=== Effect of Karenia brevis on manatees ===
Karenia brevis has harmful effects on the Florida manatee, which is already an endangered species. Exposure can be lethal, or can lead to long-term impacts. Through times of more extreme red tide events, more than 10% of manatees don't survive. Back in 2013 during an intense bloom, 300 manatees were lost. Although many manage to survive, they are left with harmful effects, specifically targeting the immune system.[1]
When Karenia brevis is found in high concentrations, it is more likely to be harmful because there is a higher concentration of brevotoxins. These sea cows become affected by these toxins through inhaling them or ingesting the algae.[2] Manatees that have been exposed to the harmful algal bloom have experienced declined lymphocyte proliferation, which is related to adaptive immune function. They have also suffered oxidative stress, leading to tissue damage and inflammation.[3] In addition to that, there is evidence of gastrointestinal and neurological issues.[2]
This is a growing issue for many reasons, including the health of the Florida manatee. The year 2003 saw some intense blooms, contributing to 26% of manatee deaths. In 2018, that number shot up to 35%. The state of Florida has implemented some legislation to help manatees, including the Endangered Species Act and the Marine Mammals Protection Act. Manatees also benefit from the Clean Water Act and the Comprehensive Everglades Restoration Act, which deal with water quality. However, these protections do not help so much with HABs. Manatee mortality is continuing to increase due to these factors.[2]
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- ^ Walsh, Catherine J.; Butawan, Matthew; Yordy, Jennifer; Ball, Ray; Flewelling, Leanne; de Wit, Martine; Bonde, Robert K. (April 2015). "Sublethal red tide toxin exposure in free-ranging manatees (Trichechus manatus) affects the immune system through reduced lymphocyte proliferation responses, inflammation, and oxidative stress". Aquatic Toxicology. 161: 73–84.
{{cite journal}}:|access-date=requires|url=(help); Check date values in:|access-date=(help) - ^ a b c Price, Shannon (March 2021). "Red tide: a blooming concern for Florida manatees". Fordham Environmental Law Review. 32: 245–249.
{{cite journal}}:|access-date=requires|url=(help); Check date values in:|access-date=(help) - ^ Walsh, Catherine J.; Butawan, Matthew; Yordy, Jennifer; Ball, Ray; Flewelling, Leanne; de Wit, Martine; Bonde, Robert K. (April 2015). "Sublethal red tide toxin exposure in free-ranging manatees (Trichechus manatus) affects the immune system through reduced lymphocyte proliferation responses, inflammation, and oxidative stress". Aquatic Toxicology. 161: 73–84.
{{cite journal}}:|access-date=requires|url=(help); Check date values in:|access-date=(help)