Reviews and syntheses: Spatial and temporal patterns in seagrass metabolic fluxes

• Published in: Biogeosciences
• Main Authors: M. Ward, T. L. Kindinger, H. K. Hirsh, T. M. Hill, B. M. Jellison, S. Lummis, E. B. Rivest, G. G. Waldbusser, B. Gaylord, K. J. Kroeker
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2022
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Ocean acidification
• Online Access: https://doi.org/10.5194/bg-19-689-2022; https://doaj.org/article/33afaa765bc94dbd831d1bce95fef5a1

Seagrass meadow metabolism has been measured for decades to gain insight into ecosystem energy, biomass production, food web dynamics, and, more recently, to inform its potential in ameliorating ocean acidification (OA). This extensive body of literature can be used to infer trends and drivers of seagrass meadow metabolism. Here, we synthesize the results from 56 studies reporting in situ rates of seagrass gross primary productivity, respiration, and/or net community productivity to highlight spatial and temporal variability in oxygen ( O 2 ) fluxes. We illustrate that daytime net community production (NCP) is positive overall and similar across seasons and geographies. Full-day NCP rates, which illustrate the potential cumulative effect of seagrass beds on seawater biogeochemistry integrated over day and night, were also positive overall but were higher in summer months in both tropical and temperate ecosystems. Although our analyses suggest seagrass meadows are generally autotrophic, the effects on seawater oxygen are relatively small in magnitude. We also find positive correlations between gross primary production and temperature, although this effect may vary between temperate and tropical geographies and may change under future climate scenarios if seagrasses approach thermal tolerance thresholds. In addition, we illustrate that periods when full-day NCP is highest could be associated with lower nighttime O 2 and increased diurnal variability in seawater O 2 . These results can serve as first-order estimates of when and where OA amelioration by seagrasses may be likely. However, improved understanding of variations in <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mtext>NCP</mtext><mtext>DIC</mtext></msub><mo>:</mo><msub><mtext>NCP</mtext><mrow class="chem"><msub><mi mathvariant="normal">O</mi><mn ...