Dr. Hudson Material Flashcards
What effect do dissolved organic carbon (DOC) have on water?
Acts like a suntan lotion and protects organisms from UV light
Define ecosystem
A biological community and its abiotic environment, functioning as a system. They exist at many spatial scales, anywhere from a pond to a biosphere
Define ecosystem ecology and give a couple examples
Examines the flow of energy and chemical cycling in habitats, as well as, the effects of natural and human induced disturbances on ecosystems (ex: air/water pollution, tree harvesting, land-use changes)
What are Energy Flow and Chemical Cycling and how are they different?
Energy Flow: The passage of energy THROUGH the components of an ecosystem.
Chemical Cycling: unlike energy flow, chemical cycling involves the circular (recycling) movement of materials within the ecosystem.
Energy flow then shows the energy from one level to the next in a system, while chemical cycling is for specific nutrients
List Abiotic factors in the environment
Energy, inorganic substances (CO2, N, O2, minerals), Organic substances (proteins, carbs, humic acids), water.
List examples of biotic inputs into an ecosystem
Animals migrating from one ecosystem to another, leaves falling from a tree on the ground or into a river.
What are two things true about Energy? What are the two laws of thermodynamics that we studied in this course
P1: 1- Energy can be converted from one form to another.
2- All forms of life depend on these conversions. Think of photosynthesis.
1st Law: energy is neither created nor destroyed. Important when understanding our energy diagrams.
2nd Law: conversion of energy from one form or another is always accompanied by a reduction in the order of the universe. aka: energy is always lost when changing form.
What is PAR? On what percentage of PAR reaches autotrophs?
PAR stands for Photosynthetically Active Radiation and falls between 380 and 710 nanometers. This is just under and just over the visible light spectrum. This is the radiant energy that is available for photosynthetic organisms. Only about 1% of PAR that reaches the autotrophs is converted to chemical energy like sugar.
What are the primary producers of an ecosystem?
The autotrophs that produce organic material from inorganic chemicals and an energy source. They are the base of the food chain.
Define Primary Production, and then the difference between GPP and NPP
The rate at which photosynthetic organisms convert solar energy to chemical energy (organic compounds). GPP stands for Gross Primary Production and describes the total amount of Carbon fixed per area per unit of time. Net Primary Production accounts for the energy lost during Gross Primary Production, and is the value that the organism actually outputs.
What is biomass, how is it processed and in what unit?
Biomass is the amount of living organic material in an ecosystem (or a sub-component of the ecosystem. In terrestrial environments it is: grams dry matter per m^2 (g/m^2). In three dimensional environments such as aquatic: grams dry matter per m^3 ( g/m^3). Can also be replaced by carbon content instead of dry matter— grams of Carbon per meters squared or cubed.
How does the Light-Dark Oxygen Method work to measure primary production?
The light bottle measures photosynthesis and respiration, while dark bottle only measures respiration. Light cannot enter the dark bottle and therefore we will have the values of respiration from the dark bottle and NPP from the light bottle to determine GPP. GPP will be NPP + Respiration. The bottle method usually uses two of each bottles. Take the mean of the two similar bottles.
Ex: Initial O2 content at dawn — 8 mg / L. 12 hours later, the clear bottle has 9.5 and 10.5 mg O2 / L and the darker bottles have 6 and 7 mg O2 / L. Notice how the dark bottles went down from their original O2 concentration.
To find the Net, we take 10 (the mean) minus 8 (start) to get 2 mg O2 / L. For respiration we take our starting value 8 - 6.5 (mean value of dark bottles) to get 1.5. GPP is now 2 + 1.5 = 3.5 mg O2 / L per 12 hours (DON’T FORGET TIME)
List two of the other methods to measure primary production that we did not go into depth on
CO2 technique (radioactive carbon dioxide uptake) and changes in water column pH.
What factors may control or limit primary production in Terrestrial systems? What about Aquatic?
Terrestrial: Intensity and Duration of Sunlight, Temperature, Moisture or Precipitation, Nutrient levels, especially Nitrogen.
Aquatic systems: Intensity and Duration of Sunlight, Temperature, Nutrient levels, particularly Nitrogen, Phosphorous, and Iron in the open water.
What are more productive, Southerly Forests or Northerly Forests?
Overall, Southerly Forests are more productive since they are productive year long, opposed to Northerly Forests that are minimally productive in the winter months of little sunshine.
What is the correlation between precipitation and temperature on productivity?
They are two of the major factors in productivity, as temperature and precipitation rise, productivity increases as well, starts to plateau when you get too much precipitation and temperatures get too high.
What is it called when water is loss through the stomata in plants?
transpiration
Compare the Calvin cycle under optimal temperature and moisture compared to when it is undergoing photorespiration
Under ideal conditions, there are high concentrations of CO2 and low O2 concentrations in the leaf of the plant. The Calvin cycle reduces CO2 and sugars are produced.
In dry, hot weather, the plant undergoes photorespiration because off the low amounts of CO2 and high O2 concentrations in leaf since the stomata closes to save water, therefore unable to exchange gasses. Calvin cycle uses O2 instead of CO2 and sugars are not produced, results in CO2 and H20
What are CAM and C4 Plants?
CAM stand for Crassulacean acid metabolism. They only open their stomata at night to obtain CO2 when temperatures are low and water loss will be minimized, cacti are an example of this.
C4 plants keep stomata closed during dry and hot conditions, and use a special enzyme system to access very low internal concentrations of CO2. Examples are corn, sugar cane, sorghum.
What affect does photorespiration have on C3 pants during hot and dry conditions? Is photorespiration a problem in C3 plants in hot and wet environments?
Photorespiration causes a reduction in C3 in hot and dry condition s up to 25%.
No, if the environment is wet, the stomata is open and photorespiration does not occur.
What is the difference between Transpiration and Evaporation?
Transpiration is the loss of water vapour to the atmosphere by land plants. While Evapotranspiration is the loss of water vapour to the atmosphere from plants and the soil. When evaporation rates are high, primary transcription increases because of the use of water by the plant to produce sugars.
If an ecosystem has adequate light, high temperatures, and sufficient moisture, but very low primary production, what is the problem?
Nutrients, there will be specific nutrients limiting primary production since the plants can’t operate to the best of their ability. These can be Carbon, Oxygen, Hydrogen, Phosphorous etc, also can be organic nutrients like vitamins. Any shortage of a nutrient can reduce primary production.
Can a nutrient still limit rates of primary production when it is present in large concentrations?
Yes, many nutrients can occur at high concentrations in ecosystems but are not bioavailable. Nutrient concentrations alone are often poor predictors of primary production.
What is the relationship between primary production and a limiting nutrient?
As the concentration of the limiting nutrient increases and is readily available in the environment, primary production increases. This is how fertilizers add to the environment.
What are the three factors that control primary production in aquatic ecosystems?
Quantity of light (PAR): northerly latitudes have shorter seasons for production.
Temperature: algal productivity increases with water temperature.
Nutrient supply: nutrients limit algal production in most environments.
What are the potential limiting nutrients in marine and freshwater systems? What is the one nutrient that differs between the two?
Nitrogen, Phosphorus, and Silicone. Iron is a limiting nutrient in marine systems but not in freshwater systems.
What does Nitrogen do for aquatic systems?
Ammonium (NH4), nitrate, and nitrite are the most important bioavailable forms of nitrogen and are used for protein synthesis in phytoplankton and bacterioplankton.
What does phosphorus do for an aquatic system?
Phosphate is the most important bioavailable form of phosphorus and is used for energy transfer (ATP), nuclei acid synthesis and cell membranes in algae and bacteria.
What does Iron do for a marine ecosystem?
Is bioavailable as ferrous iron Fe2+ and iron bound to organic ligands, is used to fix nitrogen (N2) and other functions in bacteria and algae.
What does silica do for aquatic environments?
Silicon acid H4SiO4 is the most important bioavailable form that is used in the skeleton of diatoms (a major algal group)
What did the study in 1969 at lake Kenora in Ontario determine and how was it done?
David Schindler the director, put up a plastic curtain separating the lake into two halves, they wanted to learn whether carbon, nitrogen, or phosphorus was the limiting factor in primary production. On one side they added Phosphorus which resulted in an algal bloom and lead to the banning of Phosphorus in detergents and reduction of Phosphorus inputs into sewage treatment plants to improve water quality.
Which nutrient is more often the limiting factor in aquatic ecosystems, Nitrogen or Phosphorus?
Phosphorus more often but either one or both can be limiting factors.
In the open ocean, which nutrient is most often the limiting factor and why does it have such an effect on temperature?
In the open ocean, iron is an important nutrient for phytoplankton to photosynthesize, also the belief was that having more iron in the water can capture more carbon from the atmosphere and hopefully cool down temperatures.
What are the effects of moderate grazing as a biotic factor in a prairie ecosystem? Compare this to low grazing and high grazing.
Moderate grazing rapidly release nutrients back into the environment through egestion, excretion, and decomposition for the re-uptake of vegetation, stimulating plant productivity. Low grazing permit nutrients to be locked up in biomass in vegetation, while high grazing rates reduces vegetation biomass to such low levels that autotrophs cannot increase biomass in the ecosystem.
How does grazing help a prairie?
Moderate grazing gets rid of old grass and allows more sunlight to be accessible to plants, also through urination, nitrogen gets back into the soil.
What is rugosity and why is it important?
Rugosity is the wrinkling of a surface. This is used to describe forest canopy’s. When rugosity is height, there is a variable of canopy heights, and light use is more efficient since all light is being used at different height levels.
Which ecosystems have the highest net primary production, which has highest percentage of Earth’s production?
Algal beds and reefs are number one for percentage, making them very productive but they come in low quantities so they do not contribute to very much of the Earth’s Net Production. Tropical forests are second for average NPP as well as the percentage of Earth’s net primary production. The ocean has a very low average net primary production proportional to its % of Earth’s surface, but has the highest percentage of Earth’s net primary production.
Define trophic structure, food chain, and trophic level
Trophic structure determined the route that energy flows through the ecosystem, a food chain is the sequence of food transfers from trophic level to trophic level. A trophic level is just one link on a food chain.
List the 5 positions of trophic levels in a food chain
Producers (autotrophs): organisms that make organic food molecules from inorganic material.
Primary consumers (herbivores): organisms that eat only producers
Secondary consumers: organisms that eat primary consumers. Ex: small mammals, frogs, or spiders.
Tertiary consumers: organisms that eat secondary consumers. Ex: snake, pike fish.
Quarter consumers: organisms that eat tertiary consumers. Ex: apex predators, hawks, killer whales.
What is a detritivore/decomposed?
A consumer that eats detritus, the dead material produced by all trophic levels (ex: plant waste and carrion). Examples of detritivores are earthworms, vultures, but most importantly bacteria and fungi.
What are recalcitrances?
Recalcitrances are compounds that refuse to breakdown and stay in their inorganic form. Detritivores cannot use this as energy and instead sinks into sediments as inaccessible energy.
What are some of the difficulties of depicting the flow of energy in a food chain?
Omnivore organisms feed at different trophic levels, difficult to determine what level they are. Some animals feed at different trophic levels at different times through their lives,. Matter may pass through an organism more than once, example is that the feces of animal A may be consumed by animal B and at a later time animal A may eat animal B. Some plants feed on animals. Many microorganisms make a living autotrophically and heterotrophically.
Define a food web. What are a problem that come with food chains?
Multiple food chains, a network of interconnecting food chains. Provides a detailed information about who eats who, more realistic but complex.
Besides complexity, food webs don’t account for the detritus system, resulting in a larger amount of energy that is accounted for.
What is secondary production?
The rate of biomass production by heterotrophic or consumer organisms. Secondary production may refer to all consumers, or a sub-component of consumers in an ecosystem. This production is expressed in the same units as NPP,
What is the relationship between primary and secondary production?
In general, ecosystems with high primary production tend to have elevated secondary production.
What are the three fundamental efficiencies when referring to energy flow within a trophic level?
Ingestion/consumption efficiency (IE), Assimilation efficiency, Production efficiency
Define Ingestion / Consumption efficiency
% of total productivity available at one trophic level that is consumed (ingested) by the trophic level above. For primary consumers, IE is the % of NPP that finds its way into the gut of herbivores. There is generally more plant biomass available than can be eaten, due to plant adaptations.
How does ingestion efficiency change in herbivores depending on the environment?
Low efficiency in forests, about 5%, 25% in grasslands, and 50% in phytoplankton dominated communities. The remainder of plant production dies without being eaten and enter the detrital system.
How does ingestion efficiency change in regards to secondary consumers, specifically carnivores eating herbivores?
IE ranges from 5-100%. Predators must locate, capture and consume their prey. Prey has adaptations such as camouflage, indigestible adaptations, such as a shell.
What is assimilation efficiency?
The fraction of ingested energy that is assimilated (crosses the gut lining into the body) by an organism. Remainder of the energy that is not assimilated is egested as feces. Consumption of plant tissues has an AE of about 30%. Most of the energy is locked up in cellulose and lignin, which are resistant to breakdown.
How does assimilation efficiency change for carnivores?
AE for carnivores is generally higher, at around 80% since there is no cellulose or lignin. But many insects still have adaptations such as exoskeletons that cannot be digested.
What is the difference between ingestion efficiency and assimilation efficiency?
Ingestion is literally just what proportions can a trophic level consume of the level below. If there is 100% biomass of grass available of bison to eat, and they only eat 30% annually, then their IE would be 30%. Assimilation efficiency would be regarding the nourishment they obtain from the grass. Since plants have lignin and cellulose, it is generally low.
Define food quality and how it relates to Assimilation efficiency
Food quality is associated with the Assimilation efficiency since food quality is defined as the ease of assimilating prey. For example, soft fruit with a thin peel has a much higher food quality than say a coconut.
Can a consumer improve their assimilation efficiency?
Yes they can through mastication, digestive enzymes, symbiotic relationships, and the length and shape of their guts. All of these would improve AE.
Define production efficiency (PE)
Production efficiency is the proportion off the assimilated energy that is converted into new biomass (tissue)- the remainder is largely lost to respiration. The resulting increase in biomass is secondary production. Invertebrates have a high PE of 30 to 40%, losing relatively little energy to respiratory heat.
How do endotherm’s and ectotherm’s production efficiency vary?
Endotherms use about 98% of their assimilated energy in maintaining homeostasis. Vertebrate ectotherms divert about 44% of their assimilated energy to secondary production, since less is lost to cellular respiration. However, ectotherms that put more into secondary production, have lower AE as well.
How do assimilation efficiency and production efficiency relate?
Since assimilation efficiency is the amount of nutrients you get from what you eat, production efficiency is the process of using that same energy towards new biomass.
What is incomplete ingestion, incomplete assimilation, and incomplete transfer of energy into biomass?
Incomplete ingestion represents all of the primary production that cannot be consumed. Incomplete assimilation is that not all ingested energy crosses the gut lining into the organism. Incomplete transfer of energy is energy lost to metabolic activities like respiration, opposed to biomass production like reproducing or growing.
What is trophic transfer efficiency and how is it calculated?
Trophic transfer efficiency is the energy available to an upper trophic level and is calculated by multiplying IE x AE x PE. This provides an estimation of the amount of energy that is available to the level above, as we go higher in level, less energy is available at each stage.
What is the range and rough average for trophic transfer efficiency? How does it change as we get higher in the food chain?
Energy transfer range between trophic levels is usually around 10%, while the range is anywhere from 1% to 90%. You can multiply trophic transfer efficiency at each level to get the energy available for the next highest level, from the original. Because of this loss in energy, trophic levels in a food chain are FINITE. 5 and 6 are kind of the max.
What are some implications for top trophic levels?
Top consumers must be mobile and search for prey over large areas to obtain adequate numbers of prey. They also must have a low abundance since they have access to little energy. This makes them susceptible to extinction.
True or false, every ecosystem has a detritus foot chain?
True, also, detrital systems are responsible for the majority of secondary production.
How do patterns of energy flow differ in the following four ecosystems? Forest, Grassland, Plankton Community, Stream Community.
Forest: Most energy from NPP goes to dead organic matter, while the rest goes to the grazer system. Most of the energy from NPP in Dead organic matter gets picked up by the decomposed system and then respirated.
Grassland is very similar to Grassland except a little lest energy in the decomposer system.
Plankton community: Much more energy into the grazing system than that of the decomposer system.
Stream community: Much Lower NPP, so arrows leading to Grazer system and dead organic matter look about the same. Besides that, it looks similar to the grassland and Forest ecosystem. A lot of energy comes from the external environment, a level below dead organic matter is called Terrestrial catchment.
What is the difference between the grazing food chain and the detrital food chain?
Grazing food chain is created by herbivores that eat autotrophs, and carnivores that eat herbivores. The detrital good chain has a base of detritus as the source of energy, eaten by decomposer herbivores, which are eaten by carnivores.
Is primary production more associated with the grazing system or the detrital system? Why is this so?
Detrital system. Since most of the energy produced in the grazing system goes to the detritus food chain, we can infer that more energy production is then prevalent in that food chain. Fun fact: Algae and phytoplankton contribute little Dead organic matter to the detrital system, hence why aquatic communities have a lower amount of energy in the detrital system, and are therefore have more production in the grazing food chain.
How does the pyramid of abundance differ between Grassland Ecosystem and a Forested Ecosystem?
Grassland abundance size decreases as you move up the pyramid. Grass is most abundant, then primary consumers, secondary, tertiary, etc. In a Forest, since the size of the primary producers (huge trees) is much larger than that of the primary consumers (small insects), it creates an inverted pattern of abundance between producers and consumers, the rest follows accordingly.
