Marine Habitats Flashcards
What is the deepest and largest ocean?
Pacific
Portion of the Earth’s surface covered by ocean is 61% in the N hemisphere and 80% in the S hemisphere
All major oceans are interconnected
What are the different zones which the ocean can be spilt into?
1) Littoral zones= Close to shore= Negligible proportion of marine habitats but still high productivity
2) Continental shelf= Extends from continents, shallow water= Makes up 3% of habitats
3) Oceanic areas= Made up of various different zones, continental slopes and abyssal plains and mid-oceanic ridges
Layers of water: epipelagic (‘surface’ 6000 m)
What are the different wavelengths of light which penetrate to different depths of the ocean?
Clear ocean: Blue light
Coastal waters: Deepest= Green, Least= Red
Therefore: Red algae found at greater depth (as they contain phycoerythrin which absorbs green and blue light but reflects red light)
What causes waves? What causes larger waves?
Water particles do not move along a wave, but in circles
Wind action= Waves
Larger waves= Greater wind and longer uninterrupted distance
Massive forces generated by waves= 1 cubic metre of water= 1 tonne
What causes tides?
Tides: Rise and fall of sea level
Caused by interaction of centrifugal forces from spinning Earth with gravitational effect of moon & sun
Causes building of water around Earth
Wave with a very long wavelength, moving around Earth as it rotates
Usually 2 high tides and 2 low tides per day
Spring tide= Moon and sun along the same line
Neap tide= Moon at right angle from sun
The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since the Earth is also being pulled toward the moon (and away from the water on the far side). Since the earth is rotating while this is happening, two tides occur each day.
Why is the ocean’s climate important?
Warm currents move towards poles and cold towards the tropics= Giant thermostat
Coastal upwelling= Process in which deep, cold water rises toward the surface, winds blow across the ocean surface push water away, water rises from beneath the surface to replace the water that was pushed away= Important for nutrient transport, especially in tropics
What is El Nino- Southern Oscillation?
One climate-control system in which atmospheric and oceanic processes are linked= Massive effects on marine conditions and production off the West coast of South America
What happens to temperatures and nutrients at high latitudes, temperate regions and tropics?
Latitude: How far north or south it is from the equator
High latitudes: Waters are well mixed through depths= Nutrients are continually redistributed to the surface, temperatures stay relatively constant
Most of the heat energy of sunlight is absorbed in the first few centimeters at the ocean’s surface, which heats during the day and cools at night as heat energy is lost to space by radiation. Waves mix the water near the surface layer and distribute heat to deeper water such that the temperature may be relatively uniform
Temperate: at mid-latitudes- Seasonal thermoclines form + temperatures are much lower (0 to 10 degrees celsius)
Tropics: at low-latitudes- Permanent thermocline exists= preventing vertical mixing and nutrient redistribution
Thermocline: Thin, layer of large body of water in which temperature changes more rapidly with depth than it does in layers above or below (middle layer changes temperature much more)
Ocean: Divides upper mixed layer from calm deep water below
Where are the areas where there is high global primary production?
High availability of nutrients e.g. continental shelves (where rivers run in) + temperate and polar seas (e.g. North Sea and North Atlantic)
Tropic oceans: Only areas with upwelling currents have high productivity
What are some examples of Marine organisms?
- Phytoplankton (top)= Contain protists organisms, can photosynthesise
- Nekton (middle)= Mostly bigger animals such as fish and mollusc and squid
- Benthos (deepest)= Invertebrates
What is the Antarctic food web like?
Relatively simple, short food chains possible due to high abundance of nutrients and plankton- Rely mostly on primary production from phytoplankton, grazing by zooplankton and predation of fish
Highly efficient food chains as only have few links= Energy lost at just a few trophic levels
Example: Phytoplankton —> Krill –> Baleen whale
What us the Kelp forest like?
In temperate sublittoral= Just after littoral (which is just after the coast), but is always submerged. Very shallow
- Main kelp species in British waters belong to Laminaria
- Seaweed structure: Holdfast, stipe and blame
- One of the most productive habitats on Earth
- Refuge for invertebrates e.g. crustaceans, also fish and mammals such as seals
What is the rocky intertidal (littoral) donation like?
Dominated by biota of marine origin
- Upper limit: Determined by physical stress (temperature, desiccation)= Emersion period when tide is out
- Splash zone: Lichens and limpets, high tide zone
What are coral reefs like?
-Wide range of niches, very high biodiversity (25% of marine fish species found here)
-Different forms of corals: depending on exposure e.g. high wave action= Encrusting species, moderately exposed= Branched
-Corals are anthozoan cnidarians
-Colonial= Individual polyps are connected
-Hermatypic (reef building) corals secrete calcium carbonate skeletons, mostly in warm and shallow waters
-Most hermatypic corals contain symbiotic zooxanthellae (photosynthetic, unicellular, dinoflagellate protein)= Contribute to nutrition by fixing carbon
Symbiotic: Both provide nutrients to each other
-Coral bleaching: Zooxanthellae is expelled if coral gets stressed (bleaching) due to increased temperatures, acidification, deposition etc..
Zooxanthellae expelled as these conditions change= carbon fixation stops and polyp dies= leaving only calcium carbonate skeletons
What is the evolution of coral reefs?
1) Fringing reef= Close inshore
2) Barrier reef= Separated from land by lagoon
3) Atolls= Annular (ring forming) reefs formed round volcanic islands
