Investigating algicidal amines as agents for chemical control of toxic dinoflagellate Karenia brevis
Date
2023
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
The dinoflagellate Karenia brevis causes harmful algal blooms, called red tides, that increasingly disrupt ecosystems and economic activity in the western coast of Florida. Strategizing for a future of imminent red tide demands interventive control options for severe blooms. Bio-inspired chemical control attempts to synergistically merge the concepts of chemical control and biotic control, incorporating the logistical advantages of the former and the environmental consciousness of the latter. Amine compounds identified in a dinoflagellate-specific bacterial algicide were assessed for their potential to control the abundance of K. brevis. First, dose-response of K. brevis to four selected compounds was measured. Three of those, ammonia, putrescine, and spermidine, controlled K. brevis and had lesser effects on a nontarget algal species. To improve dose efficiency, combinations of these compounds were screened for synergistic interaction. Three combined amine doses potentiated by synergisms proceeded to testing on natural microbial communities collected from a field site subject to red tide. The impact of these doses on nontarget microbes was compared. 0.9 ppm ammonium with 7.5 ppm putrescine, hereafter “NP”, emerged as preferable with respect to effects on photosynthetic biomass and photophysiological stress. Next, NP was applied to a naturally-occurring red tide where it controlled K. brevis and restructured microbial communities. Dynamics in microbial communities and water chemistry parameters were then monitored over 7 days in NP-treated. NP demonstrated control of non-K. brevis dinoflagellates in non-red tide communities, with specificity over diatoms and other phytoplankton groups. Effects of NP on pH, turbidity, and dissolved oxygen of mesocosms revealed pertinent considerations for future field application. Putrescine had short residence times whereas ammonia accumulated to potentially toxic levels. Ultimately, NP, formulated from commercially-available and relatively inexpensive amine compounds produced by naturally-occurring algicidal bacteria, exhibited potent, taxonomically-specific control of K. brevis in complex natural microbial communities. Thus, efforts to replicate this result and further engineer NP for eventual field deployment are supported.
Description
Keywords
Bacterial algicide, Bio-inspired, Harmful algal blooms, Amine compounds, Karenia brevis