ECEC - life in the sea

Question 1

what percentage of the world is ocean?

Answer 1

71% (81% of southern

hemisphere, 61% of northern hemisphere)

Question 2

what is the average depth of the ocean?

Answer 2

3794 m

Question 3

2 facts about water liquidity

Answer 3

1) water molecules joined by weak hydrogen bonds

2) Water is liquid at unusually high temperatures - over wide temp ranges

Question 4

does water have a high or low specific heat capacity?

Answer 4

unusually high for a room temperature liquid - can store heat for a long time

Question 5

2 facts about water density

Answer 5

1) denser than air

2) Maximum density = -4 - water sinks below ice

Question 6

2 facts about light in water

Answer 6

1) Light can penetrate several 100 meters of clear still water
2) Red light absorbed before blue light

Question 7

2 facts about sound in water

Answer 7

1) Travels faster in water than air

2) Speed of sound increases with high temp and density

Question 8

how is salinity measured?

Answer 8

measured in practical salinity units

Question 9

what are the consequences of increased salinity?

Answer 9

1) lowers freezing point
2) Density increases
3) Water sinks - salt water sinks under fresh water
4) Colder water sinks - denser
5) Sea ice extrudes salt leaving saltier water underneath

Question 10

how much sun do marine photoautotrophs capture?

Answer 10

3% of the suns energy that hits the sea

Question 11

what are the 2 major types of marine photoautotrophs?

Answer 11

1) macrophytes (seaweeds)

2) phytoplankton

Question 12

3 facts about macrophytes

Answer 12

• benthic photoautotrophs
• need light
• need to be attached to sea bed
  therefore restricted to shallow coastal areas

Question 13

how did phytoplankton overcome coastal dependence and have the ability to occur throughout the ocean?

Answer 13

small single cells which can float - produce about half the oxygen in the atmosphere

Question 14

what are the 4 major classes of marine phytoplankton?

Answer 14

1) cyanobacteria
2) haptopytes
3) dinoflagellates
4) diatoms

Question 15

3 facts about phytoplankton

Answer 15

1) all small
2) very abundant
3) reproduce quickly

Question 16

what are 2 major problems for phytoplankton?

Answer 16

1) tend to sink (life threatening) - bigger cells sink faster - the smaller the better
2) nutrients also sink but light restricted to surface waters - light at top but nutrients at bottom

Question 17

what would happen if the ocean was constantly in a 2 layered state?

Answer 17

life would not be able to persist

Question 18

what 4 natural occurrences overcome the 2 layered ocean dilemma?

Answer 18

1) mixing by wind
2) earths rotation
3) surface currents
4) localised upwelling of nutrient rich deep waters

Question 19

describe thermohaline circulation?

Answer 19

cold water sinks near poles and moves towards the equator - tropical water is lifted, mixed and upwelled - as it is warmed at surface it then moves towards the poles - great ocean conveyor belt

Question 20

how do organisms survive in the 2 layered ocean?

Answer 20

1) migration - Seasonal or daily

2) Phenology (timing of biological events e.g. breeding - plankton blooms)

Question 21

what are the outcomes of the 2 layered ocean?

Answer 21

1) physical processes = patchy but very structured ocean -life has evolved to exploit this
2) Marine ecosystems are very distinct and exist in a distinctive form - adapted to live in different parts of the sea

Question 22

how much salt per 1000g or sea water?

Answer 22

35g - 86% Nacl