BIOL 228 FINAL

Question 1

Define commensalism

Answer 1

Type of symbiosis where one species benefits and one is not really affected in a meaningful way –> epiphytes growing on trees

Question 2

What are the two different kinds of mutualism?

Answer 2

Obligate and Facultative
First must be in the mutualistic interaction, other one doesn’t have to be

Question 3

Define ecosystem ecology

Answer 3

Ecosystem ecology 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)

Ecosystem science tends to focus more on processes than on individual organisms.

Question 4

Explain the different pathways of energy and chemicals in a system

Answer 4

Energy flows through the components of an ecosystem

Chemicals and nutrients are recycled in a circular manner throughout an ecosystem

Question 5

What are the four most important kinds of energy in an ecosystem?

Answer 5

Thermal energy –> heat
Radiant energy –> light –> drives many processes (from the sun), such as water cycle and air currents, a small amount is used for photosynthesis
Kinetic –> motion
Chemical

Question 6

What is PAR?

Answer 6

Photosynthetically Active Radiation

The fraction of radiant energy that is available for use by photosynthetic organisms

Use CO2 and H2O plus radiant energy to make sugar and O2

Question 7

Define primary production

Answer 7

The rate at which photosynthetic organisms convert solar energy into chemical energy (organic compounds)

Measured over a unit of time

Question 8

Explain the difference between GPP and NPP

Answer 8

Gross Primary Production (GPP) → total amount of carbon fixed per area per unit time

Net Primary Production (NPP) → Total amount of carbon fixed per area per unit time minus cellular respiration ( R ) by the autotrophs
–>Represents the carbon available for the rest of the food chain

Question 9

Explain the difference between GPP and NPP

Answer 9

Gross Primary Production (GPP) → total amount of carbon fixed per area per unit time

Net Primary Production (NPP) → Total amount of carbon fixed per area per unit time minus cellular respiration ( R ) by the autotrophs
–>Represents the carbon available for the rest of the food chain

Question 10

Explain the light and dark bottle method for measuring both GPP and NPP in an ecosystem

Answer 10

Respiration will occur in both bottles, whereas photosynthesis will only occur in the clear bottle

NPP will occur in the light bottles
GPP will be the NPP from the light bottles plus the bottle of just respiration (dark)

NPP = O2 in clear bottles after 12 hours - initial O2 concentration
R = (O2 will go down) Initial O2 content - final O2 concentration in dark bottles
GPP = NPP + R

Question 11

What main factors control or limit primary production in a terrestrial or aquatic ecosystem? (4/3)

Answer 11

Terrestrial
Intensity and duration of sunlight –> more intensity means more available energy, longer duration increases growing season

Temperature –> photosynthesis is better at warmer temps

Moisture and precipitation –> usually better when higher, however too much causes water logging meaning roots cannot properly uptake nutrients
Nutrient levels, N

Aquatic
Intensity and duration of sunlight
Temperature
Nutrient levels, N, P, Fe

Question 12

Explain the relationship between precipitation and temp on an ecosystems productivity in terms of plants

Answer 12

Plants exchange gasses in stomata
Water is lost through stomata
When hot and dry plants close stomata to prevent water loss –> loss of water is called transpiration
Low CO2 in leaf, high O2
Closing means gasses cannot be exchanged
Reduces primary production in C3 plants
Goes into alternate version of Calvin cycle called photorespiration where plants are not growing

Question 13

Define evapotranspiration and describe its relationship with primary production

Answer 13

Evapotranspiration is the loss of water vapor to the atmosphere from plants AND soil

In warm, wet environments, evapotranspiration is high

High evapotranspiration = high primary production

Question 14

Explain how nutrient limitation may exist even if there is a lot of that nutrient

Answer 14

Nutrients can occur at a high rate but not be bioavailable
Therefore the limiting step becomes the rate at which a nutrient can become mineralized (become bioavailable)

Faster it can mineralize = higher PP

Question 15

What are the four nutrients that limit PP in aquatic ecosystems?

Answer 15

NH4 (ammonium and nitrates) –> important for proteins synthesis in phytoplankton

PO4 –> used in ATP transfer, and cell membranes in algae –> P is most limiting nutrient in lakes

Fe –> mainly oceans, fixes N

Si –> used in diatom skeletons

Question 16

Explain what is meant by “Ironing the Oceans”?

Answer 16

John Martin found that Fe was the limiting nutrient in pacific ocean
Open ocean fertilization experiments have been conducted trying to provide ocean with more Fe, increasing PP and lowering global temp

Ironing the Ocean
Random dude Russ George straight up dumped a buncha iron in the ocean to try and stimulate plankton growth to provide more food for salmon
There was not monitoring behind this, science isn’t there yet
Ended up producing a bunch of methane gas, that some phytoplankton produce toxic chemicals when too stimulated

Question 17

Explain the effect of grazing on PP

Answer 17

Low grazing → rates permit nutrients to be locked up in biomass in vegetation, rendering the nutrient unavailable for further plant production

Moderate grazing → nutrients are rapidly released back into the environment for reuptake into vegetation, stimulating further plant production
–>peak primary production

Overgrazing → reduces vegetation biomass to such low levels that autotrophs cannot increase biomass in the ecosystem (low production)

Question 18

Explain the relationship between habitat complexity and NPP, also explain the term rugosity

Answer 18

NPP is higher in more complex ecosystems
Rugosity –> refers to the degrees of wrinkling of a surface

Forests with tree biodiversity have gaps in the canopy (high rugosity) allowing greater light use effiency

Question 19

Define the terms trophic structure and food chain, what are the different trophic levels in a food chain?

Answer 19

Trophic structure–> determines the route that energy flows through the ecosystem

Food chain–> the sequence of food transfers from trophic level to trophic level

Producers (autotrophs)–> organisms that make organic food molecules from CO2, H2O and other inorganic raw materials, e.g., a plant, an alga, or a photosynthetic bacterium

Primary consumers (herbivores)–> organisms that eat only producers (e.g., a grasshopper, aphid, or bison)

Secondary consumers –> organisms that eat primary consumers (e.g., small mammals, frogs, spiders)

Tertiary consumers –> organisms that eat secondary consumers (e.g., a snake, a pike)

Quaternary consumers–> organisms that eat tertiary consumers (e.g., hawks, killer whales, muskies)

Detritivore/decomposer –> a consumer that eats detritus, the dead material produced by all trophic levels (e.g., plant waste and carrion). Such organisms include earthworms, and vultures, but the most important decomposers are bacteria and fungi

Some animals may operate at multiple trophic levels at once or throughout their lives (omnivores, amphibians)

Food chains start with many microscopic organisms

Question 20

Define secondary production

Answer 20

The rate of biomass production by heterotrophic or consumer organisms

Expressed in g C/M2/day, or kJ

Question 21

Explain the three process that detail energy transfer efficiencies within a trophic level

Answer 21

Ingestion efficiency (IE) –> % of total productivity available at one trophic level that is consumed by the trophic level above
–> generally more plant biomass is available than can be eaten (bison don’t eat ALL the grass), the rest of the plant biomass dies without being eaten
–> 25% in grasslands
–> for secondary consumers is % of herbivore productivity consumed by carnivore (5-100%)
–> prey adaptions like spines or shells lower IE

Assimilation efficiency (AE) –> fraction of ingested energy that is assimilated (crosses gut lining)
–> energy that is not assimilated is egested as feces
–> consumption of plants is about 30%, cellulose and lignin are hard to fully digest
–> carnivores usually have AE of 80%, some shells like chitin cannot be digested either
–> food quality refers to the ease at which food is assimilated
–> Improvements in mastication, digestive enzymes, symbiotic relationships and the length and shape of the gut represent features that can be modified through evolution to improve AE

Production efficiency (PE) –> proportion of the assimilated energy that is converted into new biomass, remainder lost to respiration
–> resulting biomass = secondary production
–> invertebrates (ectotherms) have much higher PE than vertebrates (endotherms) as endotherms use most of their assimilated energy in respiration to maintain constant body temp

Question 22

What is trophic transfer efficiency and what does it imply (3)?

Answer 22

The amount of energy available to an upper trophic level –> IE x AE x PE = TTE

Usually around 10%, meaning less and less energy is available to upper trophic levels, resulting in the food chain being finite, hard to pass 5 levels

10% (0.1) x 5 levels results in 0.01% of initial energy remaining

Implications
Top consumers much be mobile to search a wide area
Must have low density, not enough energy to maintain dense predator populations
Top consumers more susceptible to extinction

Question 23

Explain the relationship between grazing and detrital food chains in terms of production

Answer 23

Grazing food chains rarely dominate the energy flow (2% in a forest example)
Detrital food chains are responsible for most of the secondary production (35% GPP in same forest)

Two are closely integrated, energy for detrital comes from all steps of grazing
energy flow is unidrictional in grazer, multidirectional in detrital

plankton communities will have a much higher proportion going to grazing food chain as no cellulose

Question 24

What are the three kinds of ecological pyramids?

Answer 24

Biomass, Abundance and Energy

Can be inverted, usually the fault of trees (lots of mass, little density)
Energy cannot be inverted ( tropohic transfer efficiency)

Question 25

What is the impact of the human energy pyramid

Answer 25

They can choose their own, due to TTE, technically 10x more humans could be fed if we only ate plants and not meat 75% of agricultural land is for feeding animals not humans 70% of water withdrawals are for agriculture

Question 26

Explain the issue with DDT contaminant cycling

Answer 26

Certain top predators have high concentrations of toxins DDT despite low concentraions in the environment DDT is resistant to breakdown and accumulates through Biological magnification DDT is transferred with a greater efficiency than the general trophic efficiency DDT interferes with egg shell formations and can be toxic with age Other persistent organic pollutants (POPs) accumulate in cold regions where they condense

Question 27

Explain the issues with Hg levels in tuna (article)

Answer 27

in 2007, Hg levels were above limit in canned tuna More Hg accumulates in older fish/ higher up the food chain Hg binds to proteins in tissue Biomagnifys Hg

Question 28

What is biogeochemical cycling?

Answer 28

process by which matter cycles from the living world to the nonliving physical environment and back again different from energy flow as matter is recycled

Question 29

Fully explain the carbon cycle and its sinks and sources

Answer 29

Carbon is mainly present as inorganic carbon as CO2 Oceans are large carbon sinks Close relationship between respiration of plants and animals, plants make inorganic carbon organic, animals cellular respirate to return carbon back to its inorganic form Some forms of organic carbon like lignin and cellulose may remain in organic form for 100s of years Limestone and fossil fuels are large terrestrial resovoirs, is released by weathering or human impacts

Question 30

Explain the diurnal and seasonal patterns regarding the carbon cycle

Answer 30

CO2 increases during the night and winter when plants are not photosynthesizing Limestone rock is biggest sink for carbon, followed by oceans and fossil fuels

Question 31

List some impacts of global warming and climate change

Answer 31

Temps rise More fires Less sea ice --> even higher temps Coral bleaching more cyclones rising ocean levels less biodiversity northward movement of many animals increase lake salinity --> jackfish drought less freshwater for crops Canada has v bad greenhouse gas emissions

Question 32

Explain the nitrogen cycle, and the 5 main steps and what is the largest source of cycling?

Answer 32

N is needed to produce many biomolecules All N ultimately came from atmosphere --> large sink, most abundant gas in atmosphere (78%) Most N is as N2 which is not bioavailable --> few organisms can make it so --> usually limiting nutrient N enters ecosystem via microbial fixation N leaves via denitrification 1. N fixation --> conversion of N2 to NH3 (oxygen free environment needed) --> root nodules and symbiotic N fixers (on legumes) --> nitrogenase 2. Nitrification --> conversion of NH3/ NH4+ to nitrate (NO3-) --> also accomplished by bacteria 3. Assimilation --> plants (via roots), bacteria and algae absorb N compounds and incorporate N into organic compounds to be used 4. Ammonification --> breakdown of organic N compounds to NH3 or NH4+ --> decomposers --> can be re recycled again 5. Denitrification --> reduction of nitrate to N2 --> denitrifying bacteria --> low O2 environment steps 1 and 5 are on the "outside" of the loop largest source of N flux is in the oceans, followed by internal cycling in land plants

Question 33

What is cultural eutrophication?

Answer 33

The indirect human fertilization of surface waters, occurs when excess N and P leech into waters from fertilization, causes algal blooms among other things severely ruins water quality, kills fish, loses biodiversity, increase toxins further N and P are responsible

Question 34

Explain the human impacts of excess N in groundwater

Answer 34

NO3 moves into water table, high concentrations dangerous to drink especially for infants Blue baby syndrome

Question 35

Broadly explain information about the P cycle

Answer 35

P is a component of many biomolecules PO4 is the main form taken up by organisms Unlike C and N, P does not have gaseous form, travels in atmosphere as dust PO4 comes from rock weathering (apatite) --> slow process Often a limiting nutrient, easily becomes biounavailable PO4 becomes available as it weathers from rock --> PO4 is lost when it becomes buried deeply in soils or sediments --> may be recycled multiple times before becoming "lost" Largest pool of P in sediments, followed by soils

Question 36

Explain human impacts on the P cycle (article)

Answer 36

mineable P deposits are declining, as it binds too quickly and becomes unavailable Ostara --> Saskatoon is extracting struvite from sewage treatment plants, removing struvite lowers maintenance costs and it can be reused as fertilizer for further sales System recovers 75% of P Crystal green fertilizer --> less environmental damage

Question 37

Broadly explain the sulfur cycle

Answer 37

Important in some AA SO4 used by plants, other forms reduced by bacteria Cycle includes gas, liquid and solid phases, meaning it cycles at a global scale Largest pools are in sedimentary rock, marine sediments and the oceans S enters earth surface via both wet and dry deposition --> various atmospheric S compounds combine with moisture and fall S can also fall from fires and volcanic activity

Question 38

What is atmospheric ocean sulfur?

Answer 38

AKA DMS (dimethylsulfide) major biogenic gas that enters atmosphere from ocean DMS is oxidized to sulfate aerosols which are involved in cloud formation Clouds help cool climate DMS may help

Question 39

What are some human impacts of the sulfur cycle

Answer 39

Accumulation of acid rain via fossil fuel burning Lowering pH fucks w alot of animals, dissolves shells Increased acidification ruins biodiversity Precambrian shield is sensitive to acid (north sask) but much of the acid production is USA BABYY

Question 40

What is a lotic system? What are its two main structural components?

Answer 40

Lotic systems are river or stream systems --> flowing water Riffles --> zones of fast moving water (rapids) --> erosional zones with only large stones remaining --> zones of high PP via periphyton --> algae growing on rocks --> zones of high secondary production too --> aquatic larvae Pools --> slower moving and deeper --> sediments can deposit --> high rates of decomposition --> low production unless aquatic plants are there, needs light to reach bottom, provides habitat for organisms

Question 41

What is the hyporheic zone?

Answer 41

The subsurface sediments of a stream or river Between stream water and ground water Water moves in and out via up and downwelling, resulting in nutrient exchange

Question 42

How are streams and rivers classified?

Answer 42

via stream order a small headwater stream without any tributaries is a 1st order stream When two streams of same order join it becomes one bigger Headwater streams = orders 1-3 Medium size streams = orders 3-6 Rivers = order 6+ (think of branches on a tree, tips are 1s, main stem is the highest)

Question 43

What is the difference between heterotrophic and autotrophic ecosystems?

Answer 43

Heterotrophic --> respiration exceeds PP (lower light) Autotrophic --> PP exceeds respiration

Question 44

What are lotic systems classified as? What are the main inputs into a lotic system?

Answer 44

Heterotrophic system (R>P) Input from riparian (streamside) vegetation Input from coarse particular organic matter (CPOM) Input from fine particulate organic matter (FPOM) Input from dissolved organic matter (DOM)

Question 45

What are the four classifications of consumers in a lotic system, what do they do?

Answer 45

Shredders --> breakdown leaf litter that remains after being dissolved by water CPOM --> turns rest into FPOM --> stonefly and cranefly larvae Collectors --> collect FPOM --> different in riffles and pools --> blackfly larva (riffles) -->mayfly larva (pools) Scrapers --> scrape algae off of rocks --> what is not ingested floats away as FPOM --> also mayfly larva Predators --> the shit that eats the other shit on this list

Question 46

What is unique about nutrient cycling in rivers? What does it depend on (3)? What is it described as?

Answer 46

Material moves downstream via drift, added spatial component Downstream movement depends on Flow rate --> higher flow = more nutrient loss Physical retention --> storage of nutrients in dams Biological retention --> uptake and storage in living organisms described as a longitudinal spiral Length = average downstream distance of a spiral Tight = high retaining power, caused by lots of debris or dams Open = low retention, caused by flooding or lack of structure

Question 47

Define and explain the RCC, explain its effects on each stream order

Answer 47

River Continuum Concept Describes integration Links stream size, organic inputs, organic processing and invertebrate communities Order 1-3 headwater 90% of organic pop comes from outside input --> heterotrophic Mainly shredders and collectors few grazers (less algae) Order 4-6 riparian vegetation less important less shading = more PP slower velocity, more biodiversity becomes autotrophic fewer shredders, more grazers and collectors Rivers order 6+ less riparian inputs however shifts back to heterotrophic --> too deep for sunlight to reach more pelagic instead of benthic organisms more collectors on bottom --> FPOM dominant some shortcomings --> prairie rivers get a lot more light

Question 48

What are some human impacts on rivers

Answer 48

2/3rds of water flowing is dammed most dammed minus Canada and Russia don't grow crops in the damn desert

Question 49

What is a lentic system, what are some elements of its physical structure? (3)

Answer 49

Lake or pond system --> no moving water Formed many diff ways' Epilimnion --> warm well mixed surface water --> photic Metalimnion --> region of rapid temp and density changes, in the middle Hypolimnion --> cold, O2 poor dark zone, little mixing

Question 50

Explain the thermal structure of a lentic system over the seasons

Answer 50

Winter stratification --> low density 0degC water at surface below ice --> denser 4degC water at bottom --> hence why ice is only at the surface Spring turnover --> ice melts, water mixes --> isothermic Summer stratification -->waters warm, low density warm water above colder denser water --> establishes the limnions Fall turnover --> surface cools --> lake mixes again

Question 51

Explain the two light zones in a lentic system,

Answer 51

Photic zone --> upper waters, photosynthesis and respiration occurs, goes to 1% light intensity Aphotic zone --> dark, only respiration

Question 52

What is the littoral zone

Answer 52

shore region of a lentic system --> goes from shore to end of photic zone

Question 53

what is the pelagic zone?

Answer 53

open water area in lakes --> away from shore has plankton, phytoplankton and zooplankton has pelagic fish

Question 54

What is the benthic zone?

Answer 54

The bottom of the lake, usually anoxic, less diversity filter feeders present

Question 55

Explain the energy flow in a lentic system

Answer 55

Energy production influcened mainly by littoral zone --> less impact in bigger lakes due to size difference negative relationship between littoral and pelagic PP --> phytoplankton can shade out littoral zone detrital system also plays large role as there's lots of input from terrestrial environments --> in most lakes R exceeds P except for very large or productive ones due to this productive capacity or trophic status often limited by P Oligotrophic --> low P, low productivity Mesotrophic --> medium P, medium productivity Eutrophic -->high P, high productivity

Question 56

Why are oceanic food webs so different (2)

Answer 56

Predators lack grasping appendages, can only eat what fits in mouth No need for cellulose / support structures or appendages (animals)

Question 57

Describe the features of a marine or open ocean system

Answer 57

Phytoplankton are main primary producers despite 80% of light absorbed in the first 10m despite being easily N or P limited, their vastness means they account for 50% of carbon fixation --> P limited (bc not in atmosphere, no gas) Lots of N2 in oceans --> can be fixed by cyanobacteria

Question 58

Explain the process by which coral reefs work and are maintained. What are some human impacts on them (article)

Answer 58

Reefs require occasional disturbance to promote diversity and prevent highly competitive species from taking over --> cyclones Corals are Symbiotic Photosynthetic Dinoflagellates --> Known as zooxanthellae that form relationship w hard corals ----> provide organic substances to the host --> 90% of energy needs --> they receive shelter and inorganic nutrients from host Corals consist of many feeding polyps Calcification required to form reef When corals get stressed they lose the zooxanthellae --> bleaching from sunlight or acid 2016 -2017 heat wave in AUS bleached like 93% or great barrier reef

Question 59

What are the two main factors in determining a biome?

Answer 59

Annual precipitation and average temp

Question 60

List some typical qualities of a grassland

Answer 60

High evaporation Severe droughts Fertile soils medium rainfall dominated by grazers or borrowers requires fires to be maintained

Question 61

What are the two growth forms of grass?

Answer 61

Sod grasses --> develop solid mat above soil Bunch grasses --> they bunch

Question 62

What are the three kinds of prairie and their characteristics?

Answer 62

Short grass prairie --> driest grasses under 50cm dense sod grasses used for ranching (too dry for crops) impacted by overgrazing found in very south sask Mixed grass prairie --> medium precipitation mix of sod and bunch grass grass height 1.5m more north than short grass variable between wet and dry years cropland Tall grass prairie not in sask, east MAN high precipitation most productive 2-3m tall susceptible to tree invasion --> needs fire

Question 63

Why does grass come back so quick after a fire?

Answer 63

most of its biomass is underground

Question 64

Explain the role of carbon and organic matter in the grassland, as well as the root to shoot ratios

Answer 64

grassland is a carbon sink -->20% of carbon on land, accumulates slowly Most biomass is below ground Have a greater than 1 root to shoot ratio because of this, unique to grassland and tundras Root to shoot --> pos correlated with temp, negative with precipitation reflects water availability

Question 65

How productive are grassland systems?

Answer 65

Very productive in a production / biomass ratio However due to less precipitation they are less productive than a temperate forest production will increase with precipitation production will decrease with increasing temp --> water loss (unlike forests) --> also minerals are less available in hot soil --> moderate grazing stimulates production regular fire stimulates production, removes woody plants, BUT ALSO reduces layer of dead biomass which can shade soil --> can make it worse in already dry grasslands

Question 66

Whats the deal with the northeast swale?

Answer 66

Northern saskatoon piece of prairie Could save it but also could be ruined by new housing developments Discussion about fixing up the interior of the city and slowing the developments outwards Sustainability

Question 67

What are the general characteristics of the Boreal forest / Taiga

Answer 67

Coniferous forest --> most in Canada, Alaska and Siberia Covers 11% of the earth May have been even more extensive but harvesting and foresting have reduced size Many lakes and wetlands Mineral poor soils Varied climate Permafrost Need at least one month above 10 to regenerate Favours Jack pine in sask, fewer conifers in the south --> aspen dominates (deciduous) Aspen grow quick after fire but die off allowing large spruce trees to take hold

Question 68

What is / was the BOREAS study?

Answer 68

Boreal Ecosystem Atmosphere Study 1990s Large scale study of interactions Site in PA Determined moderate values of PP ~40% of NPP is below ground (less than prairies) Still a carbon sink Increased CO2 is going to pull carbon out of sinks

Question 69

What is the main human impact on the boreal forest?

Answer 69

Moutain Pine Beetle Eats and rots trees at a very fast rate Has been moving north into most of Canada Helped by warming temperatures, if its gets too cold the larvae die off Also needs dense forests to disperse rapidly --> southern Canadian boreal is less dense, northern region is colder.