Description: Alpine ecosystems on the Tibetan Plateau are being threatened by ongoing climate warming and intensified human activities. Ecological time-series obtained from sedimentary ancient DNA (sedaDNA) are essential for understanding past ecosystem and biodiversity dynamics on the Tibetan Plateau and their responses to climate change at a high taxonomic resolution. Hitherto only few but promising studies have been published on this topic. The potential and limitations of using sedaDNA on the Tibetan Plateau are not fully understood. Here, we (i) provide updated knowledge of and a brief introduction to the suitable archives, region-specific taphonomy, state-of-the-art methodologies, and research questions of sedaDNA on the Tibetan Plateau; (ii) review published and ongoing sedaDNA studies from the Tibetan Plateau; and (iii) give some recommendations for future sedaDNA study designs. Based on the current knowledge of taphonomy, we infer that deep glacial lakes with freshwater and high clay sediment input, such as those from the southern and southeastern Tibetan Plateau, may have a high potential for sedaDNA studies. Metabarcoding (for microorganisms and plants), metagenomics (for ecosystems), and hybridization capture (for prehistoric humans) are three primary sedaDNA approaches which have been successfully applied on the Tibetan Plateau, but their power is still limited by several technical issues, such as PCR bias and incompleteness of taxonomic reference databases. Setting up high-quality and open-access regional taxonomic reference databases for the Tibetan Plateau should be given priority in the future. To conclude, the archival, taphonomic, and methodological conditions of the Tibetan Plateau are favorable for performing sedaDNA studies. More research should be encouraged to address questions about long-term ecological dynamics at ecosystem scale and to bring the paleoecology of the Tibetan Plateau into a new era.

Description: This report describes the activities performed within Task 1.3 “Summary of gas solubility and degassing kinetics (type A)” until the end of month 39 of the REFLECT project. Two series of experiments have been carried out that assess the degassing process of type A geothermal fluids respectively in bulk and porous media. This has resulted in an improved understanding of the process and the associated physical phenomena by utilizing experimental equipment and data analysis tools specifically created for this task.

Description: In an era of accelerating biological globalization and climatic warming, it is vital to understand how introduced species integrate. Pacific Manila clams Ruditapes philippinarum were introduced for aquaculture to Europe in the 1970s, spread and became harvested from the Mediterranean Sea to British coasts. From the Dutch Rhine Delta, Manila clams immigrated stepwise into the southern Wadden Sea, and by long distance jump dispersal they arrived in the northern Wadden Sea in the 2010s. Encounters remained few until 2021, when live clams were often found in intertidal seagrass beds and around mixed beds of Pacific oysters with native mussels. Shell lengths reached up to 74 mm with a longevity of 7–8 years. Adult abundances remained low (〈10 clams m−2), although larval numbers substantially increased in 2022 and 2023. Strong predation on spat may constitute ecological resistance to the immigrant. Haplotype diversity at mtDNA COI gene fragments is high and its composition is mixed from dominant haplotypes of other European sites, suggesting multiple introductions or an unknown source with an already mixed population. Currently, this is the most northern (55◦ N) population of R. philippinarum in continental Europe, but with the rapid expansion of this genetically variable population, further northward spread can be expected.

Description: Rivers are an important transport route of anthropogenic litter from inland sources toward the sea. A citizen science approach was used to evaluate the litter pollution of rivers in Germany: schoolchildren within the project “Plastic Pirates” observed Floating macrolitter at 282 sites and took meso-/microplastic samples (i.e. particles 1 mm - 25 mm) at over 164 sites across the entire 28 country during the years 2016 and 2017. Floating macrolitter quantities ranged from 0 to 8 items m-1 h-1 (average of 0.34 ± 0.89 litter items m-1 h-1) and floating macrolitter was sighted at 54% of sampling sites. The quantities of floating meso-/microplastics ranged from 0 to 220 particles h-1 (average of 6.86 ± 24.11 meso-/microplastics h-1). They were present at 57% of the sampling sites. Given that only particles 〉 1 mm were sampled and analyzed, the pollution of rivers in Germany by microplastics is likely a ubiquitous problem, regardless of the size of the river. We identified six plastic pollution hotspots where 60% of all meso-/microplastics collected in the present study were found. The composition of the particles at these hotspots indicates plastic producers and possibly the construction industry and wastewater treatment plants as point sources. An identification of litter hotspots would enable specific mitigation measures, adapted to the 38 respective source, and thereby prevent the release of large quantities of small plastic particles in rivers. The adopted large-scale citizen science approach was especially suitable to detect pollution hotspots by sampling a variety of rivers, large and small, and enabled a national overview of litter pollution in German rivers.

Description: Deliverable D2.3 reports the work performed in task 2.3 “Metal complexation and mineral precipitation” within the Reflect project. The task is divided into the subtasks 2.3.1 “Mineral solubility and precipitation kinetics”, 2.3.2 “Mineral precipitation by impedance spectroscopy” and 2.3.3 “Modelling mineral solubility”. A combination of experimental design, performed experiments and numerical modelling have increased the knowledge of mineral solubility and precipitation at high salinity condition in geothermal fluids.

Description: To assess the spatiotemporal evolution of the heterotrophic dinoflagellate Noctiluca scintillans in the North Sea, the Helgoland Roads time series and Continuous Plankton Recorder survey were analysed using generalized additive models. Over the last decades, blooms of N. scintillans have occurred more frequently and intensively in many regions. This harmful algal bloom forming species can alter food webs, reduce ecosystem productivity, and lead to economic losses while causing lower aquacultural yields. After the 1990s, N. scintillans abundances have significantly increased by 1.65-fold and a significant prolongation of the bloom window was found (from 27.5 to 98 days in recent decades) off the island of Helgoland, Germany. Significant correlations were found between bloom initiation and nutrients, as well as light availability since these factors lead to increased prey availability. Highest abundances of N. scintillans were associated with water temperatures around 17 °C and wind speed below 6 ms−1 causing dense surface accumulations. Solar radiation of more than 200 Wm−2 was identified as a main driver for post-bloom conditions as it can deteriorate the cells and lead to the decline of N. scintillans abundances. In the southern North Sea, N. scintillans occurrences have intensified and spread since the 1980s with hotspots identified as the coastal waters adjacent to the estuaries of the Elbe and Rhine rivers.

Description: Microplastic (MP) pollution is an important challenge for human life which has consequently affected the natural system of other organisms. Mismanagement and also careless handling of plastics in daily life has led to an accelerating contamination of air, water and soil compartments with MP. Under estuarine conditions, interactions with suspended particulate matter (SPM) like fine sediment in the water column play an important role on the fate of MP. Further studies to better understand the corresponding transport and accumulation mechanisms are required. This paper aims at providing a new modeling approach improving the MP settling velocity formulation based on higher suspended fine sediment concentrations, as i.e. existent in estuarine turbidity zones (ETZ). The capability of the suggested approach is examined through the modeling of released MP transport in water and their interactions with fine sediment (cohesive sediment/fluid mud). The model results suggest higher concentrations of MP in ETZ, both in the water column as well as the bed sediment, which is also supported by measurements. The key process in the modeling approach is the integration of small MP particles into estuarine fine sediment aggregates. This is realized by means of a threshold sediment concentration, above which the effective MP settling velocity increasingly approaches that of the sediment aggregates. The model results are in good agreement with measured MP mass concentrations. Moreover, the model results also show that lighter small MP particles can easier escape the ETZ towards the open sea.

Description: Mit dem Journal „System Erde“ berichtet das Deutsche GeoForschungsZentrum GFZ über die unterschiedlichen Facetten seiner Forschungsarbeiten. Die Reihe richtet sich vor allem an Entscheiderinnen und Entscheider in Wissenschaft, Gesellschaft und Politik, an interessierte Wissenschaftlerinnen und Wissenschaftler sowie an die fachinteressierte Öffentlichkeit.