Fróðskaparrit - 01.01.1999, Blaðsíða 171

VATNPLANTUR í FØROYSKUM VØTNUM VIÐ BLEYTUM VATNI
TAKA LÆTTLIGA ÓLÍVRUNNIÐ KOLEVNIUPP
175
tween non-CCM and CCM species. Rather,
the species show a continuous gradient in
carbon extraction capacity, which reflects
genotypical differences in carbon uptake
efficiency and the great plasticity in inor-
ganic carbon uptake physiology generally
observed for aquatic macrophytes. For
species restricted to C02 use and for
species running a CCM, the affinity for in-
organic carbon is greatly dependent on en-
vironmental conditions. Under conditions
where the restriction on inorganic carbon
uptake is high, the plants respond by en-
hancing the resource allocation towards
carbon uptake, resulting in an improved
affmity and extraction capacity for inorgan-
ic carbon (Sand-Jensen and Gordon, 1993;
Madsen, 1993; Madsen et al., 1996). The
restriction of inorganic carbon uptake rates
is not governed by the supply rate of C02
and other inorganic carbon species alone;
of more importance is the balance between
the supply rate and the demand for inorgan-
ic carbon by the plants. Environmental pa-
rameters other than inorganic carbon will,
therefore, affect the extent of inorganic car-
bon limitation and the extent of limitation
will be inversely coupled to the extent to
which other factors limit plant growth and,
thereby, affect inorganic carbon demand.
Thus, it cannot be excluded that among
species in the border-zone between non-
CCM and CCM species some species cate-
gorised as non-CCM might actually have a
concentrating system with a very low effi-
ciency and vice versa.
A number of the species tested and found
to rely on diffusive entry of C02 and C-3
photosynthesis have developed mecha-
Table 3.
Inorganic carbon extraction capacityfor submer-
ged macrophyte species in Faroese lakes. Inor-
ganic carbon extraction capacity was measured by
pH-drift experiments at an alkalinity ofl.O and
0.125 meqv L1 and is expressed asfinal-pH after
16 hours incubation at 10 flC and 250 (mol m'2 s'1
PAR. Mean (s.d., n = 3-6; n.a. = not analysed.
Talva 3.
Førleiki hjá vatnplantusløgum í føroyskum vøtnum
at taka ólívrunnið kolevni upp. pH-rekroyndir
mátaðu førleikan at taka ólívrunnið kolevni upp, tá
ið alkaliið er 1.0 og 0.125 meqv. L-1 og verður
nevnt endaligt pH, tá ið tilgerðartíðin er 16 tímar
við 10 °C og 250 (mol m-2 s-1 PAR. Miðal (s.d.)
n=3-6; n.a.=ikki sundurgreinað.)
Species Final-pH
1.0 meqv 0.125 meqv
L'1 L'1
Nymphaea alba 8.44±0.16 n.a.
Isoetes lacustris 8.55±0.04 n.a.
Sparganium angustifolium 8.58±0.04 n.a.
Lobelia dortmanna 8.62±0.25 n.a.
Callitriche stagnalis 8.72±0.03 n.a.
Littorella uniflora 8.75±0.24 n.a.
Eleocharis acicularis 8.93±0.15 n.a.
Fontinalis antipyretica 9.02±0.01 n.a.
Juncus bulbosus 9.07±0.02 n.a.
Nitella sp. 9.07±0.05 n.a.
Potamogeton polygonifolius 9.19±0.06 n.a.
Callitriche hamulata 9.27±0.09 n.a.
Potamogeton natans 9.52±0.47 8.52±0.56
Utricularia vulgaris 9.70±0.18 9.43±0.52
Potamogeton alpinus 10.00±0.10 9.92±0.08
P. praelongus 10.03±0.08 9.96±0.07
P. gramineus 10.12±0.16 9.85±0.10
Myriophyllum altemiflorum 10.13±0.02 9.82±0.08
Potamogeton obtusifolius 10.21±0.07 9.51±0.23
P. filiformis 10.26±0.09 9.64±0.03
Spirogyra sp. 10.39±0.41 9.80±0.42
Potamogeton perfoliatus 10.44±0.04 10.22±0.24
Chara sp. 10.52±0.02 9.62±0.07
Cladophora sp. 10.74±0.10 10.26±0.07
Vaucheria sp. 10.87±0.16 9.01±0.59