| |
(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
|
- (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
- 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
