D4.3 Flashcards
Climate Change
1
Q
Impacts of Eutrophication and Pollution
What is eutrophication?
A
- When there is an abundance of nutrients running into water –> causes algae to thrive near the surface (for access to sunlight) and overgrow.
- The lower algae are outcompeted and die.
- The decomposers then break them down, however use up the oxegyn in the process, as they have so much matter to decompose.
- This results in insufficient oxegyn for the fish, thus they die.
2
Q
Impacts of Eutrophication and Pollution
What is meant by Biochemical Oxegyn Demand?
A
- For bacteria (primary decomposers in aquatic environments) to effectively recyle nutrients, they need oxegyen to complete their own ceulluar respiration.
- The amount of oxegyn required by the bacteria is called the Biochemical Oxegyn Demand.
- When there is an increase in DECAYING algae (from eutrophication), this increases the activity of the bacteria,
- –> increases the BOD and uses up the avilable oxegyn, netaively impacting the aquatic animals.
3
Q
Impacts of Eutrophication and Pollution
What is Biomagnification?
A
- When there are traces of toxins in the water –> the impact is worst for the higher trophic levels.
- The lower trophic levels will have a small amount –> the next trophic level eats several of them, so ends up with a higher level.
- The next trophic level eats more of those –> ends up with a higher amount (etc).
- By the highest trophic level, the amount becomes dangerous.
4
Q
Impacts of Eutrophication and Pollution
What is something referred to as ‘biodegradable?’
A
- Should be able to be broken down completely and dissolve into soil.
- Not leave any remaining chemicals or plastics.
- Something can be biodegradable if it largely dissolves but does leave behind some microplastics.
- The terms refers to something compostable and largely degradable.
5
Q
Impacts of Eutrophication and Pollution
What are classified as ‘macroplastics?’
A
- Plastics are classified based on their size.
- Any debris larger than 5mm is considered macroplastic.
- (this includes plastic bottles/ bags)
- these macroplastics can end up being mechanically broken into microplastics.
- They also create large landfills –> dangerous to aquatic life.
6
Q
Impacts of Eutrophication and Pollution
What are classified as ‘microplastics?’
A
- Plactic debris that is less than 5mm are called microplastics
- due to their small size, they can be ingested unknowingly by fish and other organisms.
- they may have previously been macroplastics but now mechanically decreased in size
- in other cases, they are actually ingredeitns in cosmetics and cleaning products.
- these microplastic ingredients are illegal most places now due to the concern over their connection to cancers/ diseases.
7
Q
Impacts of Eutrophication and Pollution
The importance of rewilding
A
- Definition: any acitivies that are conservation efforts aimed at restoring and protecting natural processes and wilderness areas.
- It is an in-situ strategy, and involves leaving the area to nature and avoids a lot of active human management.
8
Q
Impacts of Eutrophication and Pollution
The role of fertilisers in Eutrophication
A
- Is caused by an excess of nutrients in a body of water causing the algae surface overgrowth.
- One of the main causes of that surplus of nutrients is overuse of fertilisers (usually full of usable nitrogen), that then runs off in rainwater into other bodies of water.
- Despite fertilisers benefits, caution against the overuse is important to prevent eutrophicaiton.
9
Q
Impacts of Eutrophication and Pollution
The biomagnification of Mercury
A
- The burning of coal and the production of cement are two activities that are releasing Mercury into the environment.
- That mercury then runs off into bodies of water where it is converted by micro-organisms into a form called methyl mercury, which is then absorbed by small fish –> transferred up the food web.
- Larger fish who eat many smaller fish end up with higher levels.
10
Q
Impacts of Eutrophication and Pollution
The biomagnification of DDT
A
- DDT is a synthetic insecticide, that was cheap and effective against mosquitos and other vectors
(oragnsisms that functiona as a carrier of an infectious agent between organisms of a different species). - After usuage for a decade, (spraying from an aircraft), helpful insects vanished and resistance became common –> it was ending up in bodies of water.
- It was absorbed by phytoplankton and then absorbed up through the food web resulting in high levels in top predators.
- In predatory birds the high levels caused weak eggs that cracked during incubation.
11
Q
Impacts of Eutrophication and Pollution
Methods for Rewilding
A
- The most classic example of rewilding is the reintroduction of keystone species (often apex predators, but not limited to) to restore balance.
- Other examples however include creating pathways between isolated habitats to increase gene flow and stop harmful human activities such as logging or hunting.
- Once these measures are initiated, the habitat is left alone to reestablish itself naturally within management.
12
Q
Impacts of Eutrophication and Pollution
What is happening at Hinewai Reserve in NZ?
A
- Is a rewilded area that began 30 years ago.
- Started at 109 hectares but now is 1,250 hectares.
- It has been a place to regeneratie native vegetation and wildlife by removal of invasive species.
- Has also been left to slowly rebuild free of human interventions.
13
Q
Ecological Succession
Ecological Succession
A
- Defnition: a predictable series of change over time in the species that live in an area.
- It is triggered by a change in the abiotic/ biotic factors in an ecosystem leading to groups of species replacing the previous groups over time.
14
Q
Ecological Succession
What is Primary Succession?
A
- Occurs when new land is created and organisms arrive to prepare the land for other living organsisms.
- For it to be primary succession there must be no pre-existing soil.
- The land is usually rock or sand that lacks nutrients.
- The initial stages of primary succession involve mosses and lichens realeasing enzymes and chemicals that create cracks in rocks and start to form soil.
15
Q
Ecological Succession
What is secondary succession?
A
- There was a previously fully formed ecosystem in the area.
- Then there is a disturbance to the established ecosystem (like a forest fire) that dramatically reduces the living community.
- It will then have to rebuild over time.
- The key is that the event does NOT remove the soil, so regrowth occurs more quickly than with primary succession.
16
Q
Ecological Succession
What is the importance of Pioneer Species?
A
- These are the first species to live in a newly establishing ecosystem.
- When there is a bare rock during primary succession, the pioneer species are lichens and moss which are photosynthetic and do not sue roots, so can grow in harsh environments.
- They are responsible for breaking down the rock into soil.
- For secondary succesion, the pinoeer species to return first would be small grasses and flowers.
17
Q
Ecological Succession
What is a Climax Community?
A
- During the stages of succession, larger plant life arrives and outcompetes some of the initial pioneer species.
- But over time the area will increase not just in the number of organisms but in the biodiversity of organisms.
- The pinnacle of succession is the most diverse and populated ecosystem, called the Climax Community.
- The climax community is STABLE –> will remain until a dramatic change in biotic and abiotic factors or naturaul disaster.
18
Q
Ecological Succession
What is Cyclical Succession?
A
- Whilst in a forest ecosystem, succession does build to one stable climax community, that is not true for all ecosystems.
- Some are marked by a changing cycle of communities.
- Definition: A pattern of vegetation change in which a small number of species tend to replace each other over time in the absence of large-scale disturbance
19
Q
Ecological Succession
Arrest of Succession
A
- If left undisturbed, succession should continue in the predictable steps towards a climax community.
- Human activities though can prevent an ecosystem from reaching its potential and cause it to arrest (stop) in an earlier stage of succession or even more backwards.
- E.g, this occurs due to grazing by large livestock populations that keep habitats as grasslands instead of developing into forests.
20
Q
Causes of Climate Change
What is meant by the Greenhouse Effect?
A
- Short-wave radiation from sunlight such as UV radiation —> penetrates atmosphere –> is re-emitted back as high-wave raditaion.
- Greenhouse gasses trap some of that re-emitted radition and it is transmitted back and heats up earth.
- Occurs naturally, and is essential for maintaing a warm enough climate for living organisms.
- However, the addition of extra greenhouse gases through human activities has enchanced the effect and causes excess warming.
- Similar to how heat gets trapped in greenhouses.
21
Q
Causes of Climate Change
What is Infared Radiation?
A
- When sunlight (shorter wavelengths including ultraviolet rays and visable light) hits an object, some of it is absorbed and then readmitted in the form of infared radiation which is a longer wavelength form.
- This is the form of heat that gets trapped by greenhouse gases and sent back down to earth, warming it.
