Approaches to analyse and model changes in impacts: reply to discussions of “How to improve attribution of changes in drought and flood impacts”*
Kreibich, Heidi ; Blauhut, Veit ; Aerts, Jeroen C.J.H. ; Bouwer, Laurens M. ; Lanen, Henny A.J. Van; Mejia, Alfonso ; Mens, Marjolein ; Loon, Anne F. Van - \ 2020
Hydrological Sciences Journal 65 (2020)3. - ISSN 0262-6667 - p. 491 - 494.
damage - dynamic risk - hydrological extremes - new data - projecting risk
We thank the authors, Brunella Bonaccorso and Karsten Arnbjerg-Nielsen for their constructive contributions to the discussion about the attribution of changes in drought and flood impacts. We appreciate that they support our opinion, but in particular their additional new ideas on how to better understand changes in impacts. It is great that they challenge us to think a step further on how to foster the collection of long time series of data and how to use these to model and project changes. Here, we elaborate on the possibility to collect time series of data on hazard, exposure, vulnerability and impacts and how these could be used to improve e.g. socio-hydrological models for the development of future risk scenarios.
Fungal artillery of zombie flies: infectious spore dispersal using a soft water cannon
Ruiter, Jolet de; Arnbjerg-Nielsen, Sif Fink ; Herren, Pascal ; Høier, Freja ; Fine Licht, Henrik H. De; Jensen, Kaare H. - \ 2019
Journal of the Royal Society, Interface 16 (2019)159. - ISSN 1742-5689 - 10 p.
biomimetic soft cannon - dispersal range - Entomophthora muscae - force-balance model - fungal spore ejection - high-speed videography
Dead sporulating female fly cadavers infected by the house fly-pathogenic fungus Entomophthora muscae are attractive to healthy male flies, which by their physical inspection may mechanically trigger spore release and by their movement create whirlwind airflows that covers them in infectious conidia. The fungal artillery of E. muscae protrudes outward from the fly cadaver, and consists of a plethora of micrometric stalks that each uses a liquid-based turgor pressure build-up to eject a jet of protoplasm and the initially attached spore. The biophysical processes that regulate the release and range of spores, however, are unknown. To study the physics of ejection, we design a biomimetic 'soft cannon' that consists of a millimetric elastomeric barrel filled with fluid and plugged with a projectile. We precisely control the maximum pressure leading up to the ejection, and study the cannon efficiency as a function of its geometry and wall elasticity. In particular, we predict that ejection velocity decreases with spore size. The calculated flight trajectories under aerodynamic drag predict that the minimum spore size required to traverse a quiescent layer of a few millimetres around the fly cadaver is approximately 10 µm. This corroborates with the natural size of E. muscae conidia (approx. 27 µm) being large enough to traverse the boundary layer but small enough (less than 40 µm) to be lifted by air currents. Based on this understanding, we show how the fungal spores are able to reach a new host.