TY - JOUR
T1 - Nearshore drift dynamics of natural versus artificial seagrass wrack
AU - Baring, Ryan
AU - Fairweather, Peter
AU - Lester, Rebecca
PY - 2018/3/5
Y1 - 2018/3/5
N2 - Drifting macrophytes such as seagrass and macroalgae are commonly found washed ashore on sandy beaches but few studies have investigated the drift trajectories of macrophytes whilst near to the coast. This is the first study to investigate the surface drifting of small clumps of seagrass released at various distances from shore, across multiple days with contrasting wind and tidal conditions, in a large gulf in southern Australia. Natural and artificial radio-tagged seagrass units generally travelled in the same directions as tides but trajectories were variable across sampling days and when tagged units were released at different distances from shore. Natural and artificial units diverged from each other particularly on days when wind speeds increased but generally drifted in the same direction and ended up within close proximity to each other at the 6-h endpoint. During calm conditions, tagged seagrass units drifted with tides for 0.25–5 km and, during one sampling day when wind speeds increased, drifted for >5 km over the 6-h time period. Only tagged units that were released closest to shore stranded on sandy beaches within the six hours of observation, so it would be difficult to predict the eventual stranding location on shorelines for macrophytes released further offshore. This study provides evidence of the variability of macrophyte drift dynamics near to coastlines. Acknowledging this variability is essential for further understanding of the ecological significance of allochthonous material arriving at shorelines, which should be integrated into future research and management of sandy-beach ecosystems.
AB - Drifting macrophytes such as seagrass and macroalgae are commonly found washed ashore on sandy beaches but few studies have investigated the drift trajectories of macrophytes whilst near to the coast. This is the first study to investigate the surface drifting of small clumps of seagrass released at various distances from shore, across multiple days with contrasting wind and tidal conditions, in a large gulf in southern Australia. Natural and artificial radio-tagged seagrass units generally travelled in the same directions as tides but trajectories were variable across sampling days and when tagged units were released at different distances from shore. Natural and artificial units diverged from each other particularly on days when wind speeds increased but generally drifted in the same direction and ended up within close proximity to each other at the 6-h endpoint. During calm conditions, tagged seagrass units drifted with tides for 0.25–5 km and, during one sampling day when wind speeds increased, drifted for >5 km over the 6-h time period. Only tagged units that were released closest to shore stranded on sandy beaches within the six hours of observation, so it would be difficult to predict the eventual stranding location on shorelines for macrophytes released further offshore. This study provides evidence of the variability of macrophyte drift dynamics near to coastlines. Acknowledging this variability is essential for further understanding of the ecological significance of allochthonous material arriving at shorelines, which should be integrated into future research and management of sandy-beach ecosystems.
KW - Arrival at shoreline
KW - Distance offshore
KW - Drifting seagrass
KW - Posidonia
KW - Radio tracking
KW - Surf zones
KW - Tides
KW - Winds
UR - https://doi.org/10.1016/j.ecss.2017.12.017
UR - http://www.scopus.com/inward/record.url?scp=85044349699&partnerID=8YFLogxK
U2 - 10.1016/j.ecss.2017.12.017
DO - 10.1016/j.ecss.2017.12.017
M3 - Article
SN - 0272-7714
VL - 202
SP - 164
EP - 171
JO - Estuarine Coastal and Shelf Science
JF - Estuarine Coastal and Shelf Science
ER -