Geoscience Reference
In-Depth Information
were differences in the slopes and maximum sizes of individuals present in
size spectra in the path of the travelling bloom.
F. Data
The model predicted that areas with high phytoplankton abundance typical-
ly had shallower size-spectrum slopes with larger individuals present, where-
as low production areas had steeper slopes and truncated size spectra
(
Figure 5
). In the Celtic Sea, the research trawl survey sampling locations
on the shelf edge are generally located in areas of higher production com-
pared to those located off the shelf edge. The Celtic Sea data show that size
spectra from sample points on the shelf edge exhibited shallower slopes and
larger maximum size classes when compared with sample points off the shelf
edge where abundance was lower.
Low production area (LPA) size spectra
High production area (HPA) size spectra
5
5
Total spatio-temporal average
HPA spatio-temporal average
HPA temporal averages
Total spatio-temporal average
LPA spatio-temporal average
LPA temporal averages
0
0
-
5
-
5
y
=
-
1.08
x
-
7.098
y
=
-
1.266
x
-
8.768
-
15
-
15
R
2
= 0.99
2
= 0.99
R
-
25
-
25
0
-
6
-
4
-
2
2
-
6
-
4
-
2
0
2
log
10
Mass (kg)
log
10
Mass (kg)
Size spectra at off-shelf stations in the Celtic Sea
(1987-2003 average)
Size spectra at on-shelf stations in the Celtic Sea
(1987-2003 average)
18
18
16
16
14
14
12
12
10
10
8
8
6
6
4
y
=
-
1.4193
x
+
21.834
4
y
=
-
2.0045
x
+
28.225
2
2
= 0.984
R
2
R
2
= 0.8782
0
0
-
2
6.5
8.5
10.5
1
2.5
14.5
-
2
6.5
8.5
10.5
12.5
14.5
log
2
mass
log
2
mass
Figure 5
The top row shows temporally averaged size spectra from the realistic
model run. The left figure shows size spectra from high production areas (HPA)
and the right figure shows size spectra from a low production area (LPA). The bottom
row shows data-based size spectra from sample locations in the Celtic Sea demon-
strating differences in slope and amount of truncation of the spectra between sites on
the shelf and off the shelf (corresponding to a HPA and an LPA). In each case, the
total spatio-temporal average size spectra (both HPA and LPA combined), the local
spatio-temporal average size spectra (the HPA and LPA separately), the temporally
averaged size spectra at a transect of spatial points and the linear fit to the local size
spectra (dashed line) are shown.
