Macroalgae and phytoplankton as indicators of ... - Naturstyrelsen

A
100
B
140
Total algal cover (%)
80
60
40
20
0
HIGH
GOOD
MODERATE
Ref. H-G G-M M-P P-B 2001 2003 2005
Cummulated algal cover (%)
120
100
80
60
40
20
0
HIGH
GOOD
MODERATE
POOR
BAD
Ref. H-G G-M M-P P-B 2001 2003 2005
C
E
Cum. cover of late successionals (%)
35
30
25
20
15
10
5
0
HIGH
GOOD
MODERATE
Ref. H-G G-M M-P P-B 2001 2003 2005
D
F
Cum. cover of opportunists (%)
60
50
40
30
20
10
0
5
HIGH
GOOD
MODERATE
POOR
BAD
Ref. H-G G-M M-P P-B 2001 2003 2005
Fraction of opportunists (%)
100
90
80
70
60
50
GOOD
HIGH
Ref. H-G G-M M-P P-B 2001 2003 2005
Number of late successionals
4
3
2
1
0
-1
HIGH
GOOD
MODERATE
POOR
BAD
Ref. H-G G-M M-P P-B 2001 2003 2005
Figure 3.12 Reference levels, class borders and actual levels of various algal variables in Roskilde Fjord: Total algal cover (A),
Cumulated algal cover (B), Cumulated cover of late-successionals (C), Cumulated cover of opportunists (D), fraction of opportunists
(E) and number of late-successional algal species (F). Algal variables are modelled for a water depth of 7 m.
The mean levels of the algal indicators in Limfjorden west of Mors were
typically within the status class moderate. Modelled mean levels of each
algal variable in each area are shown in Appendices 7-12.
3.4.6 Sensitivity of the algal variables
The variance of the residual variation was the largest of the three components
of stochastic variation, but the variance contribution from divers
and sites was also considerable (Table 3.6). Therefore, as a general rule of
thumb, all these components should be reduced by increasing both the
number of divers, sites and point samples per site in order to obtain
more precise results.
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