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Harmful Algal Blooms of the Dinoflagellate Karenia brevis in the Gulf of Mexico

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, coastal ecosystems, and human health. K. brevis blooms are associated with the production of the neurotoxin brevetoxin and its isomers, which can cause respiratory problems among beachgoers and coastal residents; in addition, these HABs often lead to mass fish mortalities and harm to marine life. 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 is part of a NOAA-funded consortium of scientists 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 this new knowlege 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 algicidal bacteria

Biological control agents like viruses and bacteria may play a natural role in controlling blooms in coastal environments. In collaboration with Dr. Joaquin Martinez (Bigelow Laboratory), we aim to isolate and characterize native bacteria and viruses to the Gulf of Mexico that may control control K. brevis populations. We have already 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 test their effect in large mesocosms in collaboration with Dr. Cindy Heil (Mote Marine Lab) to test their potential for bloom mitigation, while incorporating the molecular mechanisms to early prediction and modeling in collaboration with Dr. Kate Hubbard (FWC) and Prof. Ming Li (U. of Maryland).

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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