14.2 Ocean Acidification and Marine Ecosystems
2 min read•july 25, 2024
Ocean acidification is a growing concern as our oceans absorb more CO2 from the atmosphere. This process lowers seawater pH, making it harder for marine life to build shells and skeletons. It's like the ocean is getting a bad case of heartburn.
The impacts ripple through marine ecosystems, affecting everything from tiny plankton to big fish. Scientists are working hard to understand and address this issue, studying how different species cope and exploring ways to protect our oceans from further damage.
Understanding Ocean Acidification
Definition of ocean acidification
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- Ocean acidification decreases pH in world's oceans through absorption of atmospheric carbon dioxide (CO2)
- Increased atmospheric CO2 levels stem from burning fossil fuels, deforestation, and land-use changes
- Chemical reactions in seawater produce carbonic acid ()
- Carbonic acid dissociates into hydrogen and bicarbonate ions ()
- Carbonate system in seawater maintains equilibrium between CO2, HCO3-, and CO32- ions
- pH decrease shifts equilibrium towards more HCO3- and fewer CO32- ions
Impacts on marine ecosystems
- Calcifying organisms struggle to form calcium carbonate shells and skeletons (corals, mollusks, crustaceans)
- Certain plankton species affected (coccolithophores)
- Physiological stress disrupts acid-base balance in marine organisms
- Increased energy expenditure for internal pH maintenance
- Behavioral changes alter sensory perception and decision-making in fish
- Impaired predator-prey interactions
- Primary production potentially increases in some phytoplankton species
- Calcifying phytoplankton experience decreased productivity
- Nutrient cycling alters nitrogen fixation rates and phosphorus availability
Consequences and Research on Ocean Acidification
Consequences for biodiversity
- Biodiversity loss leads to decline in species reliant on calcium carbonate structures
- Community composition shifts
- Food web disruption changes prey availability for higher trophic levels
- Potential collapse of certain fisheries
- Ecosystem services impacted through reduced coastal protection from coral reef degradation
- Decreased carbon sequestration by calcifying organisms
- Economic losses in fisheries and aquaculture industries
- Synergistic effects with other stressors exacerbate impacts (ocean warming, deoxygenation, pollution)
Role of biogeochemical research
- Monitoring and data collection involve long-term pH and measurements
- Global observation networks established
- Experimental studies include mesocosm experiments simulating future ocean conditions
- Laboratory studies focus on individual species responses
- Modeling efforts develop predictive models for future ocean acidification scenarios
- Ecosystem models assess long-term impacts
- Mitigation strategies explore carbon dioxide removal techniques
- Restoration of coastal blue carbon ecosystems (mangroves, seagrasses)
- Policy implications inform international climate agreements
- Local and regional adaptation strategies developed
- Interdisciplinary collaboration integrates biogeochemistry with marine biology and ecology
- Social scientists contribute to socio-economic impact assessment
Key Terms to Review (18)
Altered species composition: Altered species composition refers to changes in the variety and abundance of species in a given ecosystem, often driven by environmental factors such as climate change, pollution, or habitat destruction. In marine ecosystems, altered species composition can significantly impact food webs, biodiversity, and ecosystem services, particularly in the context of stressors like ocean acidification.
Bioavailability: Bioavailability refers to the proportion of a substance, such as nutrients or contaminants, that is accessible for biological uptake and can be utilized by living organisms. It plays a crucial role in understanding how elements cycle through ecosystems and influence both biological productivity and environmental health. Factors such as chemical form, environmental conditions, and organismal physiology can affect the bioavailability of different substances, impacting everything from nutrient cycling to the responses of marine ecosystems to changing ocean chemistry.
Calcification: Calcification is the process by which organisms produce calcium carbonate (CaCO3) to form hard structures such as shells and skeletons. This process plays a crucial role in marine ecosystems, impacting ocean carbon dynamics and the overall health of marine life, particularly in the face of increasing ocean acidification. As carbon dioxide levels rise, changes in seawater chemistry can significantly affect the ability of marine organisms to calcify, influencing their survival and ecological roles.
Calcium carbonate cycle: The calcium carbonate cycle is the process through which calcium carbonate (CaCO₃) is formed, dissolved, and reformed in natural systems, playing a critical role in regulating carbon dioxide levels and influencing ocean chemistry. This cycle is essential for marine organisms that rely on calcium carbonate to build shells and skeletons, thereby impacting marine ecosystems and the global carbon cycle. It connects the ocean's chemistry with biological processes, sedimentation, and geological formations over geological timescales.
Carbon cycle: The carbon cycle is the series of processes through which carbon atoms circulate in the Earth's systems, including the atmosphere, biosphere, hydrosphere, and geosphere. This cycle plays a crucial role in regulating Earth’s climate, supporting life, and maintaining ecological balance by involving various reservoirs and fluxes of carbon across different spheres.
Carbonate chemistry: Carbonate chemistry refers to the study of carbonates, which are salts or esters of carbonic acid containing the carbonate ion (CO₃²⁻). This chemistry plays a crucial role in regulating the acidity and alkalinity of natural waters, especially oceans, and is fundamental in understanding ocean acidification and its impacts on marine ecosystems.
Coral reefs: Coral reefs are diverse underwater ecosystems made up of living coral polyps that secrete calcium carbonate to form a hard skeleton, creating structures that provide habitat for numerous marine species. These ecosystems are often referred to as the 'rainforests of the sea' due to their rich biodiversity and the vital roles they play in marine life and coastal protection.
David Archer: David Archer is a prominent climate scientist known for his work on the carbon cycle and its impact on global warming. His research has been instrumental in understanding how carbon reservoirs interact with the atmosphere, oceans, and land. Archer’s insights into carbon fluxes and ocean acidification have influenced both scientific thought and policy decisions regarding climate change mitigation.
Dissolved CO2: Dissolved CO2 refers to carbon dioxide that has been absorbed in water, playing a critical role in aquatic environments. This form of carbon is essential for processes such as photosynthesis and is also involved in the regulation of ocean pH levels, which is particularly important in the context of ocean acidification and its impacts on marine ecosystems.
Jane Lubchenco: Jane Lubchenco is a prominent American marine biologist and environmental scientist known for her work on ocean ecosystems, climate change, and marine conservation. She served as the administrator of the National Oceanic and Atmospheric Administration (NOAA) from 2009 to 2013, where she emphasized the importance of science in policy-making and promoted initiatives to address ocean acidification and its impact on marine life.
Marine Protected Areas: Marine Protected Areas (MPAs) are designated regions in oceans, seas, and coastal areas where human activities are regulated to protect the natural environment and biodiversity. These areas aim to conserve marine life, restore fish populations, and enhance ecosystem resilience against threats like climate change and ocean acidification. MPAs play a crucial role in maintaining healthy marine ecosystems and can provide a refuge for vulnerable species.
Ocean feedback loops: Ocean feedback loops refer to processes in which changes in the ocean's physical, chemical, or biological systems lead to further changes in those systems, creating a cycle of interaction that can amplify or dampen effects such as climate change. These loops are critical because they can impact ocean acidification and marine ecosystems, influencing everything from carbon storage to species distribution.
Oceanic co2 uptake: Oceanic CO2 uptake refers to the process by which the oceans absorb carbon dioxide (CO2) from the atmosphere, significantly influencing global carbon cycling and climate change. This uptake plays a crucial role in regulating atmospheric CO2 levels, as oceans act as a major carbon sink, helping to mitigate the effects of anthropogenic emissions. However, increased CO2 levels can lead to ocean acidification, which poses risks to marine ecosystems and biodiversity.
PH Levels: pH levels measure the acidity or alkalinity of a solution on a scale from 0 to 14, with 7 being neutral. Understanding pH levels is crucial as they influence chemical reactions, biological processes, and the health of ecosystems in both terrestrial and aquatic environments, especially in the context of carbon dynamics and the impacts of acidification on marine life and soil chemistry.
Reduced growth rates: Reduced growth rates refer to the decline in the rate at which marine organisms, particularly calcifying organisms like corals and shellfish, develop and reproduce. This phenomenon is primarily driven by ocean acidification, which impacts the availability of carbonate ions necessary for building calcium carbonate structures. As atmospheric CO2 levels rise and ocean chemistry changes, these reduced growth rates can have cascading effects on marine ecosystems and their ability to adapt to environmental changes.
Restoration ecology: Restoration ecology is the scientific study and practice of repairing and restoring ecosystems that have been degraded, damaged, or destroyed. This field focuses on the principles and techniques necessary to return ecosystems to their natural state, enhancing biodiversity and ecosystem services. It connects deeply with environmental sustainability efforts, addressing the impacts of human activity and environmental change on ecosystems.
Saturation State: Saturation state refers to the level of dissolved calcium carbonate (CaCO₃) in seawater, indicating whether the water is undersaturated, saturated, or supersaturated with respect to this compound. This term is crucial in understanding how ocean chemistry affects marine life, particularly organisms that rely on calcium carbonate for their shells and skeletons. The saturation state influences the ability of these organisms to maintain their structures in changing oceanic conditions, especially those related to acidification and temperature fluctuations.
Shellfish beds: Shellfish beds are areas in aquatic environments where shellfish such as clams, oysters, and mussels live and grow. These beds are crucial ecosystems that provide habitat, contribute to biodiversity, and play a significant role in nutrient cycling within marine environments. The health of shellfish beds is significantly affected by environmental changes, including ocean acidification, which can disrupt the delicate balance of these ecosystems.