Ocean VL 1 Flashcards

1
Q

What are the two main categories of organisms in the pelagic zone?

A

1) Holo-pelagic: Organisms that spend their entire life in the pelagic zone (e.g., Ctenophora, Chaetognatha).

2) Mero-pelagic: Organisms that spend only part of their life cycle in the pelagic zone (e.g., larvae of benthic animals like Porifera, Polychaeta, and Crustacea).

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2
Q

What is the difference between neritic and oceanic plankton?

A

Neritic plankton:
* Found in the shelf region, with strong light availability and bottom influence.
* Includes phytoplankton like diatoms and dinoflagellates, and zooplankton like copepods and meroplanktic larvae.

Oceanic plankton:
* Lives in deeper waters, with no bottom influence.
* Includes holopelagic organisms like coccolithophorids, calanoid copepods, and euphausiacea (krill).

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3
Q

What is pleuston and what are some examples?

A

Pleuston refers to organisms that live at the surface of the water. Examples include:

  • Physalia (Portuguese Man o’ War): A siphonophore with meter-long capture polyps.
  • Sailing jellyfish: These jellyfish have sails angled at 45° to the wind, allowing them to move across the surface.
  • Janthina (Veilchenschneck)e: float of foam
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4
Q

: What are phytoplankton, and why are they important?

A

Phytoplankton are the primary producers in the ocean, responsible for 95% of marine primary production. They convert sunlight into energy and form the base of the marine food web. Common types include:

  • Cyanobacteria: Dominant in nutrient-poor regions.
  • Diatoms: Characteristic of spring and autumn blooms, with silica shells.
  • Dinoflagellates: Known for “red tides” and toxin production (e.g., saxitoxins).
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5
Q

What types of zooplankton dominate the pelagic zone?

A
  • Protozoa: Single-celled organisms.
  • Rotatoria and Nauplia: Multicellular micro-zooplankton.
  • Copepods: Dominant meso-zooplankton.
  • Krill (Euphausia hanseni): One of the highest biomass species on Earth.
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6
Q

What is nekton, and how does it regulate temperature and density?

A

Nekton are actively swimming organisms in the pelagic zone, including fish, cephalopods, and marine mammals.

  • Temperature regulation: Most nekton are poikilothermic (cold-blooded), except for air-breathing animals like marine mammals.
  • Density regulation: Nekton regulate their buoyancy with structures like gas bladders (fish) or gas chambers (cephalopods).

buoyancy Auftrieb

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7
Q

What are the major migratory patterns of marine organisms?

A

1) Vertical migration: Zooplankton and some fish move up at night and down during the day to avoid predators.

2) Gonodromous migration: Movement between feeding grounds and spawning/nursery areas.
* Anadromous species: Migrate from the sea to freshwater to spawn (e.g., salmon).
* Katadromous species: Migrate from freshwater to the sea to spawn (e.g., eels).

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8
Q

How does primary production vary between different ocean zones?

A
  • Neritic zone (continental shelf): 18% of global marine production in just 10% of the ocean area, with net primary production (PP) ranging from 70-500 g C m²/year.
  • Upwelling regions: Up to 1100 g C m²/year in just 0.1% of the ocean area, with extremely high productivity.
  • Oceanic zone: Low productivity, with net PP <50-120 g C m²/year.
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9
Q

What are the characteristics of food webs in the pelagic zone?

A
  • Nutrient-rich zones (upwelling regions): Short food chains dominated by diatoms and copepods, supporting large fish populations.
  • Nutrient-poor zones (subtropical ocean basins): Longer food chains involving picophytoplankton, ciliates, and tunicates.
  • Silicon-poor zones: Dinoflagellates dominate, leading to complex microbial loops.
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10
Q

How do oceans act as a CO₂ trap?

A

Oceans absorb more CO₂ than they release, trapping approximately 2 x 10¹⁵ g C per year, which is about 30% of the anthropogenic CO₂ produced by burning fossil fuels. Fertilization with iron can further increase primary production and enhance carbon sequestration in deep water.

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