ENCN281 > Ecosystems > Flashcards

Ecosystems Flashcards

(61 cards)

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1
Q

limnology

A

study of lakes

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2
Q

maximum density of water

A

occurs at 3.94oC

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3
Q

Summer (Lake Processes)

A

stratification: most mixing at top (high temperature air) very little mixing at bottom

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4
Q

Early Fall (Lake Processes)

A

turnover: water unstratifies, completely mixes until water at colder temp

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5
Q

Late Fall (Lake Processes)

A

circulation: mixing slows down and stops when it reaches a constant temperature

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6
Q

Winter (Lake Processes)

A

stratification: ice cover on top of lake

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7
Q

Early Spring (Lake Processes)

A

turnover: as top layer heats from 0 to 4 oC it becomes more dense and sinks to bottom (slower/less mixing than autumn turnover)

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8
Q

Late Spring (Lake Processes)

A

circulation

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9
Q

Layers of Lake

A

from top to bottom (warmest to coldest)

  • Epilimnion
  • Metalimnion
  • Hypolimnion
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10
Q

Diurnal Effects

A
  • during day: algae consume CO2 = increase pH

- during night: CO2 is produced which reacts to form H+ ions = decrease pH`

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11
Q

Why are diurnal effects greater in autumn?

A

Turnover brings nutrient-rich deep water to surface = increase in algal growth = greater 02 and pH swings

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12
Q

Trophic States

A

(lowest to highest nutrients)

  • Oligotrophic
  • Mesotrophic
  • Eutrophic
  • Hypertrophic
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13
Q

Trophic status determined by:

A

amount of limiting nutrient (either phosphorous or nitrogen)
- algae produced until either N or P at low levels and no more biomass produced = one that is at low levels is the limiting nutrient

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14
Q

Eutrophication definition

A

process of becoming more eutrophic - accelerated by humans

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15
Q

Impacts of Eutrophication

A
  • nuisance or toxic algal blooms in summer
  • fish kills due to low dissolved oxygen (or migration)
  • taste and odour problems with drinking water
  • reduced quality of recreational use
  • increased density of aquatic weeds in shallow areas
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16
Q

Big eutrophication problems in NZ

A
  1. Lake Ellesmere (already very eutrophic)

2. Lake Taupo/Rotorua (threat of becoming eutrophic)

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17
Q

Lake Management Methods

A
  1. Reduce input of nutrients
  2. Remove stock of nutrients
  3. Isolate stock of nutrients
  4. Increase Depth
  5. Artificially restore ecosystem
  6. Biomanipulate to new equilibrium
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18
Q

Point Source Control

A

advanced wastewater treatment at wastewater discharge locations or plants

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19
Q

Nonpoint Source Control

A

increase land are protected by conservation

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20
Q

Diversion

A

stop treated waters getting in to water system rather than limiting/controlling amount going in

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21
Q

Dredging

A

increase depth

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22
Q

Chemical inactivation

A

addition of alum to reduce sediment P release

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23
Q

Hypolimnetic aeration

A

oxygen bubbled into bottom of reservoir to maintain DO levels

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24
Q

Herbicides/Harvesting

A

treatment with herbicide to eliminate exotic invasive species

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25
Biomanipulation
introduction of new animal species
26
Lake Management Examples
- point source control - non point source control - diversion - dredging - chemical inactivation - hypolimnetic aeration - herbicides/harvesting - biomanipulation
27
what is a system?
collection of related parts that represents the purpose or essence of a concept
28
what is a model
tool used to analyse a system
29
Rich pictures
used for initial understanding
30
Mind maps
ideas with structure emphasised and not links
31
Hierachy Trees
used to show structure and imply relations between parts
32
Entity Process diagram
used to distinguish between people and activities
33
Logic Flow Diagrams
Step by step to set out process
34
Cross-functional Diagram
used as a system that is a process with time coordination
35
Entailment trees
(fault trees) | used to show logic behind a system
36
Influence Diagrams
used to show feedback processes that occur over time
37
Stock/Flow Diagrams
allows for mathematical modelling of dynamic systems
38
Healthy System Diagram Criteria
1. Balance 2. Completeness 3. Cohesion 4. Discrimination 5. Consistency
39
carrying capacity
upper limit to growth
40
Limits to growth
- limited food - limited living space - limited breeding sites - limited nutrients - excessive contact betwen individuals
41
Types of Species Interactions
1. Competition 2. Exploitation 3. Commensalism 4. Inhibition 5. Mutualism
42
Competition
varying growth rates - local extinction | - leads to specialisation in ecological niches or extinction
43
Exploitation
benefits one species at expense of other species | e.g. predator prey, herbivory (sheep and grass), parasitism (humans and tapeworms)
44
Commensalism
helps one species - negligible effect on the other | e.g. mild parasites
45
Inhibition
harms one species with negligible impact on the other | e.g. mild competition
46
Mutualism
benefits both species | e.g. plants and birds
47
Biodiversity formation
1. Random Mutation 2. Natural Selection 3. Extinction or Specialisation - results from a long slow process of coevolution
48
Primary Production
must have species that turn source energy (sun, geo) into biomass - like the base of a pyramid
49
GPP
gross primary production = total energy converted / area-time
50
NPP
net primary production = energy converted - maintenance
51
Requirements for Primary Production
- Warmth - Sun - Moisture - Pressure - Nutrients (N,P) - Lack of Toxins
52
greater Primary Production
the greater the PP = more energy flows at higher levels of pyramid = more biodiversity
53
Bioaccumulation
- occurs when toxins are not destroyed in organisms and are not lost with the organisms waste - important for human health with lead and fish in lake rotorua
54
Food/Energy relationships should be seen as webs or chains?
webs
55
Do populations higher on a food web decrease or increase in number?
Decrease in number because the available energy decreases as they consume those lower on the web
56
Does available energy decrease or increase as one progresses up a food web?
decreases
57
Steady State System
sum of flows in = sum of flows out
58
Residence time
= stock / sum of flows out = stock / sum of flows in | a key variable
59
Elemental Abundance
- species have co-evolved to use the elements that are available
60
Phosphorous cycle
- physical states: solid and liquid - quick cycle - variety of cycles - strong human influence - sustainability issues - inorganic and organic forms
61
Nitrogen Cycle
- physical states: gas, solid, liquid - inorganic and organic forms - fast biological process but sits within larger system of slower processes
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