Table 1.
Symbionts colonizing coverslips in high-pressure vessels under simulated, deep-sea, and flowthrough vent conditions
| Incubation, d | Replicates | Symbionts, mm−2 | FDC, % | Rods, % | Length, µm | Width, µm | Cocci, % | Diameter, µm |
| Deep-sea | ||||||||
| 0.5 | 3 (3,3,4) | 16.3 ± 15.7 | 1.3 ± 2.0 | 0.0 | N/A | N/A | 100.0 | 4.2 ± 0.7 |
| 1 | 3 (3,3,5) | 47.1 ± 60.0 | 3.3 ± 3.9 | 0.5 ± 1.2 | 2.3 ± 1.3 | 0.9 ± 0.5 | 99.5 ± 1.2 | 3.7 ± 0.5 |
| 2 | 3 (3,2,5) | 30.4 ± 30.0 | 2.0 ± 3.5 | 2.8 ± 5.3 | 1.8 ± 0.9 | 0.9 ± 0.3 | 97.2 ± 5.3 | 4.3 ± 0.6 |
| 6 | 2 (3,5) | 377.9 ± 507.5 | 20.0 ± 28.3 | 0.0 | N/A | N/A | 100.0 | 3.3 ± 1.2 |
| 8 | 1 (5) | 9.8 ± 7.1 | 4.0 ± 6.9 | 0.0 | N/A | N/A | 100.0 | 4.2 ± 0.5 |
| 10 | 1 (5) | 25.9 ± 29.0 | 1.6 ± 1.3 | 0.5 ± 1.1 | 1.6 ± 0.8 | 0.9 ± 0.5 | 99.5 ± 1.1 | 4.3 ± 0.6 |
| Vent | ||||||||
| 0.5 | 3 (3,3,3) | 80.0 ± 133.8 | 7.4 ± 12.9 | 0.1 ± 0.4 | 1.5 ± 0.4 | 0.8 ± 0.2 | 99.9 ± 0.4 | 3.1 ± 1.4 |
| 1 | 3 (3,3,3) | 51.1 ± 84.1 | 5.8 ± 8.2 | 0.0 | N/A | N/A | 100.0 | 2.5 ± 0.1 |
| 2 | 1 (3) | 26.1 ± 42.9 | 4.3 ± 7.5 | 0.0 | N/A | N/A | 100.0 | 4.0 ± 0.2 |
| 6 | 2 (3,3) | 2.1 ± 0.8 | 0.0 | 0.0 | N/A | N/A | 100.0 | 2.4 ± 0.1 |
Trophosome pieces were incubated under simulated deep-sea conditions at 4 °C and 171.6 ± 0.5 µmol⋅L−1 oxygen without flow or under simulated flowthrough vent conditions at 22.4 ± 0.6 °C, 280 ± 48 µmol⋅L−1 ∑H2S and 107 ± 29 µmol⋅L−1 oxygen. Density of symbionts released and settled on coverslips (FISH-positive cells stained with symbiont-specific probe, EUB338 probe mix, and DAPI were counted on 1.125 mm2 of glass coverslips), frequency of dividing cells, relative density of rods (length and width), and cocci (diameter) are given as mean and SD. To analyze the morphological variability, a total of 100 rods and cocci (when present) was counted for each coverslip and length and width for rods and diameter for cocci were measured. Incubations were conducted in triplicate (three different specimens incubated in different high-pressure incubation vessels) for each treatment for 0.5, 1, and 2 d. The longer 6-d incubations under vent and deep-sea conditions were done in duplicate. In addition, simulated deep-sea incubations were also run for 8 and 10 d once. Replicates are given: The numbers refer to trophosome samples of different specimens, and the numbers in parentheses refer to the number of coverslips analyzed in total. N/A, data not available.