Acoustic focussing for sedimentation-free high-throughput imaging of microalgae

Hammarström, B., Vassalli, M. and Glynne-Jones, P. (2020) Acoustic focussing for sedimentation-free high-throughput imaging of microalgae. Journal of Applied Phycology, 32, pp. 339-347. (doi: 10.1007/s10811-019-01907-5)

Abstract

Microalgae play a key role in aquatic ecology, and methods providing species determination and enumeration can provide critical information about—for instance—harmful algae blooms (HABs) or spreading of invasive species. A crucial step in current methods is the use of sedimentation. This provides the enrichment needed to achieve statistical counts of sometimes rare species within reasonable timeframes, but it comes with the drawback of aggregating the sample. This is a real challenge for computer-aided identification as particle aggregates can often be erroneously classified. In this paper, we propose an alternative method based on flow-through imaging aided by acoustic-focussing, as this provides better input-data for automated counting-methods while simultaneously removing the need for manual sample preparation. We demonstrate that by acoustically focussing microalgae and other particulates in a fast-flowing water sample, it is possible to analyse up to 8 mL sample per minute with sufficient image quality to discriminate the invasive species Ostreopsis ovata from other particulates in samples taken directly from the Mediterranean. We also showcase the ability to achieve sharp images in flow-through at magnifications up to × 50.

• Item Type: Articles
• Additional Information: The authors would like to thank Dr. Francesca Sbrana (Schaefer SEE) and ARPAL Sardegna for providing environmental Ostreopsis ovata samples. Peter Glynne-Jones thanks the EPSRC for support from fellowship EP/L025035/1.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Vassalli, Professor Massimo
• Authors: Hammarström, B., Vassalli, M., and Glynne-Jones, P.
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Journal Name: Journal of Applied Phycology
• Publisher: Springer
• ISSN: 0921-8971
• ISSN (Online): 1573-5176
• Published Online: 14 September 2019
• Copyright Holders: Copyright © 2019 The Authors
• First Published: First published in Journal of Applied Phycology 32:339–347
• Publisher Policy: Reproduced under a Creative Commons License