392 John Woods
a)
DiSSOIved nltrogen
(mMoIIcu.m.)
Phy\oplankton
(organlsmslml.)
Grazing rate
(organismSllitrel30min.)
10 -
1
0 .1
0.01
0 .001
M
1000
100
10
1
/
V
0 .1
M
10000
1000
100
10
1
0 .1 .i
0 .01 #li
0.001
M
r---,
A
I
1/
A
I
1
A
~ un mI r
(
01 90 ro~ hy
V VV \(\ v.r /
\J
M
J
J
,..
S
o N o J F
h
I \~
\J v "' -
,...,.. It...
'- -
M
J
J
A
S
o N o J F
"\i \~i\
. \ I 1\"
[1
V'I
Id ~rJi
I rj
fi.\
f"y.t~ ,A
'p
M
J
J
A
S
o N o J F
Fig. 18.3 A circa 20-day cycle of primary production in the mixed layer during summer
oligotrophy. a) Variation of dissolved nitrogen, phytoplankton concentration and grazing
rate in the mixed layer.
18.7.5 Do it yourself
The case study presented above was illustrated using a CD-ROM, which contains
the Azores VPE and a tool to analyse it, called VEWdata (see 18.19). This package
is designed for users without programrning skills. It allows you to create graphs
and contour plots of the environment and audit trails of a representative sample of
plankton particles. You can obtain a copy ofthis CD-ROM by registering on http://
www.huxley.ic.ac.uklOceans/.