ECO Exam 2026

Metabolism

Set of life sustaining chemical transformations within cells

anabolism

build up of organic material, consumes energy

catabolism

break down organic matter, releases energy

Ecosystem Metabolism =

Production & Respiration

Production in an ecosystem contains what two types of production

primary production and secondary production

what is primary production in an ecosystem, what kind of metabolism is this, and chemical equation

production of organic compounds (biomass) from inorganic carbon in autotrophs; the synthesis of organic compounds from atmospheric or aqueous inorganic carbon by primarily photosynthetic organisms, anabolism

CO2 + H2O + inorganic nutrients → C6H12O6 (glucose) + O2

what is secondary production in an ecosystem and what kind of metabolism is this

biomass generation by heterotrophs through the consumption and assimilation of organic carbon from other organisms, anabolism

respiration definition not in an ecosystem:

conversion of bio chemical energy from nutrients to ATP + waste (amount of CO2 lost)

respiration is what in an ecosystem, what kind of metabolism is this, and chem formula

sum of all respiration occurring by living organisms in an ecosystem, catabolism, consumption and decomposition (by heterotrophs) and plant respiration yields energy to maintain and build new biomass, amount of CO2 that is lost from an organism or system from metabolic activity (including decay/decomposition) :

C6H12O6 + O2→ CO2 + H2O + ENERGY

What happens when Production > Respiration ?

growth

what happens when production < respiration

decrease in biomass

what happens when production = respiration

no growth and no decrease in biomass either, 0 net ecosystem productivity, known as “steady state”

Gross Primary Production (GPP):

CO2 fixed during photosynthesis

Net primary production (NPP) and the equation

CO2 fixed - CO2 respired by autotrophs (plant cellular respiration)

Equation: NPP = GPP - R(autotrophs)

Net ecosystem production (NEP) and the equation

CO2 fixed - Co2 respired by all organisms (autotrophs and heterotrophs)

Equation : NEP = GPP - (R (autotrophs) + R (heterotrophs))

Ecosystem metabolism and succession, as an ecosystem mature what happens to GPP (gross primary production)?

GPP = R (autotrophs) + R (heterotrophs) → no net accumulation of biomass

What types of ecosystems have the most productivity WORLD NPP not average NPP?

Tropical rainforests, Tropical seasonal forest, Savanna, Open Ocean

What causes an ecosystem to produce more than others and the drawbacks

More available input → more production,

while the ecosystem is able to be increasingly productive as nutrients are added to the system, eventually other factors will keep the system at bay like sunlight or CO2,

quote: “growth controlled not by total resources, but by the scarcest resource”

What are the essential minerals for primary productivity

Molybdenum, Copper, Zinc, Manganese, Iron, Boron, Chlorine, sulfur, phosphorus, magnesium, calcium, potassium, nitrogen

What is the objective of the research in Crain 2007?

investigate the shifting role of nutrient limitation and potential eutrophication effects in coastal marshes that vary in salinity

Context/Motivation of Crain 2007?

in light of widespread coastal eutrophication identifying which nutrients limit vegetation and the community consequences when limitation is relaxed is critical to maintaining the health of estuarine marshes. nutrients lead to hypoxia because excess nutrient lead to excess primary producers, plants consume oxygen at night (short hypoxia = oxygen depletion) , decomposition of excess plant matter by microbes that consume oxygen (longer hypoxia)

What was the study design of Crain 2007?

Two estuaries, three marsh types, three treatmnets (+ control), three years monitoring biomass, plant composition, and leaf chemistry

• they went from increasing salinity (oligohaline → brackish → salty)

Results of Crain 2007:

In salt and brackish:

• N and N+P plot had higher production than control and P but not statistically different from each other 

• Vegetation in salt and brackish marshes primarily limited by N

• Nutrient treatment did not change species composition

In oligohaline:

• : N+P plots had higher production than P and N additions alone but all higher than CT plots

• Vegetation in oligohaline marshes co limited by N & P

• Addition of N&P led to dramatic leads in species composition 

Main idea results of Crain 2007:

• Salt and brackish marshes were primarily limited by Nitrogen

• Oligohaline marshes co limited by Nitrogen and Phosphorous, and this limitation is essential for maintaining high species diversity and proper marsh functioning 

• Managing nutrients in watershed runoff is critical to protecting the structure and function of coastal marshes → coastal management must expand from exclusively focusing on N to additionally managing P inputs in coastal estuaries

Trophic statuses

Oligotrophic: few, scarce, little

Mesotrophic: middle

Eutrophic: good, lots

One way to measure ecosystem production?

Charles eltons pyramid of numbers

What method did Crain use to measure primary production?

harvest based method

harvest based method info, advantages, and disadvantages?

• Other name: “Clip plots” bc plants materials in a known area is clipped dried and weighed → biomass/area

• Adv: objective measurement, easy to learn

• Disadv: time consuming, labor intensive, destructive, trees and shrubs

Why does biomass equal primary production

• Production → mass/area/time

• Biomass → mass or mass/area

• Quantified into years of biomass or seasons

Light and dark bottle method info, adv, and disadvantages

• O2 production = photosynthesis

• Change in O2 → estimate productivity

• During photosynthesis there is a fixed amount of carbon that does not change, therefore in the products of the reaction between CO2 water and sunlight we can determine how much O2 is produced

• During respiration (aerobic) we take the products from the reaction of photosynthesis ( glucose and O2) and we have CO2 water and energy again, the moles of C that are respired can determine how many moles of O2 are consumed 

Example of light/dark bottle method?

• Water samples collected, filtered to remove zooplankton, divide in light and dark bottles, measure O2, incubate both, measure O2 at the end, determine the molar conversion of O2

• Equations presented 

  • NEP = GPP - R_a+h; molar conversion of O2 

  • GPP = change in O2 (light) + change in O2 (dark)  

Dimension Analysis info, adv, and disadv

• shows annual production of wood, bark, leaves, twigs, and even flowers by measuring tree diameter, and litter fall traps for foliage

• uses

• allometric relatioships are used to relate biomass to diameter, height, etc

• to scale up to an entire forest you need to measure at least 200 samples plots in order to find an accurate mean, (CI - confidence interval : variation or uncertainty)

• What kind of information ca you get if you measure more than once

What kind of information ca you get if you measure more than once?

Production (NPP) = Biomass + M + H + L + V

Mortality, Herbivory, Leaching, Volatilization

Sediment addition to salt mangrove study

• Smooth coordgrass: No sediment, +15 cm sandy sediment, +30cm, +15 cm silty sediment, +30cm 

  • Results: cordgrass dominated plots

• Black mangrove : same thing

  • Mangroves declines in sediment addition 

Mussle study context and results (“are mussels mitigating cultural eutrophication and climate change through their nitrogen and carbon regulation functions”)

• context: location was near Atlanta industry and military bases, homes on septic,

• Overall showed that mussels amplify a marshes ability to clean organic matter from coastal waters and transform that C & N into plant tissues for storage

• Mussels increase C+N storage capacity, increasing marsh blue carbon benefits

Measuring Energy flows in ecosystems importance

• primary production is the energy basis of the food web

• creates a metric of ecosystem health

  • cultural eutrophication

  • lost growth potential due to toxins, invasive, disturbance

• Trophic transfer efficiency

  • How efficient is the system at converting light energy into upper trophic level energy

Metabolism in flowing waters throughout the day would look like what

at the beginning of the day there is a lower concentration of oxygen in the water because of respiration overnight, once the sun goes down the oxygen does as well, later in the day more oxygen is produced because of the sunlight and diffusion into the atmosphere is greater.

how to calculate the metabolism in flowing waters

1. find the oxygen mass balance DO/time (dissolved oxygen overtime) = GPP (gross primary productivity) - ER (ecosystem respiration) + D (reaeration flux)

2. find GPP using daytime DO variation

3. find ER from nighttime DO variation (assume constant during the day)

4. estimate diffusion based on DO saturation deficit

5. estimate D by using turbulence between water air (velocity, depth)

   1. D = k (DO saturation - DO actual)

   2. k is estimated from imperical relationships

OConnor and Dobbins (1958) formula

k = 3.93(U^0.5*H^-1.5) U = velocity H = depth of water

Churchill et al formula (1962)

k = 5.026( U * H^-1.67)

Owens et al formula (1964)

k = 5.32 U ^0.67 / H^1.85 U= velocity H= depth

what is the formula for DO saturation (mg/L)?

0.0042T² - 0.3489T + 14.479

Production:Respiration ecology concept in general and in flowing water

as the flowing water system becomes narrower there is more autotrophy (P/R<1) and vise versa there is more heterotrophy (P/R>1) if the ratio is close to 1 then the system has matured and reached an equilibrium.

Law of conservation of mass (Antoine Laurent Lavoisier)

nothing is created there is an equal quantity of matter before and after the operation and all must be assumed to have true equality between constiuents of substances

Biogeochemistry

The study of the chemical, physical, geological, and biological processes and reactions that govern the cycles of matter & energy:

• examples: Carbon, Nitrogen, Phosphorous, Water, … 

What did Vladimir Vernadsky do?

The Biosphere(1926): first time anyone formally recognied life as a geological force that shapes the earth 

How does productivity relate to material cycles?

GPP requires inorganic nutrients, the secondary production requires NPP, decomposers require NPP and secondary production for organic matter to mineralize into inorganic nutrients.

Decomposition

the process by which substances (mostly plants) are broken down into simpler forms:

• Energy released

• Organic → inorganic (mineralization)

• Most essential nutrients are recycled, and the rest are lost from the ecosystem through leaching, runoff, gas emissions, or permanent burial.

What kinds of animals decompose?

• Microfauna, microflora : <100 micro meters, bacteria, fungi, nematodes, protozoa

• Mesofauna: 100micro m -2mm, mites, potworms

• Macrofaunra : (2-20 mm) millipedes

• Megafauna : >20 mm, earthworms, snails, crabs, other invertebrates

• Vertebrate scavengers: consumer animal carrion

Factors driving decomposition rate?

Respiration is much slower in the low O2 environments of wetland soils so P>R → organic matter accumulates, carbon sequestration leading to carbon sequestration.

• Carbon quality and nutrient status

  • Higher C:N or C:P → slower decay

  • More complex C → slower decay 

    • Starch (sugars), cellulose, hemi-cellulose, lignin, phenols, aromatics 

Examples of different ecosystems and their levels of decomposition

high altitudes have low nutrient availability therefore they will have slow decomposition. While areas with tropical systems they have high nutrient availability and high decomposition.

How many tons, and grams, is in 1 petagram?

1×10^15 grams = 1 billion metric tons

The Carbon Cycle: Major storages and fluxes, what are the major storages? And what do the blue boxes, brown boxes, and white/tan boxes in the diagram represent?

• Mainly in plants, bacteria, fungi, animals, dead organic matter, dissolved CO2, coal, oil, natural gas, limestone, atmosphere (CO2), assimilation, respiration (assimilation and respiration are happening in the ocean as well)

Blue boxes:

• ocean/atmospheric storage

Brown boxes:

• terrestrial storages

White/tan boxes

• fluxes

The Carbon Cycle has three key drivers what are they?

1. Biological processes: P & R

2. Carbonate sedimentation

3. CO2 exchange between atmosphere and ocean

Explain how the biological processes production and respiration contribute to the carbon cycle

1. Primary Production: photosynthesis turning inorganic carbon to organic carbon

CO2 + H2O → glucose + oxygen

1. respiration : energy production (stored in ATP) from oxiding one element and reducing another by moving elections

2. Aerobic respiration: aerobic organisms (plants, animals, microbes) using O2 to accept electrons from oxidation of organic C (yields energy)

glucose + oxygen → carbon dioxide + water + energy

1. Anaerobic respiration: anaerobic and faculatative aerobic microbes can use other compounds (besides oxygen) to accept electrons: denitrification, sulfate reduction, iron reduction. See this in detail in the wetland structures (smell sulfur around wetlands?)

who accepts the electron during respiration

oxygen

who gives the electron during respiration?

glucose

explain carbon sedimentation, where it occurs, and how it contributes to the carbon cycle

Carbon is in the lithosphere a calcium carbonate precipitates when carbon dioxide is dissolved in water and turns into carbonate which combines with available calcium unless an oversupply of CO2 leads to an excess of H+ in the water which competes with calcium for carbonate, slow process but steady with 18 mil pg in the lithosphere, the entire Floridian peninsula is calcium carbonate,

explain how ocean-atmosphere exchange contributes to the carbon cycle

1. autotrophs : co2 uptake via photosynthesis

2. Gas exchange: co2 diffuses into (out of) ocean until partiral pressures equilibrate

What is a trend

a general direction of change, change over time, movement in a certain direction that allows prediction of future change

regression analysis:

examining the relationship between a dependent variable and independent variable

trend analysis, why do it, and what are some types

quantifying rate of change over time in an dependent variable, to understand change overtime: trends, seasonality, cycles, and random noise, and to predict and forecast, types: linear, non-linear, breakpoint, forecasting, (exponential, polynomial, seasonal, damped, …)

linear regression, explain R² and the formula for r²

R² tells us how well factor x predicts responses in y, it ranges from 0 to 1 and respresents the proportion of variation in y is explained by x

formula = TSS- RSS / TSS

TSS = total sum of squares, variation from the mean, SUM ((Yi - Yi)²) basically the difference from the data points from the mean

RSS = residual sum of squares, variation from the fitted model line, SUM ((Yi - Yi)²) its the same idea but instead of the mean it will find the difference from a linear trend line

anthropogenic (caused by humans) carbon release name 4 primary ways humans contribute to carbon release

1. deforestation 10-15% of human CO2 emissions

   1. burning biomass, reducing capacity for uptake, energy intensive mechanized process (harvesting, transport, milling), soil respiration/decomposition (rather than sequestration, soil oxidized and decomposes releasing CO2)

2. burning of fossil fuels : 80-85% of human CO2 emissions

3. methane (30% more powerful than CO2) byproduct of oil extraction

   1. thawing permafrost releases trapped methane through cracks, increases microbial decomposition (respiration), and exposure of organic matter (glacier retreat, erosion of shoreline), dam reservoirs the water speeds up decomposition of flooded biomass releasing methane

4. cement production

   1. 6% of global carbon emissions

   2. cement production uses a lot of energy and often uses fossil fuels for energy

   3. CO2 is a byproduct of cement production

What causes climate change?

changes in earths orbit, solar changes (the suns output), volcanic eruptions all predictable cycling, but changes in atmospheric chemistry is what has most driven climate change (natural and anthropogenic)

List green house gases, which 3 are the most significant, and how do GHGs work

carbon dioxide, water vapor, methane, nitrous oxide. the most significant are carbon dioxide, methane, and nitrous oxide. GHGs absorb a portion of outgoing solar radiation and reflect it back to earth, adding GHGs to the atmosphere instensifies the greenhouse effect, warming earths climate

why is there a driving oscillation for mean CO2 concentration and what is it driven by

the oscillation is driven by the seasonal cycle of plant vegetation. During the spring and summer, land plants wake up, grow new leaves, and undergo massive amounts of photosynthesis. During autumn and winter, the process completely reverses Plant growth slows or stops, deciduous trees shed their leaves, and vegetation dies back (respiration). While seasons happen globally, the oscillation is highly uneven because of Earth's geography The Northern Hemisphere Dominates: The Northern Hemisphere contains the vast majority of the world's landmass and dense terrestrial forests. The overall, year-over-year upward climb of the curve is driven entirely by human activities, primarily the burning of fossil fuels and deforestation.

What are the four Key Messages for the Southeast region in the Fourth National Climate Assessment?

Urban infrastructure and health risks; increasing flood risks in coastal and low-lying regions; natural ecosystems will be transformed; economic and health risks for rural communities

Why is the Southeast especially vulnerable to climate impacts, given its demographics and development?

It has many low-lying and coastal areas, many of the fastest-growing urban areas, and poorer communities on average

Why is air quality a particular concern in Southeastern cities?

More stagnant air days lead to fine particulate buildup, causing heart and lung disease; urban growth also adds aeroallergens

How do the urban heat island effect and elevated nighttime temperatures affect health?

Cities retain heat through the night, making heat a serious health risk (heat stroke, heat-related illness and death)

Why is the Southeast well suited to vector-borne disease spread?

It has the most suitable conditions for year-round mosquito populations, and warming expands habitable areas (e.g., dengue, Zika, malaria)

Which infrastructure is predicted to be especially vulnerable in the Southeast?

Water-related infrastructure such as bridges, stormwater systems, and water/wastewater treatment facilities

Name the two main drivers of thermal and ice-related sea level rise.

Thermal expansion of warming water and melting ice caps

What happens to stormwater systems under intensifying rainfall and flooding?

They deteriorate and often cannot handle the intense floods, leading to more road closures and property damage

What is saltwater intrusion and why does it matter?

Salt water moving into freshwater aquifers and soils, harming drinking water supply, agriculture, and infrastructure (roads, rail)

What cultural resource is at risk from coastal flooding in the Southeast?

Historic and prehistoric archaeological sites (about 13,000 recorded sites)

Why does 'effective rain' decrease as temperatures rise?

Higher temperatures increase evapotranspiration, so plants need more water and less rainfall is effectively available

What is the example of tropical species encroaching on temperate ones in Florida?

Mangroves expanding into salt marshes as winters warm

What will sea level rise do to coastal ecosystems?

Convert coastal terrestrial and freshwater ecosystems into tidal saline habitats, pushing coastal ecosystems inland at the cost of upslope/upriver ecosystems

Which region has more wildfire than the Southwest, and what is prescribed fire?

The Southeast; prescribed fire is purposeful low-intensity burning in a controlled setting that reduces wildfire risk

Give examples of freeze-sensitive invasive species expected to expand northward.

Burmese python and Brazilian pepper tree

How does development and human migration worsen ecosystem vulnerability?

It reduces natural ecosystem area (deforestation) and removes natural barriers to floods and coastal erosion

What health-care challenge do rural Southeastern communities face?

Less access to health care, with about one-third of rural hospitals at risk of closing

Which economic sectors are vulnerable, and what is a major heat-related economic impact?

Timber, agriculture, and manufacturing; large loss of labor hours from extreme heat

How do ocean changes affect rural coastal communities?

Rising seas and acidification make fishing less viable for communities relying on it for food and income

What is wet bulb temperature and why does it matter for heat stress?

A measure combining temperature and humidity; at high values sweat can no longer evaporate off skin effectively, causing extreme heat stress

Which temperature trends were highlighted for the Southeast?

More days above 95°F, more nights above 75°F, and longer freeze-free seasons

Why do poorer communities experience climate impacts more severely?

They have fewer resources to adapt, rebuild, or afford health care and clean energy, which increases pre-existing inequalities

Why do the N and P cycles matter?

• Nitrogen: inside of all amino acids that construct our proteins

• Phosphorus: a fundamental element in metabolic reactions

  • ADP/ATP → energy 

What drives the nitrogen cycle the most and what can impact the cycle the most

bacteria drive the patterns the most, and if soil is oxidized or not greatly effects the processes of the nitrogen cycle

Why are we concerned with the nitrogen cycle/ nitrogen in general?

1. Limiting nutrient? Eutrophication (algae blooms if there is not enough nitrogen) 

2. Toxicity: NH4+ and NO3 → methemoglobinemia (if there is too much nitrogen)

3. Oxygen consumption (NOD): Nitro oxygen demand

What are the forms of nitrogen species we are concerned with?

1. Nitrate (NO3-)  and Nitrite (NO2-) = Oxidized nitrogen

2. Ammonia and ammonium = ammonia - N

3. Organic nitrogen

   1. Amino acid

   2. Urea and uric acid (a way of releasing nitrogen from the body?)

   3. Purines and pyrimidines

   4. 40% of N in wastewater

Describe nitrogen fixation, and needs what conditions to occur (Aerobic or anaerobic)? who are the mutualists involved?

biological (bacteria) transformation of atmospheric N2 to NH4 (ammonium)

• symbiosis between plants and bacteria (diazatrophs) or cyanobacteria (BG-algae)

aerobic conditions

Nitrogen-fixing bacteria and host plants, primarily legumes

How can lighting contribute to the nitrogen cycle

lighting provides energy to break nitrogen bonds

nitrogen oxides convert to nitrates in precipitation that transport to soil where

Describe ammonification, and needs what conditions to occur (Aerobic or anaerobic)? where does organic N come from?

biological transformation (bacteria) of organic N to inorganic ammonia

• aerobic and anaerobic heterotrophic bacteria

  • kinetically more rapid than nitrification which leads to a build up of ammonia

can occur in either anaerobic or aerobic conditions

dead animals

define nitrification, what does bacteria does this process involve, and what conditions need to occur (Aerobic or anaerobic)? and where does this occur?

biological transformation (aerobic bacteria) of ammonia or ammonium to oxidized N (nitrates)

• chemoautotrophic and heterotrophic aerobic bacteria

needs aerobic conditions

in the soil

Denitrification, and needs what conditions to occur (Aerobic or anaerobic)?

Nitratite is converted to nitrogen gas by anaerobic bacteria

1. Carried out by facultative heterotrophs: organotrophs, chemolithotrophs, photolithotrophs, diazotrophs, an archea 

2. Requires two things: carbon source, anaerobic conditions

Needs anaerobic conditions

Mineralization of nitrogen

organic mactromolecules to inorganic bioavailable Nitrogen forms during decomposition, plants cant take up inorganic forms there has to be bacteria 

Assimilation in nitrogen cycle. are these forms organic or inorganic?

process by which plants take up nitrate, nitrite, and ammonium

• All inorganic forms of N plants therefore need microbes to acquire N and persist 

inorganic