Final answer:
Many species of marine organisms are weakened and unable to maintain their shells due to ocean acidification, which is caused by increased CO₂ levels leading to more acidic oceans that inhibit the absorption of essential ions for shell formation.
Step-by-step explanation:
The weakening of marine organisms and their inability to produce and maintain shells is attributed to ocean acidification, a direct effect of rising atmospheric CO₂ levels. This phenomenon increases the concentration of hydrogen ions (H*) in the ocean, making the environment more acidic and hindering the absorption of calcium and carbonate ions (CO3²-). These ions are crucial for the formation of aragonite, a form of calcium carbonate that many marine species use to build their shells and skeletons.
Coral reefs, which are highly diverse marine ecosystems, suffer from processes like coral bleaching and the loss of symbiotic algae due to higher temperatures and changing water chemistry. Additionally, the broad spectrum of organisms, from the coral itself to mollusks, vertebrates, and even the tiny pteropods, are affected. These marine species require a stable calcium carbonate equilibrium to form the basic structures of their existence, which is disturbed by the acidifying oceans.
When considering humans, the reduction in marine biodiversity and the health of marine ecosystems directly impacts human carrying capacities due to our dependence on these systems for food, economic activities, and ecological services. The consequences of ocean acidification, therefore, have far-reaching implications that extend beyond marine life to affect human societies.