Successional development of the phototrophic community in biological soil crusts, along with soil formation on Holocene deposits at the Baltic Sea coast

Harsh environmental conditions form habitats colonized by specialized primary microbial colonizers, e.g., biological soil crusts (biocrusts). These cryptogamic communities are well studied in drylands but much less in temperate coastal dunes, where they play a crucial role in ecological functions. Following two dune chronosequences, this study highlights the successional development of the biocrust’s community composition on the Baltic Sea coast. A vegetation survey, followed by morphological species determination, was conducted. Sediment/soil cores of the different dune types were analyzed to uncover the potential impacts of the biocrust community on initial soil formation processes, with special emphasis on biogeochemical phosphorous (P) transformations. Biocrust succession was characterized by a dune type-specific community composition, shifting from thinner algae-dominated biocrusts in dynamic dunes to more stable moss-dominated biocrusts in mature dunes. The change in the biocrust community structure was accompanied by an increase in Chl a, water, and organic matter content. In total, 25 algal and cyanobacterial species, 16 mosses, and 26 lichens across all sampling sites were determined. The pedological characterization of these cores elucidated initial processes of soil genesis, such as decalcification, acidification, and the accumulation of organic matter with dune and biocrust development. Furthermore, the chemistry of iron (Fe)-containing compounds such as the Fedithionite/Fetotal ratios confirmed mineral weathering and the beginning of soil profile development. The biocrusts accumulated P over time, while the P content in the underlying sediment did not change. That implies that biocrusts take up P from the geological parent material in the dunes, thereby accumulating available P in the ecosystem, which gets transferred into subsoil horizons through leaching or redeposition. The relative proportion of the bioavailable P pool (56% to 74% of Pt) increased with dune succession. That happened at the expense of more stable bound P, which was transformed into labile P. Thus, the level of plant available P along the dune chronosequences increased due to the microbial activity of the biocrust organisms. It can be concluded that biocrusts of temperate coastal dunes play a crucial role in maintaining their habitat by accumulating nutrients and organic matter, supporting soil development and subsequent vegetation

Vascular surveillance by haptotactic blood platelets in inflammation and infection

Breakdown of vascular barriers is a major complication of inflammatory diseases. Anucleate platelets form blood-clots during thrombosis, but also play a crucial role in inflammation. While spatio-temporal dynamics of clot formation are well characterized, the cell-biological mechanisms of platelet recruitment to inflammatory micro-environments remain incompletely understood. Here we identify Arp2/3-dependent lamellipodia formation as a prominent morphological feature of immune-responsive platelets. Platelets use lamellipodia to scan for fibrin(ogen) deposited on the inflamed vasculature and to directionally spread, to polarize and to govern haptotactic migration along gradients of the adhesive ligand. Platelet-specific abrogation of Arp2/3 interferes with haptotactic repositioning of platelets to microlesions, thus impairing vascular sealing and provoking inflammatory microbleeding. During infection, haptotaxis promotes capture of bacteria and prevents hematogenic dissemination, rendering platelets gate-keepers of the inflamed microvasculature. Consequently, these findings identify haptotaxis as a key effector function of immune-responsive platelets

Successional Development of the Phototrophic Community in Biological Soil Crusts on Coastal and Inland Dunes

(1) Biological soil crusts (biocrusts) are microecosystems consisting of prokaryotic and eukaryotic microorganisms growing on the topsoil. This study aims to characterize changes in the community structure of biocrust phototrophic organisms along a dune chronosequence in the Baltic Sea compared to an inland dune in northern Germany. (2) A vegetation survey followed by species determination and sediment analyses were conducted. (3) The results highlight a varying phototrophic community composition within the biocrusts regarding the different successional stages of the dunes. At both study sites, a shift from algae-dominated to lichen- and moss-dominated biocrusts in later successional dune types was observed. The algae community of both study sites shared 50% of the identified species while the moss and lichen community shared less than 15%. This indicates a more generalized occurrence of the algal taxa along both chronosequences. The mosses and lichens showed a habitat-specific species community. Moreover, an increase in the organic matter and moisture content with advanced biocrust development was detected. The enrichment of carbon, nitrogen, and phosphorus in the different biocrust types showed a similar relationship. (4) This relation can be explained by biomass growth and potential nutrient mobilization by the microorganisms. Hence, the observed biocrust development potentially enhanced soil formation and contributed to nutrient accumulation

Biocrust and sediment characteristics of biological soil crusts in coastal sand dunes in northern Germany

This dataset comprises environmental parameters for biological soil crusts in coastal sand dunes in northern Germany. Biological soil crusts (biocrusts) are autonomous ecosystems consisting of prokaryotic and eukaryotic microorganisms growing on the topsoil. They colonize global climatic zones, including temperate dunes. This study examined changes in the community structure of biocrust phototrophic organisms along a dune chronosequence at the Baltic Sea compared to an inland dune in Northern Germany. The community composition and their shift between different successional stages of dune development were related to physico-chemical sediment properties. A vegetation survey followed by species determination and sediment analyses were conducted. The sampling took place on the 25th of April and on the 5th of May 2020. The samples were collected at a costal dune area, namely the Schaabe spit on the island Rügen, Mecklenburg Wester-Pomerania, Germany, and in an inland dune area at Verden (Aller), Lower Saxony, Germany. Biocrust samples were taken along one transect per study site. Each transect followed a natural succession gradient in the dune area. Along each transect, the different successional dune stages were visually identified and further named as dune subsites. At each subsite, a sampling plot of 1 m2 was established and used for further vegetation analyses, biocrust and sediment sampling. Along the Schaabe spit transect four subsites with one sampling plot each were established and three subsites were established in the inland dune in Verden. For the vegetation survey seven different functional groups were defined describing the overall surface coverage: Thin (1-3 mm) green algae-dominated biocrusts were defined as early successional stages. Later successional stages, in which the green algae biocrusts became slightly thicker (3-8 mm) and moss-covered, were defined as the intermediate successional biocrust stage. Moss-dominated biocrusts and those who additionally lichenized characterized the mature successional stages of biocrusts. Vascular plants, and litter (dead material, i.e., pine needles, leaves, and branches) were two of the non-cryptogamic but still biotic functional groups. Bare sediment was the only abiotic functional group. The predefined functional groups were recorded within each plot according to the point intercept method by Levy and Madden (1933). Each of the seven sampling plots was divided into 16 equal subplots (0.0625 m2). A 25 cm x 25 cm (0.0625 m2) grid of 25 intersections was placed randomly into 4 of these subplots. Within each sub-plot, the functional groups were recorded by 25 point measurements according to the approach of Williams et al. (2017). That allowed 100 point measurements per sampling plot (1 m2)

Microbial community composition of biological soil crusts in coastal sand dunes in northern Germany

This data collection comprises environmental data and taxonomic parameters of the investigated biocrusts of sampling sites in coastal and inland sand dunes in northern Germany. Sampling took place in spring 2020 and winter 2021. Biocrusts and uppermost sediment samples were collected along dune successional gradients and sequenced by LGC Genomics Ltd. Corresponding sequence data of biocrust organisms are archived at the European Nucleotide Archive

Morphological determination of the phototrophic community composition of biological soil crusts in coastal sand dunes in northern Germany

This dataset comprises the microbial community composition of biological soil crusts in north-German sand dunes. For this we obtained enrichment cultures of phototrophic microorganisms, by placing fragments of biocrusts of the same Petri dishes as used for sequencing, in Petri dishes with Bold Basal (1N BBM) agarized medium (Bischoff and Bold 1963). Cultures were grown under standard laboratory conditions: with a 12-hour alteration of light and dark phases and irradiation of 25 μmol photons m-2 s-1 at a temperature 20 ± 5 ºС. Microscopic study of these raw cultures began in the third week of cultivation. Morphological examinations were performed using Olympus BX53 light microscope with Nomarski DIC optics (Olympus Ltd, Hamburg, Germany). Micrographs were taken with a digital camera (Olympus LC30) attached to the microscope, and processed by the Olympus software cellSens Entry. Direct microscopy of rewetted samples was performed in parallel with cultivation for evaluation of dominating species of algae and cyanobacteria in the original samples. Morphological identification of the biocrust organisms was based mainly on Ettl and Gärtner (2014) for green microalgae, and on Komárek (2013) for cyanobacteria, as well as on some monographs and papers devoted to taxonomic revisions of the taxa of interest (Darienko and Pröschold 2019). Moss and lichens samples were air-dried after collection. For determination, a microscope with a maximum magnification of 400x was used. Morphological identification of mosses followed Frahm and Frey (2004) with taxonomical reference to (Hodgetts et al. 2020). Lichens were determined according to Wirth et al. (2013). Morphologically critical species of the genus Cladonia where additionally analyzed by thin-layer chromatography according to (Culberson and Ammann 1979) in solvent system A

DataSheet_1_Successional development of the phototrophic community in biological soil crusts, along with soil formation on Holocene deposits at the Baltic Sea coast.pdf

Harsh environmental conditions form habitats colonized by specialized primary microbial colonizers, e.g., biological soil crusts (biocrusts). These cryptogamic communities are well studied in drylands but much less in temperate coastal dunes, where they play a crucial role in ecological functions. Following two dune chronosequences, this study highlights the successional development of the biocrust’s community composition on the Baltic Sea coast. A vegetation survey, followed by morphological species determination, was conducted. Sediment/soil cores of the different dune types were analyzed to uncover the potential impacts of the biocrust community on initial soil formation processes, with special emphasis on biogeochemical phosphorous (P) transformations. Biocrust succession was characterized by a dune type-specific community composition, shifting from thinner algae-dominated biocrusts in dynamic dunes to more stable moss-dominated biocrusts in mature dunes. The change in the biocrust community structure was accompanied by an increase in Chl a, water, and organic matter content. In total, 25 algal and cyanobacterial species, 16 mosses, and 26 lichens across all sampling sites were determined. The pedological characterization of these cores elucidated initial processes of soil genesis, such as decalcification, acidification, and the accumulation of organic matter with dune and biocrust development. Furthermore, the chemistry of iron (Fe)-containing compounds such as the Fedithionite/Fetotal ratios confirmed mineral weathering and the beginning of soil profile development. The biocrusts accumulated P over time, while the P content in the underlying sediment did not change. That implies that biocrusts take up P from the geological parent material in the dunes, thereby accumulating available P in the ecosystem, which gets transferred into subsoil horizons through leaching or redeposition. The relative proportion of the bioavailable P pool (56% to 74% of Pt) increased with dune succession. That happened at the expense of more stable bound P, which was transformed into labile P. Thus, the level of plant available P along the dune chronosequences increased due to the microbial activity of the biocrust organisms. It can be concluded that biocrusts of temperate coastal dunes play a crucial role in maintaining their habitat by accumulating nutrients and organic matter, supporting soil development and subsequent vegetation.</p