Capstone Title

Toxic Shock Syndrome: Deaths of Florida Manatees (Trichechus manatus latirostris) When Exposed to Harmful Algal Blooms

Defense Date

9-2007

Document Type

Capstone

Degree Name

M.S. Marine Biology

First Advisor

Edward Keith

Second Advisor

Scott Schatz

Abstract

Harmful algal blooms annually affect a myriad of marine organisms and ecosystems. Such events deleteriously affect the health of marine organisms, as well as humans, and also degrade the environment. In addition, harmful algal blooms can also have a negative economic impact on marine related industries.

The Florida manatee (Trichechus manatus latirostris) is a federally endangered marine mammal, residing on both coasts of the Florida peninsula. The species faces many anthropogenic and natural threats, including exposure to harmful algal blooms.

Algal blooms of the dinoflagellate Karenia brevis result in the release of high concentrations of brevetoxins into the manatee. Brevetoxins can be phagocytized or internalized, instigating the release of inflammatory mediators. This can cause a down-regulated immune system response in the manatee and result in an increased (and often fatal) incidence of toxic shock syndrome secondary to toxin release. It has not been determined if toxic shock syndrome in manatees is due to the bacteria Staphylococcus aureus and Streptococcus pyogenes, as seen in human incidences of toxic shock. However, it has been shown that animals that have previously undergone immunosuppression due to bacterial infections may be more susceptible to additional deleterious health effects such as harmful algal bloom brevetoxins.

While the Florida manatee has been shown to have a strong immune system and to be resistant to several diseases, the onset of unfavorable environmental conditions has been shown to compromise the immune system, often leading to infections. In addition, such infections can also make the species more susceptible to other opportunistic pathogens. Accordingly, toxic shock syndrome could be the result of previous immunosuppressive events such as prior exposure to harmful algal blooms. Such events could result in other diseases or infections in manatees due to immune system deterioration.

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