Researchers develop a new monitoring approach that could provide coastal managers and shellfish growers with up to seven weeks of advance warning of toxic algal events.
Researchers at the University of California, Santa Cruz have developed a new approach for detecting early biological signals associated with harmful algal blooms (HABs), potentially giving seafood producers and coastal managers significantly more time to prepare for events that can lead to fishery and shellfish-harvesting closures.
The technique focuses on copepodamides, chemical compounds released by microscopic marine predators called copepods. When certain algae, including Pseudo-nitzschia, detect these compounds, they can respond by dramatically increasing production of domoic acid, a neurotoxin that can accumulate in seafood and cause serious illness in marine mammals and humans.
Researchers used a passive sampling technology known as Solid-Phase Adsorption Toxin Tracking (SPATT) to capture these chemical signals from seawater. During a 28-month monitoring program at the Santa Cruz Municipal Wharf, the researchers found that copepodamide concentrations could be used to predict Pseudo-nitzschia blooms approximately six weeks in advance. The approach provided as much as seven weeks of advance warning for domoic acid contamination in sentinel mussels.
That represents a potentially significant improvement over conventional monitoring, which generally relies on directly measuring algal abundance or toxin concentrations and may provide only days to about a week of advance warning before conditions reach levels requiring management action.
Potential Benefits for California Seafood
Earlier detection could have important implications for California’s commercial seafood sector. Domoic acid can move through marine food webs, accumulating in shellfish and forage species and creating risks for both seafood consumers and marine wildlife.
When toxin concentrations exceed regulatory safety thresholds, agencies can impose harvesting restrictions or closures to protect public health. While those measures are an important component of seafood safety, unexpected closures can also create significant challenges for fishermen, shellfish growers, processors, distributors and coastal communities.
A forecasting system that provides several additional weeks of lead time could potentially help industry participants prepare for changing conditions, adjust harvesting and marketing plans, and reduce some of the disruption associated with emergency closures.
The research is particularly notable because the SPATT technology is already used by monitoring programs along the Pacific Coast and elsewhere. Researchers say the new chemical measurements could potentially be incorporated into existing monitoring systems without requiring major new infrastructure investments.
A New Piece of the HAB Forecasting Toolbox
The research represents a shift toward incorporating biological interactions within the marine food web into harmful algal bloom forecasting.
Traditional forecasting approaches have focused heavily on environmental factors such as ocean temperature, currents, nutrient availability and upwelling. The new method adds information about interactions between microscopic predators and algae – providing another potential indicator of when toxic blooms are developing.
Researchers at UC Santa Cruz are now looking at ways to expand the technology, including potential deployment on autonomous underwater vehicles and ocean gliders. The long-term goal is to develop higher-resolution predictive maps of HAB risk throughout the California Current.