %, respectively. Ice-free shelf stations had higher TOC63 and possibly fresher organic matter (high δ13C, low δ15N) than ice-covered more northern stations. The opposite trend was observed for total inorganic carbon. We found that these trends in biogeochemical parameters were spatially structured by the winter sea ice concentration and biological production differences, and exhibited a south-north separation of the Polar Front region. The low and stable organic carbon accumulation rate (1.7–13.4 g Corg m-2 y−1; ARtoc) is a function of slow sedimentation rates, and high degradation and residence time in the water column and at the sediment–water interface. Overall, the ARtoc has been stable for the past 100 years, with a slight increase from the early 1970s to the present at the shelf and slope stations. Our results highlight that spatial scales of variability of the studied sedimentary parameters are linked to spatial patterns of important environmental variables (e.g., chlorophyll-a, sea ice concentration) in the region. In contrast, no seasonal differences were observed in the sediment parameters of revisited stations, and the dated sediment geochemical profiles did not exhibit substantial longer-term variation. This means that climate-induced changes in variables that modify the sedimentary geochemistry of the environment may affect benthic community activity and structure before leaving a record in ARtoc.

• O'Brien, Phoebe; Angeles, Inés Barrenechea; Cermakova, Kristina; Pawlowski, Jan; Alve, Elisabeth & Nordberg, Kjell [Vis alle 7 forfattere av denne artikkelen] (2024). Assessing Environmental Quality in a Historically Polluted Fjord: A Comparison of Benthic Foraminiferal eDNA and Morphospecies Approaches. Journal of Geophysical Research (JGR): Biogeosciences. ISSN 2169-8953. 129(12). doi: 10.1029/2023JG007781. Fulltekst i vitenarkiv Vis sammendrag

  This study is the first assessment of a fjord Ecological Quality Status (EcoQS) by comparing both the traditional morphology-based and emerging metabarcoding techniques in benthic foraminifera. For this, we focus on historically polluted Idefjord on the Swedish Norwegian border, which has experienced high effluent load from pulp and paper mill for almost a century. Based on our results, the morphological data was more sensitive to “naturally stressed” conditions, like course sediments and cascading water inflows at fjord sills. Generally, both data sets report congruous responses in the EcoQS and benthic foraminiferal assemblages to environmental stress factors, showing highest diversity at the coastal reference station and the outer fjord, with a diversity decline in proximity of industrial facilities and at the most oxygen depleted sites in the inner fjord. Genetic methods tend to overestimate EcoQS at highly anoxic sites probably due to a presence of dormant propagules or extraorganismal DNA, emphasizing a

• Klootwijk, Anouk Tosca & Alve, Elisabeth (2022). Does the analysed size fraction of benthic foraminifera influence the ecological quality status and the interpretation of environmental conditions? Indications from two northern Norwegian fjords. Ecological Indicators. ISSN 1470-160X. 135. doi: 10.1016/j.ecolind.2021.108423. Fulltekst i vitenarkiv Vis sammendrag

  The introduction of the European Water Framework Directive has increased the interest in benthic foraminifera as a biomonitoring tool. This prompted the need to standardise the methods used to analyse benthic foraminifera, including which sediment fraction to analyse. In some regions benthic foraminifera produce small (< 125 µm) adult tests, and the current study assessed the effect of analysing the > 63 µm or > 125 µm fraction on determining the Ecological Quality Status (EcoQS) in two fjords in northern Norway. The diversity indices Shannon-Wiener index (H’log2) and Hurlbert’s rarefaction index (ES100), and the multi-metric Norwegian Quality Index (NQI), from both the > 63 µm and > 125 µm fraction resulted in the same or similar EcoQS, reflecting good environmental conditions in both fjords. The same applied to the AZTI’s Marine Biological Index (AMBI), except at one location which had moderate EcoQS. At this location especially, more foraminifera with a tolerant or opportunistic response to organic matter enrichment occurred in the > 63 µm fraction than in the > 125 µm fraction. Hence, the higher H’log2 and ES100 of the > 63 µm fraction can be somewhat misleading as it indicates better environmental conditions, whereas the AMBI indicates more organic matter input. The Stainforthia group and Epistominella vitrea, indicating organic matter enrichment and increased primary productivity were, however, mostly absent in the > 125 µm fraction. Their absence in this fraction could have consequences for monitoring potential anthropogenic pressure factors and identifying long-term changes in environmental conditions when using this fraction. This study suggests the > 125 µm would be mostly sufficient for determining the EcoQS in northern Norway.

• Dolven, Jane Karine Lønne & Alve, Elisabeth (2021). Naturally changing reference conditions: Evidence of isostatic uplift being the main cause of changes in ecological status in a SW Norwegian fjord system. Ecological Indicators. ISSN 1470-160X. 131. doi: 10.1016/j.ecolind.2021.108162. Fulltekst i vitenarkiv Vis sammendrag

  According to the European Water Framework Directive (WFD), restoration actions are needed if the present-day ecological quality status (EcoQS) is worse than good. However, less stringent environmental objectives may be allowed if the water body’s natural condition is such that it may be unfeasible or unreasonably expensive to achieve good conditions. In the Inner Skjolda- and Grindefjord, an isolated and shallow silled fjordsystem on the SW coast of Norway, the present EcoQS (based on benthic foraminifera and macroinvertebrates) is bad due to anoxic conditions in the bottom water. Paleoecological foraminiferal data in two dated sediment records were used to establish in situ reference conditions. The data revealed that the current bad EcoQS did not deviate from the natural reference condition which existed just prior to the onset of the industrial revolution. Further back in time, the record showed poor EcoQS and a strong dominance of the opportunistic foraminiferal species Stainforthia fusiformis, indicating unfavorable conditions for benthic foraminifera already >2000 years ago. The changing ecological status during the pre-industrial period was probably caused by the inner fjordsystem becoming gradually more isolated and stratified, and the bottom water more stagnant with decreasing oxygen concentrations, in response to isostatic uplift. Our study shows that reference conditions at a location may represent a natural succession of environmental changes i.e., the natural baseline does not have to represent only one environmental condition but may vary naturally over time. We therefore suggest that the conditions just prior to the onset of the industrial revolution should be used when defining reference conditions according to the WFD.

• Klootwijk, Anouk Tosca; Sweetman, Andrew K.; Hess, Silvia; Alve, Elisabeth; Dunlop, Kathrine M. & Renaud, Paul Eric (2021). Benthic foraminiferal carbon cycling in coastal zone sediments: The influence of the assemblage structure and jellyfish detritus. Estuarine, Coastal and Shelf Science. ISSN 0272-7714. 261. doi: 10.1016/j.ecss.2021.107535. Fulltekst i vitenarkiv
• Klootwijk, Anouk Tosca; Alve, Elisabeth; Hess, Silvia; Renaud, Paul Eric; Sørlie, Carsten & Dolven, Jane Karine Lønne (2020). Monitoring environmental impacts of fish farms: Comparing reference conditions of sediment geochemistry and benthic foraminifera with the present. Ecological Indicators. ISSN 1470-160X. 120. doi: 10.1016/j.ecolind.2020.106818. Fulltekst i vitenarkiv Vis sammendrag

  Intensive fish farming is a major industry, but the extent of organic matter (OM) and heavy metal pollution by fish farms is debated. This study established in situ reference conditions using geochemical parameters and fossil benthic foraminiferal assemblages in dated sediment cores to identify potential impacts of fish farming in two basins of the inner Øksfjord, Northern Norway. Living (rose Bengal stained) benthic foraminifera were used to assess the present day environmental conditions. The fossil foraminiferal records were compared with the living foraminifera, which in turn were compared with macrofaunal data. Long-term (> 100 yrs) sediment core records of the geochemical parameters (TOC63, C/N, δ13CVPDB TOC and heavy metals) and foraminiferal indices (Norwegian Quality Index (fNQI), AZTI’s Marine Biotic Index (fAMBI), fHlog2, ES100) did not indicate an impact from fish farming through time. Long-term changes in foraminiferal absolute abundances and relative abun- dances of ecological groups (EGs) reflecting organic matter (OM) tolerance suggest that the OM supply slightly increased compared to reference conditions. Relative abundances of Brizalina skagerrakensis and Epistominella vitrea, previously associated with phytodetrital input, suggest a minor increase in primary productivity com- pared to reference conditions. The Stainforthia group (S. fusiformis and S. feylingi), indicative of OM enrichment, in the living foraminiferal assemblages may indicate a response to fish farming activities, but foraminiferal seasonality could not be excluded as a potential cause. The indices of both fossil and living foraminifera, in addition to the macrofauna showed a good to high Ecological Quality Status (EcoQS) through time and at present. This indicates that environmental conditions have been and still are acceptable.

• Hess, Silvia; Alve, Elisabeth; Andersen, Thorbjørn J. & Joranger, Tore (2020). Defining ecological reference conditions in naturally stressed environments – How difficult is it? Marine Environmental Research. ISSN 0141-1136. 156. doi: 10.1016/j.marenvres.2020.104885. Fulltekst i vitenarkiv
• Deldicq, Noemie; Alve, Elisabeth; Schweizer, Magali; Asteman, Irina Polovodova; Hess, Silvia & Darling, Kate [Vis alle 7 forfattere av denne artikkelen] (2019). History of the introduction of a species resembling the benthic foraminifera nonionella stella in the oslofjord (Norway): Morphological, molecular and paleo-ecological evidences. Aquatic Invasions. ISSN 1798-6540. 14(2), s. 182–205. doi: 10.3391/ai.2019.14.2.03. Fulltekst i vitenarkiv Vis sammendrag

  Specimens resembling the benthic foraminifera Nonionella stella (Cushman and Moyer, 1930), a morphospecies originally described from the San Pedro Basin, California, USA, were observed for the first time in the Oslofjord (Norway) in 2012. This study investigates the Oslofjord Nonionella population in order to confirm its nonindigenous species (NIS) status and assess its introduction time. Morphological characterisation based on SEM imaging complemented by molecular identification using small subunit (SSU) rDNA sequencing and assessment of the recent past record (sediment core), were performed on material collected in the Oslofjord in 2016. Examination of the dead fauna showed that specimens resembling N. stella only appeared recently in the Oslofjord, confirming the NIS status of this population. Moreover, DNA results indicate that the Oslofjord specimens differ genetically from N. stella sampled in the Santa Barbara Basin (California USA). Hence, we propose to use the name Nonionella sp. T1 for the specimens sampled in the Oslofjord for the time being. In the southern part of the Skagerrak, specimens morphologically similar to Nonionella sp. T1 were reported as NIS in the Gullmar fjord (Sweden) in 2011 and in the Skagerrak in 2015. Molecular data indicate that the two populations from Gullmar- and Oslofjords are identical, based on their SSU rDNA sequences. In addition, analyses of foraminiferal dead assemblages suggest that the population from the Gullmar fjord settled prior to the Oslofjord population, i.e. ~ 1985 and about 2010, respectively. This implies that Nonionella sp. T1 may have been transported from Sweden to Norway by northward coastal currents.

• Bouchet, Vincent MP; Telford, Richard J; Rygg, Brage; Oug, Eivind & Alve, Elisabeth (2018). Can benthic foraminifera serve as proxies for changes in benthic macrofaunal community structure? Implications for the definition of reference conditions. Marine Environmental Research. ISSN 0141-1136. 137, s. 24–36. doi: 10.1016/j.marenvres.2018.02.023. Fulltekst i vitenarkiv Vis sammendrag

  Benthic macrofauna is one of the most widely used biological groups to assess the ecological status of marine systems. Lately, attention has been paid to similar use of benthic foraminifera. In this study, distribution patterns of benthic foraminiferal and macrofaunal species were investigated simultaneously in 11 fjords in southeastern Norway in order to assess correlations and responses to environmental conditions. Selected fjords allowed to investigate contrasted environmental conditions from low total organic carbon (TOC) content (sediment TOC < 2.7%) in normoxia (bottom-water [O2] > 2 mL O2.L−1) up to high TOC content (> 3.4%) in severe hypoxia (< 0.5 mL O2.L−1). Environmental parameters comprised bottom-water dissolved oxygen, grain size, total organic carbon, total nitrogen (TN), pigments and depth below threshold (DBT). Foraminiferal and macrofaunal community data were significantly correlated (Procrustes analysis m2 = 0.66, p = 0.001). Hence, benthic foraminiferal distribution patterns mirror those of benthic macrofauna. However, as opposed to the foraminifera, macrofauna was not recorded at the most oxygen-depleted stations and, hence, was more sensitive to severe oxygen depletion. With regard to assigning species to ecological groups for ecological quality status assessment, the results suggest that species, e.g. Spiroplectammina biformis (foraminifera), Scalibregma inflatum (macrofauna), may exhibit different ecological requirements depending on their habitat. Considering the observed congruent patterns of benthic foraminifera and macrofauna, palaeo-communities of benthic foraminifera could be used as indicators of reference conditions for benthic macrofaunal community structure. This would however need further developments of algorithms to perform such a translation.

• Alve, Elisabeth; Hess, Silvia; Bouchet, Vincent M P; Dolven, Jane K & Rygg, Brage (2018). Intercalibration of benthic foraminiferal and macrofaunal biotic indices: An example from the Norwegian Skagerrak coast (NE North Sea). Ecological Indicators. ISSN 1470-160X. 96, s. 107–115. doi: 10.1016/j.ecolind.2018.08.037. Fulltekst i vitenarkiv Vis sammendrag

  The present study illustrates how benthic macrofauna indices can be adapted to foraminifera through intercalibration of data from common sites. As an example of how benthic foraminifera can fit into governmental monitoring programs, we focus on Norwegian conditions by proposing a new foraminifera-based multimetric index, NQI_f. The index is an adaptation of the Norwegian Quality Index (NQI), which is an internationally intercalibrated macrofauna index. The study is based on published and new data for soft-bottom benthic foraminifera, macro invertebrates, and associated bottom water dissolved oxygen and sediment total organic carbon (TOC). Paired samples of foraminifera and macrofauna were collected at the same stations, at more or less the same time, along the Norwegian Skagerrak coast, NE North Sea. The intercalibration was based on linear regression and the EcoQS class boundary values for the foraminifera indices were derived from boundary values for the macrofauna indices defined by the Norwegian governmental guidelines. The correlations between foraminifera and macrofauna for the multimetric NQI and the diversity indices H′log2 and ES100 were all acceptable for intercalibration (according to the Water Framework Directive’s guidelines) but NQI showed the best correlation. Both foraminifera- and macrofauna-indices showed significant correlations with the bottom water dissolved oxygen concentration, and for some indices, with the TOC content in the sediment. Overall, the foraminifera and macrofauna indices reflected the environmental conditions similarly but at the most oxygen depleted stations only foraminifera were present. Based on the present findings and on previous studies which show a potential of fossil foraminifera to define in situ reference conditions, we recommend that foraminifera are accepted as a Biological Quality Element within the WFD.

• Duffield, CJ; Alve, Elisabeth; Andersen, N; Andersen, TJ; Hess, Silvia & Strohmeier, Tore (2017). Spatial and temporal organic carbon burial along a fjord to coast transect: A case study from Western Norway. The Holocene. ISSN 0959-6836. doi: 10.1177/0959683617690588. Fulltekst i vitenarkiv
• Duffield, Christopher James; Alve, Elisabeth; Andersen, Nils; Andersen, Thorbjørn J.; Hess, Silvia & Strohmeier, Tore (2017). Spatial and temporal organic carbon burial along a fjord to coast transect: A case study from Western Norway. The Holocene. ISSN 0959-6836. 27(9), s. 1325–1339. doi: 10.1177/0959683617690588. Fulltekst i vitenarkiv Vis sammendrag

  We investigated spatial and temporal changes in accumulation rate and source of organic carbon on a gradient along the Lysefjord and the more coastal Høgsfjord, Western Norway. This was achieved through analysis of total organic carbon and nitrogen content of sediment cores, which were radiometrically dated to the early 19th and 20th centuries for the Høgsfjord and Lysefjord, respectively. Benthic foraminifera (protists) were utilized to determine changes in organic carbon supply and Ecological Quality Status (EcoQS) by their accumulation rate (benthic foraminiferal accumulation rate (BFAR)), assemblage composition, species diversity, individual species responses and the composition of stable carbon isotopes of the tests (shells) of Cassidulina laevigata, Hyalinea balthica and Melonis barleeanus. Organic carbon accumulation rates were greatest closest to the river Lyse at the head of the Lysefjord (83–171 g C m−2 yr−1). The organic carbon at the head of the fjord is mainly terrestrial in origin, and this terrestrial influence becomes progressively less seaward. The δ13C in H. balthica tests as well as the benthic foraminiferal assemblage composition also showed a clear fjord to coast gradient. Organic carbon accumulation rates were lower and less variable at the seaward study sites (13–61 g C m−2 yr−1). We observe no temporal trend in organic carbon, carbon isotopes, EcoQS or foraminiferal assemblage composition in the Lysefjord. In contrast, in the Høgsfjord, there seems to have been an increase in organic carbon accumulation rates during the 1940s. Subsequent accumulation rates are stable. The foraminiferal assemblages in the surface sediments reflect a recent transition from good/moderate to moderate/bad EcoQS.

• Murray, John W. & Alve, Elisabeth (2016). Benthic foraminiferal biogeography in NW European fjords: A baseline for assessing future change. Estuarine, Coastal and Shelf Science. ISSN 0272-7714. 181, s. 218–230. doi: 10.1016/j.ecss.2016.08.014. Fulltekst i vitenarkiv
• Alve, Elisabeth; Korsun, Sergei; Schönfeld, Joachim; Dijkstra, Noortje; Golikova, Elena & Hess, Silvia [Vis alle 8 forfattere av denne artikkelen] (2016). Foram-AMBI: A sensitivity index based on benthic foraminiferal faunas from North-East Atlantic and Arctic fjords, continental shelves and slopes. Marine Micropaleontology. ISSN 0377-8398. 122, s. 1–12. doi: 10.1016/j.marmicro.2015.11.001. Fulltekst i vitenarkiv
• Duffield, Christopher James; Hess, Silvia; Norling, Karl & Alve, Elisabeth (2015). The response of Nonionella iridea and other benthic foraminifera to "fresh" organic matter enrichment and physical disturbance. Marine Micropaleontology. ISSN 0377-8398. 120, s. 20–30. doi: 10.1016/j.marmicro.2015.08.002. Fulltekst i vitenarkiv
• Duffield, Christopher James & Alve, Elisabeth (2014). A tray designed to improve the wet-picking method. Journal of Micropalaeontology. ISSN 0262-821X. 33(1), s. 105–107. doi: 10.1144/jmpaleo2013-026. Fulltekst i vitenarkiv
• Hess, Silvia; Alve, Elisabeth & Reuss, Nina S. (2014). Benthic foraminiferal recovery in the Oslofjord (Norway): Responses to capping and re-oxygenation. Estuarine, Coastal and Shelf Science. ISSN 0272-7714. 147, s. 87–102. doi: 10.1016/j.ecss.2014.05.012. Fulltekst i vitenarkiv
• Duffield, Christopher James; Edvardsen, Bente; Eikrem, Wenche & Alve, Elisabeth (2014). Effects of different potential food sources on upper-bathyal benthic foraminifera: an experiment with propagules. Journal of Foraminiferal Research. ISSN 0096-1191. 44(4), s. 416–433. doi: 10.2113/gsjfr.44.4.416. Fulltekst i vitenarkiv
• Alve, Elisabeth & Goldstein, Susan T. (2014). The propagule method as an experimental tool in foraminiferal ecology. I Kitazato, Hiroshi & Bernhard, Joan M. (Red.), Approaches to study living foraminifera. Collection, maintenance and experimentation. Springer Science+Business Media B.V.. ISSN 9784431543886. s. 1–12. doi: 10.1007/978-4-431-54388-6. Fulltekst i vitenarkiv
• Dolven, Jane Karine Lønne; Alve, Elisabeth; Rygg, Brage & Magnusson, Jan (2013). Defining past ecological status and in situ reference conditions using benthic foraminifera: A case study from the Oslofjord, Norway. Ecological Indicators. ISSN 1470-160X. 29, s. 219–233. doi: 10.1016/j.ecolind.2012.12.031. Fulltekst i vitenarkiv
• Hess, Silvia; Alve, Elisabeth; Trannum, Hilde Cecilie & Norling, Karl (2013). Benthic foraminiferal responses to water-based drill cuttings and natural sediment burial: Results from a mesocosm experiment. Marine Micropaleontology. ISSN 0377-8398. 101, s. 1–9. doi: 10.1016/j.marmicro.2013.03.004. Fulltekst i vitenarkiv Vis sammendrag

  Effects of burial by water-based drill cuttings and natural test sediment on living (stained) benthic foraminifera were investigated in a mesocosm experiment. After 193 days, the foraminiferal response in sediment covered with drill cuttings was compared to the response in sediment covered with defaunated natural test sediment. Increasing thickness of added material, independent of type of material, significantly reduced the benthic foraminiferal abundance and species richness. While most species managed to migrate through added sediments of up to 12 mm thickness, results indicate that a burial depth of 24 mm severely limits the migration capability of the foraminifera. Textularia earlandi and Bulimina marginata dominated the 0–1 cm of sediment (including added material) in most mesocosms but the former was most resistant to maximum burial (24 mm). The physical disturbance caused by the burial triggered reproduction in surviving populations of B. marginata and Nonionellina labradorica. Addition of water-based drill cuttings and defaunated natural test sediments impacted the microhabitat of N. labradorica differently. Stainforthia fusiformis seems to be the species most tolerant to the water-based drill cuttings. Results indicate that the foraminiferal faunal composition respond differently to the two different materials added, even if only agglutinated forms are considered. This agrees with earlier macrofaunal results from the same experiment which indicate that the water-based drill cuttings represent an additional stress factor for the benthic community.

• Schönfeld, Joachim; Alve, Elisabeth; Geslin, Emmanuelle; Jorissen, Frans; Korsun, Sergei & Spezzaferri, Silvia [Vis alle 8 forfattere av denne artikkelen] (2012). The FOBIMO (FOraminiferal BIo-MOnitoring) initiative-Towards a standardised protocol for soft-bottom benthic foraminiferal monitoring studies. Marine Micropaleontology. ISSN 0377-8398. 94-95, s. 1–13. doi: 10.1016/j.marmicro.2012.06.001. Fulltekst i vitenarkiv
• Bouchet, Vincent; Alve, Elisabeth; Rygg, Brage & Telford, Richard (2012). Benthic foraminifera provide a promising tool for ecological quality assessment of marine waters. Ecological Indicators. ISSN 1470-160X. 23, s. 66–75. doi: 10.1016/j.ecolind.2012.03.011. Fulltekst i vitenarkiv
• Goldstein, Susan T. & Alve, Elisabeth (2011). Experimental assembly of foraminiferal communities from coastal propagule banks. Marine Ecology Progress Series. ISSN 0171-8630. 437, s. 1–11. doi: 10.3354/meps09296. Fulltekst i vitenarkiv
• Murray, John W. & Alve, Elisabeth (2011). The distribution of agglutinated foraminifera in NW European seas: Baseline data for the interpretation of fossil assemblages. Palaeontologia Electronica. ISSN 1935-3952. 14(2). Fulltekst i vitenarkiv
• Murray, John W.; Alve, Elisabeth & Jones, Bob W. (2011). A new look at modern agglutinated benthic foraminiferal morphogroups: their value in palaeoecological interpretation. Palaeogeography, Palaeoclimatology, Palaeoecology. ISSN 0031-0182. 309(3-4), s. 229–241. doi: 10.1016/j.palaeo.2011.06.006. Fulltekst i vitenarkiv
• Alve, Elisabeth; Murray, John W. & Skei, Jens (2011). Deep-sea benthic foraminifera, carbonate dissolution and species diversity in Hardangerfjord, Norway: An initial assessment. Estuarine, Coastal and Shelf Science. ISSN 0272-7714. 92(1), s. 90–102. doi: 10.1016/j.ecss.2010.12.018. Fulltekst i vitenarkiv
• Alve, Elisabeth & Goldstein, Susan T. (2010). Dispersal, survival and delayed growth of benthic foraminiferal propagules. Journal of Sea Research. ISSN 1385-1101. 63(1), s. 36–51. doi: 10.1016/j.seares.2009.09.003. Fulltekst i vitenarkiv
• Alve, Elisabeth (2010). Benthic foraminiferal responses to absence of fresh phytodetritus: A two-year experiment. Marine Micropaleontology. ISSN 0377-8398. 76(3-4), s. 67–75. doi: 10.1016/j.marmicro.2010.05.003. Fulltekst i vitenarkiv
• Lepland, Aivo; Andersen, Thorbjørn J.; Lepland, Aave; Arp, Hans Peter H.; Alve, Elisabeth & Breedveld, Gijs D. [Vis alle 7 forfattere av denne artikkelen] (2010). Sedimentation and chronology of heavy metal pollution in Oslo harbor, Norway. Marine Pollution Bulletin. ISSN 0025-326X. 60(9), s. 1512–1522. doi: 10.1016/j.marpolbul.2010.04.017. Fulltekst i vitenarkiv
• Nagy, Jenø; Hess, Silvia & Alve, Elisabeth (2010). Environmental significance of foraminiferal assemblages dominated by small-sized Ammodiscus and Trochammina in Triassic and Jurassic delta-influenced deposits. Earth-Science Reviews. ISSN 0012-8252. 99(1-2), s. 31–49. doi: 10.1016/j.earscirev.2010.02.002. Fulltekst i vitenarkiv
• Alve, Elisabeth; Lepland, Aivo; Magnusson, Jan & Backer-Owe, Kristian (2009). Monitoring strategies for re-establishment of ecological reference conditions: Possibilities and limitations. Marine Pollution Bulletin. ISSN 0025-326X. 59(8-12), s. 297–310. doi: 10.1016/j.marpolbul.2009.08.011. Fulltekst i vitenarkiv
• Alve, Elisabeth (2009). A bisected Pelosina rejoined! Journal of Micropalaeontology. ISSN 0262-821X. 28, s. 183–184. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Asteman, Irina Polovodova; Alve, Elisabeth; Dolven, Jane; Eliassen, Nicole; Ferraro, Mattia & Hess, Silvia [Vis alle 18 forfattere av denne artikkelen] (2023). Spreading of an alien benthic foraminifer in the North Sea: a reason to be worried? Fulltekst i vitenarkiv Vis sammendrag

  In the Skagerrak-Kattegat (eastern North Sea), the alien benthic foraminifer Nonionella sp. T1 (previously referred to as “Nonionella stella”) was reported for the first time in 2011 and 2012 in the Swedish and southern Norwegian fjords, respectively. Based on dated sediment cores its first occurrence can be traced back to the 1980s in the Gullmar Fjord, to the 2000s in the Öresund and to 2010 in the Oslofjord. Since then, Nonionella sp T1 has spread all over the Kattegat and coastal Skagerrak, according to sampling campaigns performed between 2016 and 2022. The species is now highly abundant in the entire Kattegat, including the Öresund, as well as in fjord mouths of the seasonally hypoxic Gullmar Fjord, the oxic Hakefjord and the long-term polluted Idefjord as demonstrated by molecular and morphospecies data. At the same time, Nonionella sp T1 is rare to absent in the Baltic Sea, Skagerrak deep basin and in deep fjords of western and northern Norway. This study shows some preliminary results on the species’ present distribution in the study area and raises questions about the driving factors and potential effects on the local biodiversity.

• Hess, Silvia; Alve, Elisabeth & Helland, Aud (2023). Retrospective benthic foraminiferal community studies: a sensitive method to determine early environmental changes. Fulltekst i vitenarkiv
• Freitas, Thaise Ricardo de; Hess, Silvia; Renaud, Paul Eric & Alve, Elisabeth (2023). Spatio-temporal distribution patterns of benthic foraminifera in the northern Barents Sea. Fulltekst i vitenarkiv
• Ziegler, Amanda; Freitas, Thaise Ricardo de; Altenburger, Andreas; Alve, Elisabeth; Bluhm, Bodil & Bodur, Yasemin V. [Vis alle 17 forfattere av denne artikkelen] (2022). Lack of (or weak) seasonality in Barents sea and Nansen Basin sediments and biota? A preliminary assessment. Fulltekst i vitenarkiv
• Freitas, Thaise Ricardo de; Hess, Silvia; Renaud, Paul Eric & Alve, Elisabeth (2022). Seasonal variability on living benthic foraminiferal biodiversity in the northern Barents Sea: preliminary results. Fulltekst i vitenarkiv
• Freitas, Thaise Ricardo de; Hess, Silvia; Renaud, Paul Eric & Alve, Elisabeth (2022). Benthic foraminiferal biodiversity in the northern Barents Sea: preliminary results. Fulltekst i vitenarkiv
• Freitas, Thaise Ricardo de; Alve, Elisabeth; Hess, Silvia & Renaud, Paul Eric (2021). Drivers of organic carbon distribution and accumulation in the Northern Barents Sea. Fulltekst i vitenarkiv
• Klootwijk, Anouk Tosca; Alve, Elisabeth; Silvia, Hess & Carsten, Sørlie (2020). Utilizing benthic foraminifera and geochemical parameters in modern stratigraphy as a tool to solve challenges in biomonitoring. Fulltekst i vitenarkiv Vis sammendrag

  This study investigated the potential impact of fish-farming using fossil and living benthic foraminiferal assemblages, as well as associated geochemical parameters, in dated sediment cores from inner-Øksfjord, Northern Norway. Previous studies suggest that organic carbon emissions from fish-farming have introduced algal blooms and spatial changes in organic carbon loading of fjord sediments, ecosystem functioning and benthic community structures. Currently, these spatial changes are difficult to interpret as long-term (last 100 years and thus pre fish-farm) changes have not been studied making it difficult to exclude natural causes of observed gradients. Furthermore, in the majority of cases pre fish-farm environmental conditions are unknown as the initiation of the farm often pre-dates biomonitoring efforts. The aim of this study was to reconstruct long term changes to identify potential impact(s) of fish-farming in the fjord. To assess such potential impact(s), sediment cores were collected from the inner fjord’s main and sub-basin. The geochemical parameters total organic carbon, C/N ratios, sediment stable carbon isotopes and trace metal concentrations showed no temporal changes. Pre fish-farm benthic foraminiferal assemblages indicated that environmental conditions naturally differed between the basins. The assemblages showed no temporal changes in the diversity indices (H’log2, ES100) traditionally used in Norwegian biomonitoring studies and indicated that good ecological conditions persisted. The sensitivity index AMBI didn’t change for the main-basin but higher AMBI scores were found in upper part of the sub-basin core signifying a larger abundance of organic matter tolerant species. Increasing relative abundances of Brizalina skagerrakensis in the main-basin and Epistominella vitrea in both basins indicated increased phytodetritus input during the past decades. In both basins Cassidulina reniforme, a species sensitive to increased organic matter input, declined. In the sub-basin opportunistic Stainforthia showed a rapid increase in relative abundance. This study illustrates the sensitivity and suitability of foraminifera as a biomonitoring tool.

• Klootwijk, Anouk Tosca; Alve, Elisabeth; Silvia, Hess & Carsten, Sørlie (2019). The impact of fish farming in an arctic fjord investigated using geochemical parameters and benthic foraminiferal assemblages. Fulltekst i vitenarkiv Vis sammendrag

  The impact of fish farming in an arctic fjord investigated using geochemical parameters and benthic foraminiferal assemblages

• Hess, Silvia; Sjetne, Lars Birkeland & Alve, Elisabeth (2018). Does aquaculture activity have an impact on the benthic environment? - A study from Hardangerfjorden (SW Norway). Fulltekst i vitenarkiv
• Deldicq, Noémie; Alve, Elisabeth; Schweizer, Magali; Asteman, Irina Polovodova; Hess, Silvia & Darling, Kate [Vis alle 7 forfattere av denne artikkelen] (2018). Is the foraminiferal species resembling Nonionella stella a non-indigenous species (NIS) in the Oslofjord (Norway)? Fulltekst i vitenarkiv
• Klootwijk, Anouk Tosca; Alve, Elisabeth; Silvia, Hess & Renaud, Paul Eric (2018). Benthic foraminiferal response to carbon loading introduced by “jelly-falls”: An ex-situ experiment using material from Kaldfjord (Northern Norway). Fulltekst i vitenarkiv Vis sammendrag

  Organic carbon (OC) burial in marine sediments plays a key role in long-term carbon sequestration regulating atmospheric CO2 concentration. Fjords, with their deep, narrow basins and high sedimentation rates, have been estimated to account for 11% of the annual marine carbon burial world-wide. So far, research efforts have mainly focussed on quantifying the amount of OC stored in fjord sediments. However, recent changes in quantities and sources of OC, as a consequence of anthropogenic activities, affect the benthic ecosystem structure and function, and can alter the ecological quality status of fjord habitats. The overall aim is to characterise and quantify accumulation rates of OC in northern Norwegian fjord sediments, and describe the associated benthic foraminiferal responses. One aspect is the response of the benthic foraminiferal community to carbon loading by “jelly-falls”. Recently “jelly-falls” have become larger and more frequent but their effect on processing and accumulation of carbon on the sea floor is not known. Study material was collected from Kaldfjord, Norway, in September 2017 and used for an ex-situ carbon-uptake experiment. Experimental chambers were obtained by box- coring in the inner, middle and outer fjord along a fjord to coast gradient. Experimental chambers received δ13C isotope labelled algae and different amounts of jelly fish, to assess the effect of different concentrations of carbon to the benthic foraminiferal assemblages. The δ13C content, representing the incorporation of 13C-labelled algae into foraminiferal cytoplasm, will indicate their response to the OC loading from “jelly-falls”. Impacts of ambient OC inputs, and potential threshold levels for healthy communities along the fjord to coast gradient, will be investigated. Data on sediment TOC, grain size, and sediment isotope signatures from the field provide additional information regarding differences in background environmental conditions within the fjord. Results increase our understanding of the benthic foraminiferal community response to organic carbon and aid towards developing benthic foraminifera as a monitoring tool.

• Alve, Elisabeth (2018). Sjekker mudderet i havbunnen. [Internet]. https://titan.uio.no/node/3008. Fulltekst i vitenarkiv
• Alve, Elisabeth (2018). Advances in Foraminiferal Biomonitoring. Fulltekst i vitenarkiv
• Alve, Elisabeth (2017). Steilene: Mørk fortid på overflaten, mørk fremtid på bunnen. [Internet]. https://titan.uio.no/node/2101. Fulltekst i vitenarkiv
• Alve, Elisabeth (2017). Definering av referansetilstanden i kystfarvann. Fulltekst i vitenarkiv
• Alve, Elisabeth (2017). Historiebok på fjordbunnen. Fulltekst i vitenarkiv
• Alve, Elisabeth (2016). Hvordan fastsette naturtilstanden i kystmiljøer med naturlig stressede vannforekomster? Fulltekst i vitenarkiv
• Hess, Silvia; Alve, Elisabeth; Joranger, Tore & Oen, Amy M P (2016). Defining pre-industrial ecological status (reference conditions) in heavily polluted shallow harbor areas – a case study from SE Norway. Fulltekst i vitenarkiv
• Hess, Silvia; Guilini, Katja; Michiels, Diego; Torper, Magnhild; Alve, Elisabeth & Sweetman, Andrew Kvassnes [Vis alle 7 forfattere av denne artikkelen] (2016). Meiofauna monitoring in two different fjord systems of the Norwegian west coast: Does the mass appearance of Periphylla periphylla (a deep-sea jellyfish) have an impact on the benthic community? Fulltekst i vitenarkiv
• Alve, Elisabeth (2015). Foraminiferer i historiens og miljøets tjeneste. Fulltekst i vitenarkiv
• Duffield, Christopher James; Alve, Elisabeth; Andersen, Nils; Andersen, Thorbjørn J.; Hess, Silvia & Strohmeier, Tore (2015). Benthic foraminifera and organic carbon along a fjord to coast transect in western, Norway. Fulltekst i vitenarkiv
• Alve, Elisabeth (2015). Kan foraminiferer brukes til å fastsette naturtilstand, og under hvilke forhold? Fulltekst i vitenarkiv
• Duffield, Christopher James & Alve, Elisabeth (2014). Experiments with benthic foraminifera: Improving our understanding of the conditions of the past. Fulltekst i vitenarkiv
• Bouchet, Vincent Marcel Pierre; Beaugrand, Grégory; Goberville, Eric; Richirt, Julien & Alve, Elisabeth (2014). Assessing reference conditions of marine systems: Numerical approaches using benthic foraminifera. Fulltekst i vitenarkiv
• Korsun, Sergei; Alve, Elisabeth; Golikova, Elena; Hess, Silvia; Husum, Katrine & Panieri, Giuliana [Vis alle 7 forfattere av denne artikkelen] (2014). Does AMBI, a commonly used macrofauna-based ecological monitoring measure, work for benthic Foraminifera? The Fobimo-NE Atlantic group. Fulltekst i vitenarkiv
• Duffield, Christopher James & Alve, Elisabeth (2014). Effect of sediment disturbance and oxygen depletion on benthic foraminifera with focus on Nonionella iridea. Fulltekst i vitenarkiv
• Alve, Elisabeth; Bouchet, Vincent; Dolven, Jane Karine Lønne; Hess, Silvia; Magnusson, Jan & Oug, Eivind [Vis alle 8 forfattere av denne artikkelen] (2013). Marine soft-bottom bio-monitoring strategies: Can microfossils make a difference? Fulltekst i vitenarkiv
• Duffield, Christopher James & Alve, Elisabeth (2013). Experiments with the propagules of deep water benthic foraminifera. Fulltekst i vitenarkiv
• Duffield, Christopher James & Alve, Elisabeth (2013). Feeding habits of deep water benthic foraminifera: An experiment with propagules. Fulltekst i vitenarkiv
• Bouchet, Vincent Marcel Pierre; Alve, Elisabeth; Rygg, Brage & Telford, Richard (2013). Benthic foraminifera provide a. promising tool for ecological quality assessment of marine waters (vol 23, pg 66, 2012). Ecological Indicators. ISSN 1470-160X. 26, s. 183–183. doi: 10.1016/j.ecolind.2012.10.002. Fulltekst i vitenarkiv
• Bouchet, Vincent; Hess, Silvia; Dolven, Jane Karine Lønne & Alve, Elisabeth (2012). The use of fossil benthic foraminifera to define reference conditions for present-day marine waters. Geophysical Research Abstracts. ISSN 1029-7006. 14. Fulltekst i vitenarkiv
• Alve, Elisabeth (2012). Kan vi bruke fossiler i miljøovervåking av fjordene våre? Fulltekst i vitenarkiv
• Bouchet, Vincent; Hess, Silvia; Dolven, Jane Karine Lønne; Alve, Elisabeth & Telford, Richard J. (2012). Benthic foraminifera as indicators of ecological quality of coastal marine systems. Fulltekst i vitenarkiv
• Alve, Elisabeth (2012). Bruk av foraminiferer til etablering av tidsserier. Fulltekst i vitenarkiv
• Simenstad, Line Madsen & Alve, Elisabeth (2012). Vår egen tidsalder. [Journal]. Klassekampen. Fulltekst i vitenarkiv
• Goldstein, Susan T.; Alve, Elisabeth & Bernhard, Joan M. (2012). THE PROPAGULE BANK AS AN EXPERIMENTAL TOOL IN FORAMINIFERAL ECOLOGY. Fulltekst i vitenarkiv
• Alve, Elisabeth (2012). Morphospecies and cryptic species; ecology and palaeoecology. Fulltekst i vitenarkiv
• Alve, Elisabeth (2011). Perspektiver på dagens miljøsituasjon i indre Oslofjord. Fulltekst i vitenarkiv
• Alve, Elisabeth (2011). How to determine in situ reference conditions? Key aspects of the PES project. Fulltekst i vitenarkiv
• Alve, Elisabeth (2011). Fossiler tar temp’en: Om utradisjonelle metoder i marin miljøovervåking. Fulltekst i vitenarkiv
• Alve, Elisabeth & Dolven, Jane Karine Lønne (2011). Bruk av mikrofossiler for å karakterisere utvikling av økologisk miljøstatus i sedimenter. Fulltekst i vitenarkiv
• Goldstein, Susan T.; Alve, Elisabeth & Bernhard, Joan M. (2011). Applications of the foraminiferal propagule bank: A novel approach to understanding the ecology of Foraminifera. Fulltekst i vitenarkiv
• Husum, Katrine & Alve, Elisabeth (2011). Wet vs. dry counting of benthic foraminiferal assemblages: a case study from Norwegian fjords. Fulltekst i vitenarkiv
• Schönfeld, Joachim S.; Spezzaferri, Silvia; Jorissen, Frans J.; Alve, Elisabeth & Korsun, Sergei (2011). The use of foraminifera for bio-monitoring of marine environments – results and recommendations from the FOBIMO workshop. Fulltekst i vitenarkiv
• Alve, Elisabeth (2011). Ecology of benthic foraminifera: Particularly aspects relevant to environmental monitoring. Fulltekst i vitenarkiv
• Hess, Silvia; Alve, Elisabeth & Trannum, Hilde Cecilie (2010). Impact of water-based drill cuttings on benthic foraminifera and macrofauna: a mesocosm experiment. Fulltekst i vitenarkiv
• Nagy, Jenø; Hess, Silvia & Alve, Elisabeth (2010). Facies assessments of paralic deposits based on foraminifera: Triassic-Jurassic of the northwest European margin. Fulltekst i vitenarkiv
• Hess, Silvia; Alve, Elisabeth & Trannum, Hilde Cecilie (2010). Effects of water-based drill cuttings vs physical burial on benthic foraminifera and macrofauna: a mesocosm experiment. Fulltekst i vitenarkiv
• Alve, Elisabeth & Dolven, Jane K. (2010). Indre Oslofjord, ”Naturtilstanden”, Vanndirektivet og Metodikk-konservatisme. Fulltekst i vitenarkiv
• Bouchet, Vincent; Alve, Elisabeth; Rygg, Brage; Telford, Richard J. & Reuss, Nina (2010). Determining ecological quality status of coastal waters using benthic foraminifera: calibration with benthic macrofauna. Fulltekst i vitenarkiv
• Hess, Silvia; Alve, Elisabeth; Rygg, Brage & Telford, Richard J. (2010). Monitoring benthic community recovery in the Oslofjord: responses to capping and reoxygenation. Fulltekst i vitenarkiv
• Alve, Elisabeth & Dolven, Jane Karine Lønne (2010). Defining "reference" conditions: monitoring inner Oslofjord, Norway. Fulltekst i vitenarkiv
• Hess, Silvia & Alve, Elisabeth (2009). Monitoring colonization processes in the inner Oslofjord: benthic foraminifera as a tool for ecosystem characterization. Fulltekst i vitenarkiv
• Hess, Silvia & Alve, Elisabeth (2009). Monitoring the colonization of a new substrate (Quaternary clay) in the inner Oslofjord by benthic foraminifera. Fulltekst i vitenarkiv
• Bouchet, Vincent Marcel Pierre; Alve, Elisabeth; Rygg, Brage & Oug, Eivind (2009). Determine past and present ecological status of fjordic coastal waters: calibrating benthic foraminifera and macrofauna. Fulltekst i vitenarkiv
• Bouchet, Vincent Marcel Pierre; Alve, Elisabeth; Rygg, Brage & Oug, Eivind (2009). Combined use of benthic foraminifera and macrofauna to determine past and present ecological status in coastal environments. Fulltekst i vitenarkiv
• Hess, Silvia; Alve, Elisabeth & Helland, Aud (2021). E 16 og Vossebanen, Arna-Stanghelle. Miljøforholdene i Sørfjorden og Veafjorden, Vestland, dagens og tidligere tiders tilstand. Statens vegvesen, rapport UAS-01-Q-00029. Fulltekst i vitenarkiv
• Husum, Katrine; Ninnemann, Ulysses S; Rydningen, Tom Arne; Alve, Elisabeth; Altuna, Naima El Bani & Braaten, Anna Hauge [Vis alle 13 forfattere av denne artikkelen] (2020). Paleo Cruise 2018: Cruise Report. Septentrio Academic Publishing. Fulltekst i vitenarkiv
• Dolven, Jane Karine Lønne & Alve, Elisabeth (2018). Miljøgifter i indre Oslofjord: Kartlegging av historisk forløp gjennom analyser av utvalgte miljøgifter i daterte sedimentkjerner. Fagrådet for vann- og avløpstekninsk samarbeid i indre Oslofjord. Fulltekst i vitenarkiv
• Dolven, Jane Karine Lønne; Hess, Silvia; Hylland, Ketil & Alve, Elisabeth (2018). Foraminiferer som miljøindikator for vannkvalitet og levevilkår på sjøbunnen i Indre Oslofjord. Fagrådet for vann- og avløpstekninsk samarbeid i indre Oslofjord. Fulltekst i vitenarkiv Vis sammendrag

  Tidligere undersøkelser i Indre Oslofjord har vist at bunnlevende foraminiferer (meiofauna) reflekterer miljøforholdene de lever i og kan dermed brukes til å gi informasjon om økologisk tilstand og levevilkår på sjøbunnen. For å kartlegge dagens tilstand i Indre Oslofjord og like utenfor Drøbaksterskelen, og å vurdere utviklingstrenden i fjordsystemet, ble det i oktober 2017 samlet inn bunnsedimenter på 12 stasjoner. Bunnsedimentene ble undersøkt med hensyn på levende foraminiferfaunaer, kornfordeling, total organisk karbon og C/N-forhold. I tillegg ble det gjennomført hydrografiske målinger (temperatur, salinitet og oksygen) gjennom vannsøylen på hver av stasjonene. Resultatene viser at den økologiske tilstanden (nEQR) er «svært god» (tilstandsklasse I) utenfor Drøbaksterskelen og i sydlige deler av Vestfjorden. Deretter forringes tilstanden gradvis innover i fjorden til Bunnefjorden hvor den økologiske tilstanden er «svært dårlig» (V). I to sub-bassenger avviker tilstanden fra tilstanden i deres respektive hovedbasseng: 1) Det delvis «isolerte» Steilenebassenget (St 2) i Vestfjorden hvor forholdene er dårligere enn i Vestfjorden forøvrig, dvs. tilstandsklasse IV («dårlig») og 2) den nordøstre del av Bekkelagsbassenget (RC5 og RC9) hvor tilstanden er i klasse II («god»), dvs. bedre enn nærliggende stasjoner. Sistnevnte skyldes forbedringstiltak igangsatt med flytting av utløpsledningen fra Bekkelaget renseanlegg til dypere vann tidlig på 2000-tallet. I de indre deler av fjorden er det et stort avvik mellom dagens økologiske tilstand («svært dårlig») og naturtilstanden («svært god») som tidligere er beregnet basert på fossile foraminiferfaunaer i daterte sedimentkjerner. I ytre deler av Vestfjorden og utenfor Drøbaksterskelen samsvarer nåværende tilstand godt med naturtilstanden. Økt hyppighet av den opportunistiske arten Stainforthia fusiformis utenfor Drøbaksterskelen peker i retning av økt eutrofiering i senere år. En invaderende art, Nonionella stella, som først ble registrert i Indre Oslofjord i 2012 er nå til stede og til dels hyppig på alle stasjoner, bortsett fra de mest oksygenfattige Bunnefjordstasjonene. Det er generelt høyt organisk karbon (TOC)-innhold («svært dårlig» tilstand) i overflatesedimentene i Indre Oslofjord, og innholdet korrelerer godt med både diversitetsindeksene (H’log2 og ES100) og den sammensatte indeksen NQI. Unntaket er representert ved en stasjon i Bekkelagsbassenget (RC5), som ble kunstig tildekket med ren marin leire i 2007. Korrelasjonen mellom foraminiferdata og målte oksygenkonsentrasjoner i bunnvannet er svært god. Faunasammensetningen (klyngeanalysen) for alle stasjonene støtter opp under dette. Samlet gir dette en sterk indikasjon på at oksygen er en av de viktigste faktorene som styrer sammensetningen av foraminiferfaunaene i Indre Oslofjord. Variabiliteten i foraminiferfaunen er undersøkt for en sterkt belastet stasjon (St 2) og en referansestasjon (Im4x). Analyser av artsdiversitet og jevnhet basert på 10 replikater fra hver stasjon viser at det ikke er signifikant endring for de ulike indeksene ved analyse av flere enn tre replikater fra samme stasjon. Variabiliteten mellom replikatene fører imidlertid til at bruk av færre enn fire replikater per stasjon kan medføre feilklassifisering. Det anbefales å benytte minst fire replikate prøver ved sammenligning av to eller flere lokaliteter siden det gir vesentlig økt teststyrke (mulighet til å fastslå korrekt klasse og å skille mellom stasjoner).

• Alve, Elisabeth; Hess, Silvia; Sørlie, Carsten; Klootwijk, Anouk Tosca & Dolven, Jane Karine Lønne (2018). Akvakultur og naturtilstand i en Nordnorsk fjord: har miljøstatus forandret seg? 7Letras. Fulltekst i vitenarkiv
• Pedersen, Are; Alve, Elisabeth; Alvestad, Tom; Borgersen, Gunhild; Dolven, Jane & Gundersen, Hege [Vis alle 11 forfattere av denne artikkelen] (2016). Bløtbunnsfauna som indikator for miljøtilstand i kystvann. Ekspertvurderinger og forslag til nye klassegrenser og metodikk. Miljødirektoratet. Fulltekst i vitenarkiv
• Hess, Silvia & Alve, Elisabeth (2014). Undersøkelser av den historiske oksygenutviklingen og naturtilstanden i Horten Indre Havn. 7Letras. ISSN 9788291885445. Fulltekst i vitenarkiv
• Dolven, Jane K. & Alve, Elisabeth (2010). Naturtilstanden i indre Oslofjord. Fagrådet for vann- og avløpsteknisk samarbeid i indre Oslofjord. Rapport no. 106. ISSN 9788291885391. Fulltekst i vitenarkiv
• Alve, Elisabeth; Helland, Aud & Magnusson, Jan (2009). Bærumsbassenget et naturlig anoksisk basseng. Norsk institutt for vannforskning (NIVA). ISSN 9788257754709. Fulltekst i vitenarkiv

Se alle arbeider i NVA