Intro to Marine Ecosystems

Question 1

How much of the world is oceans?

Answer 1

71%

Question 2

What are the major causes of marine life?

Answer 2

Benthic - on (epifauna) or in (infauna) the sea bed

Demersal - associated with the sea bed

Pelagic - in the water column, includes passive drifters (e.g. plankton) and active swimmers (e.g. nekton)

Many benthic organisms have planktonic larvae which links the benthic and pelagic realms

Question 3

What are the main primary producers in marine ecosystems?

Answer 3

Phytoplankton

Question 4

What are the main features of phytoplankton?

Answer 4

Overcome coastal dependance by being single celled (small) and by floating

Occur throughout oceans but not homogeneously

Phytoplanktons are responsible for 50% of all photosynthesis and so are responsible for 50% of oxygen production

Question 5

What did NASA’s MODIS show when looking at productivity?

Answer 5

Ocean is heterogenous and has structure

Question 6

How does the ocean overcome the two-layered dilemma?

Answer 6

Mixing of surface waters by wind

Coriolis effect due to Earth’s rotation

Surface currents driven by ocean-atmosphere interactions

Localised upwelling of nutrient-rich deep waters driven by the above

Question 7

How can the seas be divided?

Answer 7

Horizontally by geography (Ocean basins)

Vertically by depth (Depth zones)

Biologically by productivity

Biogeographically by species composition, ecosystems, biomes and ecoregions

Question 8

What are all the ocean basins?

Answer 8

Pacific

Atlantic

Indian

Arctic

Southern

Question 9

What are all the major seas?

Answer 9

North

Baltic

Mediterranean

Caribbean

Red

South China

Question 10

What is combined to create divisions?

Answer 10

Oceans and seas

Question 11

What are the features of the ocean floor?

Answer 11

Shelf = continental shelf (at sea level)

Slope

Rise

Sea mount (filled with life)

Guyot

Island (if a sea mount breaks sea level)

Mid-ocean ridge

Abyssal plain (most deep sea is this)

Trench

Question 12

What are the major depth zones?

Answer 12

Epipelagic/eutrophic zone (50-200m) - light enough for photosynthesis

Mesopelagic/dysphotic zone (up to 1000m) - enough light for animals to see but not for plants, has the highest abundance of vertebrates

Bathypelagic/aphotic zone (to 6000m) no light but is 3/4 of the marine world

Hadal zone (>6000m) the deep ocean trenches

Question 13

What is Longhurst’s biogeographical provinces?

Answer 13

Oceans are divided into four pelagic biomes based on the physical forces regulating the distribution of phytoplankton

Polar biome

Westerlies Biome (temperate)

Trade-Winds Biome (Tropical)

Coastal Boundary Zone Biome