Are Ecosystem Engineering Traits Fixed or Flexible : A Study on Clonal Expansion Strategies in Co-occurring Dune Grasses

Many vegetated coastal ecosystems are formed through ecosystem engineering by clonal vegetation. Recent work highlights that the spatial shoot organization of the vegetation determines local sediment accretion and subsequently emerging landscape morphology. While this key engineering trait has been found to differ between species and prevailing environmental conditions, it remains unknown how the interplay of both factors drive shoot organization and therefore landscape morphology. Here, we compared the spatial shoot organization of young, clonally expanding plants of the two dominant European dune grass species: sand couch (Elytrigia juncea) and marram grass (Ammophila arenaria) across a range of coastal dune environments (from Denmark to France). Our results reveal that, on average, sand couch deployed a more dispersed shoot organization than marram grass, which has a patchy (Lévy-like) organization. Whereas sand couch exhibited the same expansion strategy independent of environmental conditions, marram grass demonstrated a large intraspecific variation which correlated to soil organic matter, temperature and grain size. Shoot patterns ranged from a clumped organization correlating to relatively high soil organic matter contents, temperature and small grain sizes, to a patchy configuration with intermediate conditions, and a dispersed organization with low soil organic matter, temperature and large grain size. We conclude that marram grass is flexible in adjusting its engineering capacity in response to environmental conditions, while sand couch instead follows a fixed expansion strategy, illustrating that shoot organization results from the interaction of both species-specific and environmental-specific trait expression

Resilience of beach grasses along a biogeomorphic successive gradient:Resource availability vs. clonal integration

Contains fulltext : 213623.pdf (publisher's version ) (Open Access

A global analysis of how human infrastructure squeezes sandy coasts

Coastal ecosystems provide vital services, including water storage, carbon sequestration, biodiversity, and coastal protection. Human disturbances, however, cause massive losses. The most direct impact is habitat destruction through infrastructure development, restricting the space available to coastal ecosystems and impeding their capacity to adapt to sea level rise by landward retreat – a phenomenon called ‘coastal squeeze’. While shoreline retreat is intensively studied, coastal congestion through infrastructure remains unquantified. Here we calculated the distance to the nearest human-made structure along 263,900 transects worldwide to show that infrastructure occurs at a 560-meter median distance from the shoreline. Moreover, we find that 18% of global sandy shores harbour less than 100 m of infrastructure-free space, and that 14-17% of the unimpacted space may drown by 2100 according to sea level rise projections. Further analyses show that population density and gross domestic product explain 40-44% of observed squeeze variation, emphasizing the intensifying pressure imposed as countries develop and populations expand. Encouragingly, we find that nature reserves relieve squeezing by 3-5 times, illustrating their effectiveness. Yet, at present only 16% of world’s sandy shores has a protected status. We therefore argue that expansion of nature reserves could be key to preserving coastal resilience to sea level rise

Cross-habitat interactions in the Wadden Sea

Here, we report on the results of the OBN-project ‘Cross-habitat interactions in the Wadden Sea’. Evidence is mounting that ecological linkages between spatially separated key-habitats are vital for the functioning of these habitats. However, management of these habitats rarely considers such spatial interactions in their conservation or restoration approaches. The presented work was carried out in close collaboration with the project ‘Restoration of Griend’, and as such formed part of an integrated investigation into the importance of spatial connectivity between the island Griend and the surrounding mudflats for the restoration and conservation of this, and similar slands. The main goals were to (1) understand how spatial connectivity drives the functioning of the island and the surrounding habitats, and (2) provide recommendations regarding the integration of spatial connectivity into future management approaches

Dysregulated innate and adaptive immune responses discriminate disease severity in COVID-19

The clinical spectrum of COVID-19 varies and the differences in host response characterizing this variation have not been fully elucidated. COVID-19 disease severity correlates with an excessive pro-inflammatory immune response and profound lymphopenia. Inflammatory responses according to disease severity were explored by plasma cytokine measurements and proteomics analysis in 147 COVID-19 patients. Furthermore, peripheral blood mononuclear cell cytokine production assays and whole blood flow cytometry were performed. Results confirm a hyperinflammatory innate immune state, while highlighting hepatocyte growth factor and stem cell factor as potential biomarkers for disease severity. Clustering analysis reveals no specific inflammatory endotypes in COVID-19 patients. Functional assays reveal abrogated adaptive cytokine production (interferon-gamma, interleukin-17 and interleukin-22) and prominent T cell exhaustion in critically ill patients, whereas innate immune responses were intact or hyperresponsive. Collectively, this extensive analysis provides a comprehensive insight into the pathobiology of severe to critical COVID-19 and highlight potential biomarkers of disease severity

Biogeomorphological aspects of a model barrier island and its surroundings - interactions between abiotic conditions and biota shaping the tidal and terrestrial landscape: a synthesis

Barrier islands occur in north-western Europe between the North Sea and the Wadden Sea along the coast of Denmark, Germany and the Netherlands. Geomorphological units such as dunes and salt marshes are built by wind, water and sediment. The biota also feed back to the units by trapping sand and silt, transported by water and wind thus (de)stabilizing the local substrate and are able to modify their own abiotic environment. Hence, we refer to them as biogeomorphological units, thus including the role of engineering biota. We consider seven units: tidal basin, island head, intertidal flats, dune arc complex, wash-over complex, island tail with salt marsh, and green beach. We focus on the well-studied West-Frisian island of Schiermonnikoog, the Netherlands, from which we integrated published data. The biogeomorphological units are built with bioengineering species, and in turn provide habitats for plant- and animal species. These communities are subject to succession until climax stages with various timescales. These temporal aspects are derived from long-term measurements in the field, including the study of chronosequences. Biogeomorphological units also affect each other, including feed-backs from animals, plants and micro-organisms. Based on that we present a conceptual model of this particular barrier island. Knowledge gaps that can be identified include 1) interactions among geomorphological units, 2) interactions among these units and bio-engineers to come to biogeomorphological units, and 3) multiple spatialtemporal scales. Human interference such as Aatmospheric deposition applies to all islands and is difficult to manage. Other human interferences may, however, differ among individual islands and their surroundings. They can be managed such as various intensities of fisheries, sand suppletion, extraction of groundwater, the attitude of local people towards artificial sand-drift dikes and livestock grazing

Ecologische kantelpunten in de Nederlandse grote wateren : Discussie memo over recente inzichten, voorbeelden en onderzoeksvragen

Deze memo beschrijft recente inzichten op het terrein van ecologische kantelpunten die zijn opgedaan in onderzoek en bij Rijkswaterstaat. Gegeven de korte projectduur (twee maanden) is er niet gestreefd naar volledigheid, maar zijn er inzichten bijeengebracht die behulpzaam zijn om de discussie aan te zwengelen over wat de kantelpuntentheorie kan betekenen voor het beheer, evaluatie en monitoring van de grote wateren. In het sterk gemodificeerde Nederlandse watersysteem is het moeilijk om vast te stellen of alternatieve evenwichten onder gelijke condities mogelijk zijn en dat kantelpunten hiertussen plaatsvinden. Alternatieve evenwichten en terugkoppelingsmechanismen zijn het best onderbouwd en omschreven in de literatuur voor de Waddenzee en Veluwemeer. In de estuaria zijn er veel indicaties maar ook veel onzekerheden. In het rivierengebied is het de vraag of alternatieve evenwichten kunnen bestaan. Het beter begrijpen van terugkoppelingsmechanismen in de Nederlandse zoete en zoute wateren, en de interacties hiertussen, wordt echter breed onderschreven. Terugkoppelingsmechanismenzijn met het kantelpuntenconcept goed te onderzoeken voor alle watersystemen en een beter begrip hierover is nuttig voor beleidsevaluaties, het inschatten van het effect van ecologische ingrepen en monitoringsplannen. Het is belangrijk om ook rekening te houden met ‘onbekende’ en niet kwantificeerbare factoren die de veerkracht van een ecosysteem kunnen beïnvloeden. Er is nog niet veel bekend over de invloed van microverontreinigingen, trofische cascades (vissen, vogels), microbiële bodemactiviteit en de rol van hydromorfologische dynamiek in rivieren en estuaria op de ecologische veerkracht van een watersysteem. Het is aan te bevelen om eerst met een aantal casestudies teverkennen wat de mogelijkheden en datavereisten zijn om met langjarige tijdreeksen (ecologie, waterkwaliteit) indicatoren te bepalen die iets zeggen over verandering in ecologische veerkracht. Voorts doen wij de aanbeveling om het begrip ' Safe operating Space’ beter hanteerbaar te maken voor wateren natuurbeheerders