| 1. |
- Ferraro, Mattia, et al.
(författare)
-
Establishing the current relation between observed oxygen conditions and oxygen proxies in western Norwegian fjords
- 2022
-
Ingår i: 14th International Palaeoceanography Congress (ICP), Bergen (Norway).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Recently, there have been alarming reports regarding the de-oxygenation of Norwegian fjords due to climate change. Warming coastal waters and a suggested decrease in the renewal frequency of the fjords’ deep, stagnant basin water have been linked to the reduced oxygen concentrations. The fjords are economically important to Norway, and the water quality is (of course) of uttermost importance to the local ecosystem. Here I present a new project, FJO2RD, which investigates recent changes in the physical forcing and the renewal frequency while utilising paleo records from sediment archives to provide information on natural variability in fjord oxygenation during the last ca. 400 years. New multi- and gravity cores will be obtained from two fjords, Masfjorden and Lurefjorden, in western Norway. The oxygenation history will be reconstructed based on benthic foraminiferal assemblages and geochemical analyses. The Mn/Ca ratio will be analysed to study the extent of hypoxic conditions and past oxygen dynamics, and the Ba/Ca ratio to study runoff variability and stratification. The stable carbon isotopes will infer remineralisation associated with the change in oxygen. Dissolved oxygen concentrations will further be quantified using a modified Behl dissolved oxygen index, which is a method that calculates changes in oxygen concentrations by using a weighted average for each oxygen category as 0.1 mL/L for dysoxic, 0.5 mL/L for suboxic, and 1.5 mL/L for weakly hypoxic-oxic conditions. The results of these analyses will be used as the basis for my PhD-thesis
|
|
| 2. |
- Ferraro, Mattia, et al.
(författare)
-
Multi-century reconstruction of environmental conditions in Lurefjorden, Norway.
- 2024
-
Ingår i: 24th Nordic Geological Winter Meeting, 10-12th Jan, 2024, Gothenburg, Sweden.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Benthic foraminiferal assemblages are identified to reconstruct changes in environmental conditions over the last few centuries in Lurefjorden, a western Norwegian fjord. From ca. 1970 until present days the relative abundance of Brizalina skagerrakkensis, an efficient bio-indicator for organic matter fluxes, is enhanced relative to the preceding time interval. Hence, our results suggest that there is an increase of the organic matter within the Lurefjorden basin in the last 50 years. Over the same period, there is also an increase in the absolute abundance of agglutinated species, indicating lower oxygen concentration in the water. A lowering of the oxygen concentrations may have taken place as a response of a greater oxygen consumption caused by a higher organic matter supply in the water column. Accoridng to Aksnes (2009), Lurefjorden was subject to an increased freshening of Norwegian coastal waters (NCW), which has led to a decrease in sunlight penetration into the water column, affecting the oxygen levels and the behavior of marine life within the basin, between 1935 and 2007. Furthermore, we used diversity indices to study the ecological status of the area, showing significant growth in diversity, abundance, and richness within the benthic foraminiferal community over the past 50 years. Our observations highlight that an increase in the input of organic matter over the last century has led to a change in the benthic foraminifera community in the Lurefjorden basin.
|
|
| 3. |
- Polovodova Asteman, Irina, 1980, et al.
(författare)
-
Spreading of an alien benthic foraminifer in the North Sea: a reason to be worried?
- 2023
-
Ingår i: International Congress FORAMS2023, Perugia, Italy, 25-30th June. - Perugia, Italy : Micropress Europe & The Grzybowski Foundation.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 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.
|
|
