SoundToxins manual: Puget Sound Harmful Algal Bloom Monitoring Program. [Revised December 2015].

Abstract

Shellfish are critical to the culture, economy and ecology of Puget Sound. They shape habitats, provide food for humans and other species, and perform water-filtering functions important to all organisms that live in or near the Sound. Native American tribes have long incorporated shellfish into their daily lives through ceremony and art as well as food. Today Washington State is a national leader in farmed bivalve shellfish, an industry that provides more than 3,200 family-wage jobs and contributes an estimated $270 million to the economy (Washington Shellfish Initiative 2011). The majority of shellfish-farming and recreational harvest opportunities are in rural communities. Recreation and tourism associated with shellfish harvesting on state-owned beaches annually accounts for more than $1 million in license sales and an estimated economic value of $5.4 million (Washington Shellfish Initiative 2011). Ensuring safe and wholesome shellfish for consumption relies on water free of terrestrial and legacy pollutants and toxins from harmful algal blooms (HABs). A phytoplank - ton bloom can be harmful in several ways. Some blooms can produce anoxic (no oxygen) or hypoxic (low-oxygen) conditions in the water column. This occurs when one or two species dominate a bloom and block the sunlight from other organisms in the lower water column. Other plank - ton begin to die and decompose. The process of decom - position consumes oxygen. Fish die for lack of oxygen and decomposition continues. Eventually, the massive bloom dies as well, removing any additional oxygen from the water column. This entire process can lead to a fish and/or shellfish die-off, resulting in negative economic impacts. Harmful algal bloom events lead to closures of shellfish beds, lost fisheries production, and reductions in tourism and associated service industries. Fisheries-related busi- nesses close, insurance and unemployment rates rise, and public resources are redirected to advisories and monitoring programs. Human health can also suffer during harmful algal blooms. About 50 known species of phytoplankton produce toxins. As toxins move through the food web, they bioaccumulate in the tissues of large fish and marine mammals. Humans can contract illnesses from eating contaminated shellfish and fish, and medical treatment can be expensive. Several types of algal toxin present in Puget Sound require vigilant monitoring to ensure safe shellfish consumption. Hydrophilic (water-loving) toxins such as the domoic acid produced by Pseudo-nitzschia spp. and paralytic shellfish toxins from Alexandrium catenella are currently monitored and regulated by the Washington State Department of Health (WDOH). A recent explosion of various lipophilic (fat-loving) algal toxins, including dinophysistoxins from Dinophysis spp., have caused various human illnesses and prompted a complete ban on the importation of Washington shellfish into the European Union. Of greatest immediate concern is the presence of algal toxins associated with diarrhetic shellfish poisoning (DSP), which triggered a beach closure and a recall of commercial product from Sequim Bay in August 2011.