Interaktive abiotische Stresseinflüsse auf arktische marine Makroalgen

In Arctic coastal ecosystems, marine macroalgae are exposed to a multitude of abiotic and biotic stressful conditions, including naturally seasonal variations and additionally potential effects of climate changes. Although the different abiotic variables are acting in combination and interdependently in the natural environment, the responses of macroalgae to interactive effects of multiple abiotic stressors are relatively unknown. UV-induced effects and growth temperatures are well studied on different macroalgal species, but mainly in single-factor experiments. Accordingly, the present thesis aims to detect interactive effects of combined abiotic environmental factors on Arctic marine macroalgae from the Kongsfjord (Spitsbergen) for a better understanding of their stress physiology and to estimate potential ecological implications. The study focused on physiological responses of different macroalgal species exposed to impacts of temperature stress in combination with radiation as well as salinity conditions

Interactive abiotic stress effects on Arctic marine macroalgae- Physiological responses of adult sporophytes

In Arctic coastal ecosystems, marine macroalgae are exposed to a multitude of abiotic and biotic stressful conditions, including naturally seasonal variations and additionally potential effects of climate changes. Although the different abiotic variables are acting in combination and interdependently in the natural environment, the responses of macroalgae to interactive effects of multiple abiotic stressors are relatively unknown. UV-induced effects and growth temperatures are well studied on different macroalgal species, but mainly in single-factor experiments. Accordingly, the present thesis aims to detect interactive effects of combined abiotic environmental factors on Arctic marine macroalgae from the Kongsfjord (Spitsbergen) for a better understanding of their stress physiology and to estimate potential ecological implications. The study focused on physiological responses of different macroalgal species exposed to impacts of temperature stress in combination with radiation as well as salinity conditions

Interactive effects of radiation, temperature and salinity on the Arctic endemic red alga Devaleraea ramentacea

Devaleraea ramentacea represents one of the few red macroalgal species endemic to the Arctic. Previous unifactorial experiments revealed a generally high tolerance of D. ramentacea to variation in abiotic conditions. Although in the field the effects of photosynthetically active (PAR) and UV-radiation, temperature and salinity are usually interconnected, studies on interactive effects on its physiology are scarce. Mesocosm-experiments under natural solar radiation as well as laboratory set-ups under defined, artificial radiation conditions, at three different water temperatures and at different salinities were conducted at Spitsbergen in order to reveal physiological responses of D. ramentacea under multiple abiotic stresses. Photosynthetic measurements confirm the high tolerance of adult sporophytes of D. ramentacea towards single and combined stress factors. Experimentally induced changes in the content of UV-screening mycosporine-like amino acids (MAA) and the enzymatic activity of superoxid-dimutase were studied. A specific characteristic of D. ramentacea under changing abiotic conditions is the greening of the tips. The factors inducing the loss of phycobiliproteins and the changes in physiological performance in the affected thallus fragments are addressed. Results will be discussed in the context of the species distributional patterns