14. LIFE BELOW WATER

Water Planet Chemistry: Ocean Acidification Is More Pervasive Than Previously Thought – astrobiology.com

Water Planet Chemistry: Ocean Acidification Is More Pervasive Than Previously Thought – astrobiology.com
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Water Planet Chemistry: Ocean Acidification Is More Pervasive Than Previously Thought  astrobiology.com

Water Planet Chemistry: Ocean Acidification Is More Pervasive Than Previously Thought – astrobiology.com

Global Ocean Acidification and Its Impact on Marine Ecosystems: A Sustainable Development Perspective

Introduction

Recent research conducted by an international consortium of oceanographers reveals that ocean acidification has severely affected 40% of the global surface ocean and 60% of the subsurface ocean up to 200 meters deep. This phenomenon poses significant threats to marine biodiversity and the livelihoods dependent on marine resources, directly impacting several Sustainable Development Goals (SDGs), including SDG 14 (Life Below Water) and SDG 13 (Climate Action).

Key Findings on Ocean Acidification

  1. Extent of Acidification: The study identifies a substantial decline in aragonite saturation states—a critical mineral form of calcium carbonate used by marine organisms to build shells and skeletons. This decline compromises habitats for calcifying species such as corals, oysters, mussels, crabs, and pteropods.
  2. Regional Variations: The polar regions have experienced the most significant changes in surface waters, while sub-polar regions and the west coast of North America show the largest changes in subsurface waters.
  3. Habitat Loss Estimates:

    • Tropical and subtropical coral reefs have lost approximately 43% of suitable habitats.
    • Sea butterflies (pteropods) in polar regions have lost up to 61% of their habitat.
    • Coastal shellfish species have lost 13% of their global coastline habitats.

Implications for Marine Species and Fisheries

The acidification process reduces the availability of carbonate ions, essential for calcifying organisms to maintain their shells and skeletons. This leads to weaker shells, slower growth, and increased vulnerability, affecting marine biodiversity and fisheries sustainability (SDG 14).

  • Bristol Bay Red King Crab Decline: A NOAA study correlates ocean acidification with a 21% decline in the red king crab population from 1980 to 2023, and 45% since 2000, highlighting the impact on food security and economic livelihoods.
  • Dungeness Crab Vulnerability: Acidification impacts on young Dungeness crab shells and sensory organs threaten the most valuable fishery on the U.S. West Coast.
  • Economic Losses: Shellfish hatcheries in the Pacific Northwest suffered an estimated $110 million loss due to changing ocean chemistry before adaptive measures were implemented.

Scientific Approach and Methodology

The research, published in Global Change Biology, integrates ocean carbon system observations, modeling, and biological assessments. It utilizes aragonite saturation state as a key indicator to monitor ocean acidification levels, providing a comprehensive global assessment.

Ocean Acidification: Mechanisms and Environmental Impact

The ocean absorbs approximately 25% of atmospheric CO2, which reacts with seawater to form carbonic acid. This acid dissociates into bicarbonate and hydrogen ions, lowering pH and reducing carbonate ion availability. Reduced carbonate ions hinder calcifying organisms’ ability to form and maintain calcium carbonate structures, affecting marine biodiversity and ecosystem services.

Relevance to Sustainable Development Goals (SDGs)

  • SDG 14 – Life Below Water: Protecting marine ecosystems by addressing ocean acidification is critical to sustaining fisheries, biodiversity, and coastal communities.
  • SDG 13 – Climate Action: Mitigating CO2 emissions is essential to reduce ocean acidification and its cascading effects on marine life.
  • SDG 2 – Zero Hunger: Sustaining fisheries affected by acidification supports food security for millions globally.
  • SDG 1 – No Poverty: Protecting marine resources safeguards the livelihoods of communities dependent on fishing and aquaculture.

Conclusion and Future Directions

The findings underscore the urgent need for integrated climate and ocean management strategies to mitigate ocean acidification and preserve marine ecosystems. Continued monitoring, adaptive fisheries management, and global CO2 emission reductions are imperative to achieve the SDGs and ensure the resilience of ocean life and human communities.

References

  • Feely, R. et al. (2025). Global Change Biology.
  • Litzow, M. et al. (2025). Ocean acidification may contribute to recruitment failure of Bering Sea red king crab, Canadian Journal of Fisheries and Aquatic Sciences.
  • Bednaršek, N. et al. (2020). NOAA Studies on Dungeness Crab.
Water Planet Chemistry: Ocean Acidification Is More Pervasive Than Previously Thought
A pteropod shell dissolving over time in seawater with lower pH illustrates the impact of ocean acidification on marine calcifiers. Credit: NOAA Ocean Acidification Program.

1. Sustainable Development Goals (SDGs) Addressed or Connected

  1. SDG 14: Life Below Water
    • The article focuses on ocean acidification and its impact on marine species, habitats, and fisheries, directly relating to the conservation and sustainable use of oceans, seas, and marine resources.
  2. SDG 13: Climate Action
    • The article discusses the absorption of atmospheric CO2 by oceans leading to acidification, linking human-caused emissions to environmental changes, which relates to climate change mitigation and adaptation.
  3. SDG 2: Zero Hunger
    • By highlighting the decline in economically important marine species such as crabs, oysters, and mussels, the article connects to food security and sustainable fisheries.

2. Specific Targets Under Those SDGs Identified

  1. SDG 14: Life Below Water
    • Target 14.2: Sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including restoring them to achieve healthy and productive oceans.
    • Target 14.3: Minimize and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels.
    • Target 14.4: Effectively regulate harvesting and end overfishing to restore fish stocks in the shortest time feasible.
  2. SDG 13: Climate Action
    • Target 13.2: Integrate climate change measures into national policies, strategies, and planning.
    • Target 13.3: Improve education, awareness-raising, and human and institutional capacity on climate change mitigation, adaptation, impact reduction, and early warning.
  3. SDG 2: Zero Hunger
    • Target 2.4: Ensure sustainable food production systems and implement resilient agricultural practices that increase productivity and production, help maintain ecosystems, and strengthen capacity for adaptation to climate change.

3. Indicators Mentioned or Implied to Measure Progress

  1. Aragonite Saturation State
    • Used by NOAA as a measure of how easily aragonite dissolves in seawater, indicating the level of ocean acidification affecting calcifying organisms.
    • Decline in aragonite saturation state by a fifth in significant portions of surface and subsurface waters is a key indicator of habitat suitability for marine species.
  2. Population and Habitat Decline Metrics
    • Percentage loss of suitable habitats for coral reefs (43%), sea butterflies (61%), and coastal shellfish species (13%) serve as indicators of ecosystem health and biodiversity.
    • Declines in populations of species such as Bristol Bay red king crab and Dungeness crab, linked to ocean acidification, indicate impacts on fisheries and food security.
  3. Fishery Quotas and Closures
    • Two-year closure and reduced quotas in the Bering Sea red king crab fishery reflect management responses to stock declines, serving as indicators of sustainable fishery practices.
  4. pH Levels of Ocean Water
    • Changes in ocean pH levels are an implied indicator to monitor acidification trends and their ecological impacts.

4. Table of SDGs, Targets, and Indicators

SDGs Targets Indicators
SDG 14: Life Below Water
  • 14.2: Sustainably manage and protect marine and coastal ecosystems.
  • 14.3: Minimize and address ocean acidification impacts.
  • 14.4: Regulate harvesting and end overfishing.
  • Aragonite saturation state measurements.
  • Percentage loss of suitable habitats for corals, sea butterflies, and shellfish.
  • Population declines of key marine species (e.g., red king crab, Dungeness crab).
  • Fishery closures and quota adjustments.
SDG 13: Climate Action
  • 13.2: Integrate climate change measures into policies and planning.
  • 13.3: Improve education and capacity on climate change mitigation and adaptation.
  • Monitoring atmospheric CO2 levels and ocean pH changes.
  • Scientific research outputs linking CO2 emissions to ocean acidification.
SDG 2: Zero Hunger
  • 2.4: Ensure sustainable food production and resilient agricultural practices.
  • Declines in economically important marine species affecting fisheries.
  • Economic losses in shellfish hatcheries due to ocean acidification.

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