CH8 - Aquatic Biodiversity

Question 1

Two Types of Aquatic Biomes

Answer 1

Marine and Freshwater

Question 2

Plankton

Answer 2

• free-floating, weak swimming ability
• phytoplankton are capable of photosynthesis
• zooplankton are animals

Question 3

Nekton

Answer 3

• capable of sustained locomotion (against prevailing water movement)

Question 4

Benthos

Answer 4

• bottom-dwelling organisms
• without need for swimming

Question 5

What does biodiversity in aquatic biomes depend on?

Answer 5

• temperature
• access to sunlight
• dissolved oxygen levels
• availability of nutrients (CO2, NO3 -, PO4 3-)
• aquatic photosynthesisers have adapted to these pressures

Question 6

Marine Biomes

Answer 6

• saltwater oceans cover about 71% of Earth’s surface
• oceans regulate global temperature and climate
• there are over 1mil known marine species; as many as 9mil undiscovered

Question 7

Major marine zones

Answer 7

Neritic zone: extends to the edge of continental shelf; contains 90% of all marine species
Oceanic zone: includes all waters beyond continental shelf

Question 8

Estuaries

Answer 8

• partially enclosed area of coastal water
• where seawater and freshwater mix
• constant movement of tides & currents
• nutrient-rich environment
• wide range of temperature and salinity

Question 9

Coastal Wetlands

Answer 9

• areas of coastal land that are converted with saltwater all or part of the year
• why are they important?
  
  • they filter water, protect shorelines from erosion, provide feeding and breeding grounds for many organisms

Question 10

Marsh

Answer 10

• freshwater or estuarine wetlands dominated by grasses

Question 11

Bogs

Answer 11

• inland freshwater wetlands
• dominated by mosses

Question 12

Swamps

Answer 12

• freshwater, estuarine, or marine wetlands
• dominated by trees
• i.e. mangrove swamps
  
  • tropical communities
  • dominated by halophytic trees (adapted to grow in saline conditions)

Question 13

Coral Reefs

Answer 13

• massive colonies of coral polyps living in a “skeleton” of calcium carbonate (limestone)
  
  • most coral is a mutualistic symbiosis with zooxanthelle (single-cell algae)
• oldest & most productive ecosystems
• very slow growth rate

Question 14

Threats to Coral Reefs

Answer 14

• warming & acidification of the oceans —> calcium carbonate dissolves, coral bleaching
  
  • coral becomes stressed and expels zooxanthelle
• increased UV radiation
• global warming
• runoff pesticides, fertilizers, industrial chemicals

Question 15

Oceanic Zone

Answer 15

• least productive of all ecosystems
• light only penetrates surface levels
• red wavelengths penetrate up to 1m; blue wavelengths penetrate up to 200m

Question 16

Divisions of Oceanic Zone

Answer 16

Has light
- epipelagic/photic (0m-200m)
- mesopelagic (200m-1000m)

Pitch dark
- bathypelagic (1000m-4000m), 4-10ºC
- abyssalpelagic (4000m-6000m), overlies plains of major ocean basins
- halaylpelagic (6000m-10,000m), includes open water of deep trenches

Question 17

Polar Marine Ecosystems

Answer 17

• polar caps are considered marine ecosystems bc primary food source is plankton
• Arctic Ocean- rich in nutrients (from surrounding land masses)
• Antarctic Ocean- lacks surrounding land masses, not very rich in nutrients

Question 18

Freshwater Biomes

Answer 18

• where water with a salinity of less than 1ppt accumulates/flows through surfaces of terrestrial biomes
• lentic systems: standing water (i.e. lakes, ponds, inland wetlands)
• flowing systems: moving water (i.e. streams, rivers)

Question 19

Lakes & Ponds

Answer 19

• large standing bodies of freshwater; where water fills depressions in Earth’s surface
• seasonal changes occur in temperate lakes —> overturn of water column
• during summer/winter, water becomes stratified into different temperature layers (thermocline)
• during spring/fall, waters at all layers mix (overturn) and equalize temperatures at all depths

Question 20

Four Major Zones of Lakes

Answer 20

• littoral zone- from shallow area near the shore to where rooted plants stop growing
• limnetic zone- open sunlit water surface layer; extends to the depth penetrated by sunlight
• profundal zone- deep, open water; too dark for photosynthesis
• benthic zone- bottom of lake

Question 21

Zones of Streams & Rivers

Answer 21

• source zone: headwaters of the river; cold, clear, highly oxygenated water
• transition zone: headwater streams marge to form wider, deeper streams; warmer & slower moving water supports >biodiversity (i.e. phytoplankton)
• flood plain zone: streams join into wider and deeper rivers that meander across broad, flat valleys; supports the greatest number of organism species

Question 22

Watershed

Answer 22

• aka drainage basin
• land area that delivers water, sediment, and dissolved substances to a stream/river
• characteristics: area, length, slope, soil, vegetation

Question 23

Inland Wetlands

Answer 23

• marshes, swamps, bogs, seasonal wetlands (e.g. floodplain wetlands, prairie potholes)
• why are they important?
  
  • provide food & habitat for fish, migratory waterfowl, wildlife
  • filter, dilute, and degrade toxic waste, excess nutrients, sediment other pollutants from runoff
  • reduce flooding & erosion (absorb overflows of streams & lakes)