Physiological adaptations

Abstract

1. Strategies of aquatic organisms to cope with ambient environmental conditions involve avoidance reactions or more profound behavioural and physiological adjustments, collectively called "adaptations". 2. Modulative (irreversible) and modificative (reversible) adaptations are short-term compensatory changes (acclimations) in an individual in response to environmental change, which are made possible through phenotypic plasticity. 3. Strong triggers for physiological adaptations that are more specific for the Baltic Sea than for most other water bodies are low salinity and low oxygen levels. 4. Mechanisms for adaptation to the salinity of the Baltic Sea, as well as to salinity fluctuations in Baltic coastal regions due to freshwater discharge, involve ion regulation (through ion channels, ion exchange proteins or primary ion pumps) and osmotic adaptation (e.g. Through intracellular concentrations of osmotically active substances, such as low-molecular carbohydrates, amino acids and nucleic acids). 5. Low oxygen levels are dealt with by avoidance or a more effective energy metabolism. 6. Stress proteins provide cellular and whole-body responses of organisms to a vast range of changes in environmental conditions, e.g. Water temperature, salinity, acidification, light availability, chemical pollution and hypoxia. 7. The photosynthetic apparatus of autotrophs is designed to cope with variability in irradiance; it becomes more efficient at low irradiance and more protective against excess energy at high irradiance.