Components of freshwater ecosystems

Question 1

Give four examples of services that water ecosystems provide humans

Answer 1

Transport, irrigation, hygiene, waste disposal

Question 2

Describe lentic ecosystems

Answer 2

Stationary/slow flowing water. Closed system.

Question 2

Name three types of water ecosystem

Answer 2

Lentic and lotic ecosystems and wetlands

Question 3

Give three examples of lentic ecosystems

Answer 3

Lakes, ponds, and pools

Question 4

Give three factors that can be used to classify lentic ecosystems

Answer 4

Age, size, and nutrient richness

Question 5

Describe lotic ecosystems

Answer 5

Running water. Open systems

Question 6

Give three examples of types of lotic ecosystems

Answer 6

Rivers, streams, and springs

Question 7

Describe how lotic ecosystems affect water chemistry.

Answer 7

Their catchment area influences river contents. They transfer, transport, and dilute materials and chemicals.

Question 8

Describe wetlands

Answer 8

Areas of standing water that support aquatic plants. The interface of terrestrial and aquatic ecosystems. Can be permanent or temporary, natural or artificial, and flowing or stagnant.

Question 9

How do wetlands alter stream hydrology?

Answer 9

They impede flow and enhance sediment deposition.

Question 10

Give three examples of wetland ecosystems

Answer 10

Marshes, swamps, bogs

Question 11

How do wetlands contribute to the release of detritus downstream?

Answer 11

They transform inflowing nutrients into organic forms

Question 12

Define epibenthic

Answer 12

Attached or clinging to plants

Question 13

Define neuston

Answer 13

Resting or swimming on the surface

Question 14

Define epipelic biofilms

Answer 14

A biological complex of autotrophs and heterotrophs

Question 15

What are benthic macroinvertebrates?

Answer 15

Organisms that inhabit the substrate for at least part of their lifecycle.

Question 16

What size mesh can benthic macroinvertebrates be caught in?

Answer 16

200-500μm

Question 17

What role do benthic macroinvertebrates play in freshwater ecosystems?

Answer 17

Key components of aquatic food webs (linking organic matter and nutrient resources)

Question 18

Describe zooplankton

Answer 18

Minute aquatic animals that either drift or are very week swimmers.

Question 19

Give three types of zooplankton

Answer 19

Rotifers, Cladocerans, and Copepods

Question 20

What type of organism is useful in the detection of changes in the environment and why?

Answer 20

Zooplankton because they are very sensitive.

Question 21

Give three categories of plants found in freshwater ecosystems

Answer 21

Phytoplankton, periphyton, and macrophytes

Question 22

Describe the environment where phytoplankton are found

Answer 22

Slow-flowing rivers with high temperatures and light intensity

Question 23

What are periphyton?

Answer 23

Unicellular and filamentous algae.

Question 24

Where can periphyton be found?

Answer 24

Living on the substrate or on larger plants

Question 25

What can macrophytes be used for?

Answer 25

Pollution indication

Question 26

What are the four types of macrophytes?

Answer 26

Emergent leaves, floating leaved, free floating, and submerged

Question 27

What types of organisms make up the major biological communities in lake and pond ecosystems?

Answer 27

Plankton and nekton

Question 28

What types of organisms make up the major biological communities in floodplain and permanent wetlands?

Answer 28

Plankton, nekton, epiphyton, benthos

Question 29

What type of organisms make up the major biological communities in rivers and streams?

Answer 29

Benthos

Question 30

What types of organisms make up the major biological communities in estuaries (mudflats)?

Answer 30

Epipelic biofilms

Question 31

What types of organisms make up the major biological communities in estuaries (outflow)?

Answer 31

Plankton, nekton

Question 32

What can be influenced by the physical and chemical properties of freshwater ecosystems?

Answer 32

Abundance, distribution, and biodiversity

Question 33

Describe the three layers of water depth

Answer 33

Epilimnion (surface, warmer), metalimnion (thermocline), hypolimnion

Question 34

How does water flow and how is the flow measured?

Answer 34

Flows in an open channel and is measure in discharge (volume of water passing through a given point per unit time)

Question 35

How does the velocity of flow in a river relate to depth?

Answer 35

Inverse proportionality

Question 36

What can flow also be influenced by?

Answer 36

The type of sediment bed, seasonal precipitation, catchment geology, bed slope, floods, human impacts

Question 37

What kind of flow picks up more silty and sandy substratum?

Answer 37

Rapid river flows

Question 38

What type of substrate has a greater range of invertebrates than silt-rich pools?

Answer 38

Stony substrate

Question 39

What reduces an organism's habitation and how?

Answer 39

Silt deposition alters an organisms' habitation because it alters water movement and reduces oxygen levels and food availability

Question 40

What scale is used to classify rock particle sizes?

Answer 40

Wentworth Scale

Question 41

What is the effect of low water velocity?

Answer 41

Net deposition, forming a deposition zone

Question 42

What is the effect of high water velocity?

Answer 42

Net resuspension, forming an erosional zone

Question 43

Why are some organisms able to sit on top of the water's surface?

Answer 43

The water has high surface tension (7n28Nm^-1) and the organisms attach with the least surface area possible

Question 44

What is primary production rate influenced by?

Answer 44

Light availability

Question 45

What tool is used to measure transparency in lentic ecosystems?

Answer 45

Secchi disc

Question 46

What are the respective names for the depths of water that are penetrated and unpenetrated by light?

Answer 46

Photic and aphotic zones

Question 47

What is conductivity the result of?

Answer 47

The concentration of ions

Question 48

How much more conductive is seawater than freshwater?

Answer 48

20% higher

Question 49

What is the conductivity of freshwater?

Answer 49

150-500µSeimens cm^-1

Question 50

What does high specific heat capacity and poor thermal conductivity result in?

Answer 50

Moderate diurnal and seasonal changes in water temperature and a decrease in the rate of decomposition of matter

Question 51

How does an increase in discharge affect conductivity?

Answer 51

Decreases conductivity by dilution by precipitation. Precipitation doesn't pass through the geology, therefore does not pick up an ions.

Question 52

When is dissolved oxygen especially limiting to sensitive biota?

Answer 52

At high temperatures

Question 53

Give two reasons for low levels of dissolved oxygen in water?

Answer 53

Can be limited in stratified water due to lack of transfer to lower layers and can be depleted at night due to plant respiration.

Question 54

How does temperature affect levels of dissolved oxygen?

Answer 54

Higher temperatures result in low levels of dissolved oxygen.

Question 55

How do organisms the prefer lower levels of oxygen have an advantage over those that need more?

Answer 55

They can produce with lower oxygen availability

Question 56

What ions result in water 'hardness'?

Answer 56

Ca2+ and Mg2+

Question 57

What ions result in permanent water 'hardness'?

Answer 57

Cl- and CO4 2-

Question 58

What is the pH of hard water?

Answer 58

pH>8.5

Question 59

Give two examples of factors that impact water pH levels

Answer 59

Soil geology and human activity

Question 60

Give three examples of human activity that can influence water pH

Answer 60

Cement and steel industries, potassium ion fertilisers, and sodium ion wastewater

Question 61

What is the pH of freshwater?

Answer 61

Ideally pH 4.5-10.0 but generally pH 6.5-8.5

Question 62

Give two examples of processes that can lower water pH

Answer 62

Acid mine drainage and acid runoff (which can be increased by sphagnum mosses in wet swamps and peaty areas)

Question 63

Describe particulate organic matter (POM)

Answer 63

0.2µm-1mm, allochthonous organic matter

Question 64

What is the size of coarse particulate organic matter? Give four examples of CPOM

Answer 64

>1mm. Includes living and dead planktonic organisms, leaf litter, twigs, and fruits

Question 65

What is the size of fine particulate organic matter (FPOM)?

Answer 65

0.2µm-1mm

Question 66

What size is dissolved organic matter (DOM)?

Answer 66

<0.45µm

Question 67

Give four examples of types of DOMs?

Answer 67

Anions, cations, viruses, and fine organic debris

Question 68

What material makes up major components of CPOM, FPOM, and DOM?

Answer 68

Microorganisms

Question 69

Define allochthonous organic matter

Answer 69

External materials

Question 70

Define autochthonous organic matter and give three examples

Answer 70

Indigenous plant material. Includes; periphyton, plankton, and macrophytic detritus

Question 71

Give five examples of micronutrients

Answer 71

Na, Mg, Si, K, Ca

Question 72

Give six examples of macronutrients

Answer 72

C, H, O, N, P, S

Question 73

What are C, H, O, and S usually available for?

Answer 73

Growth

Question 74

What is the ideal N:P concentration ratio in freshwater?

Answer 74

7:1

Question 75

What is nitrogen used for by organisms?

Answer 75

Amino and nucleic acids

Question 76

Define heterocyst

Answer 76

Differentiated cyanobacteria that carries out N fixing

Question 77

Give seven examples of allochthonous nitrogen loading processes

Answer 77

Rainfall, aerial deposition, dust particles, fertiliser application, fossil fuel combustion, N-fixing crops, and waste water disposal

Question 78

Give two examples of autochthonous nitrogen and phosphorus loading processes

Answer 78

Sediment and nutrient cycling

Question 79

Why can't atmospheric nitrogen be used by organisms?

Answer 79

It is unreactive because of its stable covalent bond

Question 80

What nitrogens are most and least abundant in freshwater?

Answer 80

Nitrate (NO3) is most oxidised by lake and most abundant, nitrite (NO2) is present in small amounts

Question 81

What type of nitrogen do plant cells use and how is it transferred?

Answer 81

They use a reduced form and it is transferred intercellularly as the amino group NH2.

Question 82

What does an increase in reactive nitrogen result in?

Answer 82

Higher productivity

Question 83

What does a shortage of nitrogen for terrestrial plants suggest?

Answer 83

A shortage of nitrogen available for growth in the water

Question 84

Give three examples of where phosphorus is used in organism growth

Answer 84

Nucleic acids, organelle walls, and energy molecules

Question 85

What is the relationship between phosphorus and organism growth?

Answer 85

It is a growth-limiting nutrient

Question 86

Where is phosphorus not found?

Answer 86

In the atmosphere

Question 87

Give three examples of allochthonous phosphorus loading processes

Answer 87

Weathering of rocks, human activity (inc. detergent pollution, agricultural runoff, runoff from cities (sewage)), and detritus (POM)

Question 88

Describe the process of eutrophication

Answer 88

Phosphorus is transferred into lakes and it sinks into the sediment. Movement of P from the sediment to the water is mechanical (bioturbation)

Question 89

Where is excess phosphorus stored?

Answer 89

In algae that later sinks to the substrate

Question 90

What causes a species shift and how can this challenge the biota?

Answer 90

Can be caused by increased levels of N and P. New, harmful algae can release toxins, leading to a loss or reduction of aquatic life

Question 91

What causes increased productivity and how can this challenge the biota?

Answer 91

Can be caused by increased levels of N and P. Increased organic matter, which increases respiration, decreasing oxygen availability, leading to a loss or reduction of aquatic life.

Question 92

A 2013 paper on the consequences of the human modification of the global nitrogen cycle showed what benefits?

Answer 92

Reactive nitrogen emission lead to coastal and terrestrial eutrophication.

Question 93

A 2013 paper on the consequences of the human modification of the global nitrogen cycle showed what negative consequences?

Answer 93

Freshwater pollution and biodiversity loss. O3 and PM increase in atmosphere.