We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Coastal primary productivity changes over the last millennium: a case study from the Skagerrak (North Sea).
- Authors
Binczewska, Anna; Risebrobakken, Bjørg; Asteman, Irina Polovodova; Moros, Matthias; Tisserand, Amandine; Jansen, Eystein; Witkowski, Andrzej
- Abstract
A comprehensive multi-proxy study on two sediment cores from western and central Skagerrak was performed in order to detect the variability and causes of marine primary productivity changes in the investigated region over the last 1100 years. The cores were dated by Hg pollution records and AMS 14C dating and analysed for palaeoproductivity proxies such as total organic carbon, δ13C, total planktonic foraminifera, benthic foraminifera (total as well as abundance of Brizalina skagerrakensis and other palaeoproductivity taxa) and palaeothermometers such as Mg / Ca and δ18O. Our results reveal three periods with changes in productivity in the Skagerrak region: (i) moderate productivity at ~ CE 900–1200; (ii) low to moderate productivity at ~ CE 1200–1600 and (iii) high productivity at ~ CE 1600–present. During ~ CE 900–1200, moderate productivity was likely driven by the nutrients transported with the warm Atlantic water inflow associated with a tendency for a persistent positive NAO phase during the warm climate of the Medieval Climate Anomaly. The following low productivity period at ~ CE 1200–1600 was likely caused by a lower contribution of nutrient-rich Atlantic water due to a generally more negative NAO phase and a shift to the more variable and generally cooler climate conditions of the Little Ice Age. At that time the nutrient supply was largely sustained by the Baltic Sea outflow and river runoff associated with land-use changes. Since ~ CE 1600 towards present day our data point to an increased nutrient content in the Skagerrak waters. This increased nutrient content was likely caused by enhanced inflow of warm Atlantic water, increased Baltic outflow, intensified river runoff and enhanced human impact through agriculture expansion and industrial development. Intensified human impact likely increased nutrient transport to the Skagerrak and caused changes in the oceanic carbon isotope budget, known as the Suess effect, which is clearly visible in our records as a negative shift in δ13C values from ~ CE 1750. In addition, a higher benthic foraminiferal Mn / Ca suggests slightly decreased bottom water oxygen conditions between ~ CE 1050 and 1400 in the central Skagerrak and in the last 70 years at both studied locations.
- Subjects
MARINE sediment analysis; FORAMINIFERA; MERCURY; MAGNESIUM; CALCIUM
- Publication
Biogeosciences Discussions, 2018, p1
- ISSN
1810-6277
- Publication type
Article
- DOI
10.5194/bg-2018-94