Document Type

Journal Article

Publication Title

Estuarine, Coastal and Shelf Science




School of Science / Centre for Marine Ecosystems Research




Edith Cowan University - Open Access Support Scheme 2021

Western Australian Marine Science Institution

Edith Cowan University


Said, N. E., McMahon, K., & Lavery, P. S. (2021). Accounting for the influence of temperature and location when predicting seagrass (Halophila ovalis) photosynthetic performance. Estuarine, Coastal and Shelf Science, 257, article 107414.


We show that the effect of temperature on photosynthesis of a widely distributed and ecological important seagrass species was not consistent among locations, with some evidence of acclimation to the local temperature range. This has important implications for modelling seagrass productivity and the impacts of light reduction on seagrass ecosystems. Reduced light availability is one of the main pressures negatively impacting on seagrass meadows worldwide. Our knowledge of seagrass photosynthetic characteristics is critical to predicting and managing impacts of light reducing activities but suffers from two critical information gaps: first, data is overwhelmingly derived from studies of leaf tissue and not for whole plants, and is unlikely to reflect whole plant performance under light reduction stress; and second, few studies have looked at spatial and temporal variability in photosynthetic performance of whole seagrasses. We investigated temporal and spatial variation at a range of temperatures for whole plants of Halophila ovalis, a widely distributed species, by measuring oxygen exchange of intact plants collected from four locations across a latitudinal gradient (10°) at three temperatures (17 °C, 23 °C, 28 °C). For all locations, temperature affected all photosynthetic parameters, with some parameters (NPmax, R, Ik) showing a distinct difference between tropical and temperate locations. For example, NPmax ranged from 1.35 ± 0.12 to 5 ± 0.16 mg O₂. g DW−1. hr−1 in temperate locations and from 4 ± 0.3 to 12 ± 0.68 mg O₂. g DW−1. hr−1 in the tropical location. However, the effect of temperature on photosynthesis was not consistent among locations, and often the rate of photosynthesis was greatest at temperatures approaching the mean month maximum temperature for the location, suggestive of acclimation. Time of year also affected photosynthetic rates and how temperature influenced those rates. We conclude that the application of P–I parameters to model, predict or manage the effect of light reduction of H. ovalis, and likely other seagrass species, may require site- and time-specific knowledge of P–I relationships.



Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Research Themes

Natural and Built Environments

Priority Areas

Environmental management, governance and policy