Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Seasonal study of δ18O and δ13C in living (stained) benthic foraminifera from two Swedish fjords

Filipsson, Helena L. LU orcid ; Nordberg, Kjell and Gustafsson, Mikael (2004) In Marine Micropaleontology 53(1-2). p.159-172
Abstract

In a previous 16-month seasonal study on living (stained) benthic foraminifera from two fjords on the Swedish west coast, it was reported that foraminifera proliferated in response to phytodetritus input; the strongest response came from the opportunistic species Stainforthia fusiformis. In this study, our objective was to find out if that phytodetritus input resulted in a change in the carbon isotopic composition of the foraminiferal tests. We also wanted to examine if variations in salinity and temperature (due to seasonality or deep-water exchanges) were reflected in the δ18O values. From S. fusiformis that were obtained from the Havstens Fjord (20 m) and the Gullmar Fjord (119 m) during the 16-month study, we developed a... (More)

In a previous 16-month seasonal study on living (stained) benthic foraminifera from two fjords on the Swedish west coast, it was reported that foraminifera proliferated in response to phytodetritus input; the strongest response came from the opportunistic species Stainforthia fusiformis. In this study, our objective was to find out if that phytodetritus input resulted in a change in the carbon isotopic composition of the foraminiferal tests. We also wanted to examine if variations in salinity and temperature (due to seasonality or deep-water exchanges) were reflected in the δ18O values. From S. fusiformis that were obtained from the Havstens Fjord (20 m) and the Gullmar Fjord (119 m) during the 16-month study, we developed a time series of δ18O and δ13C. After the spring blooms in the Havstens and the Gullmar Fjord, decreases of about 0.2‰ to 0.3‰ in the foraminiferal δ13C values were noted; in the Gullmar Fjord after the autumn blooms, decreases of the same order were also noted. Comparing the Havstens and the Gullmar Fjord, we found a 1‰ difference in both δ13C and δ18O; we attribute this to hydrographic differences between the two fjords. Using calculated values of δ18O, together with the measured ones, we noticed that S. fusiformis in the Gullmar Fjord seems to calcify close to equilibrium with respect to the oxygen isotopes. During autumn, water temperatures were relatively high in the Havstens Fjord, and foraminiferal abundance in the fjord was also high after a phytodetritus input; but, the measured δ18O values do not reflect these higher temperatures. This apparently contradictory combination of results might be explained by a varying δ18O composition of the water during the year, which counterbalances the temperature effect.

(Less)
Please use this url to cite or link to this publication:
author
; and
publishing date
type
Contribution to journal
publication status
published
subject
keywords
benthic foraminifera, fjords, phytoplankton, seasonal variations, skagerrak, stable isotopes
in
Marine Micropaleontology
volume
53
issue
1-2
pages
14 pages
publisher
Elsevier
external identifiers
  • scopus:8444242518
ISSN
0377-8398
DOI
10.1016/j.marmicro.2004.05.008
language
English
LU publication?
no
id
6f2295fd-88e9-4953-91f4-95c4e075f752
date added to LUP
2018-10-18 12:00:14
date last changed
2022-01-31 06:14:16
@article{6f2295fd-88e9-4953-91f4-95c4e075f752,
  abstract     = {{<p>In a previous 16-month seasonal study on living (stained) benthic foraminifera from two fjords on the Swedish west coast, it was reported that foraminifera proliferated in response to phytodetritus input; the strongest response came from the opportunistic species Stainforthia fusiformis. In this study, our objective was to find out if that phytodetritus input resulted in a change in the carbon isotopic composition of the foraminiferal tests. We also wanted to examine if variations in salinity and temperature (due to seasonality or deep-water exchanges) were reflected in the δ<sup>18</sup>O values. From S. fusiformis that were obtained from the Havstens Fjord (20 m) and the Gullmar Fjord (119 m) during the 16-month study, we developed a time series of δ<sup>18</sup>O and δ<sup>13</sup>C. After the spring blooms in the Havstens and the Gullmar Fjord, decreases of about 0.2‰ to 0.3‰ in the foraminiferal δ<sup>13</sup>C values were noted; in the Gullmar Fjord after the autumn blooms, decreases of the same order were also noted. Comparing the Havstens and the Gullmar Fjord, we found a 1‰ difference in both δ<sup>13</sup>C and δ<sup>18</sup>O; we attribute this to hydrographic differences between the two fjords. Using calculated values of δ<sup>18</sup>O, together with the measured ones, we noticed that S. fusiformis in the Gullmar Fjord seems to calcify close to equilibrium with respect to the oxygen isotopes. During autumn, water temperatures were relatively high in the Havstens Fjord, and foraminiferal abundance in the fjord was also high after a phytodetritus input; but, the measured δ<sup>18</sup>O values do not reflect these higher temperatures. This apparently contradictory combination of results might be explained by a varying δ<sup>18</sup>O composition of the water during the year, which counterbalances the temperature effect.</p>}},
  author       = {{Filipsson, Helena L. and Nordberg, Kjell and Gustafsson, Mikael}},
  issn         = {{0377-8398}},
  keywords     = {{benthic foraminifera; fjords; phytoplankton; seasonal variations; skagerrak; stable isotopes}},
  language     = {{eng}},
  month        = {{10}},
  number       = {{1-2}},
  pages        = {{159--172}},
  publisher    = {{Elsevier}},
  series       = {{Marine Micropaleontology}},
  title        = {{Seasonal study of δ<sup>18</sup>O and δ<sup>13</sup>C in living (stained) benthic foraminifera from two Swedish fjords}},
  url          = {{http://dx.doi.org/10.1016/j.marmicro.2004.05.008}},
  doi          = {{10.1016/j.marmicro.2004.05.008}},
  volume       = {{53}},
  year         = {{2004}},
}