Loading...
Please wait, while we are loading the content...
Similar Documents
Time-course of photoadaptation in the symbiotic sea anemone Anemonia viridis
| Content Provider | Semantic Scholar |
|---|---|
| Author | Harland, A. D. Davies, Peter Spencer |
| Copyright Year | 1994 |
| Abstract | The time-course of photoadaptation in the symbiotic sea anemone Anemonia viridis (Forskäl) was determined on freshly collected anemones which were maintained under low light (LL: 10 μE m-2s-1) or high light (HL: 300 μE m-2s-1) over a period of 35 d. Photosynthesis versus irradiance curves (P vs I) normalised to anemone dry weight were determined for anemones at the start of the experiment and for both groups at 7 d intervals. Photosynthetic parameters derived from the P vs I curves, Pmaxgross(the maximum photosynthetic capacity of the zooxanthellae), α (an estimate of photosynthetic efficiency) and Ik(the light-saturating irradiance), and the respiration rate, showed that anemones were high-light adapted before the experiment began. Thereafter, any observed changes occurred only in anemones adapting to the low-light regime. Pmaxgrossremained relatively constant over 35 d and there was no significant difference between LL and HL groups. In the LL group α increased and both Ikand the respiration rate decreased significantly. These photoadaptive responses were most rapid in the first 7 d, after which change was gradual until about Day 28, when photoadaptation appeared to be complete. In order to predict the physiological mechanisms of photoadaptation to low light, Pgross vs I curves normalised to zooxanthellae biomass were constructed for LL and HL anemones at 35 d. Zooxanthellae density and photosynthetic pigment content were also analysed. For LL-adapted anemones, α and chlorophyll a were higher, there were no differences in algal density and chlorophyll c2 and Ikwas lower. It is proposed that the size of the peridinin-chlorophyll a-protein complex (PCP) of the light-harvesting complex was increased to facilitate photoadaptation. Plotting Pnet vs I normalised to anemone dry weight on the 35 d-photoadapted anemones gave a measure of changes in the excess photosynthetically fixed carbon that was potentially available to the host. Net photosynthesis of the LL group was higher at subsaturating light intensities as a result of the increase in α, and at saturating light intensities Pmaxnetwas higher as a result of a decrease in the rate of respiration of the whole symbiotic association. |
| Starting Page | 45 |
| Ending Page | 51 |
| Page Count | 7 |
| File Format | PDF HTM / HTML |
| DOI | 10.1007/BF00350105 |
| Volume Number | 119 |
| Alternate Webpage(s) | https://page-one.springer.com/pdf/preview/10.1007/BF00350105 |
| Alternate Webpage(s) | https://doi.org/10.1007/BF00350105 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
