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Sophie McCoy New research reveals that accelerating ocean acidification may be forcing the California mussel to adapt, transforming its fundamental shell structure. As we were working with the older mussel samples from yr BP accessed via the Makah Cultural and Research Centerwe were struck by how visibly thicker the shells were.
So, trying to understand what was causing that pattern became our next project. To confirm the trend, the team studied modern mussel shells, shells from other decades in this century, and shells that were thousands of years old.
They determined that shell mineralogy was remarkably consistent—until about the last 15 years. This rapid structural shift feels significant. When we look at the thickness of the shells referring to our studyit appears more gradually over several decades. The shell mineral structure has changed only in the last few years.
To me, this indicates that it could be a threshold response. More recent mussels have built their shells by simply producing the calcium carbonate soup in the right location and leaving it disordered.
These disruptions in the shell formation process are specifically linked to acidification. That increases the total amount of inorganic carbon available in the ocean. However, CO2 combines with water to make carbonic acid, which drops the pH of seawater.
That changes the relative proportion of the different forms all that carbon can be in. So, more of it is available as carbonic acid or as bicarbonate, and less is available as carbonate. That requires more effort on the part of the mussel to gather that carbonate before it can make its shell.
Higher levels of skeletal magnesium triggers differences in the strength of magnesium-oxygen bonds.
This is important, because there is a direct connection between the level of organization in a shell and the robustness of these bonds.
More variable bond strengths seem to come hand in hand with disordered shell structure. This map shows the global distribution of aragonite saturation at 50 meters depth. The graphic shows areas that are most vulnerable to ocean acidification since they are regions where the saturation of aragonite is lower.
Aragonite is a calcium carbonate mineral that shellfish use to build their shells. However, a weak shell is better than no shell.
The kinds of changes being observed in the mussels are rapid, however, and signal a disruption of the normal formation process more than classic evolutionary adaptation—although adaptation might still take place.
Results that other researchers have shown from lab experiments suggests to me that we are not looking at evolutionary changes, only changes in physiology or possibly development in this particular case. These structural changes leave the California mussel fairly vulnerable to predators, but the variation the team has observed in the shell structures might also mean that the species can survive; more variability will provide more opportunities for natural selection.
That variance between mussels seems to be a stress response in newer samples, and not something that we observed in any of the historical specimens. She also covers other scientific and medical stories as well as technology.The National Climate Assessment summarizes the impacts of climate change on the United States, now and in the future.
Skip to main content shows negative correlation to naturally elevated carbon dioxide levels: Implications for near-term ocean acidification effects. Limnology and Oceanography. Exactly what is ocean acidification?
Our oceans absorb about a quarter of the carbon dioxide that humans produce by burning fossil fuels each year, and that's changing their basic chemistry. In the long-term, ocean acidification is likely to be the most significant impact of a changing climate on the Great Barrier Reef ecosystem.
The oceans absorb carbon dioxide (CO 2) from the atmosphere and are estimated to have absorbed about half the excess CO 2 .
"Climate Training Activities" shows Aquarium interpreters explaining why ocean acidification is detrimental to hard corals, and how suitable coral habitat is shrinking in the near future. The short animation shows the past, present and future of suitable coral reef habitat.
Two of the main effects on the marine environment are increased sea surface temperatures due to climate change, and ocean acidification. Increased sea surface temperatures are caused by the global warming effect of climate change.
4 Effects of Ocean Acidification on Marine Ecosystems. Ecosystems are defined by a complex suite of interactions among organisms and also between organisms and their physical environment; a disturbance to any part may lead to cascading effects throughout the system.