Ocean acidification

Definition

Ocean acidification refers to the process by which the ocean becomes more acidic due to increased carbon dioxide (CO2) emissions from human activities, leading to a decrease in pH levels of seawater. This change in the ocean's chemistry has significant implications for marine life, ecosystems, and biogeochemical cycles, affecting biodiversity and overall ocean health.

5 Must Know Facts For Your Next Test

1. Since the Industrial Revolution, ocean surface waters have experienced an average decrease in pH of about 0.1 units, translating to approximately a 30% increase in acidity.
2. Ocean acidification disrupts the ability of marine organisms like shellfish and corals to form calcium carbonate structures, affecting their growth and survival.
3. The phenomenon has cascading effects on marine food webs, as species that rely on calcification for their shells and skeletons are particularly vulnerable.
4. The changes in ocean chemistry can also impact fish behavior and physiology, including their ability to find prey and evade predators.
5. Ocean acidification is projected to worsen in the coming decades, potentially leading to significant shifts in marine biodiversity and ecosystem functions.

Review Questions

• How does ocean acidification affect marine organisms that rely on calcium carbonate for their structures?
  • Ocean acidification reduces the availability of carbonate ions necessary for the formation of calcium carbonate, which is critical for shell-building organisms like mollusks and corals. As the water becomes more acidic, these organisms struggle to maintain their shells or skeletons, leading to weakened structures and increased mortality rates. This decline not only impacts individual species but also disrupts the broader marine ecosystem that relies on these organisms for habitat and food.
• Discuss the potential implications of ocean acidification on global biogeochemical cycles.
  • Ocean acidification can significantly alter global biogeochemical cycles by affecting nutrient availability and cycling processes within marine ecosystems. For instance, decreased carbonate ion concentration impacts the biological carbon pump, which sequesters CO2 in deep ocean waters through biological processes. Changes in species composition due to acidification may further influence nutrient dynamics and primary productivity, ultimately affecting carbon storage capacity in the oceans.
• Evaluate the broader ecological consequences of ocean acidification on biodiversity and marine ecosystems.
  • The ecological consequences of ocean acidification are profound and can lead to significant declines in marine biodiversity. Vulnerable species such as corals, mollusks, and certain planktonic organisms may face extinction, disrupting food webs and altering ecosystem dynamics. As key species diminish, there could be a loss of resilience in marine ecosystems, reducing their ability to withstand additional stressors like climate change. This biodiversity loss could ultimately impact human societies reliant on healthy oceans for food, livelihoods, and ecosystem services.

Related terms

Carbon dioxide (CO2): A colorless gas that is a byproduct of combustion and respiration, which contributes to the greenhouse effect and is a key driver of ocean acidification.

pH scale:

A measure of acidity or alkalinity, where lower values indicate higher acidity; the pH of ocean water has been declining due to increased CO2 absorption.

Coral bleaching: A phenomenon where corals lose their vibrant colors and essential symbiotic algae due to stress factors like rising temperatures and acidification, leading to coral death.