Response of Ocean Acidification to Atmospheric Carbon Dioxide Removal Simulations

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Can Ocean Acidification Be Reversed?

A recently published research paper helps answer how oceans may respond to a removal of CO2 from the atmosphere. Here is a summary from the published paper. You can find the full paper online in the Journal of Environmental Sciences.

About The Study:

  • Study Focus: Investigates ocean acidification response to atmospheric CO2 removal using Earth system modeling.
  • Model: Uses the UVic Earth System Climate Model v2.10.
  • Simulations: Atmospheric CO2 rises 1% yearly to 4× pre-industrial levels, then decreases by 0.5%, 1%, or 2% yearly to pre-industrial levels.

Findings:

  • Surface Ocean Response: Quick response in annual mean surface ocean carbonate chemistry to atmospheric CO2 removal.
  • Deep Ocean Lag: Deep ocean carbonate chemistry lags behind atmospheric changes, still acidified when CO2 returns to pre-industrial levels.
  • Seasonal Cycles: Changes in the seasonal cycle of carbonate chemistry lag behind atmospheric CO2 decline.

Surface Chemistry Variables:

  • pH, hydrogen ion concentration, and aragonite saturation state adjust rapidly to CO2 removal.
  • Seasonal amplitudes of these variables lag behind, remaining altered when CO2 reaches pre-industrial levels.

Mechanisms:

  • DIC (Dissolved Inorganic Carbon) changes primarily drive changes in carbonate chemistry variables.
  • Seasonal changes are mostly due to changes in the ocean’s buffering capacity.

Deep Ocean Acidification:

  • Slower response than surface waters due to slow DIC penetration.
  • Even with pre-industrial CO2 levels, deep ocean remains acidified for decades/centuries.

Implications:

  • Marine ecosystems face a lagged recovery, with continuous acidification threatening marine life.
  • Amplified seasonal cycles can exacerbate impacts on marine organisms.

Acknowledgments: Supported by National Natural Science Foundation of China and Zhejiang Provincial Natural Science Foundation of China.

Considerations:

  • Didn’t consider the ballast effect or deep-sea carbonate sediments, which could buffer acidification.
  • Calls for more studies to understand carbonate chemistry’s impact on marine ecosystems under CO2 removal scenarios.

Declaration: No competing financial interests or personal relationships affecting the study.

Changes Across Marine Habitats Due To Ocean Acidification

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Research Paper Summary:

Title: Functional Changes Across Marine Habitats Due to Ocean Acidification

Published in Global Change Biology, Jan 2024

Overview:
This study examines how ocean acidification (OA), caused by increased CO2 levels, affects marine ecosystems. Using natural CO2 vents as models, researchers observed changes in marine communities across various habitats and depths. The findings highlight significant changes in species diversity and ecosystem functions due to acidification.

Key Takeaways:

  • Decreased Diversity: Both species and trait diversity tend to decrease under ocean acidification. This reduction in biodiversity can lead to less resilient marine ecosystems.
  • Habitat-Specific Responses: The impact of OA varies significantly across different habitats and depths. For example, some areas see a greater loss of calcifying species, which are crucial for building marine structures like reefs.
  • Changes in Ecosystem Functions: Essential functions within the ecosystems, such as nutrient cycling and habitat provision, are altered due to shifts in species traits and interactions.
  • Use of Natural Vents: Studying natural CO2 vents helps scientists predict and understand the future impacts of ocean acidification on marine life. These vents mimic the conditions expected in the oceans at the end of this century under high CO2 scenarios.
  • Implications for Conservation: The study underscores the need for strategies to mitigate the effects of ocean acidification and protect marine biodiversity.

This infographic from the research paper provides a great summary of the findings:

The infographic presents a comparative analysis of the impact of ocean acidification (OA) on four different marine habitats: Deep Reef, Reef, Cave, and Shallow Reef. The information is organized into two main categories: changes in biodiversity (top) and changes in cover of specific functional groups (bottom). Here’s the main takeaways:

Changes in Biodiversity (top):

  • Each habitat is analyzed for changes in species richness, functional entity richness, and functional dispersion, with percentage changes indicated on the horizontal axes.
  • A red circle denotes a decrease and a blue circle indicates an increase.
  • The “Deep Reef” and “Cave” habitats show significant decreases in all three biodiversity metrics, while the “Reef” shows an increase, and the “Shallow Reef” shows a mix of increases and decreases.

Changes in Cover of Functional Groups (bottom):

  • These are measured as changes in the percentage cover of different ecological roles: autotrophs, filter feeders, herbivores, habitat-forming species, and calcifiers.
  • Red bars indicate a decrease in cover percentage, while blue bars indicate an increase.
  • Notably, “Deep Reef” shows a decrease in filter feeders, habitat-forming species, and calcifiers, while “Cave” demonstrates declines across all categories except autotrophs.
  • The “Reef” habitat shows slight changes, and the “Shallow Reef” exhibits increases in autotrophs and calcifiers but decreases in other categories.

pH Values:

  • Each habitat panel lists the average pH value measured, which is a primary indicator of acidity. Lower pH values signify higher acidity.
  • The average pH is followed by a range in parentheses, representing the variability.

21st-Century Ocean Acidification in Antarctic Protected Areas

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The research paper “Severe 21st-century ocean acidification in Antarctic Marine Protected Areas” by Cara Nissen et al., focuses on the future of ocean acidification (OA) in Antarctic Marine Protected Areas (MPAs) under different emission scenarios using a high-resolution ocean-sea ice-biogeochemistry model. The study highlights severe potential declines in pH and the consequences for marine biodiversity.

Map of Marine Protected Areas and Impacted Species

About This Map

This map of Antarctica featured in the study illustrates the locations of established and proposed Marine Protected Areas (MPAs) around the continent. It also highlights key marine species that may be negatively impacted by ocean acidification, with their positions around the map representing their typical habitats within these MPAs.

Key Takeaways:

  • Antarctic Vulnerability: Antarctic coastal waters, including several MPAs, are under threat from ocean acidification due to increased anthropogenic carbon uptake. These waters support exceptional biodiversity, making them critical to preserve.
  • Emission Scenarios and OA Projections: The study examines four emission scenarios, projecting significant pH declines by 2100, with the highest reductions under high-emission scenarios. This results in widespread aragonite undersaturation, affecting marine organisms that rely on calcium carbonate structures.
  • Biogeochemical Changes: Antarctic waters are highly sensitive to OA due to cold temperatures and upwelling of carbon-rich deep waters. The study highlights the enhanced vertical mixing of anthropogenic carbon on continental shelves, exacerbating local OA.
  • Impact on Marine Life: Various marine organisms, including primary producers and shell-forming species, are expected to face severe impacts from OA. The study notes potential declines in populations and shifts in community structures due to altered physiological processes and ecosystem dynamics.
  • Conservation Implications: The research supports the expansion of MPAs as a strategy to mitigate OA impacts and preserve marine biodiversity. It calls for strong emission-reduction efforts and enhanced management strategies to alleviate pressures on these ecosystems.
  • Modeling Approach: Utilizes a sophisticated modeling approach that integrates realistic ice-shelf geometry and high-resolution data, providing detailed projections that highlight the urgent need for climate action to protect Antarctic marine environments.

How Does Ocean Acidification Affect the Economy? The Hidden Costs

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how does ocean acidification affect the economy

The vast ocean, often viewed as a boundless resource, is facing a silent threat: acidification. Driven by rising atmospheric carbon dioxide, the ocean’s chemistry is subtly shifting, becoming increasingly acidic. While the consequences for marine life are well-documented, the ripple effects on our economy deserve urgent attention.

In this article, we will delve into the ways ocean acidification affects the economy, focusing on two key economic risks. Additionally, we will discuss potential solutions to mitigate these risks.

Background information: Ocean Acidification at a Glance: Ocean Acidification Infographic

effects of ocean acidification on economy summary

1. Decline in Fisheries

Ocean acidification profoundly impacts fisheries, posing severe risks to food security and economic stability. This section delves into the details:

Shellfish Vulnerability: Acidic waters inhibit the ability of shellfish like oysters, mussels, and clams to build protective shells, leading to a decline in shellfish populations. This not only impacts the seafood industry but also threatens a critical source of protein for millions worldwide. Other seafood species, like salmon, are also impacted.

Coral Reefs at Risk: Coral reefs, vital ecosystems, serve as nurseries for marine species, attracting both tourists and fishermen. As ocean acidification deteriorates coral health, it affects fisheries and the marine food chain as a whole, jeopardizing food security and economic livelihoods.

Marine Food Chain Disruption: Ocean acidification impacts microorganisms at the base of the food chain, which has far-reaching impacts, including cascading effects on fisheries as predator-prey relationships shift and fish populations are affected.

Global Consequences: The economic repercussions ripple across the globe. For instance, the Pacific Northwest of the United States, heavily reliant on shellfish aquaculture, is already experiencing significant financial losses due to declining shellfish yields.

Studies estimate global losses in shellfish harvest could reach $480 million annually by the end of the century.

2. Impacts on Tourism

The tourism sector in coastal regions is susceptible to the pervasive effects of ocean acidification, further undermining economic stability:

Declining Attractiveness: Iconic coastal destinations, known for their pristine waters and vibrant marine life, are losing their appeal as ocean acidification damages coral reefs and disrupts underwater ecosystems.

Revenue Reduction: Tourism-related businesses, including hotels, restaurants, and tour operators, suffer from reduced revenues as visitors seek alternative destinations. This results in job losses and economic hardship in affected communities.

No More Wildlife Tours: Coral reefs, once vibrant and full of life, are now threatened, leading to a reduction in biodiversity-related tours. Tourists are increasingly looking for alternative destinations, leaving a lasting impact on the economic sustainability of coastal regions.

Other Effects of Ocean Acidification on the Economy

While a decline in fisheries and tourism revenue are the two key economic risks posed by ocean acidification, acidification is having other major impacts as well, many of which have economic consequences.

Reduced Food Security

Ocean acidification also has a direct bearing on global food security, particularly for communities heavily dependent on seafood:

Nutrient Disruption: Acidic oceans disrupt nutrient availability for marine life. This can lead to altered marine food webs, affecting the abundance and distribution of fish species that are vital for global food security.

Decreased Harvests: Diminished fisheries due to ocean acidification translate to decreased seafood harvests, which can strain the availability of affordable and nutritious protein sources for vulnerable populations.

Infrastructure Vulnerability

Ocean acidification has indirect consequences for infrastructure, as coastal communities face heightened risks from rising sea levels and extreme weather events:

Coastal Erosion: Weakened coral reefs and the degradation of coastal ecosystems due to ocean acidification contribute to coastal erosion, putting infrastructure such as roads, buildings, and utilities at risk. While less visible, acidified seawater can even corrode coastal infrastructure like docks, piers, and seawalls. This increases maintenance costs and can eventually lead to structural damage, impacting ports, transportation, and coastal communities.

Increased Maintenance Costs: Infrastructure in coastal areas must contend with more frequent and severe damage, increasing maintenance costs for governments and businesses.

Solutions to Economic Effects of Ocean Acidification

Addressing both the direct and indirect economic risks of ocean acidification requires a holistic approach:

Reducing Carbon Emissions: Mitigating the root cause of ocean acidification involves reducing carbon emissions. Transitioning to renewable energy sources, enhancing energy efficiency, and promoting sustainable transportation are key steps. New projects are also working to remove carbon dioxide from the ocean.

Sustainable Practices: Implementing sustainable fishing practices, such as catch limits and protected marine areas, can help preserve fish populations and protect the livelihoods of fishermen.

Coral Reef Restoration: Investing in coral reef restoration efforts can aid in revitalizing tourism and fisheries. This includes coral transplantation and monitoring programs.

Diversification: Coastal communities should explore diversification strategies beyond fisheries and tourism, including aquaculture and alternative livelihoods, to reduce their vulnerability to the impacts of ocean acidification.

Infrastructure Resilience: Governments and communities must invest in resilient infrastructure to withstand the challenges posed by ocean acidification, including sea-level rise and extreme weather events.

Ocean acidification’s far-reaching effects on the economy are undeniable. The decline in fisheries, tourism, and its impact on coastal communities underscore the urgency of addressing this issue.  By reducing carbon emissions and implementing sustainable practices, we can mitigate economic risks, safeguard food security, and protect critical infrastructure, promoting a healthier, more secure global society.

UNESCO Scientists Explain Why the Great Barrier Reef Is in Danger: New Report

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great barrier reef in danger
Source: WHC UNESCO/Ko Hon Chiu Vincent

The Great Barrier Reef, located off the Australian coast, is the largest coral reef ecosystem on the planet and one of the most outstanding world heritage sites. It serves as a vast sanctuary for thousands of marine species, protects surrounding islands from storms, provides food, and generates revenue through ecotourism. But the Great Barrier Reef is now in great danger as it experiences its sixth massive coral bleaching event.

A new report from UNESCO scientists explains that the Great Barrier Reef is suffering from accelerating damages from human-caused climate change. They argue that the area must be listed in the record of world heritage sites as “in danger” because the deterioration is accelerating at an alarming phase, pushing the reef’s health beyond its tipping point. 

In this article, we’ll review the main points of the new UNESCO report on the Great Barrier Reef and explore the global response to the report.

Background Information:  What is Ocean Acidification?

Full Report: Report on the Joint World Heritage Centre/IUCN reactive monitoring mission to the Great Barrier Reef (Australia from 21 to 30 March 2022) (UNESCO, Nov 2022)

Why Is the Great Barrier Reef in Danger? 

Since 2015, the Great Barrier Reef has been experiencing massive coral bleaching events due to increasing ocean temperatures and ocean acidification. In fact, in 2021, scientists discovered that the global population of living corals has declined by 50% since the 1950s. This is due in large part to the ongoing usage of fossil fuels such as coal, oil, and gas around the world. 

Recent UNESCO scientists’ assessments of the Great Barrier Reef found that it is experiencing its sixth massive coral bleaching event, pushing the reef’s damage to an irreversible tipping point.

  • During their monitoring, scientists discovered around 750 out of 3,000 reefs within the Great Barrier Reef are suffering from widespread bleaching. That is about 25% of the Great Barrier Reef. 
  • James Cook University marine biology professor Jodie Rummer explains that even the healthiest coral may take a decade to recover from bleaching, and with consecutive mass coral bleaching events, we may not see adaptation and recovery as an option for them. 
  • Scientists predicted that up to 90% of coral reefs around the world may disappear in the next 20 years due to ocean acidification. The Great Barrier Reef is one of the reef areas most affected by acidification.
  • UNESCO scientists’ report argues that the Great Barrier Reef should be added to the list of world heritage sites that are “in danger.” This UN-backed recommendation comes after the World Heritage Committee’s initial recommendation of an “in danger” listing in 2021.
  • The report argues that in order to give the Great Barrier Reef a chance to combat the effects of ocean acidification, we must reduce greenhouse gas emissions, reassess carbon credit schemes and increase financial investment in protecting the reef.

What Was the Response to the UNESCO Report?

UNESCO’s push to list the Great Barrier Reef as “in danger” was received with a mixed response.

  • UNESCO advised the Australian government to boost its carbon-reduction policies and invest more in water-quality improvement programs. However, the Australian government’s policies continue to fall short of UNESCO’s critical recommendations.
  • The Australian government argues that it is unnecessary to list the Great Barrier Reef as “in danger” because they are doing enough to protect the Great Barrier Reef. For example, they cite their recent commitment to invest $1 billion in reef protection programs from 2022 to 2030. 
  • While UNESCO acknowledges that listing the Great Barrier Reef as “in danger” could affect its tourism, it may also establish Australia’s name as a world leader in terms of the conservation and protection of a world heritage site.
  • UNESCO also emphasized that categorizing the Great Barrier Reef as “in danger” on the world heritage list is essential, as it could encourage other countries to join in conservation efforts to protect it. The World Heritage Committee’s decision whether to label the Great Barrier Reef as “in danger” or not will be based on UNESCO’s assessment. UNESCO is still waiting for Australia to ensure compliance with their provided recommendations. However, the Australian government continues to deny that these recommendations are necessary. 
great barrier reef bleaching - great barrier reef in danger
Coral bleaching in the Great Barrier Reef (March 2022)
(Source: WWF Australia/ABC News)

Sources: 

“Great Barrier Reef should be placed on the ‘in danger’ list, UN-backed report shows” CNN, Nov 29, 2022

https://www.sciencedaily.com/releases/2022/05/220525182619.htm

“United Nations recommends Great Barrier Reef be added to World Heritage ‘in danger’ list” ABC News, Nov 29, 2022

https://www.abc.net.au/news/2022-11-29/united-nations-queensland-great-barrier-reef-danger-report/101705908

“Report on the Joint World Heritage Centre/IUCN reactive monitoring mission to the Great Barrier Reef (Australia from 21 to 30 March 2022)” UNESCO, Nov 2022.

https://unesdoc.unesco.org/ark:/48223/pf0000383823

How Does Ocean Acidification Affect the Food Chain? New Research Shows Impacts on Coccolithophores

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coccolithophores - how ocean acidification affect food cain
Magnified coccolithophores
Source: UCLA|Photo via hhmi.org

Increases in ocean acidity are damaging the first link in the food chain, a microorganism called coccolithophores. This is causing major impacts to marine species that rely on coccolithophores as their primary source of food. 

Recent research from the Universitat Autonoma de Barcelona’s Institute of Environmental Science and Technology illustrates how ocean acidification is affecting coccolithophores, and thus, how ocean acidification is affecting the food chain as a whole.

Background Information: What is Ocean Acidification?

Full Study: Nutritional response of a coccolithophore to changing pH and temperature (Association for the Sciences of Limnology and Oceanography (ASLO) Aug 2022).

How Ocean Acidification Decreases the Nutritional Content of Coccolithophores

microscopic coccolithophore - ocean acidification affect food chain
Source: UCSC Earthguide

Coccolithophores, part of the phytoplankton family, are single-celled plant-like marine microorganisms that are commonly found close to the surface of the ocean. Despite their microscopic size, coccolithophores play an important role in the marine food chain by serving as its foundation. Many small marine animals rely on coccolithophores as their primary source of food and energy. Even small fish and other organisms that do eat other things, like worms or small crustaceans, feed on coccolithophores when other sources of food are scarce. Marine animals obtain nutrition and energy from coccolithophores’ fat content, known as lipids. 

Coccolithophores build protective scale-like platings around themselves known as coccoliths (the oval platings shown in the image to the right). These coccoliths are made of limestone (calcite). However, ocean acidification makes it much more difficult for organisms to build calcite shells.

A 2022 study conducted by researchers from the Universitat Autonoma de Barcelona’s Institute of Environmental Science and Technology, in collaboration with the Roscoff Marine Station of France, discovered that ocean acidification has significantly reduced coccolithophores’ ability to build shells, and decreased the nutrient content in their bodies. This has massive cascading effects throughout the food chain. Here’s what you need to know about it. 

  • The researchers created a simulation of future climate conditions, causing ocean warming and triggering ocean acidification. 
  • At first, the coccolithophores showed resilience to the increase of ocean temperatures and acidity. The researchers even observed an increase in their population.
  • As the experimental ocean acidity spiked, the researchers found that coccolithophore population growth halted as the organisms began to struggle to build their shells. The acidic conditions caused the coccolithophores’ protective platings (coccoliths) to collapse. While this may seem beneficial to organisms that eat coccolithophores (because this makes them easier to eat and digest), this breakdown of their shells comes with other negative consequences.
  • Researchers also discovered that when coccolithophores were exposed to acidified ocean conditions, the nutritional content in their bodies significantly decreased. As acidification worsens, this reduced nutrient content may have a detrimental impact on the food chain.  Marine species that rely on coccolithophores for food, such as smaller fishes and zooplanktons, would be forced to feed on nutritionally deficient food.
  • Researchers concluded that as ocean acidification affects coccolithophores’ energy and nutrients, coccolithophores may also seek lower-acidity areas to try and slow ocean acidifications’ effects on their survival. This movement will pose an extra threat to marine species that rely on coccolithophores for food, as some may be unable to “follow” coccolithophores to lower-acidity conditions..

The images below show the comparison of healthy coccolithophores (a) and collapsed coccolithophores due to ocean acidification (b).

healthy coccolithophore- how ocean acidification affect food chain
Healthy coccolithophores
(Source: © Phys Org)
collapsed coccolithophore - - how ocean acidification affect food chain
Collapsed coccolithophores
 (Source: © Phys Org)

Read more: Researchers Discover How Ocean Animals Adapt to Ocean Acidification – But Adaptation Comes at a Price

Sources: 

“Ocean warming and acidification impact marine food web” Universitat Autonoma de Barcelona, Nov 2022

https://www.uab.cat/web/newsroom/news-detail/ocean-warming-and-acidification-impact-marine-food-web-1345830290613.html?detid=1345875011926

“Ocean warming and acidification impact the marine food web, study finds” Phys Org, Nov 2022

https://phys.org/news/2022-11-ocean-acidification-impact-marine-food.html

“Nutritional response of a coccolithophore to changing pH and temperature” Association for the Sciences of Limnology and Oceanography (ASLO) Aug 2022

https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lno.12204

Researchers Discover How Ocean Animals Adapt to Ocean Acidification – But Adaptation Comes at a Price

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(Source: © Andrei Savitsky/Wikimedia)

As climate change-driven ocean acidification and higher ocean temperatures continue to threaten various marine animals, some species are beginning to evolve in order to adapt to warmer, more acidic conditions. But does this evolution come at a price? A recent experiment from the University of Vermont, in collaboration with the University of Connecticut, the GEOMAR Helmholtz Center for Ocean Research in Germany, and the University of Colorado, Boulder, focuses on this question.

This March 2022 study analyzed how one copepod (a small crustacean species), Acartia tonsa, will likely evolve in order to adapt to warmer ocean temperatures and higher levels of carbon dioxide. However, these copepods’ resilience to climate change comes hand in hand with increased vulnerability to other stresses such as limited food sources.

Background Information: What is Ocean Acidification?

Full Study: Loss of transcriptional plasticity but sustained adaptive capacity after adaptation to global change conditions in a marine copepod (Brennan et al. 2022)

How Copepods Adapt to Ocean Acidification 

acartia tonsa - ocean animals adapt ocean acidification
Acartia Tonsa
Source: UC Davis

Scientists from the University of Vermont conducted a laboratory experiment to understand the effects of ocean acidification on copepods, a group of small crustacean species that serve as a food source for many marine species. Copepods also act as an important biological control agent against mosquitos carrying human diseases.

Researchers artificially evolved 23 generations of Acartia tonsa, a copepod species, in order to study the effects of ocean acidification on copepod reproductive success. The results reveal that copepods can adapt fairly quickly to a warmer, acidified ocean ecosystem, but that this rapid evolution decreases the species’ genetic flexibility, which leads to increased vulnerability to other stresses. 

Finding One: Copepods have the ability to quickly adapt to ocean acidification due to high genetic flexibility.

  • Copepods have the ability to become sexually mature and reproduce in just four to six weeks, making them a helpful organism to help scientists study evolution over shorter periods of time.  This study utilizes copepods’ ability to reproduce and create new generations in a short period of time to analyze the effect of ocean acidification and warming on the health and reproductive success of twenty-three generations of copepods.
  • Scientists created an ecosystem that simulates future ocean conditions under climate change. They exposed thousands of copepods in multiple generations to the acidic environment and tracked their health and reproductive ability.
  • The study found that copepods showed resistance to ocean acidification and continued to thrive throughout twenty-three generations. This is due to copepods’ plasticity (genetic flexibility), or the ability to manipulate their genes, allowing them to adapt to environmental changes. This includes but is not limited to: 
    • Ability to adapt to increasing temperatures in their environment
    • Ability to grow skeletons in an acidified environment 
    • Ability to generate additional energy in order to adapt to the stress caused by ocean acidification.
    • Although the results provide optimism for the future of copepod populations, the next experiment demonstrates the cost of this generational adaptability to copepods’ health and reproduction.

Finding Two: Rapid evolution in order to evolve to ocean acidification decreases copepods’ ability to adapt to other environmental stressors in the future.

  • After twenty-three generations of copepods living in an acidified environment, scientists reintroduced some of the copepods in the less acidic environment – the current acidity level of the ocean today. The new generations of copepods that were reintroduced to this less acidic environment did re-adapt to these new conditions – but with lowered ability to respond to other kinds of stressors like a limited food supply.
  • The researchers explained that, in an effort to adapt quickly to acidified conditions, the copepods lost genetic flexibility (known as “phenotypic plasticity”), their ability to genetically adapt to different environmental conditions.
  • The copepods genetically adapted to high acidity conditions, which left them all with similar genetic makeup. This left them less able to adapt to new stressors, such as a lowered food supply. Copepods in the lower-acidity environment their ancestors had come from had smaller populations and were generally less healthy.

The scientists concluded that, while there is hope for copepods and other ocean animals to adapt to increased ocean acidity and warming ocean, there may be hidden costs for those species as a result of rapid evolution.

Read more: How Ocean Acidification Affects the Development of Several Marine Species

scientist with copepods - ocean animals adapt acidification
Professor Dr. Melissa Pespeni of the University of Vermont during the copepod experiment.
 (Source: © Joshua Brown/Geomar) 

Sources: 

Brennan et al. “Loss of transcriptional plasticity but sustained adaptive capacity after adaptation to global change conditions in a marine copepod.” Nature, March 3, 2022,  DOI: 10.1038/s41467-022-28742-6.

“Ocean life may adapt to climate change, but with hidden costs.” Science Daily, March 22, 2022. https://www.sciencedaily.com/releases/2022/03/220322150905.htm.

How Is Sunscreen Killing Coral Reefs?

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sunscreen washing into ocean - reef safe sunscreen
Statistical source: Danovaro et al. 2008

Did you know that the sunscreen you apply doesn’t always stay on your skin? In fact, when we swim (or even shower), the sunscreen you’ve applied throughout the day washes off into waterways and often ends up in the ocean. In fact, around 6000 tons of sunscreen washes off into reef areas every year, according to scientists. That’s equal to the weight of nearly 50 blue whales!

While we depend on sunscreen to protect us from skin damage and disease, many sunscreens actually cause great harm to marine ecosystems. And with 80% of corals in the Caribbean lost in the last 50 years, in part due to pollution, it’s more important now than ever before to ensure we take steps to avoid damaging these important organisms further.

But how exactly does sunscreen damage coral reefs, and what can we do about it? Let’s dive in.

Protection for People, Harm to Marine Life

Researchers estimate that approximately 10%, if not more, of coral reefs around the world are threatened by sunscreen. The areas feeling the brunt of the damage are highly-tourested areas like Hawaii and the Caribbean, where thousands of tourists swim every day, leaving sunscreen behind them. 

So, how is sunscreen killing coral reefs? There are two main types of sunscreen: physical and chemical. Unfortunately, both types of sunscreen can cause harm to coral and other types of marine life.

Physical sunscreen is made of minerals that sit on top of your skin and reflect the sun’s rays. The main minerals used for this purpose are titanium dioxide and zinc oxide, which can wash off into the water. In fact, studies estimate that the average tourists on a Mediterranean beach release 4kg of titanium dioxide in a single day. When these minerals are very small (called “nanoparticles”), they can be absorbed by coral and cause severe damage.

A 2018 study found that zinc oxide nanoparticles cause extreme coral bleaching. This is because the zinc interferes with symbiosis between coral and other organisms, which leads to bleaching over time. Zinc oxide and titanium dioxide nanoparticles in the ocean may also cause chemical reactions to occur that result in hydrogen peroxide, which bleaches coral.

Chemical sunscreens contain chemicals that absorb into the skin, and then absorb UV rays before they can hit your skin. The active ingredients include “UV filtering” chemicals avobenzone, octinoxate, and oxybenzone. These are extremely potent and toxic to marine animals including coral.

New Research: How Does Sunscreen Harm Coral Reefs?

While scientists have known that oxybenzone damages coral reefs for a while, they did not know exactly how the chemical was causing harm. In May 2022, researchers at Stanford released a study that explored oxybenzone’s effects on sea anemone, an organism that’s closely related to corals. 

The researchers found that when oxybenzone was exposed to light and a sugar found in anemone tissue, not only did it kill the anemone, but the chemical metabolized into another molecule, releasing free radicals that kill coral. Sea anemones exposed to oxybenzone and sunlight died around one-three weeks after exposure.

Finally, preservatives used in sunscreen to help the product last longer can also have toxic effects on both humans and coral. For example, parabens, a class of preservatives, are used in many sunscreens to prevent the growth of bacteria and mold. However, parabens can wash off into the environment, and have been found in a wide variety of organisms all over the world, from fish to marine mammals and birds. Studies show that parabens can disrupt the hormones of a variety of animals, including humans. 

Parabens can also cause viral infections in zooxanthellae, symbiotic algae that live in healthy coral tissue and provide it with nutrients. A 2008 study showed that, because of these viral infections, coral bleaching occurred within a few hours to a few days of exposure to even very small amounts of sunscreen.

Does Sunscreen Harm Other Types of Ecosystems?

It’s not just marine life that’s impacted by sunscreen. When we shower, sunscreen is often washed off into wastewater, which makes its way into fresh bodies of water. However, due to the extreme variety of aquatic ecosystems throughout the world, the specific impacts of sunscreen in aquatic environments are still unknown. 

Many experts are calling for more research into the impacts of sunscreen on non-marine ecosystems. In August 2022, the National Academies of Sciences, Engineering and Medicine published a report calling on the US EPA to conduct further studies into the risks that UV filters cause to aquatic ecosystems (including freshwater). They explain that while we know UV filters have been found in water, sediment and even animal tissue in a variety of ecosystems, we need more information to understand the extent of the impacts they’re having on a variety of aquatic organisms. 

Government attention to the issue of sunscreen killing coral reefs is not limited to scientific data gathering, however. Next, we’ll review how a few governments have taken a stab at protecting coral reefs and other marine organisms from toxic sunscreen ingredients.

Legislation: Bans on Reef-Toxic Sunscreen

In response to concerns about the toxic effects of sunscreen on coral reefs and the intense reduction in living coral reefs, several governments have passed legislation banning sunscreen containing oxybenzone and octinoxate. 

Hawaii was the first state to ban harmful sunscreens with the passage of a bill in 2018 that banned oxybenzone and octinoxate sunscreens. In 2021, the Hawaii State Legislature passed another bill that banned two more harmful chemicals in sunscreen, avobenzone and octocrylene.

Other local and federal governments have also banned harmful sunscreens, including:

What You Can Do to Protect the Ocean from Harmful Sunscreen

There are a few things you can do to avoid putting more harmful sunscreen into the ocean.

1. Use other forms of sun protection. While sunscreen is, of course, a necessary product to protect ourselves from harmful ultraviolet rays, it should really be a last resort. Instead, use UV-protective clothing like a sun shirt to reduce the amount of sun your skin is exposed to. You can also try and spend time in the shade to protect your skin.

2. Use reef-safe sunscreen. When you do need to use sunscreen, make sure it’s a reef-safe sunscreen. First, avoid spray-on (aerosol) sunscreen, as the spray disperses into the environment much more easily than a cream, and often contains harmful chemicals. Instead, opt for a mineral sunscreen with zinc oxide and titanium dioxide that aren’t nanoparticles (if the packaging doesn’t explicitly say “micro-sized” or “non-nano,” you can be pretty sure it contains harmful nano-sized particles).

To figure out if a sunscreen is truly reef friendly, look at the label. Make sure to avoid these chemicals:

sunscreen coral reefs - reef safe sunscreen

Finally, while sunscreen in the ocean is clearly harming coral reefs, we must also take into consideration the other threats to coral reefs, including overfishing and climate change’s rising temperatures. Changing to a reef-safe sunscreen may make a small dent, but we must curb climate change in order to truly protect coral reefs and other marine life.

Researchers Discover How Ocean Acidification Unexpectedly Threatens Diatom Plankton Populations

Posted on by Team Writer

Rising ocean acidity is threatening the population of the most common type of plankton, known as diatoms, one of the main oxygen producers on the planet and the primary food source for all marine life. Despite previous beliefs that diatoms actually benefit from ocean acidification, new research from the Helmholtz Centre for Ocean Research (GEOMAR) shows that diatom populations are extremely vulnerable to the effects of ocean acidification. Continue reading for a summary of the paper’s findings.

Background Information: How Ocean Acidification Affects Diatoms

Full Study: Decline of diatoms due to ocean acidification (Nature, May 2022).

how does ocean acidification affect diatoms research
Researchers studying the effects of ocean acidification on diatom populations
Source: Ulf Riebesell/GEOMAR/European Geosciences Union

How Ocean Acidification Reduces Diatom Populations

In past years, scientists believed that diatoms are less affected than other marine organisms by the effects of ocean acidification. This was because diatoms rely on silica minerals to build their shells, rather than calcium carbonate, a substance that many other marine organisms rely on to build their shells and that is reduced by ocean acidification. In fact, some scientists previously argued that ocean acidification aids diatoms by increasing their ability to photosynthesize, and thus increasing diatom populations’ growth.

But, in a recent analysis, scientists explain how ocean acidification may reduce the population of diatoms at an alarming rate. Here’s what you need to know about it. 

The study researched the effects of ocean acidification on the dissolution of the silicon shell of diatoms. The results show that acidified seawater significantly slowed the ability of diatoms to dissolve their silicon shells, ultimately leading to a lowered ability to gain nutrients through photosynthesis.

  • The most common negative impact of ocean acidification on shell-forming marine species using calcium carbonates, such as oysters, clams, mussels, and corals, is a reduction in their capacity to form shells due to a lack of carbonate ions in more acidified seawater. While this chemical imbalance was not believed to affect diatoms due to their silicon-based shells, ocean acidification actually threatens diatoms in another way.
  • GEOMAR Helmholtz Centre for Ocean Research Kiel researchers used data from huge test tubes known as Mesocosms. These tubes were placed in different ocean biomes all around the world.  Mesocosms can contain a large volume of ocean water inside, allowing researchers to manipulate the water parameters, such as increasing or decreasing the acidity level without harming the ocean ecosystem outside.
  • Using an Earth system model, the researchers utilized the collected data to simulate the negative effects of ocean acidification on diatoms in the future, on a worldwide scale.
  • Researchers discovered that acidified seawater slows the ability of diatoms to dissolve their silicon shells, which forces them to sink into the deeper parts of the ocean. Because of this, the abundance of diatoms on the ocean surface is lowered. 
  • Researchers concluded that since diatoms needed to be at the surface water to get light to renew their shells, forcing them to sink may significantly decrease their population around the world at an alarming rate.
mesocosm - ocean acidification diatoms study
A photo of Mesocosm underwater
(Source: © Ulf Riebesell GEOMAR/University of Tasmania, IMAS) 
diatom life cycle - ocean acidification
A comparison of the diatom life cycle today (a) and in the future, the year 2200 (b), as simulated in the study.
(Source: © Nature)

Read more:

Sources: 

“Decline of diatoms due to ocean acidification. Study shows unexpected negative impact by CO2 on important plankton group” Science Daily, May 25, 2022

https://www.sciencedaily.com/releases/2022/05/220525182619.htm

“Research reveals ocean acidification is triggering a decline in diatom” UTAS, IMAS, May 31, 2022

https://www.imas.utas.edu.au/news/news-items/research-reveals-ocean-acidification-triggering-decline-in-diatoms#:~:text=%E2%80%9CThe%20reason%20for%20this%20decline,needed%20to%20form%20new%20shells.%E2%80%9D

How Ocean Acidification Affects the Development of Several Marine Species

How Ocean Acidification Affects the Development of Several Marine Species

Posted on by Team Writer

Rising ocean acidity is affecting the development of different types of marine species, such as sea urchins and brightly-colored reef fish.

  1. A recent study shows how sea urchin development is affected by ocean acidification. (more…)
  1. The Great Barrier Reef is experiencing massive coral bleaching events due to ocean acidification, which negatively affects the development of brightly-colored fish in the reef. (more…)

Background Information: What is Ocean Acidification?

Full Research: Direct and latent effects of ocean acidification on the transition of a sea urchin from planktonic larva to benthic juvenile, Are fish communities on coral reefs becoming less colorful? 

Study Shows How Ocean Acidification Affects Sea Urchin Early Stage Development

Ocean acidification has a significant negative impact on marine species and ecosystems. A recent study shows how ocean acidification affects the early development stages of some marine species, such as sea urchins. Here’s what you need to know about it.

The study researched the effects of pH on sea urchin’s development and transition from fertilization to juveniles. The result shows that low pH levels significantly affected the growth and mortality of the urchin’s larval stage. Even small changes in ocean pH (on the scale of .1) can have major impacts.

Larval Stage: Effects of Ocean Acidification

  • Sea urchin larvae were exposed to a 7.2 pH level (compared to the current ocean’s actual pH of 8.1). The sea urchins exposed to this pH exhibited the following characteristics: 
    • Higher mortality rates.
    • Higher abnormality rates. 
    • Lower growth rates.
  • The metabolism of sea urchin larvae exposed to a 7.2 pH level increased as well. The researchers believe that because of this, the urchins may be using additional energy to boost metabolic function, which might limit their growth rates. In other words, the sea urchins adapt to ocean acidification by shifting their energy to boost metabolic function, rather than other important functionalities. Researchers believe that this shift in energy may be what’s causing mortality and abnormalities throughout their development stages.

Settlement Stage

  • Researchers discovered that prolonged exposure to a 7.7 pH level significantly delayed the settlement of sea urchin larvae, an important process during which larvae settle to the ocean floor where they will eventually begin their adult life stages. 
  • However, when the sea urchin larvae were placed under a suitable algal substrate for the settlement stage, the researchers found that the larvae remained unaffected by 7.7 pH levels. This shows that algae may help reduce the effects of ocean acidification on sea urchin larvae.

Metamorphosis Stage

  • The study shows that in the metamorphosis stage, all the sea urchins that were grown at a 7.2 pH level failed to metamorphose. The researchers concluded that sea urchins that are exposed to low pH levels throughout their early development stages may find it hard to impossible to achieve metamorphosis. 
  • However, the study also shows that 30% of the sea urchin larvae that were grown at a 7.6 pH level achieved the metamorphosis stage. This shows the large impact of even a pH change of .4, compared to the 7.2 pH group of urchins.
sea urchin development - ocean acidification sea urchins
The development cycle of a sea urchin.
(Source: © Natural History Museum, London) 

Read more: How Ocean Acidification Affects Sea Urchins

Ocean Acidification Affects Brightly-Colored Fish Development Through Continuous Coral Bleaching

The Great Barrier Reef is experiencing massive coral bleaching events due to ocean acidification, which negatively affects the development of fish’s color in the reef. Here’s all you need to know about the study.

  • In the span of just three decades, the effects of ocean acidification and global warming have caused the Great Barrier Reef to lose thousands of its coral species. This phenomenon is commonly known as massive coral bleaching events. As a result of this, the number of brightly-colored fish in the Great Barrier Reef is decreasing. 
  • According to the study, the number of different types of brightly-colored fish in the Great Barrier Reef has declined significantly since the massive coral bleaching event of 1998. Scientists believe that the composition of the seafloor (texture, colors, patterns) affects the development of the coloration of fish.
  • Reef fishes developed coloration to protect themselves from predators by adapting to the different coral structures and compositions. Fish would find it useless to produce vibrant colorations in the absence of coral compositions.
  • The study concluded that the loss of vibrant composition and structure of the seafloor due to the massive coral bleaching events has a significant relationship to the inability of many fish to develop their vibrant colors. 
coral bleaching in great barrier reef
6th massive coral bleaching event in the Great Barrier Reef (2022).
(Source: © Earth.org) 

Sources: 

“Direct and latent effects of ocean acidification on the transition of a sea urchin from planktonic larva to benthic juvenile” Nature, April 01, 2022

https://www.nature.com/articles/s41598-022-09537-7

“Fish on Australia’s Great Barrier Reef are losing their colour as corals die” Independent UK, March 23, 2022

https://www.independent.co.uk/climate-change/news/great-barrier-reef-australia-fish-colour-b2041887.html