Figure 1.
Black squares represent the two water tables, holding the eight experiment tanks and experiment systems.
Figure 2.
S. pistillata bleaching at 60 m depth.
(a) Unbleached fragment during March 2010. (b) “Chicken pox” bleaching pattern during October 2010. (c) On the left, S. pistillata, on the right Mycedium sp. both bleached and alive, during September 2011. (d) Percentage of bleaching measured for 10 colonies in 60 m, surveyed along 2010. Colors represent percentage of bleaching; lighter colors represent higher parentage of bleaching. Gray line indicates average monthly PFD at midday.
Figure 3.
Algae numbers and chlorophyll concentration.
Algae numbers (black) and Chl a concentration per algae (gray) for Symbiodinium sp. within S. pistillata (a) Collected at 5 m depth during May and October (b) collected at 60 m, September and October represent bleached and partially bleached fragments; March and May are not bleached. Scales of both y-axes in figures (a) and (b) are similar for ease of comparison. n = 5 per each month in each depth, bars represent standard deviation.
Figure 4.
Photosynthesis and respiration rates for S. pistillata from 60 m.
Chl a fluorescence yield (a) and O2 production/consumption (b, c), plotted to light intensity (FI curve and PI curve, respectfully) for S. pistillata from 60 m. October and September represent bleached and partially bleached colonies, March and May are not bleached. A shallow corals plot is added for comparison. n = 5 fragments from different colonies per each line. Legend for the three plots is in Figure 4(b). Bars represent standard deviation. (b) O2 production/consumption plotted to light intensity (PI curve). Red rectangle includes PFD that is ecologically relevant for 60 m colonies and is enlarged in Fig. 4(c). (C) An enlargement of the low PFD area in the PI curve, relevant for 60 m. For better appreciation of the results, only selected fragments are presented.
Table 1.
Common photosynthetic physiological parameters, presented for deep (60 m) bleached and unbleached and shallow (5 m) S. pistillata corals.
Table 2.
Net daily O2 production/consumption (µmol O2 cm−2 Day−1) for shallow and mesophotic S. pistillata corals.
Figure 5.
Environmental gradients in the north Red Sea water column.
The environmental parameters (a) temperature, (b) Chl a, (c) total organic nitrogen and (d) logarithm of PAR in the Gulf of Eilat. Parameters are plotted along a 140 m depth gradient, during March (red), May (green), August (blue) and November (brown). Dotted line highlights 60 m depth.
Figure 6.
(a) Chl a concentration per algae (in black) and (b) algae numbers (in gray), of S. pistillata subjected to six different treatments (chilling the tank water to 21°C, hitting the tank water to 29–30°C, feeding once a day with Artemia nauplius, filtration of sea water via 0.2 µm mash creating conditions of starvation, High PFD of ∼135 µmol quanta cm−2 s−1 and Low PFD of ∼20 µmol quanta cm−2 s−1), T0 represent a measurement taken on the day the fragments were plucked, “Ctrl” is the control and “Trans” are the fraq1agments from transplantation experiment. n = 5 fragments per each treatment, control treatment includes 10 fragments. Bars represent standard deviation.