Abstract
Spartina alterniflora has a distinct flood-adapted morphology, and its physiological responses are likely to vary with differences in tidal submergence. To understand these responses, we examined the impacts of tidal inundation on the efficiency of Photosystem II (φPSII) photochemistry and leaf-level photosynthesis at different canopy heights through a combination of in situ chlorophyll fluorescence (ChlF), incident photosynthetically active radiation, and tide levels. Our result showed small declines (7%–8.3%) in φPSII for air-exposed leaves when the bottom canopies were tidally submerged. Submerged leaves produced large reductions (30.3%–41%) in φPSII. Our results suggest that when submerged, PSII reaction centers in S. alterniflora leaves are still active and able to transfer electrons, but only at ∼20% of the typical daily rate. We attribute this reduction in φPSII to the decrease in the fraction of “open” PSII reaction centers (10% of the total) and the stomatal conductance rate caused by the tidal submergence. To our knowledge, this flooding induced leaf-level reduction of φPSII for S. alterniflora in field settings has not been reported before. Our findings suggest that canopy-level φPSII is dependent on the proportion of submerged versus emerged leaves and highlight the complexities involved in estimating the photosynthetic efficiency of tidal marshes.
| Original language | English |
|---|---|
| Article number | e2022JG007161 |
| Journal | Journal of Geophysical Research: Biogeosciences |
| Volume | 128 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2023 |
Funding
This project was supported by NASA Carbon Cycle Science Grant (#NNX17AI76G) and the Georgia Coastal Ecosystems LTER's National Science Foundation funding (OCE-1237140 and OCE-1832178). This is contribution 1111 of the University of Georgia Marine Institute. The authors would like to thank Dontrece Smith, Jacob Shalack, Alyssa Peterson, John Williams, and Elise Diehl for their assistance in field transportation, field data collection, and sensor maintenance at the GCE-LTER site. The authors would like to thank Wade Sheldon, and Adam Sapp for data management at the GCE-LTER site. The authors also thank Dr. Hailong Huang for his help in the first deployment and testing of the PAM fluorometry. This project was supported by NASA Carbon Cycle Science Grant (#NNX17AI76G) and the Georgia Coastal Ecosystems LTER's National Science Foundation funding (OCE‐1237140 and OCE‐1832178). This is contribution 1111 of the University of Georgia Marine Institute. The authors would like to thank Dontrece Smith, Jacob Shalack, Alyssa Peterson, John Williams, and Elise Diehl for their assistance in field transportation, field data collection, and sensor maintenance at the GCE‐LTER site. The authors would like to thank Wade Sheldon, and Adam Sapp for data management at the GCE‐LTER site. The authors also thank Dr. Hailong Huang for his help in the first deployment and testing of the PAM fluorometry.
| Funders | Funder number |
|---|---|
| NASA Carbon Cycle Science | 17AI76G |
| University of Georgia Marine Institute | |
| Wade Sheldon | |
| National Science Foundation | OCE‐1237140, OCE‐1832178 |