Ocean deoxygenation is an additional stressor on marine life. Ocean deoxygenation is the expansion of oxygen minimum zones in the oceans as a consequence of burning fossil fuels. Along with this ocean deoxygenation is caused by an imbalance of sources and sinks of oxygen in dissolved waterLaffoley, D. & Baxter, J.M. (eds.) (2019). Ocean deoxygenation: Everyone’s problem - Causes, impacts, consequences and solutions. Full report. Gland, Switzerland: IUCN. 580pp. Individual chapters / sections within this report should be referenced as: Author(s). (2019). Title of chapter / section. In ‘Laffoley, D. Baxter, J.M. (eds.) (2019). Ocean deoxygenation: Everyone’s problem - Causes, impacts, consequences and solutions. Gland, Switzerland: IUCN. xxii+562pp.. Burning fossil fuels consumes oxygen, but because of the large atmospheric oxygen inventory, the associated relative decline of atmospheric oxygen (0.001\% per year) is about two orders of magnitude smaller than the current rate of ocean deoxygenation. The change has been fairly rapid and poses a threat to fish and other types of marine life, as well as to people who depend on marine life for nutrition or livelihood.Oceans suffocating as huge dead zones quadruple since 1950, scientists warn The Guardian, 2018Ocean's Oxygen Starts Running LowFinding forced trends in oceanic oxygenHow global warming is causing ocean oxygen levels to fall Ocean deoxygenation poses implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitats. Laffoley, D. and Baxter, J. M. (eds.) (2019) Ocean deoxygenation : everyone’s problem, IUCN Report. Ocean deoxygenation poses implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitats. Laffoley, D. and Baxter, J. M. (eds.) (2019) Ocean deoxygenation : everyone’s problem, IUCN Report. Total ocean oxygen content has decreased by 1-2\% since 1960. Following this a respiration of enhanced release of methane form melting gas hydrates in which bottom layers of water may result in the destabilization of methane gas, leading to more methane released form sediments and subsequent aerobic respiration of methane to Carbon dioxide. Another effect of climate change that causes ocean deoxygenation is circulation changes. As the ocean warms from the surface, stratification is expected to increase, which shows a tendency for slowing down ocean circulation which then increases ocean deoxygenation. Laffoley, D. Baxter, J.M. (eds.) (2019). Ocean deoxygenation: Everyone’s problem - Causes, impacts, consequences and solutions. Full report. Gland, Switzerland: IUCN. 580pp. Individual chapters / sections within this report should be referenced as: Author(s). (2019). Title of chapter / section. In ‘Laffoley, D.%DIFDELCMD < & %%% Baxter, J.M. (eds.) (2019). Ocean deoxygenation: Everyone’s problem - Causes, impacts, consequences and solutions. Gland, Switzerland: IUCN. xxii+562pp. Effects on coral reefs There has been a severe increase in mass mortality events associated with low oxygen causing mass hypoxia with the majority having been in the last 2 decades. The rise in water temperature leads to an increase in oxygen demand and the increase for ocean deoxygenation which causes these large coral reef dead zones. For many coral reefs, the response to this hypoxia is very dependent on the magnitude and duration of the deoxygenation. The symptoms can be anywhere from reduced photosynthesis and calcification to bleaching. Hypoxia can have indirect effects like the abundance of algae and spread of coral diseases in the ecosystems. While coral is unable to handle such low levels of oxygen, algae is quite tolerant. Because of this, in interaction zones between algae and coral, increased hypoxia will cause more coral death and higher spread of algae. The increase mass coral dead zones is reinforced by the spread of coral diseases. Coral diseases can spread easily when there are high concentrations of sulfide and hypoxic conditions. Due to the loop of hypoxia and coral reef mortality, the fish and other marine life that inhabit the coral reefs have a change in behavioral in response to the hypoxia. Some fish will go upwards to find more oxygenated water, and some enter a phase of metabolic and ventilatory depression. Invertebrates migrate out of their homes to the surface of substratum or move to the tips of arborescent coral colonies. Vanwonterghem, I. and Webster, N.S. (2020) "Coral reef microorganisms in a changing climate". Iscience, 23(4). . Effects on seagrass beds Globally, seagrass has been declining rapidly. It is estimated that 21\% of the 71 known seagrass species have decreasing population trends and 11\% of those species have been designated as threatened on the ICUN Red List. Hypoxia that leads to eutrophication caused form ocean deoxygenation is one of the main underlying factors of these die-offs. Eutrophication causes enhanced nutrient enrichment which can result in seagrass productivity, but with continual nutrient enrichment in seagrass meadows, it can cause excessive growth of microalgae, epiphytes and phytoplankton resulting in hypoxic conditions. Seagrass also provides many ecosystem services including water purification, costal protection, erosion control, sequestration and delivery of trophic subsidies to adjacent marine and terrestrial habitats. Continued deoxygenation causes the effects of hypoxia to be compounded by climate change which will increase the decline in seagrass populations.Waycott, M., Duarte, C.M., Carruthers, T.J., Orth, R.J., Dennison, W.C., Olyarnik, S., Calladine, A., Fourqurean, J.W., Heck, K.L., Hughes, A.R. and Kendrick, G.A. (2009) "Accelerating loss of seagrasses across the globe threatens coastal ecosystems". Proceedings of the national academy of sciences, 106(30): 12377–12381. Shrimp ponds in mangrove forests like these leave massive amounts of water pollution and compounds the negative effects of deoxygenation in mangrove forests. Effects on mangrove forests Compared to seagrass beds and coral reefs, hypoxia is more common on a regular basis on mangrove ecosystems, through ocean deoxygenation is compounding the negative effects by anthropogenic nutrient inputs and land use modification.
Ocean deoxygenation is an additional stressor on marine life. Ocean deoxygenation is the expansion of oxygen minimum zones in the oceans as a consequence of burning fossil fuels. Along with this ocean deoxygenation is caused by an imbalance of sources and sinks of oxygen in dissolved waterLaffoley, D. & Baxter, J.M. (eds.) (2019). Ocean deoxygenation: Everyone’s problem - Causes, impacts, consequences and solutions. Full report. Gland, Switzerland: IUCN. . Burning fossil fuels consumes oxygen, but because of the large atmospheric oxygen inventory, the associated relative decline of atmospheric oxygen (0.001\% per year) is about two orders of magnitude smaller than the current rate of ocean deoxygenation. The change has been fairly rapid and poses a threat to fish and other types of marine life, as well as to people who depend on marine life for nutrition or livelihood.Oceans suffocating as huge dead zones quadruple since 1950, scientists warn The Guardian, 2018Ocean's Oxygen Starts Running LowFinding forced trends in oceanic oxygenHow global warming is causing ocean oxygen levels to fall Ocean deoxygenation poses implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitats. Ocean deoxygenation poses implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitats. Total ocean oxygen content has decreased by 1-2\% since 1960. Following this a respiration of enhanced release of methane form melting gas hydrates in which bottom layers of water may result in the destabilization of methane gas, leading to more methane released form sediments and subsequent aerobic respiration of methane to Carbon dioxide. Another effect of climate change that causes ocean deoxygenation is circulation changes. As the ocean warms from the surface, stratification is expected to increase, which shows a tendency for slowing down ocean circulation which then increases ocean deoxygenation. %DIFDELCMD < & %%% Coral reefs There has been a severe increase in mass mortality events associated with low oxygen causing mass hypoxia with the majority having been in the last 2 decades. The rise in water temperature leads to an increase in oxygen demand and the increase for ocean deoxygenation which causes these large coral reef dead zones. For many coral reefs, the response to this hypoxia is very dependent on the magnitude and duration of the deoxygenation. The symptoms can be anywhere from reduced photosynthesis and calcification to bleaching. Hypoxia can have indirect effects like the abundance of algae and spread of coral diseases in the ecosystems. While coral is unable to handle such low levels of oxygen, algae is quite tolerant. Because of this, in interaction zones between algae and coral, increased hypoxia will cause more coral death and higher spread of algae. The increase mass coral dead zones is reinforced by the spread of coral diseases. Coral diseases can spread easily when there are high concentrations of sulfide and hypoxic conditions. Due to the loop of hypoxia and coral reef mortality, the fish and other marine life that inhabit the coral reefs have a change in behavioral in response to the hypoxia. Some fish will go upwards to find more oxygenated water, and some enter a phase of metabolic and ventilatory depression. Invertebrates migrate out of their homes to the surface of substratum or move to the tips of arborescent coral colonies. Vanwonterghem, I. and Webster, N.S. (2020) "Coral reef microorganisms in a changing climate". Iscience, 23(4). . Seagrass beds Globally, seagrass has been declining rapidly. It is estimated that 21\% of the 71 known seagrass species have decreasing population trends and 11\% of those species have been designated as threatened on the ICUN Red List. Hypoxia that leads to eutrophication caused form ocean deoxygenation is one of the main underlying factors of these die-offs. Eutrophication causes enhanced nutrient enrichment which can result in seagrass productivity, but with continual nutrient enrichment in seagrass meadows, it can cause excessive growth of microalgae, epiphytes and phytoplankton resulting in hypoxic conditions. Seagrass also provides many ecosystem services including water purification, costal protection, erosion control, sequestration and delivery of trophic subsidies to adjacent marine and terrestrial habitats. Continued deoxygenation causes the effects of hypoxia to be compounded by climate change which will increase the decline in seagrass populations.Waycott, M., Duarte, C.M., Carruthers, T.J., Orth, R.J., Dennison, W.C., Olyarnik, S., Calladine, A., Fourqurean, J.W., Heck, K.L., Hughes, A.R. and Kendrick, G.A. (2009) "Accelerating loss of seagrasses across the globe threatens coastal ecosystems". Proceedings of the national academy of sciences, 106(30): 12377–12381. Shrimp ponds in mangrove forests like these leave massive amounts of water pollution and compounds the negative effects of deoxygenation in mangrove forests. Mangrove forests Compared to seagrass beds and coral reefs, hypoxia is more common on a regular basis on mangrove ecosystems, through ocean deoxygenation is compounding the negative effects by anthropogenic nutrient inputs and land use modification.
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580pp. Individual chapters / sections within this report should be referenced as: Author(s). (2019). Title of chapter / section. In ‘Laffoley, D.
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Baxter, J.M. (eds.) (2019). Ocean deoxygenation: Everyone’s problem - Causes, impacts, consequences and solutions. Gland, Switzerland: IUCN. xxii+562pp..
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Laffoley, D. and Baxter, J. M. (eds.) (2019) Ocean deoxygenation : everyone’s problem, IUCN Report. Ocean deoxygenation
Ocean deoxygenation
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Laffoley, D. and Baxter, J. M. (eds.) (2019) Ocean deoxygenation : everyone’s problem, IUCN Report.
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Laffoley, D.
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Baxter, J.M. (eds.) (2019). Ocean deoxygenation: Everyone’s problem - Causes, impacts, consequences and solutions. Full report. Gland, Switzerland: IUCN. 580pp. Individual chapters / sections within this report should be referenced as: Author(s). (2019). Title of chapter / section. In ‘Laffoley, D.
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Baxter, J.M. (eds.) (2019). Ocean deoxygenation: Everyone’s problem - Causes, impacts, consequences and solutions. Gland, Switzerland: IUCN. xxii+562pp.
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Effects on coral
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Effects on seagrass
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Effects on mangrove
Mangrove