TY - JOUR

T1 - Wave dynamics alteration by discontinuous flexible mats of artificial seagrass can support seagrass restoration efforts

AU - Villanueva, Raúl

AU - Paul, Maike

AU - Schlurmann, Torsten

N1 - Funding Information: This study was done within the framework of the collaborative project “SeaArt - Long term establishment of SEAgrass ecosystems through biodegradable ARTificial meadows,” made possible through funding by the Niedersächsisches Vorab and Ministry of Science and Culture (MWK) of the Federal state of Lower Saxony under Grant No. ZN3187. R.V. extends thanks to the Graduate Academy of Leibniz University Hannover for their sponsorship during the drafting of this paper. M.P. further acknowledges funding from the research project SeaStore (Diversity Enhancement Through Seagrass Restoration) from the German Federal Ministry of Education and Research under grant agreement number 03F0859A.

PY - 2023/11/8

Y1 - 2023/11/8

N2 - Seagrass restoration can be promoted through the use of artificial seagrass (ASG). However, there is no guideline for ASG design, which requires a sound understanding of the inherent hydrodynamics in a submerged environment. Present know-how primarily stems from idealized ASG attached to a fixed bed. To develop accessible field deployment for restoration, anchored prototype scale ASG mats (coconut mesh) were proposed and tested under differing wave conditions. The aim of this study was then to: 1) analyze hydrodynamic interaction of ASG mats; and 2) assess the suitability of contemporary predictive hydrodynamic models. Velocity structure and wave propagation were measured around one and two ASG mats (separated by a 2-m gap). The mats reduced orbital velocities by up to 16% (2 mats), whereby the average reduction of all tested vegetated conditions was low (< 10 %) compared to the non-vegetated conditions. Velocities increased above the ASG, with the gap enhancing velocity (up to 11%) instead of attenuating it. Wave decay followed an exponential decrease, further enhanced by the second mat. Current models did not capture the induced hydrodynamics for the full range of wave conditions tested, with the second mat increasing uncertainties. Wave decay models generally overestimated wave attenuation (up to 30%), except for longer wave periods. Nevertheless, for the full range of conditions, the models provide accurate insight into the expected magnitude of attenuation under field conditions. It is speculated that mat flexibility affects the surrounding hydrodynamics through inherent motion, with the gap contributing to the uncertainties.

AB - Seagrass restoration can be promoted through the use of artificial seagrass (ASG). However, there is no guideline for ASG design, which requires a sound understanding of the inherent hydrodynamics in a submerged environment. Present know-how primarily stems from idealized ASG attached to a fixed bed. To develop accessible field deployment for restoration, anchored prototype scale ASG mats (coconut mesh) were proposed and tested under differing wave conditions. The aim of this study was then to: 1) analyze hydrodynamic interaction of ASG mats; and 2) assess the suitability of contemporary predictive hydrodynamic models. Velocity structure and wave propagation were measured around one and two ASG mats (separated by a 2-m gap). The mats reduced orbital velocities by up to 16% (2 mats), whereby the average reduction of all tested vegetated conditions was low (< 10 %) compared to the non-vegetated conditions. Velocities increased above the ASG, with the gap enhancing velocity (up to 11%) instead of attenuating it. Wave decay followed an exponential decrease, further enhanced by the second mat. Current models did not capture the induced hydrodynamics for the full range of wave conditions tested, with the second mat increasing uncertainties. Wave decay models generally overestimated wave attenuation (up to 30%), except for longer wave periods. Nevertheless, for the full range of conditions, the models provide accurate insight into the expected magnitude of attenuation under field conditions. It is speculated that mat flexibility affects the surrounding hydrodynamics through inherent motion, with the gap contributing to the uncertainties.

UR - http://www.scopus.com/inward/record.url?scp=85176105338&partnerID=8YFLogxK

U2 - 10.1038/s41598-023-46612-z

DO - 10.1038/s41598-023-46612-z

M3 - Article

C2 - 37940669

AN - SCOPUS:85176105338

VL - 13

JO - Scientific reports

JF - Scientific reports

SN - 2045-2322

M1 - 19418

ER -