Phosphorus-Biomass Relationships in Lakes
Water residence time (y)
S0by10
1
0.1
gard
10.----4-----------+-----------r-----.
Ojer
sjeen
8autze~ 1
reserVOIr
Moso vatn
o Hauga~
gem
1
Vreng
0.0 1 -l'-"-""'"'"'= ........ """-'-=~"'-"="--= ............ -'-'--=-__+"_'~"-'-'--'---_l
0.0001
0.001
0.01
0. \
Dilution rate D (d -I)
149
.-... .........
()t)
~
0.1
~
VJ
'<
' - '
0.01
Fig. 5.17. Examples of loading parameters from different lakes in relation to the region of
stable grazer control on algal biomass (shaded area). Open symbols are lakes from which
successful biomanipulations have been reported. while solid symbols are unsuccessful ones.
Vertical arrows denote external load reductions resulting from phosphorus abatement
measures. (Based on data from Benndorf 1987; Brabrand et al. 1990; Jeppesen et al. 1990;
Reinertsen et al. 1989; Sanni and Wrervigen 1990)
5.7 Phosphorus-Biomass Relationships in Lakes
Zooplankton. McCauley and Kalff (1981) showed that in a set of literature
data from different lakes there was a significant positive log-log relationship between zooplankton biomass and algal biomass (measured as biovolume). Rognerud and Kjellberg (1984) also found a positive correlation
between zooplankton and algal biomass (measured as chlorophyll a) in a
more homogeneous data set from large, oligo- and mesotrophic Norwegian
lakes. The linear equation fitted by Rognerud and Kjellberg (1984) had a
steeper slope than the regression model of McCauley and Kalff (1981) and
predicted much higher zooplankton levels when extrapolated to the most
eutrophic lakes considered by McCauley and Kalff (1981). This inconsistency gives some indication that the relationship between algae and
zooplankton might be different in oligotrophic and eutrophic lakes.