The Amazon

Question 1

Weathering of minerals over time

Answer 1

Minerals easiest to weather are removed first (ex: by rain)
Rate of weathering decreases over time

Question 2

Freshwater vs ocean saltwater foundational concept

Answer 2

lower salinity, low density river water flows over the top of the higher-salinity water

either saltwater will flow inland or freshwater will push it back beyond the edge of the landmass

Question 3

Freshwater Niches

Answer 3

differences in abiotic factors create niches in freshwater systems including light, water depth, bed quality, nutrient and oxygen availability

Question 4

freshwater systems with highest biodiversity have these 4:

Answer 4

varying areas of depth
availabilitly of light
high oxygen levels
high nutrient levels (not too high)
solid rock beds

Question 5

Drainage basin

Answer 5

high Andes basin has fast flow
but majority of Amazon river flows over a gradual slope

Question 6

Amazon River facts (5)

Answer 6

exceptionally wide and deep
mainly sand river bed
slow muddy water
low oxygen, few nutrients bc so large
near the equator, high rates of rain

Question 7

Biodiversity in Amazon

Answer 7

~2500 freshwater fish species found in the Amazon (that’s a lot)
high concentration of mammals, reptile predators

Question 8

Flood Pulse Effect

Answer 8

the flood cycle of a river interacting with existing abiotic and biotic processes in that river system
regular part of the ecosystem
flood becomes the main driver of what are “Seasons”

Question 9

Floodplains

Answer 9

largest on Earth
river banks extend 20km, floating meadows
flood cycle can last 6 months
different parts of the basin receive elevated rainfall levels at different times of the year

Question 10

Floodplain Rocks

Answer 10

much of the rock underlying the Amazon is from before the Cambrian
extremely weathered, few nutrients to erode
However, weathering of young Andes mountain range

Question 11

Floating Meadows

Answer 11

prolific aquatic plant growth extends over the surface of the water (can’t see water)
plants can grow 20 - 30 cm a day as flood waters rise
many aqautic plants only grow well when the region is fully flooded, mammals rely on flood cycle to eat

Question 12

Floodplain Forest Ecosystem

Answer 12

species diversity of trees within forest constantly shifting
differ species prefer different depths of water during flooding
changes in sediment deposition rates along different parts of the river

Question 13

Fish Biodiversity

Answer 13

adapted to use floodwater
ex: accessing terrestrial food, habitat, part of their lifecycle
migratory species can go to lakes that are normally isolated when the river floods

Question 14

Cons of high nutrients

Answer 14

high productivity leads to eutrophication, low levels of dissolved oxygen, fish die
produces dead zones

however, freshwater fish have evolved traits to mitigate this problem (behavoioral and physical)

Question 15

Adaptations to survive in low oxygen

Answer 15

air-breathing from the atmosphere - for a long time
migrate between areas of high oxygen
eat fish that can’t breathe

Question 16

Interspecies Interactions

Answer 16

plants use fish as seed disperses
terrestrial insects into the tree canopy
food resources from terrestrial environments

environmental heterogeneity: different species groups befit at different parts of the cycle

Question 17

Other processes increasing biodiversity

Answer 17

Diverse origins of water in the Amazon River create niche diversity along the river
Changes to the topography of the drainage basin over time

Question 18

Parent Rock

Answer 18

orignal rock type, can be transformed to create daughter materials
type of soil characterized by the size and type of rock that make up the rock component

Question 19

Parent Rock, Sediment, Plants

Answer 19

Young Andes Mountains
old continental crust before the Cambrian

Question 20

Clearwater, Blackwater, Whitewater

Answer 20

Clear water - common to a freshwater system

Black - high in plant tannins (decaying leaf matter, acidic, low nutrients)

White - Silt and nutrient rich, flows over Precambrian rock, weathered from the Andes

support the riches forests, extends from Andean slopes

Question 21

Bottom-up effect

Answer 21

Nutrient supply determines how many other species can survive in the ecosystem

*Many species of small fishes migrate between blackwater and whitewater

Question 22

Andes Uplift

Answer 22

Amazon Rainforest existed way before Andes
completely changed the drainage basin that fed the Amazon river
before Pangea breakup: Amazon basin drained towards Pacific,
Post: raise in elevation in the Andean gradually cut off drainage into Pacific
now flows towards the Atlantic ocean

can tell because some species connected with Pacific, highest species diversity found in Western region of the Amazon

Question 23

Quaternary Period

Answer 23

repeated cycles of glacier growth and retreat
during drier glacial periods: forests vastly restricted, increased niche heterogeneity
forest refugia: can support forest growth even when harsh climate eliminate forest in other regions

Question 24

fall in sea level …

Answer 24

fall in sea level will affect the end of the river first

fall in sea level means lower river bed means greater slope for water to flow down means faster flow of freshwater

fall in sea level will speed up flow

Question 25

Rise in sea level…

Answer 25

will slow down water velocity
slowed water velocity will deposit sediment earlier along the river, raises river bed, shallower slope for water to flow down

Question 26

River terrace

Answer 26

a fall in river level in a meandering river system will create multiple river terraces as the river meanders