Ocean Acidification

Dive deep into the critical environmental issue of ocean acidification and discover its devastating impact on krill, a tiny creature with a colossal role in marine ecosystems.

This video uncovers the intricate science behind how changing ocean chemistry threatens krill populations worldwide. In this video, you will learn:

• How rising CO2 levels lead to ocean acidification.
• The specific biological mechanisms by which acidification harms krill’s shells and physiology.
• The cascading effects of krill decline on the entire Antarctic food web.
• The broader implications of ocean acidification for marine biodiversity and global climate.

I chat about the latest science on Ocean Acidification exceeding the safe planetary boundary in 2020. As global industry continues to accelerate the burning of fossil fuels pumping ever increasing amounts of Greenhouse Gases into the atmosphere, the oceans attempt to absorb more and more of the CO2, greatly increasing the ocean acidity.

Here is all the latest, and not so greatest on global ocean acidification. Since colder water can dissolve more GHGs, the polar oceans are the region facing the greatest ocean acidification threat. However, ocean acidification is still increasing enough in the lower latitude regions posing increasing risk to global coral reefs.

ABSTRACT

Ocean acidification has been identified in the Planetary Boundary Framework as a planetary process approaching a boundary that could lead to unacceptable environmental change. Using revised estimates of pre-industrial aragonite saturation state, state-of-the-art data-model products, including uncertainties and assessing impact on ecological indicators, we improve upon the ocean acidification planetary boundary assessment and demonstrate that by 2020, the average global ocean conditions had already crossed into the uncertainty range of the ocean acidification boundary. This analysis was further extended to the subsurface ocean, revealing that up to 60% of the global subsurface ocean (down to 200 m) had crossed that boundary, compared to over40% of the global surface ocean. These changes result in significant declines in suitable habitats for important calcifying species, including 43% reduction in habitat for tropical and subtropical coral reefs, up to 61% for polar pteropods, and 13% for coastal bivalves. By including these additional considerations, we suggest a revised boundary of 10% reduction from pre-industrial conditions more adequately prevents risk to marine ecosystems and their services; a benchmark which was surpassed by year 2000 across the entire surface ocean.

This is the second webinar in the Acidification & Estuaries Webinar Series hosted by the Interagency Working Group on Ocean Acidification. This webinar gives an overview of the state of the science related to acidification in estuaries and discuss remaining research gaps. Speakers discuss the causes of acidification, biological impacts, and how we can assess short-term acidification events and long-term trends in estuaries.

Hosted by the Interagency Working Group on Ocean Acidification, this webinar gives an overview of coastal acidification, the importance of studying acidification in estuaries, and the role that federal agencies currently play in monitoring and researching acidification in estuaries.

Ocean acidification refers to the gradual decrease in the pH of the Earth’s oceans, primarily due to the absorption of excess atmospheric carbon dioxide (CO2). Since the Industrial Revolution, the oceans have absorbed about 30% of the CO2 emitted by human activities, leading to significant changes in seawater chemistry. This acidification process poses a profound threat to marine ecosystems, especially to the organisms at the base of the food chain and can have cascading effects through higher trophic levels.

Causes of Ocean Acidification

• Increased CO2 Emissions: The main driver of ocean acidification is the rising concentration of CO2 in the atmosphere, which dissolves in seawater to form carbonic acid. This weak acid dissociates into hydrogen ions, lowering the pH and reducing the availability of carbonate ions.
• Decrease in Carbonate Ions: Carbonate ions (CO3^2-) are critical for calcifying organisms like corals, mollusks, and some plankton to form their calcium carbonate shells and skeletons. As carbonate ions decrease due to acidification, these organisms struggle to maintain their structures.

Impacts on Marine Food Chains

• Plankton and Primary Producers: Phytoplankton are the foundation of most marine food chains, providing energy for a wide range of organisms, from small fish to large marine mammals. Certain phytoplankton species, such as coccolithophores, rely on calcium carbonate to build their shells. Acidification reduces their ability to do so, affecting their survival and reproduction. As plankton populations decline or shift in species composition due to acidification, there could be significant disruptions in the marine food web, as many marine organisms depend on plankton as their primary food source.
• Coral Reefs and Associated Ecosystems: Coral reefs are among the most biodiverse ecosystems on Earth, but they are highly sensitive to changes in water chemistry. Ocean acidification weakens coral skeletons, leading to slower growth rates and increased vulnerability to erosion. Coral reefs provide habitat and protection for numerous marine species. As reefs degrade, many species that rely on them for food, shelter, and breeding grounds may decline, impacting the broader food chain.
• Shellfish and Other Calcifiers: Mollusks, such as clams, oysters, and snails, rely on calcium carbonate for their shells. Ocean acidification reduces the availability of carbonate ions, making it more difficult for these organisms to form shells, leading to thinner, weaker shells or even shell dissolution. Shellfish are a critical food source for both humans and marine predators like starfish, crabs, and certain fish. A decline in shellfish populations could ripple through food chains, affecting both ecological balance and human fisheries.
• Fish and Marine Mammals: While most fish are not directly affected by the changes in carbonate chemistry, their food sources, such as plankton, shellfish, and corals, are. This indirect impact can lead to reduced food availability, causing population declines in fish species. Larger predators, including marine mammals (seals, whales, dolphins), depend on healthy fish populations. A disruption at lower levels of the food chain can lead to declines in these higher trophic species.
• Human Impact: Many human communities, especially coastal populations, depend on marine ecosystems for food, economic activities (fisheries, aquaculture), and tourism. As acidification impacts marine food chains, it could lead to reduced fishery yields, threatening food security and livelihoods. Long-Term Outlook
• Ecosystem Shifts: The ongoing acidification of the oceans is expected to cause shifts in species composition, with some species adapting or moving to new environments while others decline or disappear. This could lead to a restructuring of marine ecosystems, where certain species become dominant, and others, especially calcifiers, become rare.
• Cascading Effects: The collapse of coral reefs, shellfish populations, or key plankton species could lead to a cascade of effects, disrupting the balance of marine ecosystems and affecting everything from fish populations to marine mammals and seabirds.
• Uncertain Resilience: While some species may be more resilient to acidification, the long-term effects on biodiversity and ecosystem function are uncertain. Adaptive capacity varies among species, and the speed at which acidification is occurring may outpace the ability of many organisms to adjust.
• Ocean acidification represents: a significant, long-term threat to marine food chains. It alters the fundamental chemistry of the oceans, affecting the organisms at the base of the food chain and triggering ripple effects throughout marine ecosystems. As acidification continues, the long-term sustainability of marine biodiversity, fisheries, and food security will be challenged, making it critical.

Today I want to continue with a deeper dive into the topic of water, literally, by going to the furthest point downstream, where terrestrial water enters the ocean. 

Marine ecosystems are much less understood by the general public for a variety of reasons, but our actions on land have a direct effect on the health of our oceans too. Luckily there are incredible teams of people looking to address these issues with promising new solutions and over the next couple of episodes I’ll be highlighting a few of them. 

To get things started I spoke to Joost Wouters, an entrepreneur, speaker, author and the ‘Sea’EO of the Seaweed Company. I got to know Joost first as a co-instructor with me on the Ecosystem restoration design course through Gaia Education. I was fascinated with his presentation and the compelling data on the potential regenerative effects that seaweed and kelp can have in bringing back the health of coastal areas. In his role with the Seaweed Company, he and his team aim to implement CO2-reducing seaweed-based business models at large scale.

It turns out that seaweed is the fastest growing biomass in the world. Seaweed farming itself, if done responsibly, has the power to address many of the ecological challenges we face today, without the use of land, fertilizer, or freshwater. It reduces ocean acidification, promotes marine biodiversity, and even absorbs vast quantities of CO2 from the atmosphere.

Seaweed can also create highly valuable end products. It is a nutritious food source for both people and animals and can be used as an environmentally friendly alternative to petroleum-based fertilisers and plastics. At the moment it’s a unique untapped resource, and the goal of the Seaweed Company is to unlock the potential of this wondrous resource to benefit both people and the planet.

In this episode Joost starts by explaining some of the urgent issues facing marine environments and how seaweed farming can help to address them. We go over the advantages that growing seaweed has over terrestrial agriculture, the high value products that can be made from different types of seaweed, the many pilot projects around the world that his company has helped to start and much more. 

Towards the end we also examine the roadblocks that are holding this solution back from being more widely adopted and how those of you listening can learn more and get involved. 

I’ve personally been learning a lot about marine ecosystems through these interviews and truly hope that a greater awareness will begin to be built around just how essential the health of our oceans is to the health of all life, even to ecosystems that are far inland and away from any saltwater. I’m really excited for this and the next few episodes for this reason.

Valenti Sallares, director of the Spanish National Research Council’s Institute of Marine Sciences, explains to us how acidification is impacting our oceans.