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The microbial influence on Karenia brevis blooms in the Gulf of Mexico

Involved team members: Cong Fei, Carly Moreno, Iulia Bibire

Harmful algal blooms (HABs) of the dinoflagellate Karenia brevis occur annually in the Gulf of Mexico and in other coastal areas worldwide and date as far back as the 1700s. These blooms have dire consequences for local economies, environmental conditions, and human health. K. brevis blooms are associated with the production of the neurotoxin brevetoxin, which can cause respiratory problems among beachgoers and coastal residents. The duration of a bloom in nearshore Florida waters depends on physical, chemical and biological conditions that influence its initiation, persistence and demise. Our lab lab is part of a NOAA-funded consortium that aims to shed light on these factors that control blooms. Particularly, we are studying how microbes prevalent during a bloom influence the physiology and growth of K. brevis during early, middle and late stages of a bloom. Knowledge about these aspects will enable incorporation of these data into models that can better predict bloom dynamics and may help mitigate these blooms in the future. We are working on the following three aspects:


K. brevis and its beneficial microbiome

K. brevis is a mixotrophic organism that relies on bacteria to provide cofactors and vitamins such as vitamins B1, B7, and B12. We are using metagenomics, and metatranscriptomics as well as laboratory cultures to investigate bacterial communities associated with K. brevis blooms and how they may enable the proliferation of this toxigenic species in the Gulf of Mexico.


K. brevis and algicidal bacteria

As part of an effort to mitigate HABs, we are investigating several approaches to control blooms. Particularly, biological control agents like viruses and/or bacteria may play a natural role in controlling blooms. We aim to isolate and characterize microbes that already exists in the Gulf of Mexico during blooms that can control K. brevis populations. We have isolated several algicidal bacteria from these blooms that have inhibitory effects on K. brevis growth. Currently, we are investigating the molecular mechanisms that enable these bacteria to control K. brevis growth using transcriptomics and metabolomics with plans to apply these microbes to mesocosms to test their potential deployment in the field.


Long-term bloom monitoring

To understand the biological factors that influence the dynamics of K. brevis HABs in the marine environment, we are collecting monthly samples to characterize micrxobial communities in the Gulf of Mexico. With our collaborators we are combining this information with viral population dynamics to test how bacteria and viruses may play a role in influencing blooms persistence and demise.

Plain English Summary

Microalgae play a vital role in the ocean due to their ability to perform photosynthesis and generate nearly half of the oxygen we breathe in our atmosphere. However, some microalgae grow uncontrollably to form blooms that cause severe harm to coastal environments, human health and marine life. These blooms, known as harmful algal blooms (HABs) are generally increasing in occurrence throughout the world and are becoming a major problem for countries with coastal areas. One of the most well-known HABs is the Florida "red tide" caused by the microalgal species Karenia brevis. During these blooms, K. brevis produces a toxin called brevetoxin that can kill aquatic life like fish, seabirds, manatees, sea lions, and turtles. For example, the recent 2017-2019 bloom of K. brevis in FL killed nearly 600 sea turtles, 200 manatees, and 150 dolphins. There is no denying that K. brevis blooms have become the focus of public and political scrutiny. Understanding when and where K. brevis blooms occur can help scientists and the public minimize HABs' impact on marine ecology, while learning more about the causes of the blooms may ultimately help us prevent them. Our lab is part of an international consortium that studies the physical, chemical and biological factors that influence these HABs with an ultimate goal to build better prediction for when these blooms occur and dissipate.

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