Unit 4: Ecology Flashcards
Define a species
Group of organisms that can interbreed to produce fertile offspring. Members of one species can not produce fertile offspring with members of a different species.
Define a population
Group of organisms of the same species that live in the same area at the same time
Define a community
Community definition: Different populations that live together, and interact with each other in a given area.
Define a habitat
Habitat definition: Environment where a species normally lives, or the location of a living organism.
Define ecology
Ecology definition: The study of the relationship between living organisms, or between living organisms and their environment.
What are two methods of nutrition that species can use?
There are two methods of nutrition species can use: Autotrophic or heterotrophic. Some may use both depending on resource availability. Those that use both are referred to as mixotrophs
Define an autotroph
Definition: Species that synthesize their own organic molecules from simple inorganic substances. For example, from carbon dioxide or nitrates.
Other Name: Producers (they PRODUCE their own organic molecules)
What are the types of autotrophs
Types of autotrophs:
- Photoautotroph — Conduct photosynthesis by taking energy from the sunlight
- Chemoautotrophs — Conduct chemosynthesis by taking energy from oxidizing inorganic molecules
Define heterotrophs
Definition: Species that obtain pre-synthesized organic molecules from other organisms while they’re either living or recently killed, or through their non-living remains and detritus.
What are classifications of heterotrophs
- Consumers — ingest organic molecules from living or recently killed organisms
- Scavengers
- Detritivores — ingest organic molecules found in non-living remnants of organisms
- Saprotrophs — Release digestive enzymes and absorb the external products of digestion
Define consumers
Definition: Heterotrophs feeding on living or recently killed organisms through ingestion
Types:
- Herbivores — Feed on plant matter
- Carnivores — Feed on animal matter
- Omnivores — Feed on plant and animal matter
Define scavengers
Definition: Consumers that feed on dead and decaying body’s instead of hunting
Define a detritivore, detritus, and humus
Definition: Heterotrophs that get nutrients from non-living organic sources, like detritus and humus, through internal digestion
Detritus definition: Dead particulate organic matter like decaying organic matter and fecal matter
Humus definition: Decaying leaf litter intermixed in topsoil
Define a saprotroph
Definition: Heterotrophs that live on or in non-living organic matter, secrete digestive enzymes in it, and absorb the products of digestion. This is a type of external digestion.
Other name: Decomposers (DECOMPOSE dead organic material by secreting digestive enzymes)
Define a nutrient
Nutrients Definition: Material required by an organism, including elements like carbon, nitrogen, and phosphorous.
Define nutrient cycling
Nutrient cycling definition: How chemical elements are recycled after use, to be reused by other organisms.
What is a species?
A group of genetically similar living organisms which are able to interbreed and create fertile offspring (offspring which can pass on their genes). To produce fertile offspring they must be classified into the same taxa.
What is speciation?
Evolution to the point two organisms become too genetically different to produce fertile offspring.
What is a gene pool?
A collection of genes (with their allelelic forms) found in a population. Therefore, all members of a species have a common gene pool and number of chromosomes in their haploid cells.
Define a population
group of organisms of the same species that live in a particular area at the same time.
Define a community
A group of populations living and interacting in a particular area.
Define an ecosystem
A community and its abiotic environment.
Define Abiotic factors
Non-living factors, such as pH, salinity, wind speed, type of soil, etc.
Define biotic factors
Living factors in an ecosystem, such as the plants and animals.
What are the modes of nutrition through which organic molecules can be obtained?
- Autotrophic — organisms that can make their own organic molecules from carbon dioxide and other compounds are called autotrophs. Almost all plants and some organisms are capable of autotrophic nutrition. Prefix ‘auto’ means self, while ‘trophic’ has to do with feeding or nutrition.
- Heterotrophic — Organisms that obtain their organic compounds by feeding on other organisms. ‘Hetero’ means different. ‘trophic’ is to do with feeding/nutrition. They get nutrition from a different source (than themselves).
What are the modes of obtaining organic molecules per kingdom?
- Bacteria — some autotrophic and some heterotrophic
- Protoctista — come autotrophic and some heterotrophic
- Fungi — heterotrophic
- Plantae — mostly autotrophic
- Animalia — heterotrophic
What are mixotrophs?
Species that can feed both autotrophically and heterotrophically. An example is Euglena gracilis which feeds on other organisms, but has chloroplasts for photosynthesis as well.
What are the groups of heterotrophs?
- Consumers
- Detritivores
- Saprotrophs
What are consumers?
Organisms that get carbon compounds by ingestion or absorption. They consume other organisms. Some smaller consumers take in their food through endocytosis. Some parasites are considered consumers as they use rely on their host to break down food then they absorb the nutrients directly through their skin or cuticle.
What is ingestion?
The taking in of a substance.
What are the types of consumers?
Primary (1^0) — Feed only on autotrophs. Also known as herbivores.
Secondary(2^0) — Feed on primary consumers, not exclusively
Tertiary (3^0) — Feed on secondary consumers, not exclusively
Carnivores — Organisms feeding solely on other consumers.
Omnivores — organisms consuming both plants and animals
What are detritivores?
Detritivores — heterotrophs that get food from detritus, which is waste or other organic debris, through internal digestion. Most detritus or discarded material contains organic compounds that can be used as a source of energy or raw materials by detritivores following internal digestion.
What is internal digestion?
Process where an organisms digests its food inside of its body, usually with the help of a digestive tract.
What is the importance of detritivores?
Important for recycling nutrients and returning them to the soil for autotrophs.
What are saprotrophs?
Saprotrophs — Heterotrophs that get their organic nutrients from dead organisms through external digestion (extracellular digestion). Sometimes referred to as decomposers since they feed on dead organic matter from dead organisms. Examples are fungi and bacteria, which secrete digestive enzymes on decaying organic matter, increasing soil fertility. The soluble digested materials released are then absorbed and used by saprotrophs and can also re-enter the food chain when plants absorb them and use them for photosynthesis.
What is external/extracellular digestion?
Process by which organisms secrete enzymes into their environment to break down organic debris around them.
What is ecology?
Ecology — The study of relationships between living organisms and their interactions with their environment.
What is symbiosis?
Living together, refers to the outcomes of interaction between populations.
What are the types of symbiotic relationship?
Mutualism: Both organisms benefit
Commensalism: One organism benefits and the other is unaffected
Parasitism: One organism is benefited and the other is harmed
What are nutrient cycles?
The constant reuse of the chemicals necessary for organism survival. Message is that nutrients can be recycled almost indefinitely, unlike energy, which can’t be recycled and needs to be supplied by the sun. It helps move organic molecules and minerals through the food chain and back into the soil where they can be taken up by plants to re-enter the food chain.
What are chemoautotrophs?
Autotrophs that use chemical energy to make organic compounds which are used by consumers.
What are photoautotrophs?
Use energy from the sun for photosynthesis
What is a mesocosm?
Experimental tool allowing the experimenter to control the conditions in a small part of the natural environment. It can act like a model of a larger ecosystem where energy enters and leaves but matter doesn’t.
What is a mesocosm used for?
To evaluate how organisms or communities can react to environmental change
What are the types of mesocosms?
- Aquatic
- Terrestrial
What is the chi-squared test?
Statistical test to better understand communities and whether two populations are associated and dependent upon each other or not. Also known as a goodness of fit statistic. Assesses if the observed distribution of data fits with the distribution that is expected if variables are independent.
Tests the null hypothesis by making a comparison between the observed data and the expected data if variables were independent. If the observed data doesn’t fit the model the chances that variables are dependent increases and the null hypothesis is rejected.
The conventionally accepted significance level is 0.05 or 5%, however, ifthe p value is less than 0.05, or to the right of 0.05 on the table, it implies that the variables are dependent or associated. If it is more than 0.05 or equal to 0.05 it implies that the variables are independent or not associated.
What is the null hypothesis?
Hypothesis stating there is no association between the two populations being tested in the chi-squared test.
What data is a chi-squared test used for?
Categorical — data that has been counted and divided into categories.
Will not work with continuous data.
Should not be in form of percentages, or anything other than frequency (count) data.
What is ecological frequency?
Number of times a plant species occurs in a given number of quadrats. Expressed as a percentage and sometimes called a frequency index.
What is expected frequency?
The number of quadrats a population is expected to occupy in an area
How do we calculate expected frequency?
(row total * column total)/grand total = expected frequency
How do we calculate the degrees of freedom and what are they?
Degrees of freedom are calculated by multiplying the number of rows (not including total) minus one by the number of columns (not including total) minus one.
How do we calculate the chi-squared value?
x^2 = sum of (O-E)^2/E
x^2 = test statistic
Σ = the sum of
O = observed frequencies
E = Expected frequencies
If greater than critical value, null hypothesis is rejected.
What is a quadrat?
A tool used to measure population distribution in an area. Grid structure randomly placed in the area under study, and all the species within it are counted.
What is metabolism?
Biochemical reactions that collectively generate heat within the cells of organisms.
How can we use energy from the sun?
- must be converted into useable forms of energy
- producers like bacteria, protists, plants, and algae can make pigments like chlorophyll that capture light during light-dependent photosynthesis reactions
- light breaks water into protons and electrons which through electron transport pathways, ATP synthase, and the Calvin cycle, transform carbon dioxide and water into glucose and other carbon-based compounds
- converting light energy into chemical energy through carbon compounds
How do ecosystems provide chemical energy if light is not available?
- certain organisms use chemicals in their surrounding environments to make energy in a process called chemosynthesis
- chemoautotrophs (some bacteria and archaea) instead of photoautotrophs
What happens to carbon compounds made by producers?
- some are used in cellular respiration to make ATP, resulting in some heat loss
- most end up as structural components, with energy available to heterotrophs
- when consumers take it, they use it for some cellular activities (i.e. nucleic acid and protein synthesis, ion exchange across membranes, cell division, movement)
How is ATP produced?
By oxidizing glucose and other carbon compounds through respiration. Heat is lost at each step since no oxidative steps are 100% efficient.
What do living organisms do with their heat energy?
We can’t convert heat so we just release it.
What is a food chain?
Energy available to primary consumer is a lot less than energy made by producer through photosynthesis. When primary consumer is consumed by secondary, again, not all energy can be used. This order of energy flow is called a food chain.
Food chain is model showing how nutrients and energy are passed from producer to primary consumer to secondary, etc. Shows how each organism gets food and the direction of energy flow. Generally begins with plants and ends with animals.
Draw a sample food chain
Producer → primary consumer → secondary consumer → tertiary consumer
What is a trophic level?
Refers to position of an organism in a food chain, where the producer is trophic level 1. For example, the last organism in the food chain is the top predator.
Why is there not a 100% energy transfer between trophic levels?
Energy’s available to consumers mainly as carbohydrates and other carbon compounds.
- When something’s eaten, it’s not always entirely consumed (i.e. bones).
- Some material is indigestible and leaves the body with the faeces through egestion
What percent energy is transferred between each trophic level and what does it cause?
- 10% to 20% but varies with each ecosystem
- top predators have to consume more organisms to meet their energy requirements
- ecosystem is able to support fewer organisms at higher trophic levels
- decrease in biomass as we move up the food chain
What is biomass?
them mass of dried organic material which can be used as fuel in an ecosystem, expressed in terms of dry weight per unit area
What is a food web?
Models of ecosystems that represent many different food chain possibilities and show how they’re interconnected. Shows interconnectedness existing among food chains. Each organism might have several sources of nutrition and possibly several predators.
What is an energy pyramid?
- Model used to represent energy flow in a community
- Each block is a different group of organisms that might constitute a food chain
- the energy distribution between trophic levels is often depicted in the form of a stepped pyramid
- essential that trophic levels are drawn to scale with size of bar representing energy
- Terms such as producer, first consumer, second consumer, etc. should be used. Not trophic levels.
What units are used in an energy pyramid?
- energy per unit area of the ecosystem per unit time
- amount of kilojoules per square metre per year
1/kJm^2yr^1
- 1 kJ = 0.001 MJ
- units can use megajoules instead if ecosystems have larger amounts of energy
What is a numbers pyramid
- model depicting the number of individuals in each trophic level of an ecosystem
- represented as a stepped pyramid similar to the energy pyramid
What is the biomass pyramid?
- way to quantify data from ecosystems so its productivity and health can be analysed
- larger at the top typically because more producers than consumers
What forms does carbon appear in and how is it produced and what is it’s atmospheric concentration and what does it contribute to?
- most is produced by autotrophs which transform carbon dioxide into more complex carbon compounds like glucose
- 0.04% atmospheric concentration
- 400 ppm (parts per million)
- 400 micromoles per mole μmol/mol
- Three forms:
- carbon dioxide (CO2)
- methane (CH4)
- calcium carbonate (CaCO3)
- carbon cycling
What are properties of CO2 and their effects?
- heavier so will diffuse to lower layers of a forest which could pose as a problem for heterotrophs. Can however be mixed in the air due to temperature changes and wind patterns. Since it tends to sink, it’s readily available to photosynthesisers and can be trapped in water.
- Low solubility (0.88 cm^3 to 0.65 cm^3 per gram of water, with temperatures of 20 C to 30 C). Increased solubility as pressure increases. Large amounts of CO2 can be dissolved in sparkling water using pressure.
What happens when you mix carbon dioxide and water?
- carbonic acid is formed with a H2CO3 structure
- unstable and dissociates easily in water into hydrogen ions and hydrogen carbonate (aka bicarbonate ions)(HCO3) ions
- hydrogen released during this lowers pH of the water and makes it more acidic
- this is what happens when CO2 combines with the water in blood, and is why it dissolves in blood plasma. When the CO2 combines with the water it is detected by the brain and sends a signal for you to breathe
What is carbon dioxide used for in plants?
- in the calvin cycle
- to make carbohydrates and more complex carbon compounds
- lowers concentration of CO2 in the plant, setting up a concentration gradient helping the CO2 diffuse into the autotrophs
How is carbon dioxide present in aquatic ecosystems and how do aquatic plants take it in?
As dissolved carbon dioxide and hydrogen carbonate ions
How do land plants take carbon dioxide?
- as a gas
- through the stomata (pores found in leaves)
What is the stomata?
Pores found on the underside of leaves which allow for gas exchange. Aquatic plants have them on the upper side instead.
Which part of the plant cell performs photosynthesis?
Mitochondria
What is methane?
- CH4
- carbon molecule produced in anoxic (no oxygen) conditions and can oxidise into CO2 and H2O
What does methane do once formed?
May diffuse into atmosphere or accumulate in the ground
How is methane made?
- made from organic matter under anaerobic conditions my methanogenic archaeans (single-celled prokaryotes)
- gut bacteria in ruminants and other herbivores can make a lot of methane, which is then released into the atmosphere
Where are methanogenic archaeans found?
anoxic environments, the guts of ruminants, etc.
what are ruminants?
mammals that have a mutualistic relationship with methanogenic archaeans that help them digest cellulose from the cell walls in the plants they eat. this makes methane, which is released as gas from the mammal.
what types of organic matter can be used for methane production? what process is this done through?
- farm animal manure
- cellulose from plants
- ruminants chew on plants and break down the molecules like some carbohydrates into smaller monomers (using saliva) through hydrolysis
- organic matter is changed to organic acids and alcohol by a group of bacteria in a process called acidogenesis
- other bacteria convert the organic acids and alcohol into acetate through acetogenesis, carbon dioxide and hydrogen
- methanogenic bacteria can make methane either through reaction of carbon dioxide and hydrogen or through the breakdown of acetate, aka methanogenesis
1. CO2 + 4H2 → CH4 + 2H2O
2. CH3COO(-) + H(+) → CH4 + CO2
define acidogenesis
chemical process in which bacteria converts organic matter into organic acids and alcohol
define methanogenesis
chemical process in which methanogenic bacteria can make methane through the reaction of CO2 and hydrogen or through the breakdown of acetate
define acetogenesis
the chemical process in which bacteria convert organic acids and alcohol into acetate
Define a peat
- partially digested organic matter forming in acidic, water-saturated soil
- contains large amounts of carbon and can be compressed into coal after time
How are peat’s made?
- in some waterlogged areas where stagnant water makes it be anaerobic, its an environment where saprotrophs can’t grow
- results in the environment being more acidified over time
- remaining organic matter is only partially digested
- new layers of leaf litter and other organic debris fall on top of older layer making it more compressed
- this results in a peat
What are the uses of peat?
- substitute for firewood
- increasing moisture holding capacity of soil
- increasing water infiltration rate of soils rich in clay particles
- to acidify soils for specific pot plants
What are fossil fuels?
fuel deposits that we use today that were formed a long time ago
How are fossil fuels formed?
- at bottom of lakes and oceans dead organisms are decomposed
- anaerobic conditions existing in these environments leave decomposition unfinished
- saprotrophic bacteria can’t grow and decompose the vegetation, therefore organisms and the soil becomes acidic
- pressure and heat allow for chemical changes to take place
- oil and gas are formed over long periods of time
where are oil and gas found?
- porous rock but gas is not in a gaseous form
- gas reservoirs are deep in the earth under high-pressure conditions that will maintain the gas in liquid form
How is carbon trapped in biomass is released back into the atmosphere?
- hydrocarbons found in organic compounds are combined with oxygen. carbon dioxide, water, and energy are made. combustion reaction — when done to fossil fuels, always releases CO2 from organic material such as fossil fuels or biomass
- forest fires
What is calcium carbonate?
You should be able to label the processes that take place to move carbon from one form to another. For example, be able to label: photosynthesis, which changes CO2in the atmosphere into carbon compounds in plants; consumption, which moves carbon into the food chain; fossilisation orlithification, which compresses carbon into rocks, fossils or fossil fuels; and combustion and respiration, which releases carbon back into the atmosphere
- CaCO3
- important source of carbon in the environment
- makes up shells and exoskeletons
- can become porous sedimentary rock like limestone
where is calcium carbonate found?
- shells of molluscs
- exoskeletons of hard corals and crustaceans contain carbon in large quantities
- when animals die, it becomes part of sedimentary rock given conditions are not too acidic
What is lithification?
process of compressing organic matter over a long period of time until it becomes rock
What is a reservoir?
- pool or store of an element
- aka a sink
- one of the largest is the earth’s crust or lithosphere, where carbon is found as sedimentary rock and fossil fuels
- biota — portion of earth that consists of the living organism
- hydrosphere — portion of the earth that consists of water including oceans, lakes, ponds, and rivers
- atmosphere — layer of gases surrounding the earth
What is a flux?
- when carbon moves from one reservoir to another
- also the process that moves carbon from one reservoir to another
Draw a model of the carbon cycle
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what is the unit for measuring carbon?
gigatonnes: 10^15 g
What is the intensified natural greenhouse effect?
- natural greenhouse effect occurring at unnatural rate due to human activities
- problem on a global scale
What gases impact the greenhouse effect?
- most — water vapour and CO2
- others — methane, nitrogen oxides
What does it mean to be a closed system?
Not much escapes its gravity and atmosphere
How is carbon dioxide released and how is it taken out of the atmosphere?
Carbon dioxide is released by heterotrophs and autotrophs when they respire, and also through the combustion of biomass or fossil fuels. There are two ways in which carbon dioxide is taken out of the atmosphere: photosynthesis and by dissolving in oceans and lakes
How is water vapor made?
Water vapour is the gaseous form of water, formed through evaporation from bodies of water. Natural precipitation, such as rain, hail and snow, return water to the Earth as part of the water cycle
What are the main greenhouse gases
Both carbon dioxide and water vapour absorb longwave or infrared radiation and are considered the main greenhouse gases . Both gases are very abundant in the atmosphere, both naturally and due to human activity. The more greenhouse gases that are in the atmosphere, the stronger the effect of the greenhouse effect and the warmer the Earth becomes
What are greenhouse gases
Greenhouse gases – gases found in the atmosphere such as water vapour, carbon dioxide, methane and nitrous oxides, that contribute to the greenhouse effect
What is water vapour
Water vapour – water found in the atmosphere in a gaseous form. It is the most abundant greenhouse gas
What are the qualities greenhouse gases have
For a gas to contribute to the greenhouse effect, it needs to be able to absorb longer wavelength radiation. Methane (CH 4 ) and nitrous oxides (N 2 O and NO) are able to absorb longer wavelength or infrared radiation. They contribute to the greenhouse effect, but not as much as carbon dioxide and water vapour, as shown in Figure 4 . However, it should be noted that despite being released in smaller amounts, methane traps 20 times more heat than the same amount of carbon dioxide; that is, methane causes faster warming of the planet
How does methane occur
Methane occurs naturally. It escapes from melting ice and tundra in the Arctic, it escapes from landfills and marshes, and it is produced by cattle. Sometimes it is emitted during the extraction of fossil fuels
What is methane
Methane – CH 4 – a gas found in the atmosphere that is produced from methanogenic ruminant bacteria and saprotrophic bacteria
What are nitrous oxides
Nitrous oxides – NO x – a greenhouse gas that is formed both naturally and by humans, mainly through farming, industry and combustion of fossil fuels
What is the carbon dioxide equivalent
The unit used in the above Figure 5 is called carbon dioxide equivalent or CO 2 EQ, a term for describing different greenhouse gases in a common unit. For any quantity and type of greenhouse gas, CO 2 EQ signifies the amount of CO 2 which would have the equivalent global warming impact
What are the steps to the greenhouse effect
- Solar radiation,from the sun, spans the electromagnetic spectrum from approximately 100 to 4 000 nanometres (nm), with visible light comprising about 44% of its emissions. After passing through theozone layer, the layer of the atmosphere that blocksUV radiationbut is not considered a greenhouse gas, onlyshort-wavelength radiationfrom the sun reaches the Earth’s surface. Some of the short-wavelength radiation is reflected, but most passes through the greenhouse gases to the Earth’s surface.
- The Earth absorbs some of this shortwave radiation while some is reflected. This absorbed radiation isthen re-emitted, mainly asinfrared (heat), whichis a longwave radiation (with a peak around 10 000 nm).
- Part of this longer wavelength radiation escapes Earth’s atmosphere into space. However, much ofit is absorbed by greenhouse gases in the atmosphere.
- The greenhouse gases re-emit the absorbed light in all directions as heat. Some of this radiation is re-emitted towards the Earth, thus contributing toglobal warming.
Define radiation
Radiation – energy that may be a subatomic particle, for example an electron (gamma rays) or in the form of an electromagnetic wave, for example ultraviolet radiation
Define solar radiation
Solar radiation – energy from the sun that comes in the form of electromagnetic waves. This includes many types of waves such as visible light or ultraviolet light
Define the Ozone layer
Ozone layer – O 3 – is a layer of the Earth’s atmosphere that protects the Earth from ultraviolet radiation coming from the sun. It is not considered a greenhouse gas because it does not absorb longwave radiation
Define UV radiation
UV radiation – ultraviolet radiation is a type of shortwave radiation coming from the sun, but is filtered out by the ozone layer of the atmosphere
Define long-wavelength radiation
Long-wavelength radiation – also known as infrared light, a type of radiation that is emitted from the Earth and its atmosphere. Examples include, microwaves and radiowaves
Define short-wavelength radiation
Short-wavelength radiation – this type of radiation comes from the sun in the form of visible light and ultraviolet light. It is absorbed by the Earth and re-emitted as long-wavelength radiation
Define infrared rays
Infrared – this type of long-wavelength radiation is given off from the Earth in the form of heat
Define global warming
Global warming – the warming of the Earth and its atmosphere due to the intensified greenhouse effect
What are implications for the earth’s climate due to increase in global temperatures?
- Climate change:Higher global averages mean that the total amount of water that evaporates from oceans and lakes increases. More water in the atmosphere leads to heavier rainfall. Global warming can also have substantial effects on wind and ocean currents causing stronger hurricanes and typhoons.
- Rising seawater: Another consequence of the increased global temperature is the rising seawater temperature and the melting effect on the polar ice caps and glaciers around the world.
- Loss of habitat: The polar ice caps and glaciers are melting, decreasing ice habitats for some arctic organisms. Also, when these ice caps melt they cause a rise in sea levels, as mentioned above, destroying coastal habitats.
- Biotic factors: The warming of any habitat would change the species that live in the area and can cause changes to migratory patterns. Temperate species move into warmer arctic areas and compete with the arctic species. Arctic species need to adapt to competition and the change in temperature or emigrate to a new habitat. This would cause a change in the distribution of species, possibly a decrease in population sizes and, in extreme cases, extinction of species.Changes such as these could have severe impacts on the food chains of an ecosystem disrupting the food web and having a large impact on organisms in higher trophic levels. Other effects on the biota may be an increase in decomposition due to melting permafrost, which exposes saprotrophic bacteria to oxygen, releases methane, and, with an increase in temperature and moisture there will bean increase in pest species and pathogens.
Define climate
Climate: long-term weather patterns in an area or region
Define climate change
Climate change: changes in the long-term weather patterns in an area or region due to the intensified greenhouse effect
Define the precautionary principle
Precautionary principle : also known as the burden of proof, this principle states that even without concrete evidence of a causal relationship, precautionary measures should be taken to ensure that humans are not causing detrimental harm to the environment or human health
What are coral reefs
Coral reefs – a ridge in the ocean where living coral polyps attach and secrete calcium carbonate. Coral reefs are typically very diverse places found in warm shallow waters
How are coral reefs affected by global warming
Greenhouse gases consist of mainly water vapor and CO2along with methane and nitrous oxides. Because of the heavier rainfall associated with global warming, more of these molecules dissolve into rain water from the atmosphere, falling onto land, rivers, lakes, and oceans as acid rain. Carbon dioxide is more dense than other atmospheric components and, therefore, is typically found at the surface of the Earth including oceans. This CO2can dissolve directly into aquatic environments such as rivers, lakes, and oceans as well. Carbon dioxide combines with water to form carbonic acid: H2CO3. This molecule easily dissociates into H+and HCO3-. The H+freed in this dissociation lowers the pH ofwater, making it more acidic
Some of this massive amount of carbon dioxide dissolved into the oceans. As a result, the average pH of the oceans has dropped about 0.11 (pH units) causing ocean acidification. This may not seem much on a scale of 14, but it represents a 30% increase in acidity (remember the pH scale is logarithmic)
What is ocean acidification
Ocean acidification – the drop in pH of the ocean due to the absorption of carbon dioxide, which forms carbonic acid. The H+ ions become dissociated from carbonic acid causing the water to become acidic
What is the process of ocean acidification?
- Carbon dioxide from the atmosphere is absorbed by the ocean
- Carbon dioxide absorbed by the ocean is broken down, forming carbonic acid and hydrogen ions
- As hydrogen ions form bonds with carbonate atoms, bicarbonate atoms form. The concentration of carbonate atoms is therefore reduced
- Shells and coral of marine life are calcium-based, and organisms use carbona atoms to build and maintain these structure
What is calcification?
A lowering of the pH increases the solubility of calcium carbonate (hydrogen ions bond to the carbonate in place of calcium), decreasing the amount of CaCO3 that is readily available to living organisms. Calcium carbonate is used by marine organisms such as crustaceans, molluscs and corals to build their exoskeletons and shells, a process known as calcification. If less CaCO3 is available, it will slow the building of coral reefs and make them more brittle. As the coral CaCO3 exoskeletons also begin to dissolve, they will become less resilient to other factors influencing their survival
Calcification – the process used by molluscs, crustaceans, and corals to build their shells and exoskeletons using calcium carbonate
How does ocean acidification affect mollusc shells?
Ocean acidification also poses a threat to mollusc shells. These molluscs use calcium carbonate to build their shells, so as less calcium carbonate is available to them due to the rise in acidity of the ocean, their shells will become weaker
What two problems are threatening marine organisms?
While acidic oceans are certainly a problem for marine organisms that use calcium carbonate, the increase in water temperature also poses a threat. Marine organisms, including corals, are very sensitive to temperature changes in their environment. They will need to adapt to these changes or they will become extinct, decreasing the biodiversity of the oceans. Many of the organisms affected by ocean acidification and a rise in temperature are important food sources for corals. Their destruction disrupts the food chain. Since increasing concentrations of dissolved carbon dioxide leads to ocean acidification, it is very likely to have a negative impact on the ability of corals to develop, and on their ability to recover from damage.
