Ocean Acidification

(Image credit: Philip Kulisev/Monaco Explorations)

Small but Mighty

“One single BGC float is like a tiny research vessel that will operate autonomously for five to six years and send its data every 10 days,” Hervé Claustre says. A float also costs a lot less than the simplest and shortest research vessel campaign. On top of the temperature and salinity sensors already found on Core Argo floats, a BGC Argo float carries six additional sensors for sampling oxygen, pH, nitrates, chlorophyll, suspended particles, and light.

A BGC float and the six biogeochemical parameters. (Image credit: ERC REFINE)

“The idea is to understand how climate change impacts marine ecosystems, their biodiversity, and functioning,” explains Emanuele Organelli, a marine ecology researcher from the Italian National Research Council (CNR), working today for Argo Italy, a member of the Euro-Argo consortium. Dramatic changes in marine ecosystems have repercussions on living marine resources, such as fisheries all around the world. By better understanding global marine ecosystems, scientists can better advise policymakers on the urgent actions needed to anticipate and mitigate these potentially dramatic effects on marine resources.

A Suite Sensors

The BGC floats provide the tools to collect a wide array of key data for marine ecology. Oxygen sensors can detect regions where oxygen is scarce. As the oceans are getting warmer, their circulation is getting weaker. Consequently, there are fewer exchanges between oceans and the atmosphere and less oxygen entering oceans in certain areas. pH sensors can measure ocean acidification. The excess carbon dioxide from human activity is absorbed by the oceans and transforms into acid via a chemical reaction in the water. This phenomenon has dire consequences for marine life.

Nitrates, chlorophyll, and light sensors are used to monitor phytoplankton, microscopic marine algae. It is an essential component of the food chain: phytoplankton is consumed by zooplankton, microscopic drifting animals, and zooplankton is the main food source of small fish and other marine animals. Moreover, the quantity and types of phytoplankton thriving in one region give a lot of information about the local ecosystem. Each type, or community, of phytoplankton modifies the intensity and color of marine lightscapes.

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With light sensors, scientists can identify these colors and study the diversity of such communities. Scientists can also assess phytoplankton biomass in a particular area by measuring chlorophyll and suspended particles in the water. In the long run, they should be able to deduce the distribution of phytoplankton communities all around the planet. That, in turn, will help them assess how healthy marine ecosystems are and how sustainable the harvest of living marine resources is in different regions of the planet.

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Imagine: vibrant aquatic ecosystems corrupted by toxic algal blooms. Is it true that the very fabric of these blooms is woven with the threads of climate change? Let’s dig into the astonishing connection between rising temperatures, shifting ocean chemistry, and the unsettling proliferation of harmful algal blooms.

In a nutshell, global warming has caused a surge in harmful algal blooms. These microscopic troublemakers thrive in an ever-changing climate, thanks to rising temperatures and precipitation changes. As a result of absorbing excess carbon dioxide from the atmosphere, the acidification of our oceans further complicates the delicate balance, resulting in a range of changes in the composition and intensity of algal blooms. This article meticulously examines the dynamic interplay between climate change and harmful algal blooms, revealing the profound consequences for our ecosystems and society as a whole.

As you read through the sections, keep an eye on the startling revelations about the temperature-dependent toxin production, the expanding footprint of algal blooms into new regions, and the negative consequences on marine ecosystems. We’ll go over the economic and public health implications of these blooms, as well as how they affect the environment. We will also lay out critical strategies for addressing this environmental crisis in the coming weeks, as well as provide an overview of key mitigation and adaptation initiatives. It’s an honor to join me on this expedition into the heart of this issue, where science meets urgency and the fate of our aquatic ecosystems is at stake.

Understanding Harmful Algal Blooms

In the realm of environmental intricacies, comprehending Harmful Algal Blooms (HABs) is pivotal to navigating the complexities that define our changing ecosystems. These enigmatic phenomena, denoted by an insurgence of algae exhibiting harmful effects, weave a narrative of ecological disruption. Let’s delve into the layers of understanding surrounding HABs, dissecting their definition, the diverse taxonomy of harmful algae, and the nuanced factors contributing to their formation.

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The Interconnected Web: Climate Change and HABs

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Ocean Acidification: A silent but profound transformation occurs beneath the waves as our oceans absorb excess carbon dioxide. This process, known as ocean acidification, alters the very chemistry of the waters, setting the stage for a nuanced interplay with HAB dynamics. The changed water chemistry becomes a silent orchestrator, influencing the behavior and composition of harmful algal blooms. As pH levels shift, the delicate balance of marine life is disrupted, creating an environment where certain algae species thrive, further exacerbating the prevalence of HABs.

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Ocean Acidification’s Role in Algal Bloom Trends

In the intricate ballet of marine ecosystems, the role of ocean acidification in shaping the trends of Harmful Algal Blooms (HABs) emerges as a profound yet often underestimated force. This section delves into the multifaceted impacts of acidification on algal physiology, the consequential shifts in algal dominance spurred by altered pH levels, and the intricate connection between acidification and the production of toxins.

Study findings show a possible bright spot for a commercially important population hammered by a warmth-triggered crash

Bering Sea snow crab, with two specimens seen in this undated photo, support an iconic Alaska seafood harvest, but a crash in population since 2018 triggered the first ever closure of the fishery in 2022. That closure was extended for the 2023-24 season. A newly published study shows that snow crab have some resilience to ocean acidification, with eggs and embryos that fare better in acidified conditions than do those of other Alaska crab species. (Photo provided by National Oceanic and Atmospheric Administration)

The beleaguered snow crab of the Bering Sea may have one strength that could help their population endure rapidly changing marine conditions: an apparent resilience to ocean acidification.

Research by National Oceanic and Atmospheric Administration scientists in Kodiak has found that juvenile snow crabs are not harmed when reared in more acidic waters. That is a contrast with other types of crab found in Alaska waters and even with bairdi crab, commonly referred to as tanner crab, which are closely related to snow crab.

The results come from an experiment that held females for two years and observed development of embryos and larvae from eggs hatched in each of the years.

“The embryos did just fine. They hatched out just fine both years. We didn’t see any indications of negative effects on embryo development,” said Chris Long, the study’s leader and a scientist at NOAA’s Alaska Fisheries Science Center laboratory in Kodiak.

The study found some minor effects on larvae in the first year but not in the second year, he said.

The experiment’s structure duplicated the structure for an earlier tanner crab project, Long said. That project found that negative effects from acidification in tanner crab emerged in the second year, and they were profound, with 70 percent of the eggs failing to hatch, he said.

The new findings also parallel those from other research that found that snow crab shells are more resilient to acidified waters than are tanner crab shells. In that experiment, Long said, snow crab shells remained intact after two years’ exposure to acidified waters while tanner crab shells deteriorated.

Resilience to ocean acidification could be important for snow crab and other Bering Sea species. The Bering Sea is, by its nature, conducive to acidification because of its cold waters, high carbon content, wide seasonal swings and a particular combination of ocean mixing characteristics. Previous research has found that the world’s most acidic ocean waters are found in the northern Bering Sea during the winter, when sunlight is scarce and carbon-absorbing plankton cannot bloom. And Bering Sea acidification is expected to increase into the future as the oceans continue to absorb the carbon being pumped into the atmosphere.

The findings about snow crab embryos and larvae provide a bit of good news in an otherwise bleak picture for the species in Alaska that has supported a lucrative fishery in the past.

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Record-breaking ocean temperatures in the North Atlantic resulted in several intense marine heatwaves in the Northern Hemisphere last summer – but heat is only one of numerous stressors that challenge life under water. While the ocean is becoming warmer, more acidic, and less oxygenated, how can we monitor and protect the marine biodiversity we depend upon?

In June 2023, the North Atlantic ocean experienced record-breaking ocean temperatures, resulting in several unprecedented extreme marine heatwaves. Such periods of unusual heat can be detrimental to marine life, causing mass die-offs of fish and other organisms, disrupting fisheries and spurring harmful algal blooms – but heat itself is not the only climate-linked stressor affecting marine biodiversity. 

The role of satellites in measuring ocean acidification: a closer look

Satellites have become an invaluable tool in measuring ocean acidification, a phenomenon caused by increased levels of carbon dioxide in the atmosphere. Ocean acidification has the potential to cause widespread disruption to marine ecosystems, and satellites are playing a key role in helping scientists understand and monitor its effects.

Satellites can measure ocean acidification in two ways. The first is by measuring the pH of the ocean, which is a measure of the acidity or alkalinity of the water. The second is by measuring the amount of carbon dioxide in the atmosphere. Both of these measurements can be used to calculate the amount of acidity in the ocean.

Satellites can also measure the amount of dissolved inorganic carbon in the ocean, which is a measure of how much carbon dioxide is being absorbed by the ocean. This is important because the more carbon dioxide that is absorbed, the more acidic the ocean becomes.

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How satellites are helping to track ocean acidification

Satellites are playing an increasingly important role in helping scientists to track ocean acidification, a phenomenon caused by the absorption of carbon dioxide from the atmosphere. As the world’s oceans absorb more and more of this gas, their pH levels drop, making them more acidic. This has a detrimental effect on marine life, as many species are unable to adapt to the changing environment.

In recent years, satellites have become a valuable tool for monitoring ocean acidification. By measuring the concentration of carbon dioxide in the atmosphere, they can provide an accurate picture of how much is being absorbed by the oceans. This data can then be used to track changes in pH levels over time, allowing scientists to identify areas where acidification is occurring and take steps to mitigate its effects.

Satellites are also being used to monitor other factors that can affect ocean acidification, such as sea surface temperature and salinity. By combining this data with measurements of carbon dioxide levels, scientists can gain a better understanding of how these factors interact and how they contribute to the overall acidification of the oceans.

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The role of satellite data in assessing the impact of ocean acidification

Ocean acidification is a major environmental issue that is impacting marine ecosystems around the world. As atmospheric carbon dioxide levels rise, the ocean absorbs more of this gas, leading to an increase in acidity. This has a direct effect on marine life, as the increased acidity can lead to decreased calcification rates and changes in the availability of essential nutrients.

Satellite remote sensing is becoming increasingly important for oceanography. This technology provides researchers with a powerful tool to study the ocean from space, allowing them to observe and measure the ocean’s physical and biological characteristics.

The most common type of satellite remote sensing used in oceanography is passive microwave remote sensing. This technique uses microwaves to measure the brightness of the ocean’s surface, which can be used to determine sea surface temperature, sea surface height, and sea surface salinity. This data can then be used to monitor ocean currents, track storms, and study ocean circulation patterns.

Satellite remote sensing can also be used to measure ocean color. This technique uses the visible and near-infrared spectrum to measure the color of the ocean’s surface. This data can be used to measure the amount of chlorophyll in the water, which can be used to monitor the health of the ocean’s ecosystems.

Satellite remote sensing also provides researchers with a way to measure the amount of carbon dioxide in the ocean. This data can be used to study the effects of climate change on the ocean’s carbon cycle.

The benefits of satellite remote sensing for oceanography are numerous. It provides researchers with a way to observe and measure the ocean’s physical and biological characteristics from space. This data can be used to monitor ocean currents, track storms, and study ocean circulation patterns. It can also be used to measure the amount of chlorophyll in the water and the amount of carbon dioxide in the ocean. By utilizing satellite remote sensing, researchers can gain a better understanding of the ocean and its role in the global climate system.

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Analyzing the impact of satellite remote sensing on oceanography

The use of satellite remote sensing in oceanography has revolutionized the way scientists study the world’s oceans. By providing a wealth of data on the ocean’s physical and chemical properties, satellite remote sensing has enabled researchers to better understand the complex dynamics of the marine environment.

Satellite remote sensing technology has enabled researchers to map ocean currents, measure sea surface temperatures, and track the movement of pollutants. This data has been invaluable in understanding the impacts of climate change on oceanic ecosystems, as well as in predicting the future of the world’s oceans.

The ability to monitor the oceans from space has also allowed scientists to detect and monitor harmful algal blooms, which can have devastating effects on aquatic life. By providing a detailed picture of the ocean’s surface, satellite remote sensing has enabled researchers to identify areas of algal blooms and track their movement. This data has been used to develop strategies for mitigating the impacts of algal blooms on marine life.

In addition, satellite remote sensing has been used to study the effects of ocean acidification on coral reefs. By measuring changes in the ocean’s chemistry, researchers have been able to identify areas of acidification and track its progression. This data has been used to develop strategies for protecting coral reefs from the effects of acidification.

The use of satellite remote sensing in oceanography has revolutionized the way scientists study the world’s oceans. By providing a wealth of data on the ocean’s physical and chemical properties, satellite remote sensing has enabled researchers to better understand the complex dynamics of the marine environment and develop strategies for mitigating the impacts of climate change and ocean acidification.

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Link to Survey: Survey to Assess Ocean Acidification Research Capacity and Interest in the Caribbean

Description: This survey is being conducted by a Community of Practice (CoP) for Ocean Acidification in the Caribbean in collaboration with The Ocean Foundation. This group seeks to create a strategic framework and funding plan to enable increased capacity to monitor and respond to ocean change in the Caribbean, with a focus on ocean acidification. The results of this survey will assist the Caribbean CoP in seeking appropriate partners and funding to meet the needs of the region.

There are four sections of this survey. Please fill in all questions that are relevant to your work to the best of your ability.

The survey will be open until April 21, 2023. The CoP aims to report on survey results via email and at local conferences (i.e. AMLC Meeting in St. Kitts May 22-26, 2023). The overall goal is to better inform policymakers and funding agencies in the region about OA. 

The survey is only available in English. Chrome provides web page translation via google translate. You may answer the long form questions in your preferred language.

We invite you to share this survey with any additional colleagues whose work is relevant to the activities of the CoP.
If you have any questions about the survey, please contact Alexis Valauri-Orton (avalauriorton@oceanfdn.org)

To celebrate Women’s History Month, we asked women throughout NOAA Research who make lasting impacts in scientific research, leadership, and support from the field to the office to share how their work contributes to NOAA’s mission of Climate Resilience and preparing for a Climate-Ready Nation. This article highlights an interview with Kaity Goldsmith, Intramural Program Specialist in NOAA’s Ocean Acidification Program. Kaity strategically engages across NOAA offices to coordinate and fund ocean and coastal acidification research to better prepare society to respond to changing ocean conditions. 

Our conversation follows:

What does climate resilience or climate-ready nation mean to you? What would you want people to know about NOAA’s work on climate resilience?

Ocean acidification is a fundamental change in the chemistry of the ocean caused by the ocean absorbing carbon dioxide in the atmosphere. It is caused by the same forces that drive climate change and the mitigation and adaptation mechanisms are in line with creating a more climate ready nation. 

By engaging in ocean acidification research, NOAA promotes an understanding of the possible future conditions and helps communities prepare for those potential realities. I think of it as turning the headlights on in a car so the driver can see down the road and prepare accordingly. By researching the potential impacts of ocean acidification, as well as identifying scientifically sound approaches to dealing with those impacts, the nation has options and time to take climate resilience actions.  

What drew you to the field?

Like so many 19-year olds, I was searching for what my slice in this world could be as I worked towards my bachelor’s degree in Business Management. Sitting in my business classes, I couldn’t find a clear career path that suited me. On a whim one day, I applied to volunteer for an environmental NGO to give back in some small way to the environment that gave me so much solace and peace of mind. In volunteering, I realized the plethora of ways I never knew existed that I could have a career in the natural environment. That realization was an avalanche moment in my life that led me on an incredible path towards working in a field I love.  

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To celebrate Women’s History Month, we asked women throughout NOAA Research who make lasting impacts in scientific research, leadership, and support from the field to the office to share how their work contributes to NOAA’s mission of Climate Resilience and preparing for a Climate-Ready Nation. This article highlights an interview with Libby Jewett, the Director of the Ocean Acidification Program in Silver Spring. Libby founded the Ocean Acidification Program in 2011, has grown its budget and reach, and continues to steer it in important and innovative directions.

Our conversation follows:

What does climate resilience or climate-ready nation mean to you? What would you want people to know about NOAA’s work on climate resilience?

A climate ready nation is one that doesn’t accept the trajectory we are on, but rather works harder to solve the climate problem. In NOAA, we need to figure out how to enhance renewable energy and carbon dioxide removal options, without harming the oceans in the process. From an ocean acidification perspective, a climate ready nation is one in which people have essential information about how ocean acidification is playing out from local to global scales and the tools needed to adapt to its challenges.

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Tiffany Stephens, left, works at the Seagrove Kelp farm in Doyle Bay near Craig on April 14, 2021. (Photo by Jordan A. Hollarsmith/NOAA Fisheries, Alaska Fisheries Science Center)

To optimists, the plants that grow in the sea promise to diversify the Alaska economy, revitalize small coastal towns struggling with undependable fisheries and help communities adapt to climate change – and even mitigate it by absorbing atmospheric carbon.

Cultivation of seaweed, largely varieties of kelp, promises to buffer against ocean acidification and coastal pollution, the promoters say. Seaweed farms can produce ultra-nutritious crops to boost food security in Alaska and combat hunger everywhere, and not just for human beings.

“Kelp is good for everybody. It’s good for people. It’s good for animals,” Kirk Sparks, with Pacific Northwest Organics, a California company that sells agricultural products, said in a panel discussion at a mariculture conference held in Juneau in February by the Alaska Sea Grant program.

But before it achieves these broad benefits, Alaska’s mariculture industry must first address significant practical issues, including an American consumer market that has yet to broadly embrace seaweed.

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There is encouraging scientific evidence that seaweed cultivation buffers acidification locally, as described in studies from various projects, including some from China, California and New York. Seaweed farming “could serve as a low-cost adaptation strategy to ocean acidification and deoxygenation and provide important refugia from ocean acidification,” said the study from China, published in 2021 in the journal Science of the Total Environment.

But does seaweed farming result in absorption of atmospheric carbon and prevention of it streaming back into the atmosphere? The answer is complicated, according to the science. It depends on what happens to the kelp. If dead and decomposing bits are on land or in shallow waters, they would likely release carbon back into the atmosphere, scientists say.

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Scientists investigating the effects of ocean acidification, microplastic and lanthanum on marine organisms observed color changes in shellfish, immune system issues in some species, a decrease in cell counts and a fall in reproduction. Amid this trend, fish stocks have been gradually decreasing in the Black Sea and the quantity of fish stock does not meet the desired needs, an expert said while drawing attention to the importance of sustainable fishing.

Istanbul University’s Faculty of Science, Department of Biology and General Biology Department faculty members professor Murat Belivermis and professor Önder Kılıç examined the effects of ocean acidification, microplastic and lanthanum, which they refer to as the “triple stress factor,” on marine life in Turkish waters and human consumption within the scope of the project titled “Biological Effects of Stress Factors in the Marine Environment” initiated 10 years ago.

Belivermiş and Kılıç observe the effects of these factors by exposing the creatures they collect from the sea to stress factors in the marine environment they have created in their laboratory at the university, including mollusks, shrimp and sea urchins as they play a key role in the ecosystem.

Stating that they are currently working on a sea urchin species they collected from the Gulf of Saros, Belivermiş said, “These species live in the Marmara Sea and the North Aegean. It will generate important data and will serve us with many solutions for the future,” he said.

Acidification

Acidification in oceans has become a global issue and affects the seas around Türkiye. The reason behind ocean acidification is also increasing carbon dioxide emissions that cause the pH to drop in the sea, and organisms with a calcium carbonate skeleton are particularly affected by it. Living things spend their energy dealing with this acidification, reproduce less and their immune systems are affected, Belivermiş explained.

“Adopting a holistic approach, we have seen whitening in oyster species. In fact in previous studies, we saw reductions in the hemolymph cells of mussels due to acidification. This suggests a problem with the immune system, resulting in weakening or color changes in the shells.”

Kılıç noted that if ocean acidification seriously affects the lives of these species, it will lead to a decrease in the population, and this decrease will also transpire as a decrease in the human food supply.

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The Hercules robot explores a forest of corals and sponges off the coast of British Columbia, in 2018.

Around the world, coral reefs are in decline due to anthropogenic CO2 emissions. Cold-water corals, such as those found off British Columbia, attract less public attention. Yet they are as threatened by global warming as their tropical counterparts.

Off Vancouver Island, underwater mountain ranges rise in the depths of the ocean peaceful. These remains of volcanoes are home to ecosystems of phenomenal diversity, says Robert Rangeley, scientific director of the ocean protection organization, Oceana Canada.

There are huge forests, of different types of corals, such as red tree corals or bamboo. They can be several meters high. There are also glass sponges, false starfish, octopuses, tons and tons of fish, describes the researcher, who participated in an expedition to explore 13 of these seamounts in 2018.

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CO2 is also naturally captured by the oceans, where it dissolves in water to form carbonic acid. When CO2 concentrations are too high, however, it lowers the pH of the water and thus increases its acidity. The hotter the water, the more this cycle is accelerated, argues Gabriel Reygondeau.

Ocean acidification alters the calcification process of corals, which build their skeleton on limestone, explains Gabriel Reygondeau. Some of their vital growth and reproduction functions are also affected.

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Shark fossils date back to the Late Ordovician Period, when a few scales date back to 450 million years ago. AFP VIA GETTY IMAGES

If you asked Valentina Di Santo what was the most surprising finding from her latest research project, she would quickly answer, “Well, first, [the fact that] there is not much known about the effect of climate change on elasmobranchs! Sharks and ray are an important group of meso- and top predators but studies to understand the effect of climate-related stressors have been scarce, especially when compared to the vast literature on the effect of climate change on physiological responses of bony fishes.” As one of the oldest and most diverse group of marine vertebrates, elasmobranchs (sharks, skates, rays and sawfishes) have survived multiple extinctions our planet has previously faced. Wipe-outs that killed off their mighty ancestors and even dinosaurs were no match for sharks… but could they finally be facing a foe even they can’t win against?

Enter climate change.

Due to climate change, our oceans are currently experiencing severe changes, including a rise in temperature, a rise in sea level, and an increase in acidity. Ocean acidification was of particular interest to the Assistant Professor of Functional Morphology at Stockholm University because, as she puts it, “understanding intraspecific variation in responses to stressors is key to identify which traits make individuals and group of elasmobranchs more or less vulnerable to the effects of environmental change.”

Because climate change has already begun, scientists have little time to test how severely it impacts different species. It’s important therefore, that researchers focus on the different characteristics (known as ‘physiotypes’) that make individuals more or less vulnerable to rapid warming and acidification. Some of these traits include body size, local adaptation to fluctuating chemical and physical conditions, age-at-maturity. “One of these [important] traits is, for example, locomotor performance,” adds Di Santo. In many animals, locomotor performance plays a fundamental role in determining their fitness. Locomotor performance is closely related to the morphology of the structures responsible for it, such as limbs and fins. In elasmobranchs, it influences vital functions such as reproduction, migration, predator avoidance, small-scale movements, and more. By delving into the literature, the Di Santon’s team was able to integrate findings from previous work on locomotion of marine sharks and rays to identify characteristics that outline potential vulnerabilities and strength of sharks and rays under climate change.

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South of the Florida Keys lies a constellation of coral reefs—a biological and economic treasure found nowhere else in the mainland United States. Since 1990, these reefs have been protected by the Florida Keys National Marine Sanctuary, but coral health has still declined. The problems range from rising water temperatures to disease to damage caused by boaters.

Building these reefs has taken corals tens of thousands of years. Decimating them has taken humans mere decades. Since the late 1970s, healthy coral cover in the Florida Keys has fallen 90 percent.

To give these reefs a renewed chance at survival, NOAA is spearheading Mission: Iconic Reefs, one of the most ambitious reef-restoration efforts ever attempted worldwide. By 2040, the mission hopes to have restored 3 million square feet at 7 iconic reef locations—an area the size of 52 football fields—to at least 25 percent coral cover, which should be enough to allow them to repair themselves the rest of the way.

The effort involves dozens of partners: nurseries to grow millions of corals for replanting; labs and scientists to guide decisions about which corals to use and how to prepare them for conditions on the reef; technical divers to clean up dead, algae-covered reefs; and citizen-science volunteers to help plant corals and maximize their chances of survival through ongoing coral gardening—removing predators and pests, and restoring damaged corals.

But with continued climate warming and ocean acidification expected in the foreseeable future, finding and breeding corals tough enough to withstand heat stress and rising acidity must be part of the process. So, the project will take a phased approach, allowing some restoration work to begin immediately, while simultaneously supporting ongoing research.

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