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ASSAYING BOUYANCY RESPONSES AND THE PHYSIOLOGY OF PHYTOPLANKTON USING A NEPHELOMETRIC TURBIDIMETER (E)

We have developed a portable, fiber optic-based, highly modular and automated system for the investigation of physiochemical factors that affect phytoplankton dynamics in harmful algal blooms (HABs). In many freshwater aquatic ecosystems the cyanobacterial genera associated with cyanotoxin production are generally responsible for the formation of regularly occurring, persistent HABs with the potential for negative impacts on human and ecosystem health. For many planktonic cyanobacteria, buoyancy regulation in response to a light gradient provides a means of dynamic vertical migration, and is brought about by physiological strategies that affect cellular density. Methodology to conduct experiments on the role of buoyancy regulation and toxin production is needed to better understand cyanobacterial HAB dynamics. Walsby (1972), used nephelometry to assay changes in turbidity, as a proxy for changes in cellular buoyancy. Building on this work, we have developed a modernized and highly robust system. Key advances include: (i) modular scaffold based on industry-standard fiber optics to facilitate exchange of spectrophotometers and light sources; (ii) incorporation of a new generation of LED light sources that more accurately mimic the natural radiometric spectrum; (iii) pulse-width-modulated control of LED light sources, which allows photosynthetically active radiation (PAR) to be adjusted without altering the relative ratios of contributing wavelengths; (iv) digital control of pressure within the sample cell; (v) user-programmable computer-based control of instrument operation.

Authors

Dyer, S. W., Oregon Health & Science University: Institute of Environmental Health, USA, dyest@ohsu.edu

Needoba, J. A., Oregon Health & Science University: Institute of Environmental Health, USA, needobaj@ohsu.edu

Peterson, T. D., Oregon Health & Science University: Institute of Environmental Health, USA, petertaw@ohsu.edu

Details

Oral presentation

Session #:021
Date: 03/02/2017
Time: 12:30
Location: 323 B

Presentation is given by student: Yes