Molecular Probes Link Sea Lion Deaths To Toxic Algal Bloom

Harmful algal blooms in the ocean result from the rapid growth of some species of microscopic algae that produce toxic by-products. These toxins can cause public health threats and fisheries closures when transferred up the food chain, but the connection between algal blooms and marine mammal mortality has been difficult to establish. Traditional techniques used to identify the presence of potentially toxic algae work after the bloom has occurred and may even miss the bloom. In this study, the bloom of the diatom Pseudo-nitzschia australis and its associated neurotoxin domoic acid was first noted in plankton samples using DNA probe tests developed by MBARI and a toxin test developed by scientists at the National Oceanic and Atmospheric Administration’s Marine Biotoxin Research Program in Charleston, South Carolina.

"The DNA probes and toxin tests detected the short but significant bloom in Pseudo-nitzschia australis," said Dr. Scholin. "Our early alert and collaboration with marine mammal scientists and public health officials helped us collect the data needed to connect the sea lion deaths with the bloom."

These techniques, in which species-specific DNA probes bind to the RNA of the toxic algae and glow when viewed under a microscope, could be applied using a robotic device in the field. Dr. Scholin and colleagues at MBARI plan to deploy a prototype of such a device in Monterey Bay this summer.