The transport of aquatic animals by birds. [Translation from: Binnengewaesser 18, 156-159, 1950.]

A great deal has been written on the part which birds play in the dispersal of freshwater fauna. This article summarises literature on the dispersal of aquatic animals by birds and aquatic insects

Reconstructing Holocene climatic and environmental change using molecular and isotopic proxies from lake sedimentary records

Greater understanding of Holocene climatic and environmental variability and processes, as well as about feedback and forcing mechanisms of the climate system is crucial for the assessment of both natural and anthropogenic future climate and environmental changes. Compared to prior epochs in earth’s history, the climate of the Holocene is traditionally regarded as relatively stable. However, Holocene climate also showed significant fluctuations although perturbation were smaller in magnitude compared to Pleistocene. These fluctuations can be assessed by organic geochemical molecular and isotope analyses of lake sedimentary organic matter (OM) that have the potential to reveal a variety of information regarding physical, chemical and biological changes and processes of the lake, its environment, and the climate. Therefore, within the scope of this thesis, sedimentary archives from selected lakes from the Sub-Artic (Lake Torneträsk), the Mediterranean (Lake Dojran), and the African tropics (Lake Dendi) were analyzed using various analytical methods including the analysis of lipid biomarker and compound specific leaf wax stable isotopes, as well as palynological, microcharcoal, and inorganic sedimentological analyses. All three lakes are situated in key regions for the understanding of northern hemispheric Holocene climate variability and natural/anthropogenic forcing and feedback mechanisms: To constrain changes in atmospheric circulation patterns and their effects on the environment in the Fennoscandian sub-arctic, lipid biomarker, inorganic proxies, and compound specific δD analysis are applied to a Holocene sedimentary record from Lake Torneträsk (NW Sweden). Owing to its climate being influenced by both the North Atlantic and the polar frontal zone, northern Fennoscandia can be regarded as a key region to better understand the regional expression and potential threshold effects of insolation-forced migrations of atmospheric circulation systems. The results indicate a non-linear reorganization of the atmospheric circulation expressed as a change from zonal towards more meridional flow starting at ~4,000 and intensifying ~2,000 cal yrs BP. For the reconstruction of the climatic, environmental, and human impact on the southern Balkan Peninsula lipid biomarker, microcharcoal, and pollen analyses are applied to a Holocene sedimentary record from Lake Dojran (Macedonia/Greece). The southern Balkan region played a key role in the early migration of the Neolithic lifestyle to Central Europe and is thus very suitable for studies of human-environment forcing and feedback mechanisms. The results suggest a relationship between anthropogenic activity and centennial to millennial scale environmental/climatic changes, since increased human impact corresponds to phases of higher humidity and high lake levels at Lake Dojran. To detect changes in atmospheric circulation, hydrology, and vegetation in East Africa, associated with the African Humid Period (AHP), lipid biomarker and compound specific δD and δ13C analysis are applied to sedimentary OM from Lake Dendi (Ethiopia). Due to its location in proximity of the Congo Air Boundary (CAB) and the Intertropical Convergence Zone (ITCZ), the Dendi region can play a crucial role in the understanding of past changes in atmospheric circulation pattern of the tropical regions. The results indicate a rapid re-strengthening of the monsoonal circulation in the Early Holocene followed by Peak AHP conditions between ~9,800 yrs cal BP and ~8,000 yrs cal BP. Subsequently a moderate decrease in precipitation and a shift in moisture sources due to weakening monsoonal systems and associated shifts of the ITCZ and the CAB have been detected. Together, the lakes datasets suggest a thermal maximum and a northernmost position of the atmospheric circulation systems in the Early Holocene followed by a long-term trend of decreasing temperatures and environmental changes in accordance with decreasing NH summer insolation. Despite some differences in nature and timing, all tree records further indicate a southwards migration and weakening of NH atmospheric circulation systems over the course of the Holocene with significant phases of climatic/environmental changes around 4,500 yrs cal BP and 2,000 yrs

A comprehensive review: The evolution of animal models in pulmonary hypertension research; are we there yet?

Pulmonary hypertension (PH) is a disorder that develops as a result of remodeling of the pulmonary vasculature and is characterized by narrowing/obliteration of small pulmonary arteries, leading to increased mean pulmonary artery pressure and pulmonary vascular resistance. Subsequently, PH increases the right ventricular afterload, which leads to right ventricular hypertrophy and eventually right ventricular failure. The pathophysiology of PH is not fully elucidated, and current treatments have only a modest impact on patient survival and quality of life. Thus, there is an urgent need for improved treatments or a cure. The use of animal models has contributed extensively to the current understanding of PH pathophysiology and the investigation of experimental treatments. However, PH in current animal models may not fully represent current clinical observations. For example, PH in animal models appears to be curable with many therapeutic interventions, and the severity of PH in animal models is also believed to correlate poorly with that observed in humans. In this review, we discuss a variety of animal models in PH research, some of their contributions to the field, their shortcomings, and how these have been addressed. We highlight the fact that the constant development and evolution of animal models will help us to more closely model the severity and heterogeneity of PH observed in humans