The Optical Phytoplankton Discriminator

Abstract

The toxic dinoflagellate Karenia brevis forms harmful algal blooms (HABs) in the Gulf of Mexico. The toxins produced by K. brevis cause massive fish kills, contaminate bivalves such as clams and oysters, and produce toxic aerosols. These HABs result in closure of commercial seafood production, disruption of recreational fishing enterprises, and despondent tourists due to the dead fish and toxic aerosols at the beach. Mitigation of some of these harmful effects of these algal blooms can be achieved by early detection and tracking. Our observatory system for the monitoring of Karenia brevis blooms is based on the Optical Phytoplankton Discriminator (OPD) instrument. The OPD uses a HAB species discrimination algorithm to select K. brevis from mixed samples. Advances in miniaturized optical technology allowed us to put the assembly together in a unit that could be used in gliders as well as in fixed units. A variety of platforms have been adapted for the OPD such as vertical profilers, channel markers, buoys, gliders and propelled autonomous vehicles. The data is transferred in a variety of methods depending on the platform being used but includes direct cable, wireless network, VHF radio, cell phone, and satellite phones. We have expanded from detection of only K. brevis to a community structure library that includes taxonomic classes of phytoplankton. Our observatory instrument fulfills the need for near real-time ocean observing tools to detect and track harmful algal blooms.