Electronic supplementary material

Hydrobiologia

Light history-dependent respiration explains the hysteresis
in the daily ecosystem metabolism of seagrass

Matthew P. Adamsa, Angus J. P. Ferguson, Paul S. Maxwell, Brodie A. J. Lawson, Jimena Samper-Villarreal, Katherine R. O’Brien

aEmail: . Address: School of Chemical Engineering, The University of Queensland, St Lucia QLD 4072, Australia

Online Resource 1. O2 concentration vs time measured in closed chambers at the shallow (grey circles), intermediate (grey squares) and deep sites (grey triangles), and O2 concentration vs time measured in open water loggers approximately midway between the shallow and intermediate sites (red circles), and approximately midway between the intermediate and deep sites (blue circles).

Online Resource 2. Water temperature over the day, for the three depths in Swansea Shoals, New South Wales, Australia.

Online Resource 3. Parameters of the three models investigated in this paper (temperature-dependent respiration, light history-dependent GPP and light history-dependent respiration), and three properties of the daily respiration variability predicted by the light history-dependent respiration model (<Rday>/<Rnight>, Rmin, Rmax).

Variable / Site
Shallow / Intermediate / Deep
Model of temperature-dependent respiration:
GPPmax (mmol O2 m-2 d-1) / 360 / 672 / 547
Ik (µmol photons m-2 s-1) / 369 / 368 / 343
R (mmol O2 m-2 d-1) / 147 / 241 / 141
Temperature sensitivity of respiration Q10 (no units) / 5 / 5 / 5
Reference temperature T0 (°C) / 27.2 / 26.2 / 25.2
Parameters common to both light history models:
Light history timescale τ (h) / 6 / 6 / 6
Light history at midnight Ihist,0 (µmol photonsm2s-1) / 207 / 141 / 94
Model of light history-dependent GPP:
GPPmax,0 (mmol O2 m-2 d-1) / 437 / 872 / 1359
((mmol O2 m-2 d-1) / (µmol photonsm-2 s-1)) / 0.2 / 0.7 / 2.5
Ik,0 (µmol photons m-2 s-1) / 406 / 851 / 769
(no units) / 2.6 / 2.5 / 8.1
R (mmol O2 m-2 d-1) / 160 / 235 / 152
Model of light history-dependent respiration:
GPPmax (mmol O2 m-2 d-1) / 510 / 785 / 681
Ik (µmol photons m-2 s-1) / 468 / 340 / 291
R0 (mmol O2 m-2 d-1) / 136 / 433 / 135
kR ((mmol O2 m-2 d-1)/(µmol photonsm2s1)) / 0.6 / 1.0 / 1.5
Ratio of mean daytime to nighttime respiration <Rday>/<Rnight / 1.9 / 1.7 / 2.1
Minimum instantaneous respiration value Rmin (mmol O2 m-2 d-1) / 44 / 114 / 41
Maximum instantaneous respiration value Rmax (mmol O2 m-2 d-1) / 393 / 492 / 417

Online Resource 4. O2 flux vs time (grey symbols), light vs time (black line), NEM vs time predicted by our model of light history-dependent respiration (blue line), and the contribution of respiration (-R) to NEM vs time predicted by our model of light history-dependent respiration (green line), for (a) the shallow site, (b) the intermediate site, and (c) the deep site.

(a) /
(b) /
(c) /