Introduction to the marine environment

Question 1

How much of the earth’s surface does the ocean cover?

Answer 1

71%

Question 2

What is the salinity, freezing point, and density of seawater?

Answer 2

Salinity - 35% (PSU)
Freezing point- -1.8
Density - 24-28kg m-3

Question 3

How does salinity vary with depth and latitude?

Answer 3

Increasing depth = higher salinity
Higher density = lower temperature

Question 4

How is sea surface salinity determined?

Answer 4

By Evaporation and precipitation

Question 5

What drives ocean circulation?

Answer 5

Ice formation creates dense, hypersaline water that sinks below the surface water in areas of convergence.
The displacement of water elsewhere in areas of divergence drives deep ocean circulation.

Question 6

What are large circulating bodies of water driven by wind called?

Answer 6

Gyres … and they are connected to deep water currents this is called … the great ocean conveyor belt.

Question 7

Define a thermocline.

Answer 7

An area of ocean where the temperature changes (warm to cool) is called stratification.

This acts as a barrier to nutrients and phytoplankton and governs primary productivity.

Question 8

What are upwelling areas?

Answer 8

These are hotspots for primary productivity. Deep water carries lots of nutrients into the epipelagic.
Examples include Benguela, canaries, Peruvian and Californian seasonal currents.

Question 9

What are the main characteristics of upwelling areas?

Answer 9

Western seaboard and narrow continental shelves.
These areas are driven by wind which determines the thermocline and is impacted by the El Nino.

Question 10

How do El Nino and El Nina affect upwelling areas?

Answer 10

El Nino the winds slacken, upwelling stops.
El Nina the winds strengthen, and upwelling is increased.

Question 11

What are the different marine habitats?

Answer 11

Intertidal - Covered daily by tides
Benthic- Seafloor
Estuarine - Brackish - where rivers meet the sea.
Pelagic - Away from continents - open ocean.

Question 12

What are the significant marine intertidal habitats?

Answer 12

Rocky shore- solid bedrock with sessile invertebrates and algae.

Sedimentary- Dominated by infauna

Saltmarsh - Salt tolerant angiosperms

Mangroves- Salt-tolerant trees

Question 13

What are the different intertidal substrata?

Answer 13

Mud/silts and clays
Sand
Cobbles/boulders
Bedrock

Question 14

Describe an Estuary?

Answer 14

A highly complex and physiologically stressful environment.
Both are part of the marine, terrestrial, and freshwater environments.
Highly productive environments associated with blue C stores and ecosystem functions.

Question 15

What are significant marine coastal subtidal habitats?

Answer 15

Seagrasses: salt-tolerant angiosperms- superior C fixers.

Coral reefs: ecosystems reliant on zooxanthellae

Kelp forests: Dense algal forests.

Question 16

What are the terms used to describe the different marine pelagic subtidal habitats?

Answer 16

Epipelagic (0-200m)
Mesopelagic (200-1000m)
Bathypelagic (>1000)

Question 17

Name three significant marine benthic subtidal habitats.

Answer 17

Benthic - Mainly deposit feeders; limited food
Seamounts- Underwater mountains with unique deep-sea communities
Hydrothermal vents (HTV) -
Communities associated with active faults; are driven by chemoautotrophic bacteria.

Question 18

Compare the Arctic and Antarctic oceans.

Answer 18

Arctic -
Not a continent - a frozen ocean
Heavily influenced by oceanic and atmospheric circulation.
V. High primary productivity with high deposition rates.
high freshwater input
Ice microbial communities = rare
Antarctic -
A frozen continent with a fringe of sea ice.
Two main ice sheets are separated by the Transatlantic mountains
Krill is a keystone species that is correlated to sea ice.
Low freshwater input
Ice microbial communities = Common