Thermal dependence of seagrass ecosystem metabolism in the Red Sea

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16 Scopus citations


The Red Sea is one of the warmest seas with shallow seagrass ecosystems exposed to extreme temperatures, in excess of 35°C, during the summer months. Seagrass meadows are net autotrophic ecosystems, but respiration increases faster than primary production with temperature. This may lead to a shift from an autotrophic to a heterotrophic system at the highest temperatures. Although tropical seagrasses are adapted to high temperatures, the metabolic rates of Red Sea seagrasses have not yet been reported. Here we assessed the community metabolism of 2 seagrass ecosystems, an Enhalus acoroides monospecific meadow and a Cymodocea serrulata and Halodule uninervis mixed meadow, located in the central Red Sea. We measured in situ net community production (NCP), community respiration (R), gross primary production (GPP), activation energy and community production-irradiance curves along their natural temperature gradient over 1 yr by measuring diel fluctuations in dissolved oxygen. The results were species-specific; while the monospecific meadow was autotrophic throughout the year (annual weighted average NCP: 64.63 ± 11.89 mmol O2 m-2 d-1, GPP:R ratio: 1.42 ± 0.06), the mixed meadow was heterotrophic during the summer months (annual weighted average NCP: -4.15 ± 9.39 mmol O2 m-2 d-1, GPP:R: 1.04 ± 0.05). In both seagrass meadows, R and GPP increased with increasing temperature, but differences in activation energies indicated that the mixed meadow is more sensitive to increasing seawater temperatures. These findings suggest contrasting responses in tropical seagrass species to rising temperature, pointing out the potential vulnerability of seagrasses to ocean warming in the Red Sea.
Original languageEnglish (US)
Pages (from-to)79-90
Number of pages12
JournalMarine Ecology Progress Series
StatePublished - Mar 11 2019

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This research was funded by King Abdullah University of Science and Technology through baseline funding to C.M.D. C.B. was supported by King Abdullah University of Science and Technology through the Visiting Student Research Program. We thank Marco Fusi, Janna Leigh Randle and the crew at CMOR for their support during fieldwork. We thank Ute Langner for creating the maps and Greg Silsbe for his help and advice on the PI models in the phytotools package.


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