Nearshore drift dynamics of natural versus artificial seagrass wrack

Ryan Baring, Peter Fairweather, Rebecca Lester

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)164-171
Number of pages8
JournalEstuarine Coastal and Shelf Science
Volume202
DOIs
Publication statusPublished - 5 Mar 2018

Keywords

  • Arrival at shoreline
  • Distance offshore
  • Drifting seagrass
  • Posidonia
  • Radio tracking
  • Surf zones
  • Tides
  • Winds

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