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Effects of UV-radiation on crustaceans from polar and temperate coastal ecosystems [Elektronische Ressource] = Effekte der UV-Strahlung auf Crustaceen aus polaren und temperaten Küstenökosystemen / vorgelegt von Birgit Obermüller

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___________________________________________________________________________ Effects of UV-radiation on crustaceans from polar and temperate coastal ecosystems Effekte der UV-Strahlung auf Crustaceen aus polaren und temperaten Küstenökosystemen Dissertation Zur Erlangung des akademischen Grades - Dr. rer. Nat. - dem Fachbereich 2 Biologie/Chemie der Universität Bremen vorgelegt von Birgit Obermüller Diplom-Biologin Bremen 2006 I ___________________________________________________________________________ II ___________________________________________________________________________ Prüfungsausschuss: 1. Gutachter: PD Dr. Doris Abele Alfred-Wegener-Institut für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven 2. Gutachter: Prof. Dr. Gunter-Otto Kirst FB II Biologie/Chemie Universität Bremen, NW II, Leobener Strasse, 28359 Bremen 1. Prüfer: Prof. Dr. Christian Wiencke Alfred-Wegener-Institut für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven 2. Prüfer: Prof. Dr. Ulrich Saint-Paul Zentrum für Marine Tropenökologie, Fahrenheitstrasse 6, 28359 Bremen Tag des Promotionskolloquiums: 11.

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Publié par
Publié le 01 janvier 2006
Nombre de lectures 65
Poids de l'ouvrage 6 Mo

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Effects of UV-radiation on crustaceans from polar and temperate
coastal ecosystems


Effekte der UV-Strahlung auf Crustaceen aus polaren und
temperaten Küstenökosystemen



Dissertation
Zur Erlangung des akademischen Grades
- Dr. rer. Nat. -


dem Fachbereich 2 Biologie/Chemie der Universität Bremen
vorgelegt von


Birgit Obermüller

Diplom-Biologin


Bremen 2006

I ___________________________________________________________________________
II ___________________________________________________________________________









Prüfungsausschuss:


1. Gutachter: PD Dr. Doris Abele
Alfred-Wegener-Institut für Polar- und Meeresforschung,
Am Handelshafen 12, 27570 Bremerhaven


2. Gutachter: Prof. Dr. Gunter-Otto Kirst
FB II Biologie/Chemie Universität Bremen, NW II,
Leobener Strasse, 28359 Bremen


1. Prüfer: Prof. Dr. Christian Wiencke
Alfred-Wegener-Institut für Polar- und Meeresforschung,
Am Handelshafen 12, 27570 Bremerhaven


2. Prüfer: Prof. Dr. Ulrich Saint-Paul
Zentrum für Marine Tropenökologie,
Fahrenheitstrasse 6, 28359 Bremen


Tag des Promotionskolloquiums: 11. Juli 2006
III ___________________________________________________________________________
IV ___________________________________________________________________________Contents
Contents

Abbrevations VIII

Summary IX

Zusammenfassung XI

1 Introduction 1
1.1 Solar spectrum composition and determinants 1
1.2 Thirty years of ozone depletion: implications for long-term UVR trends 2
1.3 UV radiation effects: direct and indirect stress – damage – death 5
1.3.1 Direct effects are induced by absorption of photon energy 5
1.3.2 Indirect effects are mediated via photosensitising agents 6
1.4 UV-Tolerance and photoprotective responses 8
1.4.1 Avoidance 8
1.4.2 Screening 9
1.4.3 Enzymatic and non-enzymatic antioxidant pathways 10
1.4.4 DNA-Repair 10
1.5 Ecological role of amphipods in Polar coastal ecosystems 11
1.6 UV-inducible stress potential within the climate change context 12
1.7 Objectives and aims of the present study 13

2 Material & Methods 15
2.1 Study sites & radiation climate 15
2.2 Investigated species 19
2.3 Experimental conditions 21
2.3.1 UV-tubes: low/moderate UVB-dose 21
2.3.2 Sunshine simulator: high UVB-dose 21
2.4 Methods 24

3 Publications 27
V ___________________________________________________________________________Contents
Publication I 29
Effects of UV-radiation on oxidative stress parameters in polar marine amphipods,
and the role of UV-absorbing mycosporine-like amino acids (MAAs) in their diet
B. Obermüller, U. Karsten, H. O. Pörtner & D. Abele
Publication II 35
Different UVB-tolerance in herbivorous versus carnivorous amphipods from
Kongsfjorden
B. Obermüller & D. Abele

Publication III 45
Response of oxidative stress parameters and sunscreening compounds in Arctic
amphipods during experimental exposure to maximal natural UVB radiation
B. Obermüller, U. Karsten & D. Abele

Publication IV 63
UV-tolerance and instantaneous physiological stress responses of two Antarctic
amphipod species Gondogeneia antarctica and Djerboa furcipes during exposure
to UV radiation
B. Obermüller, S. Puntarulo & D. Abele

4 Additional Results 95
4.1 Underwater UVB-climate: Comparison between Potter cove and Kongsfjord 95
4.2 Temperate amphipod Chaetogammarus marinus from Helgoland (Island of
Helgoland, North Sea) 97
4.2.1 Physical UVR-screening 97
4.2.2 Enzymatic and non-enzymatic antioxidant defence and oxidative damage 98
4.3 Survival of Arctic and Antarctic amphipods: Is there a dose-dependent
effect? 100

5 Discussion 105
5.1 Is the potential for UV- and oxygen radical stress higher in the Antarctic
or the Arctic? 105
5.2 Does the artificial radiation in the laboratory reflect in-situ conditions? 106
VI ___________________________________________________________________________Contents
5.3 Is the UVR- and antioxidant protection of polar and temperate amphipods
efficient to prevent elevated stress, damage and death? 110
5.3.1 Screening by carapace as a pre-requisite for physical UV-protection 111
5.3.2 Survival as a measure of overall UV-protection 112
5.3.3 Influence of nutrition on UVR defence and damage 117
A) Mycosporine-like amino acids (MAAs) 117
B) Carotenoids 121
C) Starvation 123
5.3.4 Time scales of antioxidant defence mechanisms and sub-lethal effects 125
A) Instantaneous responses to UV-exposure (4 hours) 125
B) Short-term responses to UV-exposure (1-7 days) 127
C) Medium-term responses to UV-exposure (2-4 weeks) 129
D) Response reinforcement through combination of stressors 132

6 Conclusions & Perspectives 134

7 References 140

8 Appendix 158

Acknowledgements
Erklärung
VII ___________________________________________________________________________Abbrevations
List of frequently used abbrevations

BWF biological weighting function
DNA desoxyribonucleic acid
DOC dissloved organic carbon
DOM dissolved organic matter
DU Dobson Unit
e.g. for example, abbrevation for “exemple gratia” (Latin)
H O hydrogen peroxide 2 2
HPLC high-performance liquid chromatography
i.e. that is, abbrevation for “id est” (Latin)
K downwelling diffuse attenuation coefficient d
MAAs mycosporine-like amino acids
MDA malondialdehyde
PAR photosynthetically active radiation
PER photoenzymatic repair
Publ. Publication
PUFAs polyunsaturated fatty acids
ROS reactive oxygen species
SOD superoxide dismutase
SONSI sunshine simulator
TBARS thiobarbituric-acid-reactive substances
TOMS total ozone mapping spectrometer
UV ultraviolet
UVA ultraviolet A
UVB ultraviolet B
UVR ultraviolet radiation

VIII ___________________________________________________________________________Summary
Summary

Solar radiation is a fundamental physical force, modulating the earth’s ecosystems. The
visible range of the solar spectrum most notably comprises beneficial effects, promoting
processes such as photosynthesis, production of organic matter and oxygen generation. The
ultraviolet (UV) portion of the solar spectrum, however, induces various detrimental effects in
both terrestrial and aquatic organisms on all systemic levels. Over millions of years species
have evolved mechanisms to tolerate, avoid, and repair UV-induced damage. This balance of
damage and repair could be obstructed by recent ozone depletion, which causes a selective
increase in harmful UVB radiation reaching the earth’s surface.

I studied the effects of UV-exposure on different UV- and oxidative stress parameters and
defence systems against direct and indirect UV-damage in polar and temperate shallow water
amphipods (crustaceans). The UV-tolerance was compared in species from two different polar
regions, the Antarctic Potter Cove (King George Island) and the Arctic Kongsfjord
(Spitsbergen), currently undergoing different degrees of ozone depletion. This comparison
was carried out in relation to a reference species from a temperate North Sea coast
(Helgoland), which displays higher natural UV-impact, however, lower ozone depletion
compared to the polar areas. I distinguished between dose- and wavelength-dependent effects
and also considered the possible influence of nutrition on UV-protective capacities by
comparing herbivorous and carnivorous/necrophagous amphipods.

The investigated species were classified into three different UV-tolerance categories,
according to their sunscreening and antioxidant defence capacities. Herbivorous Gammarellus
homari (Kongsfjord) proved to be the most UV-tolerant of all investigated species. High
concentrations of dietary derived mycosporine-like amino acids and carotenoids combined
with inducible increases of antioxidant superoxide dismutase activity promoted highest
survival rates under all UVR-exposure experiments. Its high UV-tolerance threshold allows
G. homari to successfully colonise shallow water habitats in Kongsfjord.
Herbivorous Antarctic Gondogeneia antarctica and Djerboa furcipes as well as
carnivorous/necrophagous Arctic Onisimus edwardsi had deficiencies in their sunscreening
and antioxidant defence, which led to accumulation of lipid peroxidation products in the
amphipods’ tissues. As survival rates were still above 50% under most irradiation treatments,
these species were classified as moderately UV-tolerant. The species-specific UV-tolerance
IX ___________________________________________________________________________Summary
thresholds resembled thereby depth gradients of occurrence in the field, with G. antarctica
shriving in shallower, intertidal and D. furcipes and O. edwardsi in deeper, sub-tidal habitats.
Arctic carnivorous/necrophagous Anonyx nugax was the most UV-sensitive of all investigated
species, exhibiting increased mortality, bleached tissue pigmentation, impaired antioxidant
enzyme activities and increased lipid peroxidation already under exposure to a moderate
UVB-dose. Under the current UV-radiation regime, A. nugax is confined to deeper water
during midday peak irradiance and rarely found in subsurface depths in Kongsfjord.

X