Hybrid Autonomous Underwater Vehicle and Unmanned Surface Vehicle Sampling for Harmful Algal Blooms (HABs)—Prototype and Results of a Field Trial

Knowing the location and density of organisms capable of producing a harmful algal bloom (HAB) off the Oregon-Washington coast is critical to predicting their landfall on beaches where they impact the safety of shellfish harvest. Some species of Pseudo-nitzschia produce the neurotoxin, domoic acid that accumulates in shellfish and can cause a syndrome called Amnesic Shellfish Poisoning (ASP) in humans and marine wildlife. Mammals that consume contaminated shellfish can become severely ill or, in extreme cases, even die, so it is necessary to close affected shellfish beds to protect human and marine wildlife health. Along the Washington coast, razor clams and Dungeness crabs can accumulate the toxin produced by Pseudo-nitzschia, called domoic acid. Toxic blooms of Pseudo-nitzschia have caused coast-wide, yearlong closures of the razor clam fishery in WA resulting in an estimated $24.4 million in annual lost expenditures (Dyson and Huppert, 2010). Coastal Tribes may be disproportionately impacted by toxic HABs because shellfish are an integrated part of their culture and an important source of dietary protein and income.

One way to provide an early warning of Pseudo-nitzschia’s landing on coastal beaches is through offshore water sampling at HAB initiation sites. This can sometimes be challenging due to rough seas and the unavailability or expense of vessels. An autonomous vehicle would allow sampling to commence during rough weather when other types of sampling is difficult or impossible. This presentation will describe a project that used an Ocean Aero Submaran^® S10 to gather water samples at offshore HAB initiation sites. The deployment, in Fall 2018 off of Neah Bay WA, was coincident with ship-based and mooring-based sampling for HAB organisms which allowed comparing samples and sampling techniques. The mission was designed to test both the use of the S10 and whether the first prototype sampler should be expanded to gather more samples. The results of the project were used as one of the data sources, along with models, other observations, and HFR radar data, to support a Pacific Northwest HAB bulletin, developed to provide an early warning of Pseudo-nitzschia blooms for the Washington Pacific coast.