Energy and nutrient flow in ecosystems - Topic 9

What is an ecosystem

Community of living organisms interacting with each other and with their physical environment

Ecosystems consist of both WHAT and WHAT components

Ecosystems consist of both BIOTIC and ABIOTIC components

Examples of abiotic components

Elements, climate, sunlight, air

Examples of biotic components

Microbes, plants, animals

Ecosystems can be studied by following the movement of WHAT from one level to another

Ecosystems can be studied by following the movement of ENERGY from one level to another

What are the two laws of thermodynamics

1. WHAT

2. WHAT

What are the two laws of thermodynamics

1. Law of conservation of ENERGY

2. Law of ENTROPY

Law of conservation of energy

Energy can be TRANSFORMED from one form into another or transferred from one place to another, but it cannot be CREATED or DESTROYED

Law of entropy

The entropy of a system and the surroundings will INCREASE—energy will always become MORE SPREAD OUT.

Entropy is the measure of how much energy has moved from being WHAT to becoming WHAT

Entropy is the measure of how much energy has moved from being LOCALIZED to becoming WIDELY DISPERSED

Ecosystems depend on a constant input of WHAT, and that energy transfer between trophic level is WHAT, limiting the structure and productivity of WHAT

Ecosystems depend on a constant input of ENERGY, and that energy transfer between trophic level is INEFFICIENT, limiting the structure and productivity of FOOD WEBS

There is always a WHAT of energy do to WHAT when you move up tho food chain

There is always a LOSS of energy do to HEAT when you move up tho food chain

Law of conservation of matter

Matter can neither be created nor destroyed, only transformed from one form into another

Law of conservation of matter

• Atoms like carbon, nitrogen and phosphorus are WHAT through ecosystems

• Matter cycles through WHAT and the WHAT

• Unlike energy, matter is WHAT and WHAT

Law of conservation of matter

• Atoms like carbon, nitrogen and phosphorus are RECYCLED through ecosystems

• Matter cycles through ORGANISMS and the ENVIRONMENT

• Unlike energy, matter is CONSERVED and REUSED

Law of conservation of matter

• On Earth, this means the total amount of matter, including essential elements like WHAT, WHAT, and WHAT stays essentially constant over time.

• Individual atoms that compose living organisms have long histories as they WHAT through the biosphere.

• Nutrients circulate between abiotic environment and living organisms in WHAT

Law of conservation of matter

• On Earth, this means the total amount of matter, including essential elements like CARBON, NITROGEN, and PHOSPHORUS, stays essentially constant over time.

• Individual atoms that compose living organisms have long histories as they CYCLE through the biosphere.

• Nutrients circulate between abiotic environment and living organisms in BIOGEOCHEMICAL CYCLES

Radiant energy:

• The source of virtually all energy on Earth is the WHAT

Radiant energy:

• The source of virtually all energy on Earth is the SUN

Radiant energy:

• About 33% of the energy received is WHAT by the atmosphere back into space

Radiant energy:

• About 33% of the energy received is REFLECTED by the atmosphere back into space

Radiant energy:

• Of the remainder, about 42% provides WHAT to the Earth’s surface and less than 1% is captured by WHAT and forms the basis for our WHAT

Radiant energy:

• Of the remainder, about 42% provides HEAT to the Earth’s surface and less than 1% is captured by PHOTOSYNTHESIZERS and forms the basis for our ECOLOGICAL SYSTEMS

WHAT makes up most of the atmosphere

NITROGEN makes up most of the atmosphere

Autotrophs = WHAT

Autotrophs = PRODUCERS

Autotrophs definition

Synthesize their own organic compounds

What are the two types of autotrophs?

• WHAT

• WHAT

What are the two types of autotrophs?

• Photoautotrophs (phototrophs)

• Chemoautotrophs

Photoautotrophs

The energy from LIGHT used to drive conversion of CARBON DIOXIDE into ORGANIC COMPOUNDS

Chemoautotrophs

Use CHEMICAL compounds as the source of ENERGY (no sunlight)

WHAT are more prevalent - sunlight is WHAT, widespread, and WHAT energy, whereas chemical energy sources are more WHAT and WHAT.

PHOTOAUTOTROPHS are more prevalent - sunlight is ABUNDANT, widespread, and HIGH energy, whereas chemical energy sources are more LIMITED and LOCALIZED

What are the two measures of the productivity of an ecosystem

• WHAT

• WHAT

What are the two measures of the productivity of an ecosystem

• Gross primary productivity (GPP)

• Net primary productivity (NPP)

Gross primary productivity (GPP)

The rate at which PRODUCERS convert solar energy into chemical energy (photoautotrophs)

Net primary productivity (NPP)

The REMAINING chemical energy after deducting energy used for MAINTENANCE functions of producers

The measurements are measured in units if WHAT captured (WHAT) or in units of WHAT (carbon) created (WHAT)

The measurements are measured in units if ENERGY captured (kJ/m2/time) or in units of BIOMASS (carbon) created (C/m²/time)

Primary productivity: In marine environments, the most productive areas are:

• WHAT due to nutrient runoff, sunlight throughout shallower waters

• Parts of the ocean where WHAT from the deep ocean return nutrients to the surface layers where photosynthetic activity occur

Primary productivity: In marine environments, the most productive areas are:

• COASTAL ZONES due to nutrient runoff, sunlight throughout shallower waters

• Parts of the ocean where UPWELLINGS from the deep ocean return nutrients to the surface layers where photosynthetic activity occur

Primary productivity can be limited by:

• WHAT

• WHAT

• WHAT

• WHAT

Primary productivity can be limited by:

• Sunlight

• Climate (annual temperature and precipitation)

• Nutrients availability

• How much PHOTOSYNTHETIC TISSUE is present

When is NPP highest in Canada

Summer because we get more sunlight, longer days, therefore more plant growth

Factors influencing primary productivity - Sunlight

• The potential rate of photosynthesis in an ecosystem is proportional to the HWAT and WHAT of sunlight, which varies geographically and seasonally

Factors influencing primary productivity - Sunlight

• The potential rate of photosynthesis in an ecosystem is proportional to the INTENSITY and DURATION of sunlight, which varies geographically and seasonally

Factors influencing primary productivity - Sunlight

• Sunlight is most intense and day length is least variable near the WHAT

• Sunlight is less intense and day length is most variable near the WHAT

Factors influencing primary productivity - Sunlight

• Sunlight is most intense and day length is least variable near the EQUATOR

• Sunlight is less intense and day length is most variable near the POLES

Factors influencing primary productivity - Climate

In terrestrial ecosystems, mean annual net primary productivity increases with both

• mean annual WHAT

• mean annual WHAT

Speeds up WHAT

Factors influencing primary productivity - Climate

In terrestrial ecosystems, mean annual net primary productivity increases with both

• mean annual TEMPERATURE

• mean annual PERCIPITATION

Speeds up PHOTOSYNTHESIS

Factors influencing primary productivity - Nutrients

Where do organisms get the ingredients they need to make biomolecules

• Need sources of: WHAT, WHAT, WHAT, WHAT and WHAT

• Consumers get from WHAT organic matter

• Producers get from the WHAT

Factors influencing primary productivity - Nutrients

Where do organisms get the ingredients they need to make biomolecules

• Need sources of: C, N, P, O and H

• Consumers get from EATING organic matter

• Producers get from the ENVIRONMENT

What are made from these sources: C, N, P, O and H

DNA, Proteins

Factors influencing primary productivity - Nutrients

• All plants need WHAT of nutrients for maintenance and photosynthesis

• If the concentration of one nutrient drops below a critical level, WHAT (and thus WHAT) may stop

• One nutrient usually becomes a WHAT (has the greatest effect on capping productivity

Factors influencing primary productivity - Nutrients

• All plants need SPECIFIC RATIOS of nutrients for maintenance and photosynthesis

• If the concentration of one nutrient drops below a critical level, PHOTOSYNTHESIS (and thus PRODUCTION) may stop

• One nutrient usually becomes a LIMITING NUTRIENT (has the greatest effect on capping productivity

How to determine the limiting nutrient

• Add nutrients and measuring increasing WHAT

• Other nutrients may be partially limiting but not the principal bottleneck, addition may result in smaller increases in WHAT

How to determine the limiting nutrient

• Add nutrients and measuring increasing NPP

• Other nutrients may be partially limiting but not the principal bottleneck, addition may result in smaller increases in NPP

Limiting nutrients can WHAT among ecosystems

Limiting nutrients can VARY among ecosystems

Freshwater ecosystem

• generally limited by WHAT

• WHAT binds strongly to soil, limited WHAT

• Small increases cause large WHAT

Freshwater ecosystem

• generally limited by PHOSPHOROUS

• P binds strongly to soil, limited NATURAL RUNOFF

• Small increases cause large ALGAL BLOOMS

Terrestrial ecosystems:

• Generally limited by WHAT

• Requires WHAT from atmosphere (by WHAT in soil, some plants)

• Easily lost from soil through WHAT

Terrestrial ecosystems:

• Generally limited by NITROGEN

• Requires FIXATION from atmosphere (by BACTERIA in soil, some plants)

• Easily lost from soil through LEACHING

Factors influencing primary productivity - Nitrogen

• Nitrogen (N) is needed to build WHAT, but it is often WHAT

• The positive response to N fertilizer in all but WHAT ecosystems can be interpreted as evidence for widespread N limitation to productivity

Factors influencing primary productivity - Nitrogen

• Nitrogen (N) is needed to build PROTEIN, but it is often LIMITING

• The positive response to N fertilizer in all but DESERT ecosystems can be interpreted as evidence for widespread N limitation to productivity

Why aren’t desserts limiting in nitrogen

Because they are more limiting in water than nitrogen

Factors influencing primary productivity - Phosphorus

• Living things require phosphorous (ATP, DNA, phospholipids)

• Phosphorus is usually the limiting nutrient for WHAT growth in freshwater systems.

• When more phosphorus is available:
  • Phytoplankton WHAT increases
  • WHAT concentration (a proxy for algal biomass) increases
  • Water WHAT decreases

Factors influencing primary productivity - Phosphorus

• Living things require phosphorous (ATP, DNA, phospholipids)

• Phosphorus is usually the limiting nutrient for PHYTOPLANKTON growth in freshwater systems.

• When more phosphorus is available:
  • Phytoplankton BIOMASS increases
  • CHLOROPHYLL concentration (a proxy for algal biomass) increases
  • Water CLARITY decreases

Heterotrophs (consumers)

Organisms that cannot make their own food

Heterotrophs (consumers) obtain energy by WHAT

Heterotrophs (consumers) obtain energy by EATING other organisms ( Plants, animals or both)

Heterotrophs (consumers) depend on WHO directly or indirectly

Heterotrophs (consumers) depend on PRODUCERS directly or indirectly

Secondary production

• As animals eat plants, energy is transferred from producers to consumers

• Some of this energy is stored in NEW consumer BIOMASS

How do we know who is eating who

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

How do we know who is eating who

• Observation (I saw something eat something else)

• Stomach content analysis

• Scat analysis (sorting through or DNA metabarcoding)

• Stable isotopes (C, N, other tracers)

• A combination of these

Food chains or webs - how do we know who is eating who

Example:
A population of wolves became established on Pleasant Island, Alaska
in 2013. The small island had a population of deer (preferred prey for wolves) as well as harbor seals and sea otters (infrequent prey).

Proportion of sea otters in wolf diets increased as the proportion of deer decreased:

1. WHAT

2. WHAT

Food chains or webs - how do we know who is eating who

Example:
A population of wolves became established on Pleasant Island, Alaska
in 2013. The small island had a population of deer (preferred prey for wolves) as well as harbor seals and sea otters (infrequent prey).

Proportion of sea otters in wolf diets increased as the proportion of deer decreased:

1. measured by the relative frequency of occurrence of prey found in scats (DNA metabarcoding)

2. Stable carbon and nitrogen isotope analyses

Food chains or webs - Energy and trophic levels

• Inefficiency of WHAT from one trophic level to the next has profound effects on WHAT structure

Food chains or webs - Energy and trophic levels

• Inefficiency of ENERGY TRANSFER from one trophic level to the next has profound effects on ECOSYSTEM structure

Food chains or webs - Energy and trophic levels

• each trophic level contains only about WHAT as much energy as the trophic level below it

Food chains or webs - Energy and trophic levels

• each trophic level contains only about 10% as much energy as the trophic level below it

Food chains or webs - Energy and trophic levels

• The reduction of energy and biomass with increasing trophic level affects sizes of populations of organisms at the WHAT of a food webs

Food chains or webs - Energy and trophic levels

• The reduction of energy and biomass with increasing trophic level affects sizes of populations of organisms at the TOP of a food webs

Food webs can be WHAT

Food webs can be COMPLEX

In nature, organisms may consume many different WHAT and WHAT, and trophic positions are often not whole numbers

In nature, organisms may consume many different PRODUCERS and CONSUMERS, and trophic positions are often not whole numbers

Secondary productivity

How much energy is stored

Secondary productivity

• As animals eat plants, energy is transferred from WHAT to WHAT

• Some of this energy is WHAT and some is stored in WHAT (WHAT)

Secondary productivity

• As animals eat plants, energy is transferred from PRODUCERS to CONSUMERS

• Some of this energy is USED and some is stored in TISSUE (CONSUMER BIOMASS)

Assimilation = WHAT

Assimilation = Ingestion (energy consumed) - Egestion (energy excreted)

Secondary productivity (sp) = WHAT

Secondary productivity (sp) = Assimilation (energy kept) - Respiration

Net production efficiency

How much energy is STORED relative to energy ASSIMILATED from food

Net production efficiency (NPE) = WHAT

Net production efficiency (NPE) = (Secondary productivity / Assimilation) x100

Ecological efficiency

How much energy is in consumer biomass relative to net primary productivity

Ecological efficiency (EE) = WHAT

Ecological efficiency (EE) = (Secondary productivity / Net production efficiency) x 100

• The vast grasslands capture enormous amounts of solar energy through photosynthesis (WHAT). What's left after plant respiration is potentially available to grazers (WHAT). The biomass wildebeest and zebra build (WHAT) from what they eat is only a fraction of what the grasses produced (WHAT). And of that wildebeest and zebra biomass, only around 10% is available to lions because energy is lost at every step of the food chain to respiration, waste, and inefficient transfer (WHAT).

• There are so few lions relative to wildebeest because of WHAT!

• The vast grasslands capture enormous amounts of solar energy through photosynthesis (GPP). What's left after plant respiration is potentially available to grazers (NPP). The biomass wildebeest and zebra build (SP) from what they eat is only a fraction of what the grasses produced (NPE). And of that wildebeest and zebra biomass, only around 10% is available to lions because energy is lost at every step of the food chain to respiration, waste, and inefficient transfer (EE).

• There are so few lions relative to wildebeest because of ENERGETICS!

Why is there a inversion in the ocean biomass

• Terrestrial producers: SLOW turnover → Relatively HIGH standing biomass

• Phytoplankton (T1 producer): divides in hours → Relatively LOW standing biomass Inverted pyramid ≠ violation of thermodynamics

Contaminant biomagnification

Lipophilic, synthetic compounds, that:

• WHAT

• WHAT

• Toxic at relatively WHAT concentrations

Contaminant biomagnification

Lipophilic, synthetic compounds, that:

• BIOACCUMALATE

• BIOMAGNIFY

• Toxic at relatively LOW concentrations

bioaccumulate

increase in concentration over the LIFETIME of an organism

biomagnify

increase in concentration with increasing TROPHIC LEVEL

Example: Contaminant biomagnification

What are the two forces regulating trophic structure:

• WHAT

• WHAT

What are the two forces regulating trophic structure:

• Bottom-up control

• Top-down control

Bottom up control

When the abundance of organisms at LOWER trophic levels (plants or phytoplankton) determines the abundance of organisms at HIGHER trophic levels

Bottom-up control

• WHAT - cold, nutrient-rich deep water moves to the surface

• Nutrients fuels WHAT blooms, which in turns supports WHAT abundances of plankton, fish, seabirds and marine mammals

Bottom-up control

• UPWELLING - cold, nutrient-rich deep water moves to the surface

• Nutrients fuels PHYTOPLANKTON blooms, which in turns supports WHAT abundances of plankton, fish, seabirds and marine mammals

Top-down control

When predators at the TOP of the food web influence both the herbivores they eat and the plants on which herbivores feed

Top-down control

• Sea otters consume WHAT , which feed on kelp

• Removal of sea otters leads to WHAT of kelp forests

Top-down control

• Sea otters consume URCHINS, which feed on kelp

• Removal of sea otters leads to DEGRADATION of kelp forests

Disrupting biogeochemical cycles - Phosphorous

• Whole-lake experiments that identified phosphorus as the culprit behind toxic WHAT formations (eutrophication) in lakes

Disrupting biogeochemical cycles - Phosphorous

• Whole-lake experiments that identified phosphorus as the culprit behind toxic BLUE-GREEN ALGAL BLOOM formations (eutrophication) in lakes

Disrupting biogeochemical cycles - Nitrogen

• Nitrogen is the most prevalent gas (N2) in the atmosphere, so why is it often limiting

• N2 is not a WHAT form for plants, It has a WHAT bond that requires significant energy to break

Disrupting biogeochemical cycles - Nitrogen

• Nitrogen is the most prevalent gas (N2) in the atmosphere, so why is it often limiting

• N2 is not a USABLE form for plants, It has a TRIPLE bond that requires significant energy to break

Disrupting biogeochemical cycles - Nitrogen

• Fritz Haber produced a method to make WHAT from N2 and hydrogen gas

• Carl Bosch was an engineer who helped to scale the process

Disrupting biogeochemical cycles - Nitrogen

• Fritz Haber produced a method to make AMMONIA from N2 and hydrogen gas

• Carl Bosch was an engineer who helped to scale the process

Disrupting biogeochemical cycles - Nitrogen

• Today, the Haber-Bosch process accounts for roughly half of all WHAT on Earth, affecting ecosystems and contributing to WHAT.

Disrupting biogeochemical cycles - Nitrogen

• Today, the Haber-Bosch process accounts for roughly half of all REACTIVE NITROGEN on Earth, affecting ecosystems and contributing to EUTROPHICATION.

Disrupting biogeochemical cycles - Nitrogen

• Excess nitrogen-based fertilizer from agriculture in the Mississippi River basin can wash off fields during rainstorms or leach through soil into streams and eventually to the Gulf of Mexico.

• In the Gulf, the extra nitrogen fuels massive WHAT. When algae die and sink, bacteria that decompose them use up WHAT in the bottom waters.

• This eutrophication process creates very WHAT levels - fish and other marine life either flee or die, forming the seasonal “WHAT.”

Disrupting biogeochemical cycles - Nitrogen

• Excess nitrogen-based fertilizer from agriculture in the Mississippi River basin can wash off fields during rainstorms or leach through soil into streams and eventually to the Gulf of Mexico.

• In the Gulf, the extra nitrogen fuels massive ALGAL BLOOMS. When algae die and sink, bacteria that decompose them use up OXYGEN in the bottom waters.

• This eutrophication process creates very LOW OXYGEN levels - fish and other marine life either flee or die, forming the seasonal “DEAD ZONE.”

Disrupting biogeochemical cycles - Carbon

• Carbon has been WHAT in recent years

• CO2 decreases in summer because HWAT

• CO2 increases in winter because WHAT

Disrupting biogeochemical cycles - Carbon

• Carbon has been INCREASING in recent years

• CO2 decreases in summer because Trees bloom and take in CO2

• CO2 increases in winter because leaves die and get decomposed releasing CO2

Greenhouse effect

• What do you think would happen if you removed all water vapour, carbon dioxide, and methane from the atmosphere?

• What would happen if you increased the amounts of water vapour, carbon dioxide, and methane in the atmosphere?

Greenhouse effect

• What do you think would happen if you removed all water vapour, carbon dioxide, and methane from the atmosphere? TOO COLD

• What would happen if you increased the amounts of water vapour, carbon dioxide, and methane in the atmosphere? TOO HOT

Climate change A causal chain - emissions

• Emissions of WHAT have increased rapidly over recent decades.

• Global net GHG emissions from humans include

• CO2 from WHAT combustion and industrial processes

• CO2 from land use, land- use change and forestry

• WHAT; WHAT and fluorinated gases (HFCs, PFCs, SF6, NF3)

Climate change A causal chain - emissions

• Emissions of GHG have increased rapidly over recent decades.

• Global net GHG emissions from humans include

• CO2 from FOSSIL FUEL combustion and industrial processes

• CO2 from land USE, land- use change and FORESTRY

• CH4; N2O and fluorinated gases (HFCs, PFCs, SF6, NF3)

Climate change Atmospheric concentrations

• Emissions have led to increases in the atmospheric concentrations of several GHGs including the three major well- mixed GHGs WHAT, WHAT and WHAT

• Concentrations of WHAT and WHAT have increased to levels unprecedented in at least 800,000 years

• Current WHAT concentrations are higher than at any time over at least the past two million years.

Climate change Atmospheric concentrations

• Emissions have led to increases in the atmospheric concentrations of several GHGs including the three major well- mixed GHGs CO2, CH4 and N2O

• Concentrations of CH4 and N2O have increased to levels
  unprecedented in at least 800,000 years

• Current CO2 concentrations are higher than at any time over at least the past two million years.

Climate change Global temperatures

• The global surface temperature (shown as annual anomalies from a 1850–1900 baseline) has increased by around WHAT°C since 1850–1900

Climate change Global temperatures

• The global surface temperature (shown as annual anomalies from a 1850–1900 baseline) has increased by around 1.1°C since 1850–1900

Climate change Human role

• Human activities, principally through emissions of greenhouse gases, have unequivocally caused WHAT

Climate change Human role

• Human activities, principally through emissions of greenhouse gases, have unequivocally caused GLOBAL WARMING