Invasive Japanese foraminifera in a south-west Australian estuary

Abstract

An invasive foraminiferan is recorded for the first time in an Australian estuary. Trochammina hadai, originally described as endemic from Japan and subsequently found to be alien in coastal waters of California and Brazil, has been identified in estuarine sediment in the vicinity of Bunbury Port in Western Australia. Species determination is based on morphological, molecular and ecological similarities to the Japanese type. The species has not been recorded in other estuaries in Australia. Bunbury Port is a major exporter of woodchip to Japan and the introduction of T. hadai may have come from ballast water out of shallow-draught woodchip vessels. Small sediment samples of estuarine mud obtained at water depths of ~5 m contain abundant T. hadai (on average ~0.4 mm in adult diameter) that are easily recognised in microscopic view of the sediment surface by their bright reddish-brown colour. The collection of sediment samples from the estuarine floor and ballast water, and the examination of these for foraminifers, may provide a useful indicator in estuaries for the possible presence of other exotic species, particularly in the vicinity of ports.

Part 2: Descriptions of the proposed Crawford Lake GSSP and supporting SABSs. The Anthropocene Epoch and Crawfordian Age: proposals by the Anthropocene Working Group

“…Notably these species have their first occurrence datums in the same relative order in the core as their known time of introduction (Figure SFB2), and they can be used to develop a high-resolution biostratigraphy of the proposed Crawfordian stage across San Francisco Estuary. Trochammina hadai is an intercontinental marker for deposits of the proposed Crawfordian stage in shallow marine and estuarine deposits (e.g., Eichler et al, 2016;Tremblin et al, 2022;Bouchet et al, 2023). Plotting key biostratigraphical events here suggests that the time series analysis gives an approximation of age, but for some intervals may be a few years in error.…”