A team of scientists from the University of South Florida, Florida Atlantic University, and Georgia Institute of Technology used NASA satellite observations to discover the largest bloom of macroalgae in the world, an event that blankets the surface of the tropical Atlantic Ocean from the west coast of Africa to the Gulf of Mexico.

The belt of brown macroalgae called Sargassum forms its shape in response to ocean currents. This happened last year when more than 20 million tons of it – heavier than 200 fully loaded aircraft carriers – floated in surface waters and wreaked havoc on shorelines of the tropical Atlantic, Caribbean Sea, Gulf of Mexico, and east coast of Florida.

The team, which reported their findings July 4 in the journal Science, used environmental and field data to suggest that the belt forms seasonally in response to two key nutrient inputs: one human-derived, and one natural. In the spring and summer, Amazon River discharge adds nutrients to the ocean, and such discharged nutrients may have increased in recent years due to expanded deforestation and fertilizer use. In the winter, upwelling off the West African coast delivers nutrients from deep waters to the ocean surface where the Sargassum grows.

“Our measurements of nutrient concentrations in surface waters of the Western Tropical North Atlantic showed greater nitrate and phosphate availability in spring 2018 than in spring 2010, a pattern consistent with increased inputs from the Amazon River due to land use changes in the drainage basin,” said Joseph Montoya, a professor in Georgia Tech’s School of Biological Sciences. “The increase in nitrate concentration is particularly important since the growth of photosynthetic organisms like Sargassum is typically limited by nitrogen availability.”

In patches of the open ocean, Sargassum contributes to ocean health by providing habitat for turtles, crabs, fish, and birds and producing oxygen via photosynthesis like other plants.

But too much of this seaweed makes it hard for certain marine species to move and breathe, especially when the mats crowd the coast. When it dies and sinks to the ocean bottom at large quantities, it can smother corals and seagrasses. On the beach, rotten Sargassum releases hydrogen sulfide gas and smells like rotten eggs, potentially presenting health challenges for people on beaches who have asthma, for example. The bloom has gotten so large that researchers have dubbed it the Great Atlantic Sargassum Belt.

Analyzing data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) between 2000-2018, the researchers found a possible shift in Sargassum blooms since 2011.

“During our 2018 research cruise to the Western Tropical North Atlantic, we saw large rafts of Sargassum throughout our work area, a clear contrast to previous cruises to the region in 2010 and 2011,” Montoya said. “This study is a great example of how satellite remote sensing can be combined with work at sea to provide insight into a complex biological response to changes on land and in the ocean.”

Before 2011, most of the pelagic Sargassum in the ocean was found floating in patches around the Gulf of Mexico and Sargasso Sea. The Sargasso Sea is located on the western edge of the central Atlantic Ocean and named after its prolific algal resident. Christopher Columbus first reported Sargassum from this crystal-clear ocean in the 15^th century, and many boaters of the Sargasso Sea are familiar with this seaweed.

“The evidence for nutrient enrichment is preliminary and based on limited field data and other environmental data, and we need more research to confirm this hypothesis,” said Chuanmin Hu of the University of South Florida College of Marine Science, who led the study and has studied Sargassum using satellites since 2006. “On the other hand, based on the last 20 years of data, I can say that the belt is very likely to be a new normal.”

In 2011, Sargassum populations started to explode in places it hadn’t been before, like the central Atlantic Ocean, and it arrived in gargantuan gobs that suffocated shorelines and introduced a new nuisance for local environments and economies. Some countries, such as Barbados, declared a national emergency last year because of the toll the seaweed took on tourism.

“The scale of these blooms is truly enormous, making global satellite imagery a good tool for detecting and tracking their dynamics through time,” said Woody Turner, manager of the Ecological Forecasting Program at NASA Headquarters in Washington.

The team analyzed fertilizer consumption patterns in Brazil, Amazon deforestation rates, Amazon River discharge, two years of nitrogen and phosphorus measurements taken from the central western parts of the Atlantic Ocean, among other ocean properties.

“The ocean’s chemistry must have changed in order for the blooms to get so out of hand,” Hu said. Sargassum reproduces vegetatively, and it probably has several initiation zones around the Atlantic Ocean. It grows faster when nutrient conditions are favorable and when its internal clock ticks in favor of reproduction.

While the data are preliminary, the pattern seems clear: the explosion in Sargassum correlates to increases in deforestation and fertilizer use, both of which have grown since 2010.

“This is all ultimately related to climate change because it affects precipitation and ocean circulation and even human activities, but what we’ve shown is that these blooms do not occur because of increased water temperature,” Hu said. “They are probably here to stay.”

This work was funded by several programs in NASA’s Earth Science Division, NOAA RESTORE Science Program, the JPSS/NOAA Cal/Val project, the National Science Foundation, and by a William and Elsie Knight Endowed Fellowship.

This article was based on a news release from the University of South Florida.

By Yasmine Bassil, Communications Assistant

Balancing academic work and competitive sports can often be difficult, especially for a college student at Georgia Tech, but Elena Shinohara has mastered it.

Elena Shinohara, a rhythmic gymnast on the Senior National Team, was named the Rhythmic Gymnastics Sportsperson of the Year by USA Gymnastics. She received the award after the USA Gymnastics Championship in Des Moines, Iowa, on July 6, 2019. The award is determined by a collective vote from the top 12 gymnasts of the nation. Rhythmic Gymnastics Athlete Representative Rebecca Sereda presented the award.

Elena is a full-time student at Georgia Tech, completing a pre-health track and majoring in biochemistry. Her father, Minoru “Shino” Shinohara, is an associate professor in the Georgia Tech School of Biological Sciences.

Shino runs the Human Neuromuscular Physiology Laboratory, studying the mechanisms of motor learning and rehabilitation. As an expert in physiology and sports science, Shino is one of Elena’s rhythmic gymnastics coaches. Elena’s second coach is her mother, Namie “Nancy” Shinohara, a former member of the Japanese national rhythmic gymnastics team.

Hard work and dedication permeate Elena’s life; her successes in both her academic degree and gymnastics career are wonderfully exemplified by this award. Congratulations, Elena!

The monthly series "My Favorite Element" is part of Georgia Tech's celebration of 2019 as the International Year of the Periodic Table of Chemical Elements, #IYPT2019GT. Each month a member of the Georgia Tech community will share his/her favorite element via video.

July’s edition features Jennifer Leavey, a principal academic professional in the School of Biological Sciences who wears many other hats. By day, she's also he faculty director of Georgia Tech's Explore Living Learning Community and the director of the Georgia Tech Urban Honey Bee Project.

On her free time, Leavey is the lead singer of the science rock band Leucine Zipper and the Zinc Fingers, "the world's first genetically modified rock band."

Leavey's favorite element changes day by day. When we caught up with her for this episode, bismuth happened to be her favorite element of the day. 

Renay San Miguel, communications officer in the College of Sciences, produced and edited the videos in this series. 

Other videos in this series are available at https://periodictable.gatech.edu/.

June 2019, Benjamin Breer, undergraduate double major in physics and aerospace engineering 

May 2019, G. P. "Bud" Peterson, president of Georgia Tech

April 2019: Kimberly Short, Ph.D. candidate

March 2019: Elayne Ashley, scientific glass blower

February 2019: Amit Reddi, assistant professor of chemistry and biochemistry

January 2019: Jeanine Williams, biochemistry major and track star

By Samantha Mascuch and Julia Kubanek

Editor's Note: This article was published originally on June 13, 2019, in The Conversation. It is republished here through the Creative Common License.

Plants, animals and even microbes that live on coral reefs have evolved a rich variety of defense strategies to protect themselves from predators. Some have physical defenses like spines and camouflage. Others have specialized behaviors – like a squid expelling ink – that allow them to escape. Soft-bodied or immobile organisms, like sponges, algae and sea squirts, often defend themselves with noxious chemicals that taste bad or are toxic.

Some animals that can’t manufacture their own chemical weapons feed on toxic organisms and steal their chemical defenses, having evolved resistance to them. One animal that does this is a sea slug that lives on the reefs surrounding Hawaii and dines on toxic Bryopsis algae. Marine scientists suspected the toxin is made by a bacterium that lives within the alga but have only just discovered the species responsible and teased apart the complex relationship between slug, seaweed and microbe.

Ultimately, noxious chemicals allow predators and prey to coexist on coral reefs, increasing their diversity. This is important because diverse ecosystems are more stable and resilient. A greater understanding of the drivers of diversity will aid in reef management and conservation.

As marine scientists, we too study chemical defenses in the ocean. Our laboratory group at the Georgia Institute of Technology explores how marine organisms use chemical signaling to solve critical problems of competition, disease, predation and reproduction. That’s why we were particularly excited by the discovery of this new bacterial species.

Origins of a chemical defense

In a report published in the journal Science, researchers at Princeton University and the University of Maryland discovered that a group of well-studied toxic defense chemicals, the kahalalides, are actually produced by a bacterium that lives inside the cells of a particular species of seaweed.

The scientific community had long speculated that a bacterium might be responsible for producing the kahalalides. So the discovery of the kahalalide-producing bacteria – belonging to the class Flavobacteria – has solved a long-standing scientific mystery.

Bryopsis provides the bacteria with a safe environment and the chemical building blocks necessary for life and to manufacture the kahalalides. In return, the bacterium produces the toxins for the algae, which protect them from hungry fish scouring the reefs. But the seaweed isn’t the only organism that benefits from this arrangement.

The kahalalides, originally discovered in the early 1990s, also protect a sea slug, Elysia rufescens, that consumes it. The sea slugs accumulate the toxins from the algae, which then protects them from predators.

The discovery of a symbiosis between a bacterium and a seaweed to produce a chemical defense is noteworthy. There are many examples of bacteria living inside the cells of invertebrate animals (like sponges) and manufacturing toxic chemicals, but a partnership involving a bacterium living in the cells of a marine seaweed to produce a toxin is unusual.

The finding adds a new dimension to our understanding of the types of ecological relationships that produce the chemicals shaping coral reef ecosystems.

The medicinal potential of toxins

Our lab is home to an enthusiastic multidisciplinary team of marine chemists, microbiologists and ecologists who strive to understand how chemicals facilitate interactions between species in the marine environment.

We also use ecological insights to guide discovery of novel pharmaceuticals from marine organisms. Chemicals used by marine organisms to interact with their environment, including toxins which protect them from predators, often show promising medical applications. In fact, the most toxic kahalalide, kahalalide F, has been the focus of clinical trials for the treatment of cancer and psoriasis.

Currently, we conduct our fieldwork in Fiji and the Solomon Islands in collaboration with a research group led by Katy Soapi at the University of the South Pacific. There you can find us scuba diving to conduct ecological experiments or to collect algae and coral microbes to bring back for study in the laboratory.

During the course of our field work we have had the opportunity to observe Bryopsis and have been struck by how lovely it is, standing out with its bright green color against the pinks, grays, browns and blues of a coral reef.

The story of the kahalalides is a good reminder that even though seaweed-associated bacteria may be invisible to the human eye and to fish predators, microbes and their chemicals play an important role in shaping coral reef structure and diversity, by allowing organisms to thrive in the face of predation.

Samantha Mascuch is a postdoctoral fellow in the School of Biological Sciences. She receives funding from the National Science Foundation and the National Institutes of Health.

Julia Kubanek is a professor in the Schools of Biological Sciences and of Chemistry and Biochemistry and associate dean for research in the College of Sciences. She receives funding from the National Science Foundation, the National Institutes of Health and Sandia National Laboratories.

This article by Samantha Mascuch and Julia Kubanek was originally published on June 13, 2019, in The Conversation. It is republished here under the Creative Common License.

Plants, animals and even microbes that live on coral reefs have evolved a rich variety of defense strategies to protect themselves from predators. Some have physical defenses like spines and camouflage. Others have specialized behaviors – like a squid expelling ink – that allow them to escape. Soft-bodied or immobile organisms, like sponges, algae and sea squirts, often defend themselves with noxious chemicals that taste bad or are toxic.

Some animals that can’t manufacture their own chemical weapons feed on toxic organisms and steal their chemical defenses, having evolved resistance to them. One animal that does this is a sea slug that lives on the reefs surrounding Hawaii and dines on toxic Bryopsis algae. Marine scientists suspected the toxin is made by a bacterium that lives within the alga but have only just discovered the species responsible and teased apart the complex relationship between slug, seaweed and microbe.

Ultimately, noxious chemicals allow predators and prey to coexist on coral reefs, increasing their diversity. This is important because diverse ecosystems are more stable and resilient. A greater understanding of the drivers of diversity will aid in reef management and conservation.

As marine scientists, we too study chemical defenses in the ocean. Our laboratory group at the Georgia Institute of Technology explores how marine organisms use chemical signaling to solve critical problems of competition, disease, predation and reproduction. That’s why we were particularly excited by the discovery of this new bacterial species.

Origins of a chemical defense

In a report published in the journal Science, researchers at Princeton University and the University of Maryland discovered that a group of well-studied toxic defense chemicals, the kahalalides, are actually produced by a bacterium that lives inside the cells of a particular species of seaweed.

The scientific community had long speculated that a bacterium might be responsible for producing the kahalalides. So the discovery of the kahalalide-producing bacteria – belonging to the class Flavobacteria – has solved a long-standing scientific mystery.

Bryopsis provides the bacteria with a safe environment and the chemical building blocks necessary for life and to manufacture the kahalalides. In return, the bacterium produces the toxins for the algae, which protect them from hungry fish scouring the reefs. But the seaweed isn’t the only organism that benefits from this arrangement.

The kahalalides, originally discovered in the early 1990s, also protect a sea slug, Elysia rufescens, that consumes it. The sea slugs accumulate the toxins from the algae, which then protects them from predators.

The discovery of a symbiosis between a bacterium and a seaweed to produce a chemical defense is noteworthy. There are many examples of bacteria living inside the cells of invertebrate animals (like sponges) and manufacturing toxic chemicals, but a partnership involving a bacterium living in the cells of a marine seaweed to produce a toxin is unusual.

The finding adds a new dimension to our understanding of the types of ecological relationships that produce the chemicals shaping coral reef ecosystems.

The medicinal potential of toxins

Our lab is home to an enthusiastic multidisciplinary team of marine chemists, microbiologists and ecologists who strive to understand how chemicals facilitate interactions between species in the marine environment.

We also use ecological insights to guide discovery of novel pharmaceuticals from marine organisms. Chemicals used by marine organisms to interact with their environment, including toxins which protect them from predators, often show promising medical applications. In fact, the most toxic kahalalide, kahalalide F, has been the focus of clinical trials for the treatment of cancer and psoriasis.

Currently, we conduct our fieldwork in Fiji and the Solomon Islands in collaboration with a research group led by Katy Soapi at the University of the South Pacific. There you can find us scuba diving to conduct ecological experiments or to collect algae and coral microbes to bring back for study in the laboratory.

During the course of our field work we have had the opportunity to observe Bryopsis and have been struck by how lovely it is, standing out with its bright green color against the pinks, grays, browns and blues of a coral reef.

The story of the kahalalides is a good reminder that even though seaweed-associated bacteria may be invisible to the human eye and to fish predators, microbes and their chemicals play an important role in shaping coral reef structure and diversity, by allowing organisms to thrive in the face of predation.

This article by Samantha Mascuch and Julia Kubanek was originally published on June 13, 2019, in The Conversation. It is republished here under the Creative Common License.

Plants, animals and even microbes that live on coral reefs have evolved a rich variety of defense strategies to protect themselves from predators. Some have physical defenses like spines and camouflage. Others have specialized behaviors – like a squid expelling ink – that allow them to escape. Soft-bodied or immobile organisms, like sponges, algae and sea squirts, often defend themselves with noxious chemicals that taste bad or are toxic.

Some animals that can’t manufacture their own chemical weapons feed on toxic organisms and steal their chemical defenses, having evolved resistance to them. One animal that does this is a sea slug that lives on the reefs surrounding Hawaii and dines on toxic Bryopsis algae. Marine scientists suspected the toxin is made by a bacterium that lives within the alga but have only just discovered the species responsible and teased apart the complex relationship between slug, seaweed and microbe.

Ultimately, noxious chemicals allow predators and prey to coexist on coral reefs, increasing their diversity. This is important because diverse ecosystems are more stable and resilient. A greater understanding of the drivers of diversity will aid in reef management and conservation.

As marine scientists, we too study chemical defenses in the ocean. Our laboratory group at the Georgia Institute of Technology explores how marine organisms use chemical signaling to solve critical problems of competition, disease, predation and reproduction. That’s why we were particularly excited by the discovery of this new bacterial species.

Origins of a chemical defense

In a report published in the journal Science, researchers at Princeton University and the University of Maryland discovered that a group of well-studied toxic defense chemicals, the kahalalides, are actually produced by a bacterium that lives inside the cells of a particular species of seaweed.

The scientific community had long speculated that a bacterium might be responsible for producing the kahalalides. So the discovery of the kahalalide-producing bacteria – belonging to the class Flavobacteria – has solved a long-standing scientific mystery.

Bryopsis provides the bacteria with a safe environment and the chemical building blocks necessary for life and to manufacture the kahalalides. In return, the bacterium produces the toxins for the algae, which protect them from hungry fish scouring the reefs. But the seaweed isn’t the only organism that benefits from this arrangement.

The kahalalides, originally discovered in the early 1990s, also protect a sea slug, Elysia rufescens, that consumes it. The sea slugs accumulate the toxins from the algae, which then protects them from predators.

The discovery of a symbiosis between a bacterium and a seaweed to produce a chemical defense is noteworthy. There are many examples of bacteria living inside the cells of invertebrate animals (like sponges) and manufacturing toxic chemicals, but a partnership involving a bacterium living in the cells of a marine seaweed to produce a toxin is unusual.

The finding adds a new dimension to our understanding of the types of ecological relationships that produce the chemicals shaping coral reef ecosystems.

The medicinal potential of toxins

Our lab is home to an enthusiastic multidisciplinary team of marine chemists, microbiologists and ecologists who strive to understand how chemicals facilitate interactions between species in the marine environment.

We also use ecological insights to guide discovery of novel pharmaceuticals from marine organisms. Chemicals used by marine organisms to interact with their environment, including toxins which protect them from predators, often show promising medical applications. In fact, the most toxic kahalalide, kahalalide F, has been the focus of clinical trials for the treatment of cancer and psoriasis.

Currently, we conduct our fieldwork in Fiji and the Solomon Islands in collaboration with a research group led by Katy Soapi at the University of the South Pacific. There you can find us scuba diving to conduct ecological experiments or to collect algae and coral microbes to bring back for study in the laboratory.

During the course of our field work we have had the opportunity to observe Bryopsis and have been struck by how lovely it is, standing out with its bright green color against the pinks, grays, browns and blues of a coral reef.

The story of the kahalalides is a good reminder that even though seaweed-associated bacteria may be invisible to the human eye and to fish predators, microbes and their chemicals play an important role in shaping coral reef structure and diversity, by allowing organisms to thrive in the face of predation.

Much of the damage from climate change is in front of our eyes: Bleached-out coral reefs, destroyed homes and flooded neighborhoods ravaged by hurricanes, dangerous wildfires scorching Northern California forests. Worst-case scenarios involve remade coastlines, stunted crops, and social unrest caused by scarce resources.

An international group of microbiologists, however, is warning that as science tries to search for solutions to climate change, it’s ignoring the potential consequences for climate change’s tiniest, unseen victims – the world’s microbial communities.

Frank Stewart, associate professor in the School of Biological Sciences, is one of more than 30 microbiologists from nine countries who today issued a statement urging scientists to conduct more research on microbes and how they are affected by climate change.

The statement, “Scientist’s warning to humanity: Micro-organisms and climate change,” was published in the journal Nature Reviews Microbiology. Lead author is Rick Cavicchioli, microbiologist at the School of Biotechnology and Biomolecular Sciences, in the University of New South Wales (Sydney).

“The consensus statement by Cavicchiolli and colleagues is an overdue warning bell,” Stewart says. “Its goal is to alert stakeholders that major consequences of climate change are fundamentally microbial in nature. As a co-author, I'm hopeful this statement finds a wide audience of nonscientists and scientists alike and also serves as a call to action. Microbes must be considered in solving the problem of climate change.”

The impact on microbes

In the statement, Cavicchiolli calls microbes the “unseen majority” of all life on Earth. Their communities serve as the biosphere’s support system, playing key roles in everything from animal and human health, to agriculture and food production.

A cited example: An estimated 90% of the ocean’s biomass consists of microbes. That includes phytoplankton, lifeforms that are not only at the start of the marine food chain, but also do their part to remove carbon dioxide from the atmosphere. But the abundance of some phytoplankton species is tied to sea ice. The continued loss of ice as oceans warm could therefore harm the ocean food web.

“Climate change is literally starving ocean life,” Cavicchioli said in a press release about the consensus statement.

The microbiologists are also worried about microbial environments on land. Microbes release important greenhouse gases like methane and nitrous oxide, but climate change can boost those emissions to unhealthy levels. It can also make it easier for pathogenic microbes to cause diseases in humans, animals, and plants. Climate change affects the range of flying insects that carry some of those pathogens. “The end result is the increased spread of disease, and serious threats to global food supplies,” Cavicchioli said.

“Just as microbes in our bodies critically affect our health, microbes in the environment critically affect the health of ecosystems,” Stewart says. “But microbial processes are changing dramatically under global climate change, including in ways that fundamentally alter food webs and accelerate climate change.”

A call to boost research

Georgia Tech researchers such as Stewart, Mark Hay, Kim Cobb, and Joel Kostka have become experts in researching climate change’s impact on diverse ecosystems, from coral reefs to subarctic peat bogs. Much of their work already focuses on microbes and the roles they play in these stressed environments.

“For example, ocean warming is driving the loss of oxygen from seawater, leading to large swaths of ocean dominated exclusively by microbes,” Stewart says. “Our research at Georgia Tech tries to understand how such changes affect the microbial cycling of essential nutrients.”

According to the consensus paper, that kind of research should play a bigger role when governments and scientists work on policy and management decisions that might mitigate climate change. Also, research that ties biology to worldwide geophysical and climate processes should give greater consideration of microbial processes.

“This goes to the heart of climate change,” Cavicchioli says. “If microorganisms aren’t considered effectively, it means models cannot be generated properly and predictions could be inaccurate.”

Microbiologists can endorse the consensus statement and add their names to it here: https://www.babs.unsw.edu.au/research/microbiologists-warning-humanity