Reconstructing N2-fixing cyanobacterial blooms in the Baltic Sea
beyond observations using 6- and 7-methylheptadecane in sediments as specific biomarkers
"Summer cyanobacterial blooms represent a threat to the Baltic Sea ecosystem, causing deoxygenation of the bottom water and the spread of the so-called dead zones. The history of the Baltic Sea cyanobacterial blooms is known from in situ and satellite observations since the early 1980s but is still not well understood. [...]"
Authors: Jérôme Kaiser et al.
Ventilation of the Northern Baltic Sea (Preprint)
"The Baltic Sea is a semi-enclosed, brackish water sea in northern Europe. The deep basins of the central Baltic Sea regularly show hypoxic conditions. In contrast, the northern parts of the Baltic Sea, the Bothnian Sea and Bay, are well oxygenated. Lateral inflows or a ventilation due to convection are possible mechanisms for high oxygen concentrations in the deep water of the northern Baltic Sea. [...]"
Source: Ocean Science
Authors: Thomas Neumann et al.
Organic carbon recycling in Baltic Sea sediments – An integrated estimate on the system scale based on in situ measurements
"In situ measured benthic fluxes of dissolved inorganic carbon (DIC), a proxy for organic carbon (OC) oxidation or recycling rates, are used together with burial rates based on measured sediment accumulation rates (SAR) and vertical distribution of OC in the sediment solid phase to construct a benthic OC budget for the Baltic Sea system. [...]"
Source: Marine Chemistry
Authors: Madeleine M. Nilsson et al.
The Baltic Sea as a time machine for the future coastal ocean
"Coastal global oceans are expected to undergo drastic changes driven by climate change and increasing anthropogenic pressures in coming decades. Predicting specific future conditions and assessing the best management strategies to maintain ecosystem integrity and sustainable resource use are difficult, because of multiple interacting pressures, uncertain projections, and a lack of test cases for management. [...]"
Source: Science Advances
Authors: Thorsten B. H. Reusch et al.
Deoxygenation of the Baltic Sea during the last century
"Deoxygenation is a global problem in coastal and open regions of the ocean, and has led to expanding areas of oxygen minimum zones and coastal hypoxia. The recent expansion of hypoxia in coastal ecosystems has been primarily attributed to global warming and enhanced nutrient input from land and atmosphere. The largest anthropogenically induced hypoxic area in the world is the Baltic Sea, where the relative importance of physical forcing versus eutrophication is still debated. We have analyzed water column oxygen and salinity profiles to reconstruct oxygen and stratification conditions over the last 115 y and compare the influence of both climate and anthropogenic forcing on hypoxia. [...]"
Source: Procedings of the National Academy of Sciences of the United States of America (PNAS)
Authors: Jacob Carstensen et al.
Aerobic and anaerobic ammonium oxidizers in the Cariaco Basin: distributions of major taxa and nitrogen species across the redoxcline
"Depth distributions of cells and functional gene copies from anaerobic ammonium-oxidizing (anammox) bacteria, aerobic ammonium-oxidizing bacteria (AOB) and archaea (AOA) in the Cariaco Basin, Venezuela were obtained using FISH and q-PCR assays. These distributions were compared to concentrations of dissolved ammonium (NH4+), nitrite (NO2-), nitrate (NO3-), hydrogen sulfide (H2S) and oxygen (O2) along the redoxcline during 3 cruises. Cell counts of anammox bacteria and copies of their nitrite reductase gene (Scalindua-nirS) were consistently observed in 2 distinct layers: the suboxic zone (≤1.1 × 106 cells l-1) and the upper euxinic zone (≤4.7 × 106 cells l-1). [...]"
Source: Aquatic Microbial Ecology 79
Authors: Sara Cernadas-Martín et al.