Seasonal variation of Emiliania huxleyi morphology at an ecosystem monitoring site
off the east coast of Scotland
Pablo Leon Diaz, Eileen Bresnan and Pam Walsham
Marine Laboratory, 375 Victoria Road, Aberdeen, AB11 9DB, U.K. E-mail Pablo.Diaz@scotland.gsi.gov.uk
Why are coccolithophores important?
Coccolithophores
are
an
important component of the
phytoplankton community and
are the focus of many studies
about the effects of Ocean
Acidification (OA). Laboratory
research has shown contradictory
results about the impacts of OA
on
the
calcification
of
coccolithophore plates and field
studies are scarce. In this study
the diversity and seasonality of
coccolithophores are investigated
at the Stonehaven coastal
monitoring site for the first time.
Coccolithopore
cell
Satellite image
Coccolithophore bloom
Coccolith structure
Distal
shield
Stonehaven Monitoring site
Marine Scotland Science has been operating a coastal ecosystem monitoring site
at Stonehaven (lat. 56.96N/long. 2.10W) since 1997. Samples are collected
weekly 5 km offshore to record temperature, salinity, nutrients, phytoplankton
and zooplankton. Total Alkalinity (TA) and Dissolved Organic Carbon (DIC) are also
measured since 2009 to generate data on OA in Scottish waters (see poster by
Walsham et al., E-poster session 1). Since 2010 additional samples have been
collected to investigate the diversity of coccolithophores in the region.
Methods – SEM analysis
Sea water samples for the analysis of coccolithophores
were preserved using a formalin-hexamine solution and
stored in dark conditions until analysis using Scanning
Electron Microscopy (SEM). Between 5 and 10 ml of
samples were filtered through a 0.1 µm filter, rinsed to
remove salt and then air dried. Filters were splutter coated
with gold and examined with a Zeiss EVO MAIO SEM
(Institute of Medical Sciences, University of Aberdeen).
Coccolithophore cells were enumerated and classified
according to Young et al. (2003*). Emiliania huxleyi
coccospheres and coccoliths were measured from SEM
micrographs using Fiji (ImageJ) image processing package
and categorized into morphotypes.
Central area
Coccoliths
Location of
Stonehaven
monitoring site
ZEISS EVO MAIO SEM used in the study
*Young, J. R., Geisen, M., Cros, L., Kleijne, A., Sprengel, C., Probert, I. and Ostergaard, J. 2003. A guide to extant coccolithophore taxonomy.
J. Nannoplankton Res. Spec. Issue 1:1–125.
Seasonal variation of Emiliania huxleyi morphology at an ecosystem monitoring site
off the east coast of Scotland
Pablo Leon Diaz, Eileen Bresnan and Pam Walsham
Marine Laboratory, 375 Victoria Road, Aberdeen, AB11 9DB, U.K. E-mail Pablo.Diaz@scotland.gsi.gov.uk
Coccolithophore diversity
Analysis of water samples collected between June 2010 and December 2013 reveals six
coccolithophore species present at the Stonehaven monitoring site.
Emiliania huxleyi
Coronosphaera mediterranea
A seasonal cycle in coccolithophore abundance was observed, with increased
abundance during summer and early autumn and very low cell densities in
winter. E. huxleyi was the dominant specie throughout the year. The other
species/genera were mainly observed in the early summer. No
coccolithophores were observed in April.
2 µm
1 µm
Helicosphaera carteri HOL perforate
2 µm
Syracosphaera corolla
2 µm
2 µm
Average abundance (Cells/L)
E. huxleyi
4500
4000
3500
3000
2500
2000
1500
1000
500
0
2 µm
Syracosphaera spp.
Coccolithus pelagicus
Braarudii spp.
C. mediterranea
Syracosphaera spp.
S. corolla
H. carteri
Seasonal variation of Emiliania huxleyi morphology at an ecosystem monitoring site
off the east coast of Scotland
Pablo Leon Diaz, Eileen Bresnan and Pam Walsham
Marine Laboratory, 375 Victoria Road, Aberdeen, AB11 9DB, U.K. E-mail Pablo.Diaz@scotland.gsi.gov.uk
The morphological analysis of E. huxleyi cells indicate the presence of three
different morphotypes at the region: i) Type A, small coccospheres with
moderate-heavily elements and a grilled central area; ii) Type A
Overcalcified, small coccospheres with heavily elements and almost closed
central area; iii) Type B: larger coccospheres with lightly calcified elements.
Emiliania huxleyi (Type A)
Grilled
central area
1 µm
Emiliania huxleyi
(Type A overcalcified)
Increased
calcification
A seasonal variability was observed in the E. huxleyi morphotypes, with a transition in dominance
from less to more heavily calcified forms between spring and early winter. Type A was the dominant
morphotype observed.
Type A Overcalcified
Average abundance (Cells/L)
Emiliania huxleyi morphotypes
Type A
Type B
16000
14000
12000
10000
8000
6000
4000
2000
0
2 µm
Emiliania huxleyi (Type B)
Type B
This study presents the first records of coccolithophore diversity at the Stonehaven monitoring site. As
the time series extends, data collected will show if variation in the abundance of these dominant
morphotypes is driven by seasonality or influenced by larger scale environmental change such as climate
change or OA.
Acknowledgments
Solid non-grilled
central area
2 µm
Type A Overcalcified
2 µm
The authors would like to thank Kevin Mackenzie, Debbie Wilkinson and Lucy Wight from the Microscopy Unit, IMS,
University of Aberdeen for their assistance with the SEM analysis as well as all involved in the sampling team at the
Stonehaven ecosystem monitoring site. This work is funded by the Scottish Government Service Level Agreement ST03p.