Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1016/j.scitotenv.2023.169201
Licence creative commons licence
Title (Primary) Light and temperature controls of aquatic plant photosynthesis downstream of a hydropower plant and the effect of plant removal
Author Demars, B.O.L.; Schneider, S.C.; Thiemer, K.; Dörsch, P.; Pulg, U.; Stranzl, S.; Velle, G.; Pathak, D.
Source Titel Science of the Total Environment
Year 2024
Department ASAM
Volume 912
Page From art. 169201
Language englisch
Topic T5 Future Landscapes
Supplements https://ars.els-cdn.com/content/image/1-s2.0-S0048969723078312-mmc1.xlsx
Keywords Photosynthesis; Macrophyte removal; Regulated river; Metabolic theory, Light; Temperature; Resilience
Abstract Many rivers worldwide are regulated, and the altered hydrology can lead to mass development of aquatic plants. Plant invasions are often seen as a nuisance for human activities leading to costly remedial actions with uncertain implications for aquatic biodiversity and ecosystem functioning. Mechanical harvesting is often used to remove aquatic plants and knowledge of plant growth rate could improve management decisions. Here, we used a simple light-temperature theoretical model to make a priori prediction of aquatic plant photosynthesis. These predictions were assessed through an open-channel diel change in O2 mass balance approach. A Michaelis-Menten type model was fitted to observed gross primary production (GPP) standardised at 10 °C using a temperature dependence from thermodynamic theory of enzyme kinetics. The model explained 87 % of the variability in GPP of a submerged aquatic plant (Juncus bulbosus L.) throughout an annual cycle in the River Otra, Norway. The annual net plant production was about 2.4 (1.0–3.8) times the standing biomass of J. bulbosus. This suggests a high continuous mass loss due to hydraulic stress and natural mechanical breakage of stems, as the biomass of J. bulbosus remained relatively constant throughout the year. J. bulbosus was predicted to be resilient to mechanical harvesting with photosynthetic capacity recovered within two years following 50–85 % plant removal. The predicted recovery was confirmed through a field experiment where 72 % of J. bulbosus biomass was mechanically removed. We emphasise the value of using a theoretical approach, like metabolic theory, over statistical models where a posteriori results are not always easy to interpret. Finally, the ability to predict ecosystem resilience of aquatic photosynthesis in response to varying management scenarios offers a valuable tool for estimating aquatic ecosystem services, such as carbon regulation. This tool can benefit the EU Biodiversity Strategy and UN Sustainable Development Goals.
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=28467
Demars, B.O.L., Schneider, S.C., Thiemer, K., Dörsch, P., Pulg, U., Stranzl, S., Velle, G., Pathak, D. (2024):
Light and temperature controls of aquatic plant photosynthesis downstream of a hydropower plant and the effect of plant removal
Sci. Total Environ. 912 , art. 169201 10.1016/j.scitotenv.2023.169201