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Table 1 Environmental conditions at the study site

From: Fatty acid compositions associated with high-light tolerance in the intertidal rhodophytes Mastocarpus stellatus and Chondrus crispus

  (a) Period 2001–2010
October March May August
Monthly mean air temperature (°C) 12.1 ± 1.8 4.4 ± 1.6 11.2 ± 1.0 18.1 ± 1.0
Monthly min air temperature (°C) 10.5 ± 1.8 2.9 ± 1.5 9.4 ± 0.9 16.1 ± 1.1
Monthly max air temperature (°C) 13.6 ± 1.6 6.0 ± 1.6 13.5 ± 1.1 20.0 ± 1.1
  (b) Sampling event
October 2011 March 2012 May 2012 August 2012
Air temperature (°C) 10.5 4.2 9.9 16.1
Light–dark cycle (h) 10:14 11:13 16:8 15:9
Water temperature (°C) 14 4 8 16
Ek (µmol photons m−2 s−1)
 Mast-ex 71.4 ± 7.7 21.5 ± 5.3 91.8 ± 6.2 56.0 ± 4.0
 Mast-ov 75.7 ± 7.9 10.4 ± 2.6 129.9 ± 19.5 42.5 ± 4.6
 Chon-ov 83.2 ± 9.1 7.8 ± 2.0 40.1 ± 10.4 56.6 ± 7.5
10× Ek (high-light stress; µmol photons m−2 s−1)
 Mast-ex 710 220 920 560
 Mast-ov 760 100 1300 430
 Chon-ov 830 80 400 570
  1. (a) Monthly average, minimum and maximum air temperatures (°C) of the island of Helgoland (German Bight, North Sea) for October, March, May and August over the period from 2001 to 2010. Air temperatures were taken from the data base of Deutscher Wetterdienst and are given as mean ± SD (n = 28–31, depending on the days per month). (b) Air temperatures (°C) of the island of Helgoland (German Bight, North Sea) for the four sampling events (October 2011, March 2012, May 2012 and August 2012) as well as experimental conditions applied during the recovery from sampling stress (light–dark cycle, water temperature) and high-light stress exposure [water temperature, 10× saturating photon flux density of algal photosynthesis (Ek)] of algal isolates (Mast-ex, Mast-ov and Chon-ov) from the four sampling events. Ek-values were defined by P–E curve fitting after Jassby and Platt [39] and are given as mean ± SEM (n = 6). High-light stress was defined as 10× Ek, so that it was possible to expose the three algal isolates from four events to comparable stress conditions
  2. Min, minimum; max, maximum; SD, standard deviation; Mast-ex, Mastocarpus stellatus from higher levels of the lower intertidal; Mast-ov, Mastocarpus stellatus from overlapping zone in deeper levels of lower intertidal; Chon-ov, Chondrus crispus from overlapping zone in deeper levels of lower intertidal; SEM, standard error of the mean