Evaluation of a remotely operated vehicle (ROV) as a tool for studying the distribution and abundance of zooplankton

• Published in: Journal of plankton research 1995-06, Vol.17 (6), p.1233-1243
• Main Authors: Schulze, Peter C., Williamson, Craig E., Hargreaves, Bruce R.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Marine; Methods and techniques (sampling, tagging, trapping, modelling...)
• ISSN: 0142-7873; 1464-3774
• DOI: 10.1093/plankt/17.6.1233

Conventional methods for measuring zooplankton distributions are too laborious and time consuming to permit sufficient temporal and spatial resolution in many instances. An ability to make more efficient and precise measurements would be useful. We evaluated the potential for using the video system of a commercially available remotely operated vehicle (ROV) to measure the distribution and abundance of zooplankton by calibrating ROV counts with counts based on a conventional sampling procedure (a Schindler trap), and by using an ROV to measure the density of zooplankton in a small lake. As configured here, this particular ROV was suitable for measuring the density of the cladocerans Daphnia and Holopedium. It was also suitable for assessing the distribution, but not absolute densities, of Chaoborus and Leptodora. Image quality was inadequate for quantitative estimates of copepod (Diaptomus minutus) abundance, and prevented us from studying behavioral responses of copepods to the vehicle. We conclude that the ROV has at least three useful features: it can be used to locate patches of those species that are imaged effectively; a large number of samples (videotapes) can be collected almost synoptically with high spatial resolution; the ROV enables in situ observation of zooplankton. The ROV also has three important limitations: the small image volume makes it difficult to study rare organisms; inadequate image resolution precludes studies of relatively small organisms (e.g. the calanoid copepod D.minutus); zooplankton respond to the presence of the ROV.