A diverse Holocene molluscan fauna including Anadara trapezia from Royal Park, Launceston, Tasmania

Abstract

Estuarine sediments exposed during road construction at Royal Park in the city of Launceston, northern Tasmania, were found to contain a diverse molluscan fauna with some 40 species identified. An unusual occurrence was the presence of six specimens of Anadara trapezia, a species not previously encountered in situ in Quaternary marine or estuarine deposits in Tasmania. Amino acid racemisation and electron spin resonance, calibrated against radiocarbon dating, point to a late Holocene age for this estuarine sequence. A numeric age of 2600 ±400 yrs BP was derived for a specimen of A. trapezia, based on the extent of leucine and valine racemisation. Electron spin resonance data are consistent with this age assessment. The presence of A. trapezia in late Holocene sediments at Launceston may imply slightly warmer water temperatures during the late Holocene.