Aphanizomenon flos-aquae is known to produce endotoxins, the toxic chemicals released when cells die. Once released (lysed), and ingested, these toxins can damage liver and nerve tissues in mammals. In areas where water quality is not closely monitored, the World Health Organization has assessed toxic algae as a health risk, citing the production of anatoxin-a, saxitoxins, and cylindrospermopsin. Dogs have been reported to have become ill or have fatal reactions after swimming in rivers and lakes containing toxic A. flos-aquae.
Microcystin toxin has been found in all 16 samples of A. flos-aquae products sold as food supplements in Germany and Switzerland, originating from Lake Klamath: 10 of 16 samples exceeded the safety value of 1 µg microcystin per gram. University professor Daniel Dietrich warned parents not to let children consume A. flos-aquae products, since children are even more vulnerable to toxic effects, due to lower body weight, and the continuous intake might lead to accumulation of toxins. Dietrich also warned against quackery schemes selling these cyanobacteria as medicine against illnesses such as attention deficit hyperactivity disorder, causing people to omit their regular drugs.
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A Canadian study studying the effect of A. flos-aquae on the immune and endocrine systems, as well as on general blood physiology, found that eating it had a profound effect on natural killer cells (NKCs). A. flos-aquae triggers the movement of 40% of the circulating NKCs from the blood to tissues.
As a food supplement
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Upper Klamath Lake (sometimes called Klamath Lake) is a large, shallow freshwater lake east of the Cascade Range in south central Oregon in the United States. The largest freshwater body in Oregon, it is approximately 20 mi (32 km) long and 8 mi (12.9 km) wide and extends northwest from the city of Klamath Falls. It sits at an elevation of 4140 ft (1262 m).
The lake depth fluctuates due to regulation of its water supply, ranging from 8 ft (2.5 m) to 60 f (18 m) deep at average levels. The lake level is kept within 1261 to 1264 m above sea level. It is fed by several sources, including the Williamson River and is drained by the Link River, which issues from the south end of the lake. It is connected by a short channel to the smaller Agency Lake to the north. The Upper Klamath National Wildlife Refuge sits along the north edge of the lake.
Upper Klamath Lake is located in the high desert southernmost part of the state of Oregon. The lake is protected to the northwest by the Cascade Mountains with an arid sagebrush steppe to the east and south. The lake is fed by 17 rivers that deposit an average of 50,000 tons of mineral-rich silt from the surrounding 4,000-square-mile (10,000 km2) volcanic basin, making Upper Klamath Lake one of the richest nutrient traps in the world. The lake waters and its sediments have a high trace element concentration due to a prehistoric volcanic eruption event (more than 7700y/A). The event covered the area with millions of tons of mineral ash as far north as the Canadian border. The regions volcanic legacy is associated with the Pacific Ring of Fire, a geologically active region that experiences large-scale volcanic, tectonic, and glacial events.
The massive blooms of A. flos-aquae in Upper Klamath Lake affect the dynamics of the system significantly. In many years the blooms crash during the summer. The subsequent decomposition of the massive amounts of organic matter can deplete the water column of dissolved oxygen producing severely impaired conditions for fish species, including redband trout (Oncorhynchus mykiss) and two endangered species of suckers, the Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris). This decomposition also releases previously unavailable nitrogen into the water, often fueling rapid growth of the cyanobacterium Microcystis aeruginosa, which is known to produce the hepatotoxin microcystin. It is widely believed that these dynamics are a central factor in the lack of recruitment of the two endangered sucker species, thereby contributing to their continued decline.
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- Klamath Lake