Lecture 6: Organisms: Convergence in fresh water & marine systems

Question 1

the four types of freshwater aquatic systems

Answer 1

1. flowing water - streams and rivers
2. standing water - lakes and ponds
3. wetlands
4. estuaries

Question 2

how do streams form

Answer 2

it forms whenever precipitation exceeds transpiration and evaporation

Question 3

lotic systems

Answer 3

-rivers and streams
-very sensitive to changes in water flow

Question 4

river continuum

Answer 4

The continuous combination and growth of streams, to rivers, to the river mouth, and the associated shifts in environments and ecosystems

Question 5

Riparian zone

Answer 5

Distinct terrestrial vegetation that borders lotic systems and experiences seasonal flooding and an elevated water table

Question 6

streams

Answer 6

• within streams, riffles and pools represent distinct environments, but they are both low productivity
• food webs are allochthonous

Question 7

streams - what does it mean that food webs are allochthonous

Answer 7

-the organisms in streams depend on organic input at the base of the food web from outside the system to stay balanced
-this can include leaves and dead materials that fall into the stream

Question 8

rivers

Answer 8

-becomes more autochthonous as it gets larger
-has a balanced food web, but silt and turbulent water currents can reduce productivity
-Downstream movement of nutrients and life must be balanced by upstream inputs and allochthonous material.

Question 9

rivers - what does it mean for the river to be autochthonous

Answer 9

nutrients and sunlight support the algal growth from within the river

Question 10

direct ecological consequences of dams

Answer 10

-Disruption to the nutrient flow to lower regions of the river.
-Habitat conversion/destruction of large upstream adjacent area (the reservoir)
-Nutrient buildup on the upstream side of the dam.
-Movement and dispersal disruption for aquatic life, especially fish migration and reproduction.

Question 11

standing water - lakes and ponds

Answer 11

-found in glacier depressions, glacier melts and forms the standing water
-subdivided into 3 / 4 distinct ecological zones

Question 12

lentic systems

Answer 12

-lakes and ponds

Question 13

standing water - Littoral zone

Answer 13

shallow areas, with rooted vegetation

Question 14

standing water - Limnetic zone

Answer 14

-open water with floating algae

Question 15

standing water - Profundal zone

Answer 15

-very deep water with no light
-found only in deep lakes

Question 16

standing water - Benthic zone

Answer 16

sediment with burrowing and microorganisms

Question 17

Thermal zone and circulation in temperate lakes

Answer 17

-in most temperate lakes there is thermal stratification
-the surface layer and the deeper layers both have seasonally different temperatures
-a thermocline is present
-most production of biomass occurs in the surface layer where light can pass through for photosynthesis and oxygen levels are high

Question 18

temperate lakes - what is thermal stratification

Answer 18

there are distinct temperature zones in the lakes

Question 19

temperate lakes - thermocline

Answer 19

-forms between the warming and circulating surface layer and the more static deeper layer
-this region of rapid temperature change further limits mixing

Question 20

spring in temperate lakes

Answer 20

winds drive a mixing of layers and distribution of nutrients

Question 21

spring -> summer in temperate lakes

Answer 21

-thermocline forms
-high production in surface layer
-nutrients become limited and production declines

Question 22

summer -> autumn in temperate lakes

Answer 22

-thermocline disappears with seasonal cooling
-nutrients mixed with by wind turbulence

Question 23

autumn -> winter in temperate lakes

Answer 23

winter refuge for organisms in deep water

Question 24

algal bloom and human impacts in temperate lakes

Answer 24

-summer water heating and fun-offs can lead to algal blooming
-as the algae keeps blooming, the water becomes more covered and vegetation dies
-the oxygen is then used off
-when those organisms die oxygen is released, but the decomposition process burns the oxygen down
-results in no oxygen left for that system

Question 25

temperate lakes - eutrophication

Answer 25

-the algal bloom happens do to humans adding an excess of nutrients into the lakes through runoff
-bc there is an abundance of nutrients, there is no limits on the algae blooming

Question 26

wetlands

Answer 26

-they are the direct interaction of aquatic and terrestrial systems
-land that is permanently saturated and supports vegetation adapted to these condition
-plants are adapted to low oxygen concentrations in the saturated soils

Question 27

how are estuaries formed

Answer 27

at the mouth of rivers, typically when the river mouth is surrounded by land

Question 28

what are estuaries

Answer 28

Aquatic environment with a unique mix of fresh and salt water

Question 29

estuary - nutrients

Answer 29

-it is well-supplied with nutrients and sediment from rivers that deliver fresh water
-rapid nutrient exchange between the sediment and shallow water allows for high productivity

Question 30

estuary - high sediment deposition

Answer 30

-this creates salt mashes and mangrove wetlands
-salt marshes are exceptionally productive due to nutrient levels
-estuaries always have wetlands surrounding them

Question 31

Distinct zones of marine systems

Answer 31

1. Intertidal zones
2. Coral reefs
3. Neritic zone
4. Oceanic zone
5. Benthic zone

Question 32

marine systems - Intertidal zone

Answer 32

-this biome is found between the low to high tide
-the zonation of organisms is according to air exposure tolerance

Question 33

Marine systems - Coral reefs

Answer 33

-this biome found in warm, shallow marine waters
-Structural complexity and productivity of system supports high biodiversity
-this zone is defined by a narrow range of conditions
-sensitive to temperature and pH changes

Question 34

marine systems - Neritic zone

Answer 34

-Depths down to the continental shelf
-High productivity from sunlight and tidal nutrient turbulence
-subdivided into the upper photic zone and deeper aphotic zone
-deeper areas are still relatively nutrient rich because of overall productivity of the system

Question 35

marine systems - oceanic zone

Answer 35

-Nutrient availability and productivity are low
-subdivided into photic zone and aphotic zone

Question 36

marine systems - Benthic zone

Answer 36

Sediment for burrowing and micro organisms