Article Figures & Data
Figures
- Fig. 1.
Emission spectrum of the Phytoclaude lamp used to demonstrate the inhibitory effect of light on methanotrophic bacterial growth and activity.
- Fig. 2.
Variation of total methane emission and methane concentrations in the water column (at depths of 0, 1, and 2 m and at the bottom), since the beginning of filling (day zero), in January 1994. d, day.
- Fig. 3.
Dissolved oxygen and methane profiles and methane consumption measured at the BPS site in December 1995. Values are in tenths.
- Fig. 4.
Bacterial growth determined by OD at 540 nm and by total methane measurements in the incubated flasks. Replicates were incubated in darkness or under illumination at about 168 microeinsteins · m−2 · s−1 for 12 h a day. Abiotic experiments were run without an inoculum. Percent growth inhibition was calculated after 1 day of incubation. Q, quantity.
- Fig. 5.
Percent growth inhibition versus illumination delivered during bacterial growth. Experiments were run on two identical enriched cultures (A and B) obtained from water sampled at the oxycline in September 1995 and on a pure culture of M. trichosporiumOB3B. μE, microeinsteins.
- Fig. 6.
Variation of the total methane emission, the Secchi disk depth, and the oxycline depth in Petit Saut reservoir since the beginning of the filling in January 1994. d, day.
Tables
- Table 1.
Measurements of ammonium and sulfide at the BPS site on 28 May 1995a
Depth (m) Concn of: Ammonium (μmol · liter−1) Sulfide (μg · liter−1) 0 37.07 ND 2 ND 10.68 5 40.37 139.2 7 ND 171.2 10 139.46 175.36 15 203.32 178.24 20 235.25 180.8 25 ND 185.28 32 476.37 188.48 ↵a The oxycline was located at a depth of 3 m. ND, not determined.
- Table 2.
PLFA profiles determined on methanotrophic cultures and on a water sample from around the BPS oxycline in December 1996.
Fatty acid % of compositiona of: Culture Oxycline i14:0 0.33 0.73 14:1 0.1 14:0 0.49 8.85 i15:0 0.89 2.26 a15:0 0.21 1.84 15:0 0.24 2.05 i16:0 0.25 0.94 16:1ω9 0.64 0.25 16:1ω7 0.69 10.5 16:0 2.93 30.7 10Me16:0 0.06 i17:0 0.22 0.62 a17:0 0.19 1.39 17:1 0.09 0.78 17:0 0.16 0.96 18:2(8,14) 7.06 0.52 18:2(7,14) 1.65 0.31 18:1ω9 1.78 3.78 18:1ω8b 57.6 1.63 18:1ω7 19.63 4.16 18:0 3.08 26.8 19:1 0.08 20:0 0.13 0.7 - Table 3.
Illumination and growth inhibition at BPS site
Depth (m) Illumination (microeinsteins · m−2· s−1) % Inhibition (±10%) 0 760 92 1 260 85 1.5 200 84 2 130 40 3 74 32 4 21 11 6 2 0
