Organism-scale interaction with hydraulic conditions

Aquatic vegetation provides many ecosystem services with an estimated annual value of more than four trillion dollars (Costanza et al. 1997, Thomaz 2021). The services are strongly mediated by the interaction with hydraulics. Vegetation attenuates waves and current, protecting shorelines from erosion (e.g. Barbier et al. 2011; Arkema et al. 2017; Fonseca et al. 2019). Narayan et al. (2017) estimated that coastal marshes reduced flood damage due to Hurricane Sandy by $625 million. Further, the low energy environments created within vegetation provide nursery habitat for important fisheries (Costanza et al. 1997; Thomaz 2021) and promote the capture and retention of carbon carried in suspension, which contributes to the ability of aquatic vegetation to sequester larger amounts of carbon per hectare per year than rainforests (e.g. Fourqurean et al. 2012). Increasing hydrodynamic intensity can enhance nutrient uptake by individual plants (e.g. Lei and Nepf 2016; Gillis et al. 2017), but can also threaten vegetation survival (Katwijk et al. 2016). Because aquatic vegetation plays such an important role in protecting coastal environments and enhancing biodiversity, its protection and restoration have become a major focus in environmental management (Greiner et al. 2013; Sutton-Grier et al. 2015). On the other hand, excessive development of aquatic vegetation reduces channel discharge capacity, elevating flood risk. A better prediction of the hydrodynamic resistance generated by different species and areal distributions would enable managers to avoid this negative impact of vegetation. Management of vegetated landscapes, including restoration, depend on an understanding of the feedbacks between hydraulic conditions and vegetation growth and expansion (e.g. van Hulzen et al. 2007; Vandenbruwaene et al. 2011; Kondziolka and Nepf 2014). Similarly, the habitat selection and life-cycle behavior of aquatic invertebrates are closely linked to the organism-scale interaction with hydraulic conditions (e.g. Statzner et al. 1988; Smith et al. 2014; Lechner et al. 2016). Water depth, velocity, bed shear stress, and turbulence can influence habitat selection of macroinvertebrates and fish (e.g. Lamouroux et al. 1999; Dol edec et al. 2007); the swimming of fish larvae (Prada et al. 2018) and the migration of adult fish (Pavlov et al. 2008). Changes in land-use, installation of dams, and river regulation can all modify the hydraulic conditions, often having a negative impact on habitats and life-cycles. A better understanding of how hydraulics impact habitat and migration is needed to improve the restoration and management of freshwater fisheries and water resources.