Seasonality of beachwrack at Oakajee in the mid-west region of Western Australia

WA Museum Records and Supplements | Updated 6 years ago

ABSTRACT – This study examines seasonal fluctuations in beachwrack accumulations near Oakajee, Western Australia (28°34'S; 114°34'E). Twelve monthly samples were made of beachwrack concentrations at Drummonds Cove and Coronation Beach from 5 May 1998 until 10 April 1999. Four weekly samples were made from 23 July to 12 August 1998 to measure short-term variations in beachwrack volumes. There was no seasonality in beachwrack accumulations at Drummonds Cove. At Coronation Beach beachwrack concentrations were high in late summer and early winter, but declined sharply from late winter to early spring. There was considerable movement of wrack onto and off the beaches. Beachwrack accumulations migrated along the beach within Drummonds Cove, but there was no evidence of such longshore movement on the open coast. Beachwrack accumulates in bays and other protected areas and at the tip of peninsulas, such as Point Moore. Macroalgae and the seagrass genera Amphibolis and Posidonia dominated the wrack.