Many coastal areas are impacted by dead and rotting fish on beaches or at aquaculture sites, human illness and death from the consumption of toxic fish and shellfish, closure of shellfish beds due to the presence of potent neurotoxins, mass mortalities of marine mammals and birds, and subtle yet potentially devastating effects on ecosystems as toxins are transferred through food webs. These are but a few of the many manifestations of natural phenomena called harmful algal blooms (HABs). HABs have become a significant national and global concern, in part because the range of economic and public health impacts associated with them has expanded dramatically in recent years.


Red tide in Japan
Karenia brevis bloom in Florida  

Wild fish mortalities in TX Aquaculture mortalities in Japan

Of the various bloom control options, co-flocculation of HAB cells with clay is one of the most promising with respect to maximizing effectiveness and minimizing environmental impacts and costs. The principle behind cell removal using clay is flocculation/sedimentation - a process wherein small particles, through repeated collisions and adhesion, form large, rapidly-sinking aggregates (or flocs) that settle to the ocean floor.

The idea has already been applied in Asia , especially in South Korea . The efficacy of clay flocculation for controlling harmful algal blooms in the United States, and its potential impacts, have now been examined for several years from bench-top experiments to various mesocosms (e.g. limnocorrals and flumes) and open water trials.


Clay dispersal in South Korea
Clay dispersal in South Korea

 

Clay dispersal study in FL Clay dispersal study in FL