Tl. Bott et al., AN EVALUATION OF TECHNIQUES FOR MEASURING PERIPHYTON METABOLISM IN CHAMBERS, Canadian journal of fisheries and aquatic sciences, 54(3), 1997, pp. 715-725
Experiments were performed to compare C-14 uptake, dissolved O-2 and C
O2 change, and microelectrode techniques for measuring benthic primary
productivity and community metabolism at a site on the South Saskatch
ewan River, Saskatchewan. The highest estimates of primary productivit
y were obtained with O-2 microelectrodes (two to four times higher tha
n simultaneous estimates from bulk-water dissolved O-2 measurements),
presumably because measurements are biased toward active communities u
nder optimal conditions for photosynthesis. In daytime experiments las
ting similar to 1.3 and 2.4 h, estimates from C-14 uptake were higher
than those measured simultaneously from dissolved O-2 and CO2 change,
suggesting that C-14 uptake measured gross primary production (GPP) in
these short-term incubations. Differences in experimental water veloc
ity ranging from 0.2 to >6.5 cm . s(-1) had less of an effect than chl
orophyll a concentration on metabolic rates in diel experiments with r
ocks taken from a site where velocities were from 5.6 to 7.8 cm . S-1.
There was a potential for phosphorus and possibly NH4 limitation of m
etabolic activity during long-term incubations. Results highlight area
s in which further research is needed when using chambers to determine
periphyton metabolism.