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What is the primary factor that creates the stratification in the upper water column of the subtropical ocean?
At what depth does very little sunlight penetrate in the subtropical ocean?
Which condition was observed during the station occupation in July 2008 at the Bermuda Atlantic Time-series Station?
What does the term 'mixed layer' refer to in the context of ocean stratification?
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How does wind affect the stratification of the upper water column?
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What is indicated by the presence of a defined shallow wind-mixed surface layer?
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What role does particulate organic carbon play in the ocean environment?
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Which temperature indicates a significant difference in water density in the upper ocean layers?
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What is the primary factor limiting the new supply of nitrogen and phosphorus in the upper thermocline?
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What happens to the particulate organic carbon produced by phytoplankton growth?
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Why should the deep chlorophyll maximum (DCM) not be interpreted strictly as a depth maximum in phytoplankton biomass?
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What C:N:P stoichiometric ratio did Alfred Redfield associate with plankton biomass?
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What influences the depth to which sunlight can penetrate in the ocean?
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Redfield observed that the dissolved N:P ratio in the deep ocean aligns closely with which ratio of plankton biomass?
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What is the result of the accumulation of particulate organic carbon in the surface ocean?
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What does ocean productivity primarily refer to?
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What role does sunlight play in the ocean ecosystem?
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What do phytoplankton do to produce organic carbon?
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Which organisms are classified as heterotrophs in the open ocean?
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What does NEP stand for in ocean productivity?
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How is NEP described in terms of the seafloor community?
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What is the euphoric zone in the ocean?
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The process of organic matter sinking into the dark ocean interior is often associated with which term?
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What role do photoautotrophs play in ocean ecosystems?
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What essential role does iron play in organisms?
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Why does iron scarcity limit productivity in the ocean?
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What is the term for the vertical temperature gradient that drives density stratification in the ocean?
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Which type of plankton primarily utilizes silicon to form opal hard parts?
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What is the pycnocline characterized by?
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What effect does warm water have in relation to cold water in the ocean?
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Which factors drive the mixing of water layers in the ocean?
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What typically happens to diatom-associated organic matter in Si-bearing waters?
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What is primarily responsible for nutrient accumulation in deep waters?
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Which genera of cyanobacteria dominate phytoplankton in nutrient-poor tropical and subtropical oceans?
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What does Liebig's Law of the Minimum suggest regarding plant growth?
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Which factor is thought to enhance phytoplankton's light capture efficiency in polar regions?
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What type of production do smaller phytoplankton like unicellular cyanobacteria predominantly contribute to?
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What is the primary limitation on ocean productivity due to nutrient dynamics?
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How do interactions between nutrients and light affect ocean productivity?
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In the context of ocean biogeochemistry, what does NEP stand for?
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Study Notes
Ocean Productivity
- Ocean productivity refers to the production of organic matter by phytoplankton, which are single-celled plants suspended in the ocean.
- Phytoplankton are photoautotrophs, which means they use sunlight to convert inorganic carbon into organic carbon.
- This organic carbon is then consumed by heterotrophic organisms, including bacteria, zooplankton, nekton, and benthos.
Key Nutrients
- Major nutrients for phytoplankton growth include nitrogen (N), phosphorus (P), iron (Fe), and silicon (Si).
- Phytoplankton require N and P in roughly a 16:1 ratio, known as the Redfield ratio.
- Iron is a key component of essential enzymes and proteins, and its scarcity often limits productivity in the open ocean, particularly where deep water upwelling occurs.
- Silicon is a nutrient specifically for diatoms, silicoflagellates, and radiolaria, which use it to form hard parts.
Factors Affecting Productivity
- Sunlight: The amount of sunlight penetration depth is restricted to a depth of ~80m, with greater depths in less productive regions.
- Nutrient Availability: The upper sunlit layer is often nutrient-poor due to the slow mixing across the pycnocline (density gradient) or thermocline.
- Phytoplankton Size: Small, single-celled cyanobacteria like Synechococcus and Prochlorococcus dominate phytoplankton biomass in the open ocean.
- Mixing: Wind and other sources of energy are necessary to drive mixing across the pycnocline, which enables nutrient transport and exchange in the ocean.
Export Production (NEP)
- Export Production (NEP) is defined as the net amount of organic carbon exported from the euphotic zone, which is the surface layer down to 1% light penetration depth.
- NEP is equivalent to the particulate organic carbon sinking into the deep ocean plus the dissolved organic carbon that is circulated out of the euphotic zone.
Key Concepts
- Regenerated Production: The use of nutrients already present in the water column by phytoplankton.
- New Production: The production of organic matter using nutrients that have been input from outside sources, such as upwelling of deep waters.
- Co-limitation: The growth of phytoplankton is limited by a combination of different factors, such as light availability, and nutrient supply.
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Description
This quiz explores the concept of ocean productivity, focusing on phytoplankton and their role in organic matter production. It also examines essential nutrients like nitrogen, phosphorus, and iron that influence phytoplankton growth and the overall health of marine ecosystems. Test your knowledge on the factors affecting oceanic productivity and nutrient dynamics.
