Biodiversity 4 - Marine Ecosystems

Question 1

Explain marine ecosystems

Answer 1

• Classified according to the depth at which they occur, their distance from shore, and sunlight penetration
• Divided into two major types:

1. Coastal ecosystems ( Seashores )
2. Open ocean ecosystems (Pelagic division; Benthic division )

Question 2

Explain seashores

Answer 2

• Intertidal zones
• Areas where the land and sea meet
• Extend from low-tide to high-tide mark
• Alternately submerged and exposed by daily tide cycles
• Organisms need to be well adapted becuase enviro changes constantly

Question 3

What do organisms in seashores need to cope with

Answer 3

1. Large variations in the availability of seawater
2. Variations in temperature
3. Mechanical forces of wave action

Question 4

Explain the sandy shores

Answer 4

• No attachment sites available as the sand is unstable and constantly shifting
• Nearly all permanent residents live in underground burrows
• Volitle and unstable environment
• Mobile animals

Question 5

Explain oceans

Answer 5

• Play a significant role in all ecosystems
• Most of the planet’s rainfall is provided by evaporation of seawater
• World’s climate and wind patterns are affected by ocean temperatures
• Marine algae produce a large portion of the Earth’s oxygen and consume large amounts of carbon dioxide

Question 6

Explain the rocky shore

Answer 6

• Sessile organisms
• Characterised by organisms that attach themselves to rocks
• Has a littoral zone which has 3 sub zones
• Not a lot of spae leading to a lot of competition ( limiting factor )

Question 7

What are the 3 sub-zones of the littoral zone

Answer 7

• Upper littoral zone
• Mid littoral zone
• Lower littoral zone

Question 8

Explain eachh of the sub-zones of the littoral zone

Answer 8

1. Upper littoral zone – submerged only by the highest tides ( at top & more exposed to sunlight )
2. Mid littoral zone – exposed at low tide and submerged at high tide
3. Lower littoral zone – exposed only during the lowest tides ( at bottom & always covered by water )

Question 9

What makes up pelagic division

Answer 9

1. Neritic province
2. Oceanic province :

2.1 - Epipelagic zone
2.2 - Mesopelagic zone
2.3 - Bathypelagic zone
2.4 - Abyssopelagic zone

Question 10

What makes up Benthic division

Answer 10

1. Continental shelf
2. Continental slope
3. Abyssal plain

Question 11

Explain pelagic divison

Answer 11

• Open waters of any depth

Neritic province
Oceanic province

Question 12

Explain the neritic province

Answer 12

• Extends from the intertidal zone, across the shallow regions, to the edge of the continental shelf
• High concentration of organisms due to high sunlight penetration and a constant supply of inorganic nutrients from river runoff
• Photosynthetic phytoplankton form the base of the food chain

not very deep & very productive zone

Question 13

Explain coral reefs

Answer 13

• Found in the neritic province, bordering tropical coastlines
• Productivity and species diversity comparable to a tropical rain forest
• Shallow, warm waters allow much photosynthetic activity, which in turn supports a large animal biomass
• Structure of coral provides diverse habitats for animal species

Question 14

Explain coral bleaching

Answer 14

• Corals very sensitive to climate change
• Small rise in temperature stresses corals; expel their zooxanthellae symbionts
• Leads to death of the coral

Question 15

What zones make up the oceanic province

Answer 15

• Epipelagic
• Mesopelagic
• Bathypelagic
• Abyssopelagic

Question 16

Explain the oceanic province

Answer 16

Conditions change from surface to bottom of ocean:

1. Light diminishes
2. Temperatures become colder
3. Water pressure increases
4. Oxygen diminishes

Question 17

Explain the epipelagic zone

Answer 17

• Uppermost layer that extends from the water’s surface to the limit of sunlight penetration
• Majority of life in the open ocean is found here
• Well developed body of animals in zone to withstand waves

animals = fish; whales; sharks

Question 18

Explain mesopelagic zone

Answer 18

• Not enough light for photosynthesis
• Animals are mostly carnivores
• Often migrate to surface at night to feed

eg ) squid; shrimp ; red fish ( disguise from predators )

Question 19

Explain bathypelagic zone

Answer 19

• Almost entirely dark; there is some bioluminescence

(Bioluminescence is a form of chemi- luminescence where light energy is released by a chemical reaction)

• Dominated by carnivores and scavengers
• Use light source to communicate with others; attract prey; escape predators
• Lomg stomach and body; slow metabolism

Question 20

Explain benthic

Answer 20

• Refers to the sea floor

Divided into:

1. Continental shelf (sublittoral zone)
2. Continental slope (bathyal zone)
3. Abyssal plain (abyssal zone)

Question 21

Explain abyssopelagic zone

Answer 21

• Bottom layer of ocean water
• Completely dark
• Organisms need to be able to withstand enormous pressures and extreme cold of the ocean depths

Question 22

Explain ocean ccurrents

Answer 22

• Major ocean currents move heat from the equator to cooler parts of the biosphere
• Currents move in a circular path – clockwise in the
  Northern hemisphere
  and counterclockwise
  in the Southern hemisphere

Question 23

Explain hydrothermal vents briefly

Answer 23

• Vents support chemosynthetic bacteria which form the basis of unique ecosystems

Question 24

Explain hydrothermal vents fully

Answer 24

• Abyssal plain interrupted by oceanic ridges – enormous underwater mountain chains
• Ocean crust splits apart along these ridges to form hydrothermal vents
• Seawater heats up to 350°C due to volcanic reactions