Ocean VL 1 Flashcards
What are the two main categories of organisms in the pelagic zone?
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).
What is the difference between neritic and oceanic plankton?
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).
What is pleuston and what are some examples?
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
: What are phytoplankton, and why are they important?
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).
What types of zooplankton dominate the pelagic zone?
- 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.
What is nekton, and how does it regulate temperature and density?
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
What are the major migratory patterns of marine organisms?
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).
How does primary production vary between different ocean zones?
- 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.
What are the characteristics of food webs in the pelagic zone?
- 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.
How do oceans act as a CO₂ trap?
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.
