Ocean acidification, caused by increased atmospheric CO2 dissolving into seawater and lowering pH, impacts a wide range of marine life beyond coral bleaching.

**Cephalopods**—including cuttlefish, octopuses, and squids—experience physiological stress as acidified waters disrupt their ability to maintain homeostasis, affecting metabolic processes and increasing mortality, especially in vulnerable early life stages .

While most cephalopods lack external shells, some possess internal calcium carbonate structures, and acidification reduces the availability of carbonate ions, making it harder to form and maintain these structures, leading to weaker shells and greater predation risk .

Acidification also alters cephalopod behavior, impacting hunting, predator avoidance, and activity levels, which can disrupt their ecological roles as both predators and prey .

Reproductive success is compromised as changes in water chemistry reduce egg viability and larval survival .

**Marine mammals** are indirectly affected as acidification causes declines in shellfish and fish populations that form the base of their food web.

Shell-forming organisms like clams, mussels, and oysters struggle to build shells, leading to population declines and reduced food availability for marine mammals .

Fish such as Pacific cod also experience higher mortality in early life stages due to acidification and warming, further threatening food sources for marine mammals .

The resulting ecosystem disruption, including shifts in species distributions and reduced biodiversity, destabilizes the food web and poses significant risks to marine mammals .

**Other marine organisms** are also at risk.

Pteropods, small shelled creatures vital to the food web and carbon cycle, face shell dissolution in acidic waters, threatening their populations and the species that depend on them .

**Ecosystem-wide effects** include impaired shell formation in calcifiers, altered species distributions, and disrupted food webs,

Ocean acidification, caused by increased atmospheric CO2 dissolving into seawater and lowering pH, impacts a wide range of marine life beyond coral bleaching.

**Cephalopods**—including cuttlefish, octopuses, and squids—experience physiological stress as acidified waters disrupt their ability to maintain homeostasis, affecting metabolic processes and increasing mortality, especially in vulnerable early life stages .

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Content: There were 734 press releases posted in the last 24 hours and 394,615 in the last 365 days.

Study explores combined impacts of ocean warming and acidification on pacific cod

Newly hatched Pacific cod larva. (Image credit: NOAA Fisheries/Emily Slesinger)

As the climate changes, the ocean is simultaneously warming and acidifying. Both have been shown to adversely affect the vulnerable early life stages of Pacific cod. But until now, the interplay of these two environmental stressors was unknown.

new NOAA Fisheries study takes a look into the future by replicating predicted Alaska ocean conditions in the laboratory. The study is the first to look at the interactive effects of ocean warming and acidification on Pacific cod. Researchers evaluated the growth and survival of eggs and larvae at combinations of temperature and acidity representing current and future ocean environments. The findings can help improve predictions to ensure climate-ready Alaska fisheries and communities in the future.

Alaska Fish Face Multiple Climate-Driven Stressors

Ocean warming and acidification are escalating faster in Alaska and other high latitude regions than anywhere else on the planet. Alaska produces more than half of the nation’s wild-caught seafood. Local communities depend on the ecosystem for their livelihoods. Understanding how climate-driven stressors will affect these valuable resources is critical to ensuring resilient Alaska communities and a strong blue economy in the future.

Because fish are cold-blooded, temperature profoundly affects their growth and behavior. The effects of acidification are more nuanced. Fish can buffer acidity in the bloodstream but at an energetic cost.

Very young fish—eggs and larvae—tend to be the most sensitive stages of the fish life cycle to both warming and acidification. Unlike adult fish that can move to cooler waters, these tiny creatures are incapable of migrating to more favorable conditions. Subtle differences in their growth and condition can make a big difference to the number of young fish that make it to the adult population.

Laboratory set up for ocean acidification and ocean warming experiments with early stages of Pacific cod. Large tanks in the background provide chilled and ambient seawater that are mixed to temperature. Small round tanks house eggs and larvae at different temperatures and acidification levels. Acidification is controlled by bubbling carbon dioxide into the seawater: more carbon dioxide causes higher acidity (lower pH). (Image credit: NOAA Fisheries/Emily Slesinger)

Pacific cod is an important subsistence food, a key species in the food web, and the second-largest commercial groundfish catch in Alaska. Understanding how warming and acidification together may affect this ecologically, culturally, and commercially valuable species is key to predicting future climate impacts.

“Knowing how individual species will respond to multiple climate stressors helps us put together this puzzle to figure out what species are more vulnerable than others,” Emily Slesinger said. “And that will help guide ecosystem-based fisheries management to ensure their sustainability.”

Partnerships and Unique Laboratory Capabilities Expand Possibilities for Studying Alaska Species

Finding answers posed some hurdles. “It’s really challenging to study these fish that are found in remote and cold environments,” Slesinger said.

They met those challenges through partnerships and a specially equipped laboratory facility.

Fishermen played a key role. To obtain eggs and larvae for experiments, they first needed live adults, ready to spawn. Commercial fishermen used baited fishing pots to catch adults off Kodiak Island during the spawning season.

Fertilized eggs were shipped to the NOAA Fisheries Alaska Fisheries Science Center Laboratory in Newport, Oregon. The eggs and larvae were reared at six combinations of temperature (3°C, 6°C, 10°C) and acidification (ambient and high acidity). Scientists measured their hatch success, growth, nutritional condition, and mortality throughout the nine-week experiment.

“The Newport lab is very special,” Slesinger said. “What is most unique is our seawater system that can chill water to Arctic temperatures. The lab has the capacity to house many fish at all life stages and the expertise to keep them thriving. And it has the facilities to run these complicated experiments on the younger life stages.”

Experiments Reveal a Dominant Stressor

The study found that overall, Pacific cod’s early life stages were more sensitive to warming than to acidification:

  • Temperature affected all measured traits: growth, condition, and mortality
  • Mortality of both eggs and larvae was highest at the warmest temperature
  • 6°C was the optimal temperature for hatching, condition, and survival
  • At the warmest temperature (10°C), Pacific cod grew the fastest but were in poor condition with high mortality rates
  • At the coldest temperature (3°C), mortality rates were lower, but both growth and condition were also low
  • Acidification effects were more modest and inconsistent
  • The single instance of a negative effect of acidification was at the optimal 6°C temperature

“We’re seeing that either temperature or acidification drove the response—they were not additive. At optimal temperatures, Pacific cod may be impaired by acidification. At the warm temperature, they were overwhelmingly negatively impacted, but there was pretty much no effect of acidification,” Slesinger said. “Our findings suggest that temperature is the dominant stressor and ocean warming is likely the greater threat.”

The research highlights the complexity of species- and stage-specific responses to multiple climatic stressors and the importance of understanding them.

“This work is exciting because we are able to provide information about these fish that can be useful for future management. It is really important to me that my research can be directly helpful to societies, economies, and communities,” Slesinger said. “This research contributes to our common goal of ensuring productive, sustainable fishing into the future.”

Ecomagazine, 30 April 2024. Press release.

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Content: Newswise — When carbon dioxide (CO2) enters the oceans, it can make the water more acidic, which is called ocean acidification. This can make it harder for some ocean creatures, like pteropods, to build and keep their shells. Pteropods are important for the ocean environment.

Pteropods are small sea creatures, including shelled sea butterflies. Not much is known about them because of their size, and they don't survive well in captivity. A team of marine scientists studied the life cycles, abundance, and seasonal changes of shelled sea butterflies in the north-east Scotia Sea, where climate change is happening quickly.

Dr Clara Manno, a researcher at the British Antarctic Survey and the corresponding author of the study published in Frontiers in Marine Science, said that the decrease in pteropod populations in the Antarctic Ocean could have significant consequences for the food web and carbon cycle. She also said that understanding the life cycle of this important organism could help to predict the impact of ocean acidification on the Antarctic ecosystem.

Population stability essential for species survival

To study the life cycle, abundance, and seasonal variability of shelled sea butterflies in the north-east Scotia Sea, a team of marine scientists collected sea butterflies in a sediment trap, a sampling device that was anchored at a depth of 400 meters. Since observing the entire life cycle of sea butterflies in a laboratory setting is impossible, the researchers had to gather information about their spawning, growth rate, and population structure. They were able to reconstruct the sea butterflies' life cycle for a year using the samples from the sediment trap.

The scientists found that the two most commonly collected species, Limacina rangii and Limacina retroversa, have different life cycles and therefore have different levels of vulnerability to changes in the ocean. During the winter months, L. rangii, which is a polar species, can be found as both adults and juveniles, while L. retroversa, a subpolar species, is only found as adults during the winter.

Sea butterflies that exist during the coldest season are more vulnerable to increased levels of ocean acidification. This is because ocean water is more acidic during this season than during other times of the year due to cooler temperatures that increase CO2 dissolution in the ocean. The researchers explained that the life stages of sea butterflies during this time are more exposed and vulnerable to the effects of ocean acidification.

L. rangii has a survival advantage over L. retroversa because both adults and juveniles coexist during winter, which reduces the risk of population instability if one cohort is vulnerable. In contrast, if one cohort is removed from L. retroversa, the entire population could be at risk.

Prolonged exposure is a survival challenge

The researchers pointed out that although the two species are affected differently, both are likely to suffer harm if they are exposed to unfavorable conditions for prolonged periods.

The scientists cautioned that the intensifying and prolonged events of ocean acidification overlap with the spring spawning period, posing a threat to the most vulnerable life stage, the larvae. This could endanger the future populations of sea butterflies.

The research team plans to further study the sea butterflies in the Scotia Sea to see how they would be affected by the increase in the intensity and duration of ocean acidification events. They will study multiyear sediment trap samples to identify potential changes in the life cycle that may occur due to environmental changes. Dr Jessie Gardner of the British Antarctic Survey, lead author of the study, said this will be the next step in their research.

Journal Link: Frontiers in Marine Science

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Content: The Sciences

The Late Permian Mass Extinction Explained

Burning coal caused the largest mass extinction in earth’s history — the Late Permian Mass Extinction, or the Great Dying.

By Gabe AllenJul 22, 2022 10:00 AM
(Credit: Catmando/Shutterstock)

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Mass extinctions are evolutionary turning points — brief moments on a geologic time scale that drastically change the course of life on earth. One moment in particular stands out. The Permian-Triassic extinction, aka the Great Dying, eradicated more than 90 percent of earth’s marine species and 75 percent of terrestrial species 252 million years ago. It was the deadliest mass extinction event in the history of our planet, and its legacy lives on in the flora and fauna of the modern world.

The climactic and geochemical triggers for the Great Dying are unsettlingly similar to the effects of anthropogenic climate change. Global warming, ocean acidification and ozone layer-depletion caused ecological collapse.

The organisms that did recover from the extinction, did so slowly. Equatorial regions, which had been scorched beyond recognition, did not regain their characteristic biodiversity for five million years. Global ecosystems lacked both diversity and stability for at least eight million years following the event.

Survivors of the extinction event, though few, eventually repopulated the earth. These organisms are the ancestors of every living thing today. To paleontologists, the End-Permian Mass Extinction is the temporal boundary between the ancient paleozoic fauna and the modern fauna — a theoretical border between our world and a barely-recognizable predecessor.

Finding Precision

As recent as the late 2000s, the research community was significantly divided over what caused the Permian extinction. Some suggested that volcanism was at fault, while others suggested a meteor impact, like the one that wiped out the dinosaurs, caused the extinction.

Those that preferred the volcanic explanation, suspected the Siberian Traps, an expansive region of volcanic rock in present-day Siberia. The formation developed during an unrivaled period of volcanic rock on the ancient supercontinent Pangea.

“It’s the largest continental volcanic event and the largest mass extinction that we’re aware of on earth ever,” says Dr. Lindy Elkins-Tanton, a planetary scientist and professor at Arizona State University. “At the time, we didn’t know what caused either one or if they were definitively related to each other.”

In 2014, Chinese and American researchers made a breakthrough. The team extracted ancient volcanic ash from the Global Stratotype Section and Point for the early Triassic period, a site in Meishan, China that contains sediment that dates to the crisis unambiguously. By analyzing the uranium and lead isotopes contained in the ash, they put a relatively precise date on the extinction: 251.9 million years ago, give or take 70,000 years.

The next step was to date the Siberian Traps. Using the same method, the scientists analyzed samples from the site. “The bulk of this diffusive and explosive volcanism led up to the extinction,” says Elkins-Tanton, who was a part of the research team.

From these two dates, a timeline began to emerge. Intense volcanic activity on the ancient supercontinent of Pangea spewed magma through layers of basalt, coal and organic material. The combustion of these layers produced an immense amount of CO2 as well as other greenhouse gasses and chlorofluorocarbons.

Victims and Survivors

On land, both plants and animals perished in equatorial regions. At further latitudes, mosses and other lycopods began to dominate ecosystems that were once forested with conifers. Our ancestors, the tetrapods, died en masse. Survivors fled from the tropics towards the poles.

Like the mass extinctions before it, the End-Permian had an outsized impact on marine organisms. As CO2 from the atmosphere leached into the water, the ocean became more and more acidic. Simultaneously, high temperatures and cyanobacteria blooms consumed dissolved oxygen until there was little left.

Many organisms that had evolved to construct exoskeletons from minerals, found in ambient seawater, did not survive these changes in marine chemistry. The engineers of Permian reef ecosystems, rugose and tabulate corals, went completely extinct. Vast groups of externally-shelled cephalopods, ancestors of the nautilus, succumbed to the same fate. The End-Permian extinguished the last species of Trilobites as well, a group that had been on the decline since the Ordovician Mass Extinction.

Read more: The First Mass Extinction Event Explained: End-Ordovician

As with any mass-extinction, there were survivors of the Great Dying. Before the event, clam-like brachiopods were plentiful and diverse, but the extinction extinguished them in favor of their cousins, the bivalve mollusks. To this day, bivalves are widespread, while only a few orders of brachiopods remain.

Many researchers have speculated that the End-Permian may have catalyzed diversification among tetrapods. Though the extinction wiped many out permanently, the Early Triassic saw the creatures diversify and expand their ranges rapidly. This “radiation” eventually gave rise to archosaurs and later dinosaurs.

Drawing Parallels

The same factors that have driven anthropogenic global warming today drove global ecological collapse at the end of the Permian. An over-abundance of greenhouse gasses made the planet unlivable for most living organisms. Actually, the warming that initiated the End-Permian may have occurred at a much slower rate than anthropogenic global warming.

“It was the same climate change caused by the same greenhouse gasses as what we’re seeing today,” Elkins-Tanton says. “And it was almost the end of multicellular life on earth.”

However, climate scientists project that, if we can lower our emissions quickly enough, we can keep global warming to levels far below the ones that scorched the earth during the earth’s largest extinction event. It’s not too late to avoid total and complete ecological collapse.

“The rate of change might not have been as fast as today, but it changed the temperature so much that it’s really the worst-case scenario of what might happen,” David Bottjer says, paleoecologist and University of Southern California professor of earth sciences. “That’s why we should study it. To understand future scenarios for our climate.”

The future scenario, most-analogous to the End-Permian, would see humans continue to burn fossil fuels until few surviving organisms remained. It’s a scenario that may not represent the end of life on earth, but a fundamental change that would take millions of years to rebound from.

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At what stage of life are calcium carbonate-based organisms most vulnerable to changes in water pH?

How do scientists expect ocean acidification to impact specific fish species?

it will affect their physiology and growth

Which marine organism is vulnerable to increased levels of ocean acidification?

At what stage of life are calcium carbonate-based organisms most vulnerable to changes in water pH?

How do scientists expect ocean acidification to impact specific fish species?

it will affect their physiology and growth

Which marine organism is vulnerable to increased levels of ocean acidification?

At what stage of life are calcium carbonate-based organisms most vulnerable to changes in water pH?

How do scientists expect ocean acidification to impact specific fish species?

it will affect their physiology and growth

Which marine organism is vulnerable to increased levels of ocean acidification?

While most cephalopods lack external shells, some possess internal calcium carbonate structures, and acidification reduces the availability of carbonate ions, making it harder to form and maintain these structures, leading to weaker shells and greater predation risk .

Title:

Content: There were 1,862 press releases posted in the last 24 hours and 393,697 in the last 365 days.

Utilizing biogeochemical and genetic tools to understand and support clam populations in a changing ocean

Marine bivalves are at risk due to anthropogenic climate change. This poses a threat to commercial aquaculture, and the communities that depend on bivalves for food security. Ocean acidification, the lowering of seawater pH, is of particular concern for marine calcifiers, including bivalves. Ocean acidification occurs as carbon dioxide enters the atmosphere at a rate faster than natural geologic processes can buffer. It is energetically costly for marine calcifiers like clams, mussels, and oysters, to mineralize under acidic conditions, and low pH leads to the dissolution of calcium carbonate shells and skeletons. This problem warrants research on acidification adaptation strategies that will keep coastal populations healthy. Adding calcium carbonate shell hash to coastal sediments may mitigate negative effects of acidification on infaunal shellfish by altering the chemistry of pore fluids, thus providing a potential mitigation strategy for local populations, including species like the Pacific littleneck clam (Leukoma staminea).

Here, I present the first in-depth description of the shell mineralogy, microstructure, body size variability, and geochemical properties of modern L. staminea, a common eastern Pacific, shallow, infaunal bivalve. Additionally, I document the impact of ocean acidification on the shell growth and gene expression of L. staminea, and test whether adding shell hash to its infaunal environement can promote growth under acidified conditions. Juvenile clams were raised in four experimental conditions for 90 days: control seawater, acidified seawater, control seawater with shell hash, and acidified seawater with shell hash. Clam shell weight, soft tissue weight, and new shell growth were measured. The presence of shell hash increased the pH, alkalinity and aragonite saturation state of pore fluids across all treatments, and increased shell growth on average, although growth metrics were variable across and within treatments. Lastly, RNA-sequencing revealed the impacts of experimental acidification on juvenile clam gene expression. Clams grown in the presence of shell hash had gene expression profiles more similar to those grown in control (non-acidified) conditions. In all, this research suggests that adding shell hash to coastal sediments alters the chemistry of pore fluids and buffers against acidic conditions that deleteriously affects clam mineralization.

Kempf H., 2024. Utilizing biogeochemical and genetic tools to understand and support clam populations in a changing ocean. PhD Thesis, University of California, Davis. 33 p. Thesis (restricted access).

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Content: How climate change and warming waters are affecting the health of the oceans

(NEW YORK) — Oceans do so much to sustain life on Earth, including bearing the brunt of global temperatures that have been steadily warming for decades.

An IPCC special report published in 2019 found that oceans — which make up more than 70% of the world’s surface — have absorbed between 20% and 30% of human-made carbon dioxide emissions since the 1980s. They’re also responsible for absorbing more than 93% of the “combined heat stored by warmed air, sea, and land, and melted ice” since the 1970s, according to the Fifth Assessment report published in 2013 by the United Nations Intergovernmental Panel on Climate Change.

The tipping point is near, experts told ABC News. But there are collective actions to take that could revitalize oceans to a healthier state — the theme of the United Nations World Oceans Day 2022.

“We really see oceans as the biggest ally in the climate change crisis,” Lea d’Auriol, founder of nonprofit Oceanic Global, told ABC News.

This is how climate change is affecting the health of the world’s oceans:

Species are faced with adapting or becoming extinct

Currently, the oceans “are in a state of complete imbalance” that has nearly doubled since the 1990s, d’Auriol said. Look no further than the fishermen, who supply sustenance to more than three billion people who rely on seafood as their main source of protein, as witnesses that climate change is already here, d’Auriol, said.

“If you wanted to ask someone if climate change is really happening, probably the most surest answer you’d get from anyone aside from a scientist is a fisherman,” Arlo Hemphill, senior oceans campaigner for Greenpeace USA, told ABC News. “Because fishermen are seeing these things happen in real time.”

One of the changes long-time fisherman are witnessing is the presence of new species venturing north as the area with their preferred water temperature expands.

Marine organisms maintain the same temperature as the surrounding water, so that when temperature increases, so does the temperature of the organism, Martin Grosell, professor of ichthyology and chair of the University of Miami’s Department of Marine Biology and Ecology, told ABC News. As the temperature rises, the organisms require more energy to move and survive. But, conversely, the levels of oxygen in the water decrease as the temperature warms, forcing the species to move, Grosell said.

The migrations may seem innocuous, but they are disrupting ecosystems all over the world, such as the phenology, or timing, of when grey seals give birth, Hemphill said.

Conversely, species are continuing to die off due to repeated events of marine heatwaves, Anne Christianson, director of international climate policy for the Center for American Progress, a public policy research organization, told ABC News.

Coral reefs are among the most threatened marine ecosystems in the world, scientists say. Coral bleaching, a process that occurs when water is too warm and the corals expel algae from their tissues, causing them to turn completely white, is happening at “alarming” rates — increasing by a rate of 4% per year — along with an uptick in mortality events along entire regions, d’Auriol said.

A study published in the National Academy of Sciences found that coral reefs could stop growing in 10 years unless greenhouse gases are significantly reduced and that, under a worst-case scenario, 94% of all reefs could erode by 2050.

Reefs are often the indicator of the health of an ecosystem, Brenda Ekwurzel, director of climate science for the Union of Concerned Scientists, told ABC News.

Mammals that rely on Arctic ice, such as polar bears and ringed seals, one of the polar bears’ main food sources that live their lives almost entirely on the ice, are also at risk, Ekwurzel said.

Vegetation such as mangroves, seagrass plants and marshes, some of the largest carbon sinks on the planet, which absorb and store carbon dioxide from the atmosphere, are also at risk of extinction, d’Auriol said.

The number of dead zones are increasing

A dead zone, or the process of hypoxia, occurs when an algal bloom sucks up all the oxygen in an area, making it impossible for marine life to survive — essentially a biological desert, according to the National Oceanic and Atmospheric Administration.

A study published in 2008 in Science found that there were 400 dead zones around the world. By 2019, the number of dead zones had increased to about 900, d’Auriol said.

The dead zones often occur in regions with rampant nutrient runoff, such as at the base of the Mississippi River, where it empties into the Gulf of Mexico, Hemphill said.

Sea level rise will change coastal communities

The biggest contributor to sea level rise is the melting ice in the Arctic, which is heating up twice as fast as the rest of the world, according to the 2021 Arctic Report Card by NOAA. Increases in sea level rise of 6 inches to a foot since the Industrial Revolution may seem like small increments, but crucial infrastructure near oceans was not built to withstand the added inches of water, experts say.

Millions of people living in coastlines around the world, including those in mega cities such as New York, Los Angeles and San Francisco, will be displaced by the rise in sea levels, d’Auriol said.

Carbon dioxide emissions sparks ocean acidification

Ocean acidification, which occurs when water’s pH levels are lowered as a result of carbon dioxide in the atmosphere, is not directly caused by warming temperatures but rather by excess carbon dioxide emissions, Hemphill said.

“The alarming thing about it is that shellfish everything from from microscopic plankton, to clams and crabs and coral reefs themselves use calcium carbonate to build their shells,” he said. “And as the ocean acidifies, it becomes more difficult to create the shells.”

Ocean acidification, rather than coral bleaching, will likely be the culprit behind the demise of coral reefs, Ekwurzel said.

Collective actions are necessary to protect the oceans

In line with the 2022 theme for World Oceans Day, “Revitalization: Collective Action for the Ocean,” scientists and conservationists are highlighting the need for individuals, communities, nonprofits, the private sector and governments to come together to create solutions, d’Auriol said.

This includes ensuring the health of marine protected areas by eliminating housing, fishing zones and shipping traffic in the vicinity, d’Auriol said.

Governments will need to create policies to protect both human life and the health of the ocean, Christianson said.

“There isn’t one silver bullet for solving this crisis in the ocean and on land,” Christianson said.

However, the ticking time bomb is the race to drastically reduce global greenhouse gas emissions within the next decade, the experts said.

“We can’t afford to delay those solutions any longer,” Ekwurzel said.

Along the path to properly protecting and preserving oceans is ridding the narrative that oceans are a separate environmental issue from climate change and the conservation of biodiversity, d’Auriol said.

“Because we do live on a water planet, and it’s responsible for sustaining all life on Earth,” she said.

Copyright (C) 2022, ABC Audio. All rights reserved.

What do shellfish use to build their shells?

Which marine organism is vulnerable to increased levels of ocean acidification?

What do shellfish use to build their shells?

Which marine organism is vulnerable to increased levels of ocean acidification?

Acidification also alters cephalopod behavior, impacting hunting, predator avoidance, and activity levels, which can disrupt their ecological roles as both predators and prey .

How do scientists expect ocean acidification to impact specific fish species?

Which marine organism is vulnerable to increased levels of ocean acidification?

Reproductive success is compromised as changes in water chemistry reduce egg viability and larval survival .

At what stage of life are calcium carbonate-based organisms most vulnerable to changes in water pH?

How do scientists expect ocean acidification to impact specific fish species?

it will affect their physiology and growth

How does elevated water acidity affect fish ability to survive?

**Marine mammals** are indirectly affected as acidification causes declines in shellfish and fish populations that form the base of their food web.

Shell-forming organisms like clams, mussels, and oysters struggle to build shells, leading to population declines and reduced food availability for marine mammals .

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This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

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Sea urchins are struggling to 'get a grip' as climate change alters ecosystems

When you are driving through a rain storm, traction is key. If your tires lack sufficient tread, your vehicle will slip and slide, and you won't have the grip needed to maneuver safely. When torrential rains hit near-shore, shallow water ecosystems, sea urchins experience a similar challenge. Heavy precipitation can alter the concentration of salt in the ocean waters, causing lower salinity levels. Even a slight change in salinity can affect the ability of sea urchins to securely attach their tube feet to their surroundings—like tires gripping the road. This becomes a matter of life and death for the small spiny creatures, as they rely on their adhesive structures to move in the wave-battered rocky area near the seashore.

Syracuse University biologists have co-authored a study exploring how sea urchin adhesive abilities are affected by differing levels of water . The work is published in the Journal of Experimental Biology.

The survival of is vital for maintaining balance within marine ecosystems. Sea urchins are responsible for grazing around 45% of algae on coral reefs. Without sea urchins, coral reefs can become overgrown with macroalgae, which can limit the growth of corals. With the importance of for coastal protection and preservation of biodiversity, it is critical to safeguard the sea urchin population.

As causes weather extremes ranging from heat waves and droughts to heavy rains and flooding, the large amounts of freshwater pouring into nearshore ecosystems are altering habitats. A team of biologists, led by Austin Garner, assistant professor in the College of Arts and Sciences' Department of Biology, studied the impacts of low salinity and how it alters sea urchins' ability to grip and move within their habitat. Garner, who is a member of Syracuse University's BioInspired Institute, studies how animals attach to surfaces in variable environments from the perspective of both the life and physical sciences.

The team's study sought to understand how sea urchin populations will be affected by future extreme climatic events.

"While many marine animals can regulate the amount of water and salts in their bodies, sea urchins are not as effective at this," says Garner. "As a result, they tend to be restricted to a narrow range of salinity levels. Torrential precipitation can cause massive amounts of freshwater to be dumped into the ocean along the coastline causing rapid reductions in the concentration of salt in seawater."

The group's research was conducted at the University of Washington's Friday Harbor Laboratories (FHL). The study's lead author, Andrew Moura, who is a graduate student in Garner's lab at Syracuse, traveled to FHL along with Garner and researchers from Villanova University to conduct experiments with live green sea urchins. They worked alongside former FHL postdoctoral scholar Carla Narvaez, who is now an assistant professor of biology at Rhode Island College, and Villanova University professors Alyssa Stark and Michael Russell.

At FHL, the researchers separated sea urchins into 10 groups based on differing salinity levels within each tank, from normal to very low salt content. Among each group, they tested metrics including righting response (the ability for sea urchins to flip themselves over), locomotion (speed from one point to another) and adhesion (force at which their tube feet detach from a surface). In Garner's lab at Syracuse, he and Moura completed data analysis to compare each metric.

The team found that sea urchin righting response, movement, and adhesive ability were all negatively impacted by low salinity conditions. Interestingly, though, sea urchin adhesive ability was not severely impacted until very low salinity levels, indicating that sea urchins may be able to remain attached in challenging near-shore environmental conditions, even though activities that require greater coordination of tube feet (righting and movement) may not be possible.

"When we see this decrease in performance under very low salinity, we might start seeing shifts in where sea urchins might be living as a consequence of their inability to remain stuck in certain areas that experience low salinity," explains Moura. "That could change how much sea urchin grazing is happening and could have profound ecosystem effects."

Their work provides critical data that enhances researchers' ability to predict how important animals like sea urchins will fare in a changing world. The adhesion principles Garner and his team are exploring could also come in handy for human-designed adhesive materials—work that aligns with the Syracuse University BioInspired Institute's mission of addressing global challenges through innovative research.

"If we can learn the and molecular mechanisms that allow sea urchins to secrete a permanent adhesive and use it for temporary attachment, we could harness that power into the design challenges or our adhesives today," says Garner. "Imagine being able to have an adhesive that is otherwise permanent, but then you add another component, and it breaks it down and you can go stick it again somewhere else. It's a perfect example of how biology can be used to enhance the everyday products around us."

More information: Andrew J. Moura et al, Hyposalinity reduces coordination and adhesion of sea urchin tube feet, Journal of Experimental Biology (2023). DOI: 10.1242/jeb.245750

Journal information: Journal of Experimental Biology

Citation: Sea urchins are struggling to 'get a grip' as climate change alters ecosystems (2023, August 2) retrieved 2 August 2023 from https://phys.org/news/2023-08-sea-urchins-struggling-climate-ecosystems.html
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Salinity changes threatening marine ecosystems, new study shows

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How does coastal ocean acidification affect shellfish?

Fish such as Pacific cod also experience higher mortality in early life stages due to acidification and warming, further threatening food sources for marine mammals .

At what stage of life are calcium carbonate-based organisms most vulnerable to changes in water pH?

How do scientists expect ocean acidification to impact specific fish species?

it will affect their physiology and growth

How does elevated water acidity affect fish ability to survive?

The resulting ecosystem disruption, including shifts in species distributions and reduced biodiversity, destabilizes the food web and poses significant risks to marine mammals .

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The Logical Indian Crew

Rise In CO2 Levels In Air Is Wounding Sundarbans' Marine Life: Scientists

This has been analysed by a team of marine scientists working in the Sunderbans, who said ocean acidification is a part of global warming and climate change. The experts found the pH level of water dropping from around 8.3 in the early 1980s to approximately 7.9 in 2019.

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A continuous increase in the carbon dioxide (CO2) levels in the air is harming the marine life of the Sunderbans estuary in West Bengal by turning it acidic. Animals, especially with shells such as oysters, clams, crabs, and lobsters, are prone to danger.

This has been analysed by a team of marine scientists working in the Sunderbans, who said ocean acidification is a part of global warming and climate change, Hindustan Times reported. The experts found the pH level of water dropping from around 8.3 in the early 1980s to approximately 7.9 in 2019.

Speaking to the media, Abhijit Mitra, former head of the marine science department (Calcutta University), informed that the western part of Sunderban, close to the urban area, had observed a massive drop in its pH level, while the central part is declining slowly.

Mitra said the decline affects the population of shelled organisms and their shell size as well, which has become thinner and smaller. Fishermen said that several fish and other animals have gotten smaller, and they hardly get big ones.

Their population has also fallen by 35-40 per cent in the western area.

"The size of Saccostrea cucullata, a species of edible oyster around Kakdwip and Namkhana fishing harbour, has dropped by over 40 per cent. In the central Sunderbans, the size of the species has dropped by around 20 percent," the media quoted him as saying.

Asst. Professor of Indian Institute of Science Education and Research, Punyasloke Bhadury, explained that water contains calcium and carbonate ions, which the shelled animals need to develop and corals to build the reef. But the acidity reduces these components in the water, affecting the shell size and slowing down the growth of reefs.

Experts said the decline in the pH level is alarming. Just as the slightest drop in the pH level of a human body (pH 7.35 to 7.45) can make them sick, the same takes a heavy toll on marine animals.

The scientists said the decline is not just in Sunderbans but other estuaries as well.

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Which marine organism is vulnerable to increased levels of ocean acidification?

**Other marine organisms** are also at risk.

Pteropods, small shelled creatures vital to the food web and carbon cycle, face shell dissolution in acidic waters, threatening their populations and the species that depend on them .

**Ecosystem-wide effects** include impaired shell formation in calcifiers, altered species distributions, and disrupted food webs,