fundamentals of ecology

1.018/7.30J Fall 2003 Fundamentals of Ecology

Lecture 1 – Introduction to Ecology

Krebs Chapter 1:

le problems). (H, W)

The Biosphere. (H, W)

READINGS FOR NEXT LECTURE:

Introduction to the Science of Ecology

Redox Handout (please work through the examp

Vernadskii (1926).

Rowe (1992). Biological Fallacy: Life Equals Organisms. (H, W)

Remmert (1980). Ecology: The Basic Concept. (H, W)

Outline for today: I. What is ecology? II. Why study ecology? III. How to study ecology? IV. Where to study ecology? V. How will we learn about ecology?

I. What is ecology?

(9/8 and 9/11): RECITATIONS NEXT WEEK

origin of word: oikos = the family household logy = the study of

interesting parallel to economy = management of the household many principles in common – resources allocation, cost-benefit ratios

definitions: Haeckel (German zoologist) 1870: “By ecology we mean the body of knowledge concerning the economy of Nature - the investigation of the total relations of the animal to its inorganic and organic environment.”

Burdon-Sanderson (1890s): Elevated Ecology to one of the three natural divisions of Biology: Physiology - Morphology – Ecology

Andrewartha (1961): “The scientific study of the distribution and abundance of organisms.”

Odum (1963): “The structure and function of Nature.”

Definition we will use (Krebs 1972):

“Ecology is the scientific study of the processes regulating the distribution andabundance of organisms and the interactions among them, and the study of how theseorganisms in turn mediate the transport and transformation of energy and matter in the biosphere (i.e., the study of the design of ecosystem structure and function).”

The goal of ecology is to understand the principles of operation of natural systems and to predict their responses to change.

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What ecology is not Ecology is not environmentalism, nor “deep ecology.” Ecology is science, based on biological, physical and chemical principles, and should be value-free. Environmentalism advocates for certain actions and policy positions. II. Why study ecology? Curiosity – How does the world around us work? How are we shaped by our surroundings?

Responsibility – How do our actions change our environment? How do we minimize the detrimental effects of our actions? Overfishing, habitat destruction, loss of biodiversity, climate change.

Nature as a guide – The living world has been around much longer than we have and has solved many problems with creative solutions. Ecological systems are models for sustainability. How can we feed our growing population? Where will we live?

Sustainability – a property of human society in which ecosystems (including humans) are managed such that the conditions supporting present day life on earth can continue.

Ecology helps us understand complex problems. Examples: Cane toads in Australia Feral pigs in Hawai’i Nile Perch in Lake Victoria Wolves in Yellowstone

III. How to study ecology? What kinds of experiments do ecologists perform? Observations – Go into the field and see what’s happening

Microcosms – Isolate a portion, limit factors, manipulate conditions.

Mathematical models – Describe ecosystems interactions as equations. Connections to other

disciplines :

ECOLOGY

Genetics

(7) Hydrology

(1)

Behavior (7,9)

Geology (12)

adapted from Elements of Ecology, R.L. Smith and T.M. Smith, 4th Ed.

Biochemistry (5,7)

Physiology (5,7)

Atmosphericsciences

(1,12)

IV. Where to study ecology?

(Tissues) Organelle Molecule AtomOrganism

Population: Group of interacting and interbreeding organisms.

Community: Different populations living together and interacting. Populations can interact as competitors, predator and prey, or symbiotically.

:Ecosystem Organisms and their physical and chemical environments together in a particular area. “The smallest units that can sustain life in isolation from all but atmospheric surroundings.”

Biome: Large scale areas of similar vegetation and climatic characteristics.

Biosphere: Thin film on the surface of the Earth in which all life exists, the union of all of the ecosystems. This is a highly ordered system, held together by the energy of the sun.

When is an organism not an organism?

Populations are shaped by their abiotic surroundings, and, in turn, change their abiotic surroundings. For example, O2 in atmosphere from photosynthesis. Others?

These levels of organization do not exist in isolation. There are feedbacks between the largest and smallest scales.

Interactions among different levels lead to emergent properties.

Principle of hierarchical control (Odum): “As components combine to produce larger functional wholes in hierarchical series, new properties emerge. That is, one cannot explain all the properties at one level from an understanding of the components at the one below.”

V. How will we learn about ecology?

Start with energy flows At the individual level, how do organisms “make a living”? At the ecosystem level, how does energy move around?

Move on to nutrients How does nutrient availability limit organism growth? On an ecosystem and global scale, how do organisms fit in to global nutrient cycles?

Then focus on populations and communities Numerical models of the growth of individual populations Then apply these to model competition between populations for the same resources Metrics of species diversity and responses of communities to changes

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Study questions

• Give an example of organisms modifying their surroundings (not mentioned in class). • What is the relationship between ecology and environmentalism? Where does Remmert see

ecology fitting in to broader societal problems? • Why does Remmert call green plants “the first great polluters of the environment”? • What is an invasive species? Why do they pose such a serious problem for ecologists? • Give an example of an ecosystem, and explain what the associated community would consist of. • What kinds of experiments do ecologists perform? What are the advantages and disadvantages

of each? • According to Vernadskii, in what ways does life change the surface of the earth. If all forms of life

became extinct, what would happen? What does he mean by “the biosphere is the creation of the sun?” and “Under the thermodynamic conditions of the biosphere, water is a powerful chemical agent...” but on a dead Earth, water is “...a compound of weak chemical activity?”

• Rowe’s “Biological Fallacy” calls in to question using an organism-level perspective on life. Describe how energy flows would look different if you were a) inside a cell or b) in a space ship looking down on earth. Without prior knowledge, what would you call life?

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Lecture 2– Carbon and Energy Transformations


Krebs Chapter 25: Ecosystem Metabolism I: Primary Productivity

Luria. 1975. Overview of photosynthesis. (H, W)

Stowe, S. 2003. When swans inspire not a ballet, but a battle. NY Times. September 3. (H,W)

Kaiser, J. 1995. Can deep bacteria live on nothing but rocks and water? Science. 270:377. (L)

Stevens, TO and JP McKinley. 1995. Lithoautotrophic microbial ecosystems in deep basalt aquifers. Science. 270: 450. (L)

Pace, N. 1997. A molecular view of microbial diversity and the biosphere. Science. 276:734. (L)

Newman, DK and JF Banfield. 2002. Geomicrobiology: How molecular-scale interactions underpin biogeochemical systems. Science. 296:1071. (L)

Sarbu, S et al. 1996. A chemoautotrophically-based cave ecosystem. Science. 272:1953. (L)

“Nature has put itself the problem of how to catch in flight light streaming to earth and to store the most elusive of all powers in rigid form.”

Mayer, 1842, discovered law of conservation of energy

Outline for today:

I. Evolution II. Autotrophs

A. Photosynthesis B. Bacterial photosynthesis C. Chemosynthesis

III. Heterotrophs A. Aerobic respiration B. Fermentation C. Anaerobic respiration

Main question: How do organisms obtain carbon and energy needed to grow and function?

I. Evolution

Old view of the world: 5 Kingdoms. Development of new perspective on life.

Novel genetic identification techniques (C Woese in the 1970s) “Tree of Life” with 3 Domains: Eubacteria, Archaea, Eukaryotes Hydrothermal vents and hot springs Genotypic not phenotypic classifications

abgupt

Rectangle

0

0

Universal phylogenetic tree based on SSU rRNA sequences Sixty-four rRNA sequences representative of all known phylogenetic domains were aligned, and a tree was produced using FASTDNAML (43, 52). That tree was modified, resulting in the composite one shown, by trimming lineages and adjusting branch points to incorporate results of other analyses. The scale bar corresponds to 0.1 changes per nucleotide. (Pace, N. 1997. Science. 276:734-740)

Today: Release of fossil carbon 0 Dinosaurs 21%

Metazoans

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Billio

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1 Modern eukaryotes 10%

Development of ozone shield

1%2

Oxygenic phototrophs 0.1% (cyanobacteria) Prokaryotes

Archaebacteria Eukaryotes 3 Anoxygenic phototrophs Eubacteria % O2 in

(photosynthetic bacteria)

Car

bon

buria

l

atmosphere

Origin of life – 3.8 billion years ago 4 Chemical evolution

Photochemical synthesis Formation of Earth 4.5 billion years ago

Figure 2. Adapted from Brock and Madigan, Biology of Microorganisms. Major landmarks in biological evolution.

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Basic picture of life: “CH2O” and O2

Heterotrophs “nourished from others”

Autotrophs“self-nourishers”

CO2 and H2O

II. Autotrophs

These “self-nourishers” get their energy from the sun (photoautotrophs) or from reduced inorganic compounds (chemoautotrophs), and they get their carbon from CO2.

These organisms undergo two reactions. The first reaction produces ATP* and NADPH**, which provide stored energy and reducing power. For photosynthetic organisms, this is known as the Hill reaction. The second reaction, the Calvin Cycle, is common to all autotrophs, and uses stored energy and reducing power to convert CO2 to CH2O (sugar).

A. Photosynthesis (aerobic)

Who? Plants, cyanobacteria, eukaryotic algae C Source? CO2 Energy Source? Sunlight Electron Donor? H2O Where? In aerobic, light conditions

CO2 + H2O + hν ⎯⎯⎯⎯X CH2O + O2

B. Bacterial Photosynthesis (anaerobic)

Who? Bacteria (e.g. Purple sulfur bacteria) C Source? CO2 Energy Source? Sunlight Electron Donor? H2S Where? In anaerobic, light conditions

CO2 +2 H2S + hν ⎯⎯⎯⎯X CH2O + 2 S + H2O

C. Chemosynthesis

Who? Chemoautotrophic bacteria, aka chemolithoautotrophs C Source? CO2

3

Energy Source? Reduced inorganic compounds (CH4, NH4, H2S, Fe2+) Electron Donor? Reduced inorganic compounds Where? In microaerobic or anaerobic, dark conditions

Sulfur oxidizing bacteria: H2S Æ S Æ SO42

Methanotrophs: CH4 (methane) Æ CO2+ - Nitrifying bacteria: NH4 Æ NO2 Æ NO3

Iron oxidizing bacteria: Fe2+ Æ Fe3+

*ATP = adenosine triphosphate. (ADP = adenosine DI phosphate) **NADPH = nicotinamide adenine dinucleotide phosphate

III. Heterotrophs

These organisms (“nourished by others”) get their energy and carbon from reduced organic compounds.

ATP and NADH*** are produced, which can then be used elsewhere in the cells.

A. Aerobic respiration

Who? Aerobic eukaryotes and prokaryotes C Source? CH2O Energy Source? CH2O Electron Acceptor? O2 Where? Aerobic conditions

These reaction is essentially the reverse of the Calvin cycle. O2 is the final electron acceptor. Plants also carry out this reaction to get energy for their growth and metabolic processes.

CH2O + O2 ⎯⎯⎯⎯X CO2 + H2O

B. Fermentation

Who? Eukaryotes and prokaryotes C Source? CH2O Energy Source? CH2O Electron Acceptor? organic compounds Where? Anaerobic conditions

This is only the first part of respiration and results in partial breakdown of glucose. The products are organic acids or alcohols (e.g., lactic acid, ethanol, acetic acid) rather than CO2.

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- -

C. Anaerobic respiration

Who? Prokaryotes only C Source? CH2O Energy Source? CH2O Electron Acceptor? Oxidized inorganic compounds (SO4

2-, Fe3+, NO3+, etc.)

Where? Anaerobic conditions

Very similar to aerobic respiration, except that O2 is not the final electron acceptor. Instead, another -oxidized compound such as SO4

2-, NO3 , or CO2 is the final electron acceptor.

Iron reducing bacteria: Fe3+ Æ Fe2+

Denitrifying bacteria: NO3 Æ NO2-NO2 Æ N2

Sulfate reducing bacteria: H2S Æ S Æ SO42

Methanogens: CO2 Æ CH4 (methane)

***NADH = nicotinamide adenine dinucleotide (a relative of NADPH. NADH is used for ATP production, while NADPH is associated with biosynthesis)

Study Questions:

• What is a Winogradsky column? What are the light, oxygen and sulfide levels in each layer, and which organisms dominate each layer? What are the energy and carbon sources for each kind of organism?

• Describe the significance of the discovery of deep-sea hydrothermal vents. • Why has Rubisco been called the most important protein on Earth? • What is unique about the cave ecosystems described in Sarbu’s article? What are the differences

and similarities to hydrothermal vents? • Banfield and Newman’s article mentions the benefits of advances in genetic techniques for

understanding microbial community structure and the identities of microorganisms. Given what you know about metabolic diversity, why is it so hard to culture most microorganisms in a laboratory?

• If a lake is covered in algae, how do anoxygenic photosynthetic bacteria, which live underneath the algae, manage to obtain sufficient light to carry out photosynthesis?

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Lecture 3 – Primary Productivity

Behavior (7,9)


Noble IR and R Dirzo. 1997. Forests as human-dominated ecosystems. Science. 277:522-525.

Field, CB et al. 1998. Primary production of the biosphere: Integrating terrestrial and oceanic components. Science. 281:237-240. (H,W)

Broad, WJ. 2003. Deep under the sea, boiling founts of life itself. NY Times. 9/9 (H,W)

Krebs. Pages 97-102: “Light as a Limiting Factor.”

Questions for today: How do energy and carbon move through ecosystems?

How do terrestrial and aquatic ecosystems vary? What limits their productivity? Outline: I. Scale II. Definitions

A. Terms to describe productivity B. Residence times and turnover rate

III. Distribution on the Earth MOVIE NIGHT:

Monday 9/15 @ 7:30pm

“Cane Toads”

IV. Terrestrial Productivity A. Limiting factors B. Measurement

I. Scale

(A) “Metabolism” of a Cell

Biological Work - Motility - Biosynthesis - Transport - Electrical Potential - Light Emission

Inorganic Nutrients

N,P,Fe,S etc 1 µm

[“CH2O”] Dissolved Organic Carbon

CO2

CO2

O2

DNA

Nucleus

Mitochondrion

Chloroplast

O2

CO2 ADP

NADP

“CH2O” ATP NADPH

O2

H2O

“CH2O” NADH

CO2 NAD

ATP

ADP

O2 GROWTH

Solar

(B) “ Metabolism ” of a Drop of the Ocean

CO21 mm

O2

UpwelledInorganic Nutrients

“[CH2O]”

“CH2O”

O2CO2

Recycled Inorganic Nutrients

Fecal pellets

Phytoplankton

Zooplankter

Energy

(B) “ Metabolism ” of a Drop of the Ocean

CO21 mm

O2

UpwelledInorganic Nutrients

“[CH2O]”

“CH2O”

O2CO2

Recycled Inorganic Nutrients

Fecal pellets

Phytoplankton

Zooplankter

Energy

(C) “Metabolism ” of an Ocean

Deep Sea Sediments

Inorganic Nutrients

Inorganic Nutrients

“ CH O2 ”

O 2 Remineralized Nutrients

Mixed Layer

100m

4000m

“ [CH O]2 ” O 2

CO 2 O 2

40,000

600

700

Carbon inventoryx 1015g C

Animals Plants

(C) “Metabolism ” of an Ocean

Deep Sea Sediments

Inorganic Nutrients

Inorganic Nutrients

“ CH O2 ”

O 2 Remineralized Nutrients

Mixed Layer

100m

4000m

“ [CH O]2 ” O 2

CO 2 O 2

40,000

600

700

Carbon inventoryx 1015g C

Animals Plants

-+

1

II. Definitions A. Terms to describe Productivity

gross primary productivity (GPP) = rate of conversion of CO2 to organic carbon per unit surface area

Units: g C m-2 year-1, or Kcal m-2 year-1

gross primary production has units of g C year-1 for a lake, forest, field, etc.

respiration by autotrophs (RA) = how much energy or carbon is used for plant metabolism

net primary production (NPP) = GPP – RA = how much energy or carbon is stored as biomass

respiration by heterotrophs (RH) = how much energy or carbon is used for heterotroph metabolism

net community production (NCP) = GPP – RA – RH = NPP – RH

photosynthetic efficiency (PE) = 100*(incident radiation converted to NPP)/(total incident radiation)

n.b. We’re using energy and (reduced) carbon interchangeably. Conversion: 39 kJ per g C

B. Residence times and turnover rates f = flux (mass/area/time). use GPP (how much is entering the system)

M = mass (biomass/area)

Mean residence time (MRT) = M/f = (g/m2) / (g/m2/year) = years

Fractional turnover (k) = 1 / MRT * 100 = % turning over each year

Study Questions: 1. What is the difference between net and gross primary productivity? What is the difference between net

community productivity and net primary productivity? How would you measure these difference? 2. What regulates primary productivity in terrestrial? How is this reflected in the global distribution of primary

production? 3. What is the turnover rate in a forest? What does it signify? How is it measured? 4. What is functionally and physiologically similar about phytoplankton and trees? What is different? 5. How will increases in atmospheric CO2 affect global productivity? 6. Discuss the principles behind remote sensing to terrestrial productivity. What limits the quality of the data? 7. Describe 2 strategies plants have developed to deal with low water availability. 8. According to Noble and Dirzo, human domination of forests extends beyond plantations and actively

managed lands. In what other ways do humans alter forest ecosystems, and how do the authors recommend minimizing the detrimental impacts?

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Adapted from: Begon,1996

Comparison of Young and Mature Forests

Young Mature Biomass (kg m-1) 9.7 58 NPP (g m-2 y -1) 1060 1300 % mass in

Wood 60 80 Leaves 10 1 Roots 30 19

Turnover time (y) 8.5 43.5 Tree age (y) 40–45 150–400Respiration/GPP 0.80 1.00

TABLE 23.1N ET P RIMARY P RODUCTION AND P LANT B IOMASS OF W ORLD E COSYSTEMS

Ecosystems (in order of productivity)

Area(106 km2 )

Mean net primary production per unit area

(g/m2 /yr)

World net primary production

(109 mtn/yr)

Mean biomass per unit area

(kg/m2 )

ContinentalTropical rain forest 17.0 2000.0 34.00 44.00Tropical seasonal forest 7.5 1500.0 11.30 36.00Temperate evergreen forest 5.0 1300.0 6.40 36.00Temperate deciduous forest 7.0 1200.0 8.40 30.00

Boreal forest 12.0 800.0 9.50 20.00Savanna 15.0 700.0 10.40 4.00Cultivated land 14.0 644.0 9.10 1.10Woodland and shrubland 8.0 600.0 4.90 6.80Temperate grassland 9.0 500.0 4.40 1.60Tundra and alpine meadow 8.0 144.0 1.10 0.67

Desert shrub 18.0 71.0 1.30 0.67Rock, ice, sand 24.0 3.3 0.09 0.02Swamp and marsh 2.0 2500.0 4.90 15.00Lake and stream 2.5 500.0 1.30 0.02

Total continental 149.0 720.0 107.09 12.30MarineAlgal beds and reefs 0.6 2000.0 1.10 2.00

Estuaries 1.4 1800.0 2.40 1.00Upwelling zones 0.4 500.0 0.22 0.02

Co ntinental shelf 26.6 360.0 9.60 0.01Open ocean 332.0 127.0 42.00 0.003

Total marine 361.0 153.0 55.32 .01World total 510.0 320.0 162.41 3.62

Source: Smith, 2001.

50

40

30

20

10

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lect

ance

Atm

osph

eric

ab

sorp

tion

Atm

osph

eric

ab

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tion

TM 5TM 7

TM 4

TM 1

TM 2

TM 3

Bare soil

Vegetation

0.4 0.6 1.21.00.8 1.4 1.81.6 2.42.22.0 µm

WavelengthVisible Near Infrared

A portion of the solar spectrum showing the typical reflectance from soil (-----) and leaf (- - - - ) surfaces and the portions of the spectrum that are measured by the LAND-SAT satellite.

Adapted from: Schlesinger, 1997.

Adapted from: Schlesinger, 1997.

TM4

/ TM

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9

8

7N

ear i

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y=1.92 x (0.583)

R2 = 0.915

4

3

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0 16 181412108642Leaf area index (m2/m2)

1500

Net

prim

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prod

uctio

n(g

m-2

yr-1

)1000

500

0 10 155 20

LAI

NPP is directly related to leaf-area index (LAI)for forests in the northwestern United States

Adapted from: Smith, 2001.

3000

2000

1000

2000 400 600 800 1000 1200Actual evapotranspiration (mm)N

et p

rodu

c tiv

i ty a

bove

gro

und

per y

ear (

g/m

2 )

Adapted from Krebs

700

600

500

400

300

200

100

0 0 1.0 2.0 3.0 4.0

xx

x

x

xxx

xx

x

xx

x

xx x

x

x

x

+++++

+

Desert herbsOld field herbsDeciduous chaparral shrubsEvergreen shrubs and treesSouth African shrubs

NPP

(nm

olC

O2

g-1

s-1 )

Leaf nitrogen (mmol g-1)

Terrestrial NPP Co-opted by Humans

Source NPP Co-opted (Pg)Cultivated Land 15.0Grazing Land

Converted Pastures 9.8

Consumed on natural grazing lands 0.8

Burned on Natural Grazing Lands 1.0

Subtotal 11.6

Forest harvests 2.2

Forest Land

Killed during harvest 1.3

Shifting Cultivation 6.1

Land Clearing 2.4

Forest plantation productivity 1.6

Subtotal 13.6Human Occupied Areas 0.4

Total Terrestrial NPP Co-opted 40.6

Total Terrestrial NPP 132.1

Percent Co-opted 30.7%

Source: Vitousek at al. 1986 Bioscience 36:368


Lecture 4 – Primary Productivity in Aquatic Ecosystems

Perkins, S. 2003. Slow turnover: Warming trend affects African ecosystem. Science News. 163:404. (H)

Raloff, J. 2003. Zebra mussels to the rescue. Science News. 163:365. (H)

Falkowski, PG. 2002. The ocean’s invisible forest. Scientific American. 287:38-45. (H,W)


Chisholm, SW. 1992. What limits phytoplankton growth? Oceanus. 35:36-46. (H,W)

Outline for Today: I. Review Global Distribution II. Measurement techniques III. Limiting factors for freshwater and marine systems

A. Light B. Nutrients

1. Distribution and availability 2. Biological requirements (next class)

Study Questions 1. Explain why light tends to be more limiting in freshwater or coastal systems than in the open

ocean. 2. Explain the concept of a limiting nutrient. How would you design an experiment to determine

which nutrient is limiting in a particular system? 3. What are the challenges associated with using uptake of 14CO2 to measure primary productivity? 4. Why are phytoplankton so much more productive (on the basis of biomass) than land-based

plants? Approximately how much do phytoplankton and land-based plants contribute to global primary productivity?

5. Why did scientists used to think that phosphorus, rather than nitrogen, should be the limiting nutrient in oceans? Why is nitrogen often the limiting nutrient instead? And what role does Fe play in nitrogen limitation in oceans?

6. Both Chisholm and Falkowski explain how adding iron to the world’s oceans may enhance their primary productivity, but caution against taking drastic actions on a large scale. Why would the addition of iron enhance productivity? Why might this not be a panacea for elevated atmospheric CO2 levels?

GPP RH

About 15% NPP falls below the thermocline. Less than 1% makes it to the sea floor

NPP

Aquatic ecosystem RA

zooplanktonbacteriafish

Thermocline

200m

3000m

phytoplankton

NCP

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1

Relative Light Intensity (I/Io)

k = 0.02

k = 0.1

dI/dt = -kZ

I=Ioe-kZ

Io

ZD

epth

(m)

Photosynthesis as a function of depth for 3 kinds of lakes

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4

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Rate of Photosynthesis

Dep

th (m

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Eutrophic(Clear Lake)

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Dep

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)

Photoinhibition (Castle Lake)

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Dep

th (m

)Oligotrophic(Lake Tahoe)

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Dep

th (m

)

data modified from Krebs Figure 25.5

North Pacific Central Gyre

ZcDep

th (m

)

Temperature(oC)

Phosphate(µm/L)

Nitrate(µm/L)

Chlorophyll(µm/L)

Primary production(mgC/m3/half-day expt.)

0

100

200

300

10 15 20 25 0 0.2 0.4 0.6 0.8 0 3 6 9 12 0 0.1 0.2 0.3 0 2 4 6 8

1% Light levelZc

Adapted from: Krebs Figure 25.7

Thermal stratification in lakes

Temp

Epilimnion(well-mixed,

nutrient-poor)Thermocline

Hypolimnion(often O2 depleted

nutrient-rich)

WindNutrients

Dep

th

But, lakes don’t usually look this way year-round…


Lecture 5 – Limiting Nutrients and Redfield Ratio


Nemani RR et al. 2003. Climate-driven increases in global terrestrial net primary production from 1982 to 1999. Science. 300:1560-3. (H,W)

Krebs. Chapter 26. “Ecosystem Metabolism II: Secondary Production”

REMINDER:

Problem Set 1 Due next Tuesday during lecture.

No late problem sets please!

From last class: A few more thoughts on terrestrial primary productivity How to integrate all the aspects we talked about?

While one factor may dominate, many factors involved:

NPP = f(NPPmax, PAR, LAI, T, CO2, H2O, NA) Where: NPPmax = maximum for given ecosystem/vegetation type PAR = photosynthetically active radiation LAI = leaf area index T = temperature [CO2] = atmospheric CO2 concentration H2O = soil moisture NA = index of nutrient availability

How does climate change affect each of these parameters? For instance, atmospheric CO2. If [CO2] continues to increase, will this increase global NPP? GPP? Some things to consider: Experiments have shown increases in plant biomass with increased atmospheric CO2. Over the past 100 years, the annual rings of tree trunks have not gotten thicker.

Leaves from olive branches in King Tut’s tomb have a higher density of stomates than leaves of olive trees in modern-day Egypt. Other studies have shown decreased stomatal density since the Industrial Revolution. What does this mean for water use efficiency? Productivity?

If global temperatures increase 1ºC, or 3ºC, how will this change global NPP? GPP? Consider:

Effect of higher temperature on plants, on animals, and on bacteria that feed on detritus. Effect of higher temperatures +/or higher CO2 on the distribution of C3 vs. C4 plants.

What is a limiting factor? On what time scale? Limiting for whom?

Limiting nutrient analogy: Baking cookies

Recipe:0.5 cup eggs3 cups flour

2 cups sugar 0.1 cup baking soda

1 cup butter

Questions:

• If you start with equal amounts of all ingredients, which one is the limiting?

• If someone brings you more of that ingredient, which ingredient will now belimiting?

• If you start with 60 cups of flour, 50 cups of sugar, 10 cups of butter, 10 cups of eggs and 2 cups of baking soda, which ingredient will be limiting?

Canadian Research and Development Magazine 1970:

“Has the international joint commission…been a party to whatmay prove to have been the most incredible scientific/political hoax in the history of Canadian and American Relations?What hoax? Do you believe phosphates are the key nutrient in the process of eutrophication? You are wrong! You have hung phosphates without a fair trial.”

Proctor and Gamble:

“The problem of man-caused eutrophication is the most complex subject in our world. It truly encompasses the ‘mystery of life on earth.’ Thus we are attempting to understand and answer the questions: Why do plants grow?How can we retard or stop their growth?”

Northwestern Ontario – Experimental Lake 226

N + C added

N + C + P added

Image courtesy of Oceans and Fisheries, Canada.http://www.dfo-mpo.gc.ca/home-accueil_e.htmNote: image usage policy: http://www.dfo-mpo.gc.ca/copyright/copyright_e.htm

Schindler September 4, 1973

Pollution and Recovery in Lake Washington

Source: Edmondson,1991 (Figure 1.8)

Adapted from Krebs Figure 23.24

Marine phytoplankton samples

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0.15

0.10

0.05

0.00

-0.05Nitrogen Iron Silica Phosphorous



Lecture 6 – Introduction to Secondary Productivity

Pauly D and V Christensen. 1995. Primary production required to sustain global fisheries. Nature. 374:213-4. (H,W)

Guterl, F. 2003. Troubled seas: Ninety percent of the big fish have already been caught. Newsweek. July 14 edition, p 46. (H,W)


Krebs. Chapter 23 pages 463-469. “Food Chains and Trophic Levels”

REMINDER:

Pre-proposal due Thursday! No late proposals!

MOVIE NIGHT:

Re-showing of Cane Toads Thursday, 8pm Food provided

The last few lectures, we have focused on primary productivity. As we saw previously, autotrophs are able to capture 1-2% of the incoming solar radiation. We are now going to explore what happens to the energy stored in autotrophic biomass. Secondary productivity is defined as the rate of biomass accumulation by heterotrophs (herbivores, carnivores and detritivores).

biomass

Pn-1

NU = not used

In

Fn

Pn

Rn

An

Dead organic matter compartment of

decomposer system

For trophic level n:

biomass

Study questions 1. What is the real truth to Dogbert’s insights? What is the wast2. Define a trophic level. What are the difficulties in assigning a3. Describe the difference between exploitation, assimilation an

ranges of each of these efficiencies? How do they combine t4. According to the Newsweek article, what are the consequenc

overfishing of top predator fish? 5. According to Pauly and Christensen’s article, how much of aq

amount of fish caught annually? How does this number diffeWhy does it seem unlikely that humans will be able to harvesthan is already being harvested?

Pn-1 = Productivity at trophic level n-1 NU = Productivity from trophic level n-1 not used by trophic level n In = Amount of energy ingested Fn = Amount of energy lost as fecal matter (but available to detritivores) An = Amount of energy assimilated (i.e. available for metabolism) Rn = Amount of energy lost to respiration Pn = Productivity of trophic level n (evident as growth and reproduction)

ed step? species to a single trophic level? d production efficiencies. What are the typical o give an overall ecological efficiency? es throughout the marine food web of

uatic primary productivity is required for the r between freshwater and marine systems? t much more of the world’s aquatic productivity

∆N : ∆P

20 : 1

Correlation between the concentration of nitrate and phosphate in waters of the Atlantic, Indian, and Pacific Oceans

Source: Redfield, 1934

Western Atlantic

∆C : ∆N

7 : 1

Units:

[NO3]=10-3 millimols per liter [CO3]=10-2 millimols per liter


Western Atlantic

∆O2 : ∆N

6 : 1

Units:

[NO3]=10-3 millimols per liter


Deep Water Samples

REDFIELD HYPOTHESIZED:The proportions of elements in the

atmosphere and the sea are controlled by the biogeochemical cycle

If the elemental composition of the deep ocean water is dictated by the composition of the plant material, the elements should vary in constant proportion from place to place.

CO2 + PO4 + NO3 Dead Organisms + O2 Deep Sea

NO3 + PO4 + O2 Living Organisms + O2

100% Saturation

O2

Mixed Layer

Depth

PO4NO3

O2 Minimum

1) ∆O2 between surface and minimum is ≈`the amount used to oxidize the organic compounds as they settle out of the euphotic zone

2) Measured N:P:C ratios in mid-ocean, surface and deep ocean at various times

Adapted from Krebs Fig. 23.3

Adapted from: Odum (1972)

From Smithand Smith2001

Assimilation Efficiencies (A/I) for different types of organisms

Herbivore Carnivore Microbivore Saprotroph

Invertebrates 40% 80% 30% 20%

Vertebrates 50% 80% -- --

From Heal and Mac Lean, 1975

The more similar you are to your food, the more efficient you are at assimilating it

Microbivore = an organism that feeds on microorganismsSaprotroph = a fungus that feeds on detritus

Production Efficiency of Various Animal Groups (ranked in order of increasing efficiency)

Group P /A %1 Insectivores 0.862 Birds 1.293 Small Mammal Communities 1.514 Other Mammals 3.145 Fish and social insects 9.776 Non-insect invertebrates 25.07 Non-social insects 40.7Non-insect invertebrates8 Herbivores 20.89 Carnivores 27.610 Detritivores 36.2Non-social insects11 Herbivores 38.812 Detritivores 47.013 Carnivores 55.6

Source: Begon (1996)

Courtesy of Eli Meir. Used with permission.

Cod

•Bottom-dweller but stays relatively close to the surface (within

a few hundred meters).

•Can reach up to 200 pounds and live 20 - 30 years

•Large females can lay 10 million eggs / year

•Eats anything that moves and is smaller than mouth

Cod Fishing

When Columbus sailed, “1000” Basque ships were fishing

Georges Bank and Newfoundland.

If 1/2 of these were in Georges Bank and each ship pulled

in 20 tons of cod, catch was about 10,000 tons / year.

By mid 1500’s, 60% of fish eaten in Europe were cod.

Recipe book of Charles V in France

Salt cod is eaten with mustard sauce or with melted

fresh butter over it.

- Guillaume Tirel, Le Viandier, 1375

Cokkes of Kellyng

Take cokkes of kellyng; cut hem smalle. Do hit yn a

brothe of fresch fysch or of fresh salmon; bowle hem

well. Put to myllke and draw a lyour of bredde to hem

with saundres, safferyn & sugure and poudyr of pepyr.

Serve hit forth, & otheyr fysch amonge: turbut, pyke,

saumon, chopped & hewn. Sesyn hem with venyger &

salt.

-anonymous manuscript from fifteenth century

How Much Cod Can Be Caught?

From Pauly and Christensen See text 546-547

TABLE 2 Global estimates of primary production (PP), of PPR to sustain world fisheries (mean for 1988-1991,

net weight), and of the mean trophic levels (TL) of the catches, by ecosystem type

PPR (catches +discards)

Ecosystem

type

Area

(106 km2)

PP

(gC m-2 yr-1)

Catch

(g m-2 yr-1)

Discards

(g m-2 yr-1)

TL of the

catch

Mean

(%)

95%

Confidence

interval

Open ocean 332.0 103 0.01 0.002 4.0 1.8 1.3-2.7

Upwellings 0.8 973 22.2 3.36 2.8 25.1 17.8-47.9

Tropical

Shelves

8.6 310 2.2 0.671 3.3 24.2 16.1-48.8

Non

tropical

shelves

18.4 310 1.6 0.706 3.5 35.3 19.2-85.5

Coastal/reef

systems

2.0 890 8.0 2.51 2.5 8.3 5.4-19.8

Rivers and

lakes

2.0 290 4.3 n.a. 3.0 23.6 11.3-62.9

Weighted

means (or

total)

(363.8) 126 0.26 0.07 2.8 8.0 6.3-14.4

-- --

Assimilation Efficiencies (A/I)

for different types of organisms



Vertebrates 50% 80%




Group P /A %

1 Insectivores 0.86

2 Birds 1.29

3 Small Mammal Communities 1.51

4 Other Mammals 3.14

5 Fish and social insects 9.77

6 Non-insect invertebrates 25.0

7 Non-social insects 40.7

Non-insect invertebrates

8 Herbivores 20.8

9 Carnivores 27.6

10 Detritivores 36.2

Non-social insects

11 Herbivores 38.8


13 Carnivores 55.6


Krebs Fig 26.4

118 Secondary Production

Table 6.1 A simple taxonomic-trpohic categorization of heterographic organisms. For each category

the characteristic assimiliation (A/C) and growth (P/A) efficiencies are given. (From Heal and Maclean,

1975.)

Trophic Function

Herbivore Carnivore Microbivore Saprotoroph

A/C P/A A/C P/A A/C P/A A/C P/A

Micro

organi

sms

- - - - - - - 0.40

Inverti

brates

0.40 0.40 0.80 0.30 0.30 0.40 0.20 0.40

Vetebr

ate

homot

herms

0.50 0.02 0.80 0.02 - - - -

Vetebr

ate

heterot

herms

0.50 0.10 0.80 0.10 - - - -

0.00

0.05

0.10

0.15

0.20

0.25

0.30 P

rop

ort

ion

0 2 4 6 8 10

Food chain length

Georges Bank Cod Summary

Georges Bank 240 x 120 km in size

Primary productivity 0.9 kg C / m^2 / year

Cod range from trophic level 4 - 6

Transfer efficiencies ~ 10% between trophic levels

What is a guess at sustainable harvest?

Digression - Confidence Limits and

Sensitivity Analysis

What if energy transfer was 8% instead of 10%?

What if less of Georges Bank was suitable habitat?

What about other species of bottom fish?

Ecological calculations are almost worthless without some

measure of the confidence boundaries. Often confidence is

assessed through sensitivity analysis - how much difference

would mistakes in the input values make to the final result?

Columbus and Cabot

In 1492, Columbus sailed the ocean blue.

In 1497 John Cabot “discovers” Cape Cod and the Basque fishing

vessels

In 1500’s there is a cod rush to Massachusetts up to Newfoundland

In 1930’s, factory trawlers arrive.

In 1960’s, U.S. and Canada increase fishing effort

In 1990’s …

NOAA Pub CRD0204

How could catch be at 50,000 tons for years?

Productivity Biomass

(Standing Stock)

What happens to system when cod

are removed?

Trophic cascades

Brooks, J. L. and S. I. Dodson, 1965. Predation, body

size, and composition of plankton. Science 150:

28-35

Keystone Species

Paine, R. T., 1966. Food web complexity and species

diversity. The American Naturalist 100: 65 - 75.

Question: What controls the diversity of and

relative abundance of different species in the

intertidal community?

First careful observations of the community

Transplant different species and find which ones are

competitively dominant (dominance hierarchy)

Construct food web for predatory species

What will happen if one of the species is removed?

The answer …

is in your next EcoBeaker lab

Wrap-up

Ecology can make some general predictions about what

might happen to Georges Bank system.

Ecology can also make some predictions about whether and

how long it might take cod populations to recover.

More on the first topic at the end of the course, when

discussing communities.

More on the second topic in a couple weeks, when talking

about population growth.


Lecture 8 – Introduction to Biogeochemical Cycles

Rietschel M. 2003. Analysis pours cold water on flood theory. Nature. 425:111. (H,W)

Ramanujan K. 2003. Ocean plant life slows down and absorbs less carbon. (H, W) http://www.eurekalert.org/pub_releases/2003-09/nsfc-op1091603.php. accessed 9/16/03


Krebs. Chapter 27. Ecosystem Metabolism III: Nutrient Cycles

Outline for today: I. Discussion of pre-proposals II. Biogeochemistry

a. Dinosaur question b. Reservoirs and residence times c. Example: methane

III. Guest speaker: Anna Mehrotra Study questions: • What are the major compartments that we consider when drawing biogeochemical cycles? What

are some of the major sub-compartments that we also consider? • Explain what two factors contribute to a compound having a long residence time in an ocean or in

the atmosphere. • What are some major differences between the global biogeochemical cycles for P vs C, or CO2 vs.

CH4? • Wetland, rice patties, termites and cows are major sources of CH4. Why? • More of a brain teaser than study question (Hint: think about residence times and fluxes, see

water cycle Krebs Figure 28.7)


Lecture 6 – Introduction to Secondary Productivity

Pauly D and V Christensen. 1995. Primary production required to sustain global fisheries. Nature. 374:213-4. (H,W)

Guterl, F. 2003. Troubled seas: Ninety percent of the big fish have already been caught. Newsweek. July 14 edition, p 46. (H,W)


Krebs. Chapter 23 pages 463-469. “Food Chains and Trophic Levels”

REMINDER:

Pre-proposal due Thursday! No late proposals!

MOVIE NIGHT:

Re-showing of Cane Toads Thursday, 8pm Food provided

The last few lectures, we have focused on primary productivity. As we saw previously, autotrophs are able to capture 1-2% of the incoming solar radiation. We are now going to explore what happens to the energy stored in autotrophic biomass. Secondary productivity is defined as the rate of biomass accumulation by heterotrophs (herbivores, carnivores and detritivores).

biomass

Pn-1

NU = not used

In

Fn

Pn

Rn

An

Dead organic matter compartment of

decomposer system

For trophic level n:

biomass

Study questions 1. What is the real truth to Dogbert’s insights? What is the wast2. Define a trophic level. What are the difficulties in assigning a3. Describe the difference between exploitation, assimilation an

ranges of each of these efficiencies? How do they combine t4. According to the Newsweek article, what are the consequenc

overfishing of top predator fish? 5. According to Pauly and Christensen’s article, how much of aq

amount of fish caught annually? How does this number diffeWhy does it seem unlikely that humans will be able to harvesthan is already being harvested?

Pn-1 = Productivity at trophic level n-1 NU = Productivity from trophic level n-1 not used by trophic level n In = Amount of energy ingested Fn = Amount of energy lost as fecal matter (but available to detritivores) An = Amount of energy assimilated (i.e. available for metabolism) Rn = Amount of energy lost to respiration Pn = Productivity of trophic level n (evident as growth and reproduction)

ed step? species to a single trophic level? d production efficiencies. What are the typical o give an overall ecological efficiency? es throughout the marine food web of

uatic primary productivity is required for the r between freshwater and marine systems? t much more of the world’s aquatic productivity

∆N : ∆P

20 : 1

Correlation between the concentration of nitrate and phosphate in waters of the Atlantic, Indian, and Pacific Oceans


Western Atlantic

∆C : ∆N

7 : 1

Units:

[NO3]=10-3 millimols per liter [CO3]=10-2 millimols per liter


Western Atlantic

∆O2 : ∆N

6 : 1

Units:

[NO3]=10-3 millimols per liter


Deep Water Samples

REDFIELD HYPOTHESIZED:The proportions of elements in the

atmosphere and the sea are controlled by the biogeochemical cycle

If the elemental composition of the deep ocean water is dictated by the composition of the plant material, the elements should vary in constant proportion from place to place.

CO2 + PO4 + NO3 Dead Organisms + O2 Deep Sea

NO3 + PO4 + O2 Living Organisms + O2

100% Saturation

O2

Mixed Layer

Depth

PO4NO3

O2 Minimum

1) ∆O2 between surface and minimum is ≈`the amount used to oxidize the organic compounds as they settle out of the euphotic zone

2) Measured N:P:C ratios in mid-ocean, surface and deep ocean at various times

Adapted from: Odum (1972)

From Smithand Smith2001

Assimilation Efficiencies (A/I) for different types of organisms



Vertebrates 50% 80% -- --



Microbivore = an organism that feeds on microorganismsSaprotroph = a fungus that feeds on detritus


Group P /A %1 Insectivores 0.862 Birds 1.293 Small Mammal Communities 1.514 Other Mammals 3.145 Fish and social insects 9.776 Non-insect invertebrates 25.07 Non-social insects 40.7Non-insect invertebrates8 Herbivores 20.89 Carnivores 27.610 Detritivores 36.2Non-social insects11 Herbivores 38.812 Detritivores 47.013 Carnivores 55.6



Cod

•Bottom-dweller but stays relatively close to the surface (within

a few hundred meters).

•Can reach up to 200 pounds and live 20 - 30 years

•Large females can lay 10 million eggs / year

•Eats anything that moves and is smaller than mouth

Cod Fishing

When Columbus sailed, “1000” Basque ships were fishing

Georges Bank and Newfoundland.

If 1/2 of these were in Georges Bank and each ship pulled

in 20 tons of cod, catch was about 10,000 tons / year.

By mid 1500’s, 60% of fish eaten in Europe were cod.

Recipe book of Charles V in France

Salt cod is eaten with mustard sauce or with melted

fresh butter over it.

- Guillaume Tirel, Le Viandier, 1375

Cokkes of Kellyng

Take cokkes of kellyng; cut hem smalle. Do hit yn a

brothe of fresch fysch or of fresh salmon; bowle hem

well. Put to myllke and draw a lyour of bredde to hem

with saundres, safferyn & sugure and poudyr of pepyr.

Serve hit forth, & otheyr fysch amonge: turbut, pyke,

saumon, chopped & hewn. Sesyn hem with venyger &

salt.

-anonymous manuscript from fifteenth century

How Much Cod Can Be Caught?

From Pauly and Christensen See text 546-547

TABLE 2 Global estimates of primary production (PP), of PPR to sustain world fisheries (mean for 1988-1991,

net weight), and of the mean trophic levels (TL) of the catches, by ecosystem type

PPR (catches +discards)

Ecosystem

type

Area

(106 km2)

PP

(gC m-2 yr-1)

Catch

(g m-2 yr-1)

Discards

(g m-2 yr-1)

TL of the

catch

Mean

(%)

95%

Confidence

interval

Open ocean 332.0 103 0.01 0.002 4.0 1.8 1.3-2.7

Upwellings 0.8 973 22.2 3.36 2.8 25.1 17.8-47.9

Tropical

Shelves

8.6 310 2.2 0.671 3.3 24.2 16.1-48.8

Non

tropical

shelves

18.4 310 1.6 0.706 3.5 35.3 19.2-85.5

Coastal/reef

systems

2.0 890 8.0 2.51 2.5 8.3 5.4-19.8

Rivers and

lakes

2.0 290 4.3 n.a. 3.0 23.6 11.3-62.9

Weighted

means (or

total)

(363.8) 126 0.26 0.07 2.8 8.0 6.3-14.4

-- --

Assimilation Efficiencies (A/I)

for different types of organisms



Vertebrates 50% 80%




Group P /A %

1 Insectivores 0.86

2 Birds 1.29

3 Small Mammal Communities 1.51

4 Other Mammals 3.14

5 Fish and social insects 9.77

6 Non-insect invertebrates 25.0

7 Non-social insects 40.7

Non-insect invertebrates

8 Herbivores 20.8

9 Carnivores 27.6


Non-social insects

11 Herbivores 38.8


13 Carnivores 55.6


Krebs Fig 26.4

118 Secondary Production

Table 6.1 A simple taxonomic-trpohic categorization of heterographic organisms. For each category

the characteristic assimiliation (A/C) and growth (P/A) efficiencies are given. (From Heal and Maclean,

1975.)

Trophic Function

Herbivore Carnivore Microbivore Saprotoroph

A/C P/A A/C P/A A/C P/A A/C P/A

Micro

organi

sms

- - - - - - - 0.40

Inverti

brates

0.40 0.40 0.80 0.30 0.30 0.40 0.20 0.40

Vetebr

ate

homot

herms

0.50 0.02 0.80 0.02 - - - -

Vetebr

ate

heterot

herms

0.50 0.10 0.80 0.10 - - - -

0.00

0.05

0.10

0.15

0.20

0.25

0.30 P

rop

ort

ion

0 2 4 6 8 10

Food chain length

Georges Bank Cod Summary

Georges Bank 240 x 120 km in size

Primary productivity 0.9 kg C / m^2 / year

Cod range from trophic level 4 - 6

Transfer efficiencies ~ 10% between trophic levels

What is a guess at sustainable harvest?

Digression - Confidence Limits and


What if energy transfer was 8% instead of 10%?

What if less of Georges Bank was suitable habitat?

What about other species of bottom fish?

Ecological calculations are almost worthless without some

measure of the confidence boundaries. Often confidence is

assessed through sensitivity analysis - how much difference

would mistakes in the input values make to the final result?

Columbus and Cabot

In 1492, Columbus sailed the ocean blue.

In 1497 John Cabot “discovers” Cape Cod and the Basque fishing

vessels

In 1500’s there is a cod rush to Massachusetts up to Newfoundland

In 1930’s, factory trawlers arrive.

In 1960’s, U.S. and Canada increase fishing effort

In 1990’s …

NOAA Pub CRD0204

How could catch be at 50,000 tons for years?

Productivity Biomass

(Standing Stock)

What happens to system when cod

are removed?

Trophic cascades

Brooks, J. L. and S. I. Dodson, 1965. Predation, body

size, and composition of plankton. Science 150:

28-35

Keystone Species

Paine, R. T., 1966. Food web complexity and species

diversity. The American Naturalist 100: 65 - 75.

Question: What controls the diversity of and

relative abundance of different species in the

intertidal community?

First careful observations of the community

Transplant different species and find which ones are

competitively dominant (dominance hierarchy)

Construct food web for predatory species

What will happen if one of the species is removed?

The answer …

is in your next EcoBeaker lab

Wrap-up

Ecology can make some general predictions about what

might happen to Georges Bank system.

Ecology can also make some predictions about whether and

how long it might take cod populations to recover.

More on the first topic at the end of the course, when

discussing communities.

More on the second topic in a couple weeks, when talking

about population growth.


Lecture 8 – Introduction to Biogeochemical Cycles

Rietschel M. 2003. Analysis pours cold water on flood theory. Nature. 425:111. (H,W)

Ramanujan K. 2003. Ocean plant life slows down and absorbs less carbon. (H, W) http://www.eurekalert.org/pub_releases/2003-09/nsfc-op1091603.php. accessed 9/16/03


Krebs. Chapter 27. Ecosystem Metabolism III: Nutrient Cycles

Outline for today: I. Discussion of pre-proposals II. Biogeochemistry

a. Dinosaur question b. Reservoirs and residence times c. Example: methane

III. Guest speaker: Anna Mehrotra Study questions: • What are the major compartments that we consider when drawing biogeochemical cycles? What

are some of the major sub-compartments that we also consider? • Explain what two factors contribute to a compound having a long residence time in an ocean or in

the atmosphere. • What are some major differences between the global biogeochemical cycles for P vs C, or CO2 vs.

CH4? • Wetland, rice patties, termites and cows are major sources of CH4. Why? • More of a brain teaser than study question (Hint: think about residence times and fluxes, see

water cycle Krebs Figure 28.7)

How would a C atom from a dinosaur

end up in your sandwich?

Global Nutrient Cycling

Precipitation Volatilebioelements only

Volatilebioelements only

H20(+ volatileBioelements)

Evaporation

OCEAN

Dead organicmatter

Sinking

Marinefood web

Dead organic matter

Terrestrialfood web

Bioelementsin solution

Weathering

Uptake

Terrestrial biosphere

Decomposition

Death

Losses by water runoff

Adapted from Krebs, 2001. Figure 27.1

Atmosphere

Fresh water

Rocks

Land Oceans

Sediments

Reservoir: How much of a substance is present in one of these compartments

100

0.001Mesopause

MESOSPHERE

STRATOSPHERE

TROPOSPHERE

Stratopause

Tropopause

80 0.01

60

Pres

sure

( hPa

)

Hei

ght (

k m)

1

40

20 100

0 1000

40-100 -60 -40 -20 0 20-80

Temperature (oC)

Adapted from http://www.met-office.gov.uk/research/stratosphere/

Sources Sinks535 515

(Natural 160 + Anthropogenic 375)Global Methane Cycle

(units of 1012 g CH4/yr)

stratosphere

troposphere

CH4Reaction with OH

oceans

445

115

40

30

termites

10

wetlands

30

fossil fuel(mining, burning)

100

85

landfills +other wastetreatment

90cows

Data from Schlesinger, 1997

Sources Range Likely

NaturalWetlands

Tropics 30- 80 65Northern latitude 20- 60 40Others 5- 15 10

Termites 10- 50 20Ocean 5- 50 10Fres hwater 1- 25 5Geological 5- 15 10Total 160

Anthropogenic

Fossil fuel relatedCoal mines 15- 45 30Natural gas 25- 50 40Petroleum industry 5- 30 15Coal combustion 5- 30 15

Waste management systemLandfills 20- 70 40Animal waste 20- 30 25Domestic sewage treatment 15- 80 25Enteric fermentation 65-100 85Biomass burning 20- 80 40Rice paddies 20-100 60

Total 375

Total sources 535

SinksReaction with OH 330 -560 445Removal in stratosphere 25- 55 40Removal by soils 15- 45 30

Total sinks 515

Atmospheric increase 30- 35 30

Estimated Sources and Sinks of Methane in the Atmospherein Units of 1012 g CH4/yra

Range Likely

NaturalWetlands

Tropics 30- 80 65Northern latitude 20- 60 40Others 5- 15 10

Termites 10- 50 20Ocean 5- 50 10Fres hwater 1- 25 5Geological 5- 15 10Total 160

Anthropogenic

Fossil fuel relatedCoal mines 15- 45 30Natural gas 25- 50 40Petroleum industry 5- 30 15Coal combustion 5- 30 15

Waste management systemLandfills 20- 70 40Animal waste 20- 30 25Domestic sewage treatment 15- 80 25Enteric fermentation 65-100 85Biomass burning 20- 80 40Rice paddies 20-100 60

Total 375

Total sources 535

SinksReaction with OH 330 -560 445Removal in stratosphere 25- 55 40Removal by soils 15- 45 30

Total sinks 515

Atmospheric increase 30- 35 30

in Units of 1012 g CH4/yra

What is the probability that a water molecule from Napoleon’s urine is in your water bottle?

The Global Water Cycle Pools (km3)

Fluxes (km3/yr)

Atmosphere 13,000

Ice 33,000,000

Soil Waters 122,000

Groundwater 15,300,000

Oceans 1,350,000,000

11,000 71,000

River flow 40,000

385,000 425,000

40,000

Net transport to land

Reference: Schlesinger, 1997

1.018/7.30J Fall 2003 Fundamentals of Ecology Lecture 9 – Nitrogen and Phosphorus Cycling Outline for today: I. Review of Biogeochemical cycling mechanics and Mass balance

a. Reservoirs and Fluxes b. Sources and sinks

II. Nitrogen a. Role in biology b. Reservoirs c. Nitrogen Sources d. Nitrogen Sinks

III. Phosphorus a. Role in biology b. Reservoirs c. Phosphorus Sources d. Phosphorus Sinks

Study questions: • Why is nitrogen fixation only carried out by prokaryotes? Why didn’t humans and plants evolve a

way to fix nitrogen from the atmosphere directly? • Would nutrients have a longer residence time in deciduous or coniferous forests? Why? • In today’s Nitrogen cycle is nitrogen fixation balanced by denitrification? I. Review of Biogeochemical cycling mechanics and Mass balance

a. Reservoirs and Fluxes, Sources and sinks Inputs > outputs (sink) Inputs < outputs (source) Mass balace: ΣInputs - ΣOutputs + ΣSources - ΣSinks = ∆Mass Steady state: ∆Mass =0

II. Nitrogen Atomic # 7 … 14.0067 g mol –1 B.P. –195.8°C

a. Role in biology N is an essential component of proteins, nucleic acids and other cellular constituents.

b. Reservoirs – 79% of the atmosphere is N2 gas. The N=N triple bond is relatively

difficult to break ,requires special conditions. As a result most ecosystems are N-limited. N2 dissolves in water, cycles through air, water and living tissue.

c. Nitrogen Fixation Abiotic: lightning (very high T and P) 107 metric tons yr-1 ~ 5-8% of total annual N

fixation. (weathering of rocks is an insignificant source) Biotic: Nitrogen fixation by microbes, (prokaryotic bacteria) typically either free-

living azobacter or rhizobium living symbiotically with plants (such as legumes). Total N fixed by biological processes is approx. 1.75 x108 metric tons yr-1

Biological mechanism of nitrogen fixation: uses an enzyme complex called nitrogenase consisting of two proteins – an iron protein and a molybdenum-iron protein.

N2+ 8H+ + 8e -+ 16 ATP = 2NH3+ H2+ 16ADP + 16 Pi oxidised f

Adapted from http://helios.bto.ed.ac.uk/bto/microbes/nitrogen.htm#Top The Fe protein gets reduced by electrons donated by ferredoxin. Then the reduced Fe protein binds ATP and reduces the molybdenum-iron protein, which donates electrons to N2, producing HN=NH. In two further cycles of this process (each requiring electrons donated by ferredoxin) HN=NH is reduced to H2N-NH2, and this in turn is reduced to 2NH3. • ferredoxin is generated by either photosynthesis, respiration or fermentation, depending on the

type of organism • nitrogenase is inhibited in the presence of oxygen. N-fixing prokaryotes operate either

anaerobically (Clostridium, Desulfovibrio, Purple sulfphur Bacteria) or develop special mechanisms such as extremely high respiratory rates (Azobacter) and/or cellular features to limit oxygen diffusion, or else develop symbiotic relationships (Rhizobium) where the host plant scavenges oxygen. Cyanobacteria, protect nitrogenase in special heterocysts which possess only PS I.

Industrial: The Haber-Bosch process (1909)– high P and relatively high T, uses

Iron as a catalyst to convert N2 to ammonia (usually further processed to urea and ammonium nitrate (NH4NO3) – still the cheapest means of industrial N fixation. 5x107 metric tons yr-1

Combustion Side Effect: High T and P oxidizes N2 to Nox 2x107 metric tons yr-1

Since 1940s amount of N available for uptake has more than doubled. Anthropogenic N

erredoxin erredoxin

roteinrotein

rotein

TP FP

+

reduced f

oxidised Fe preduced Fe p2e-

oxidised Mo Fe protein reduced Mo Fe p

4 A 4 A

2e-2 H

HN=NH N2

H2N=NH2 HN=NH

2NH3 H2N=NH2

inputs are now equal to biological fixation. d. Nitrogen Cycling

plants directly take up NH4

+ or NO3-

Nitrification by chemoautotrophs Bacteria of the genus Nitrosomonas oxidize NH3 to NO2

-

Baceria of the genus Nitrobacter oxidize the nitrites to NO3-

Denitrication Anaerobic respiration of NO3- to dinitrogen gas by several specis of Psuedomonas, Alkaligenes, and Bacillus Sources of anthropogenic N loads: Fertilizers, Legume Crops, Atm Deposition, Sewage, Deforestation, Draining of wetlands

160

140

120

100

80

60

0

0

4

2

0 1960 1965 1970 1975 1980 1985 1990 1995

(million metric tons

MERICA

MERICAAFRICASIAEUROPENORTH A

OCEANIASOUTH AND CENTRAL AWORLD

Trends in Fertilizer Use Adapted from the Food and Agriculture Organization of the United Nations (FAO), FAOSTAT Statistical Database (FAO, Rome, 1997).

Fate of N? In most terrestrial and freshwater ecosystems N is a limiting nutrient, gets cycled efficiently. What happens when plants have enough N (i.e. greater 16:1 N:P ratio)? Flushing/erosion – dissolved and particulate matter in streamwater, (DIN, DON, TN, Org N) leaching to groundwater – NO3

- is an anion, does not sorb well to clays, highly water soluble. When N saturation of ecosystem occurs, excess N tends to leave the system in the form of nitrate. , VOCs, denitrification, burning, emigration, harvesting Effects of Increased N loading: Eutrophication in aquatic systems, coastal algal blooms and “Dead Zone”, fish kills, increased turbidity, selective pressures in terrestrial systems favoring species-poor grasslands and forests Nitrate MCL – 10mg L-1 … Nitric oxide – precursor of acid rain and smog Nitrous oxide – long lived greenhouse gas that can trap 200 times as much heat as CO2 III. Phosphorus – Atomic # 15 … 30.97 g mol –1 B.P. 280°C P is very reactive, does not exist in pure elemental form. In contact with air, it forms phosphate PO43

-. In water, phosphates are protonated to form HPO4

2-, H2PO4- and H3PO4.

PO43- orthophosphate, the most simple molecular form of phosphate, aqueous form under very basic

or alkaline conditions HPO4

2- : aqueous form under basic or alkaline conditions H2PO4- : aqueous form under neutral conditions H3PO4 : aqueous form under very acidic conditions

a. Role in biology

Phosphorus is an essential nutrient for plants and animals in the form of ions PO4

3- and HPO42- . It is found in

DNA-molecules (it binds deoxyribose sugars together forming the backbone of the DNA molecule), ATP and ADP, and lipid cell membranes (phospholipids). P is also a fundemental to tissues such as bones and teeth.

b. Reservoirs – Unlike C, N and other important bioelements P does not exist in a gaseous state at typical environmental Temps and Pressures. Cycles through water (DOP and DIP), soils and sediments (adsorption to mineral surfaces) and organic tissue/humic material.

c. Phosphorus Sources – Found in sedimentary rocks such as apatite

(Cax(OH)y(PO4)z), fossilized bone or guano. Weathering from phosphate rocks found in terrestrial rock formations and some ocean sediments (PO4 is soluble in H2O). Guano (excrement of fish-eating birds) mining for fertilizers and sewage. Detergents have historically contained Na3PO4, though newer types are avoiding it.

d. Phosphorus Sinks – uptake of orthophosphate by plants through the roots,

incorporation into plant tissue and heterotroph tissues, decomposition returns P to water and soils via microbial mineralization; eventually it is washed out to the oceans, sinks to the floor (becomes limestone) and is not recycled for millions of years.

Adapted from: http://www.starsandseas.com/SAS%20Ecology/SAS%20chemcycles/cycle_phosphorus.htm


Lecture 10 – Sulfur Cycles O III

I A

Global climate change articles (handed out separately)

Krebs Chapter 28 pages 590-607

READINGS FOR NEXT THURSDAY’S LECTURE:


utline for today:

. Quizzes I. Global climate change discussion next Thursday II. Sulfur

A. Reservoirs and residence times B. Biology of sulfur C. Global S cycle D. Human Impacts E. Isotope analyses

II. Sulfur

. Reservoirs and residence times

Reservoir Size (10 12 g) Flux (10 12 g/yr) MRT (yr)

Atmosphere 2 270 __________

Seawater 1.3 x 10 9 310 __________

Sedimentary Rocks 7.4 x 10 9 220 __________

Land Plants 8500 24 __________

Soil Organic Matter 16000 72 __________

Will S be well - mixed in the atmosphere?

Reservoir Size (10 12 g) Flux (10 12 g/yr) MRT (yr)

Atmosphere 2 270 __________

Seawater 1.3 x 10 9 310 _________

Sedimentary Rocks 7.4 x 10 9 220 __________

Land Plants 8500 24 __________

Soil Organic Matter 16000 72 __________

Will S be well - mixed in the atmosphere?

B. Biology of sulfur

SO42- S0 H2S

org S assimilation

mineralization (decomposition)

requires energy

releases energy

reduced oxidized

C. Global cycle Adapted from Smith,200. Elements of Ecology.

The Global Sulfur Cycle

Dust

Wet and dry deposition

905

8 90

180Biogenic

gases

Transport to sea

Transport to land20

4

Human mining and extraction

150

Rivers

130

Natural weathering and erosion

72

Pyrite39

Hydrothermal sulfides 96

Deposition

Sea salt

Biogenic gases

4

161445


Fluxes (1012 g S/yr)

The Global Sulfur Cycle

Dust

Wet and dry deposition

905

8 90

180Biogenic

gases

Transport to sea

Transport to land20

4

Human mining and extraction

150

Rivers

130

Natural weathering and erosion

72

Pyrite39

Hydrothermal sulfides 96

Deposition

Sea salt

Biogenic gases

4

161445


Fluxes (1012 g S/yr)

D. Human impacts

Global SO2 Emissions

Adapted from Charlson et al. 1992 Science 255:423

E. Isotope analyses

δ34S = 1000 * [(34S/32S)sample – (34S/32S)standard] / (34S/32S)standard in ‰

Smelters, Refineries, Automobiles?

Great Salt LakeCopper

SmeltersRefineries

Autos

δS34 = +1.5 δS34 = +3.1

δS34 =+1

δS34 =+5.3 H2S

δS34 =+16

Anaerobic bacteria

δS34 = +1.5

δS34 = +5.3

δS34 = +3.1

δS34 = +6.4

Mean Values

Smelters Strike

Mean Values(expected +9) (expected +16)

Smelters, Refineries, Automobiles?

Great Salt LakeCopper

SmeltersRefineries

Autos

δS34 = +1.5 δS34 = +3.1

δS34 =+1

δS34 =+5.3 H2S

δS34 =+16

Anaerobic bacteria

δS34 = +1.5

δS34 = +5.3

δS34 = +3.1

δS34 = +6.4

Mean Values

Smelters Strike

Mean Values(expected +9) (expected +16)

Study questions: • Name the major ways in which the sulfur cycle resembles and does not resemble the nitrogen and

phosphorus cycles. • What are major anthropogenic and non-anthropogenic sources of S emissions into the

atmosphere? • How does acid rain form? How does acid mine drainage form? • Explain how sulfate reducing bacteria indirectly create SO2 emissions. • Explain how isotope ratios can be used to determine the relative contributions of different sources.


Lecture 11 – Carbon Cycle

Bentley M. 2003. Synthetic trees could purify air. BBC. http://news.bbc.co.uk/2/hi/science/nature/2784227.stm. accessed 10/10/03

Whitehouse D. 2003. Photosynthesis puzzle solved. BBC. http://news.bbc.co.uk/2/hi/science/nature/3174582.stm. accessed 10/10/03

Global climate change articles (handed out last class)


Outline for today: I. Finish S cycle / Stable Isotope Analyses II. Global Carbon Cycle

A. C in the news B. Global cycle C. Carbon and temperature D. Ecological effects of increasing CO2

The Global Carbon Cycle

Burial 0.1

Ocean 38,000

92 90

Atmospheric Pool 750

+3.2/yr

Soils 1500 Net destruction

of vegetation

0.90.9

120 60

GP P

R p 60

6

Rivers 0.8

Land s

560 plant


Pools (10 1 5 g C)

Fluxes (10 15 g C/yr) Rocks

81,000,000 Fossil Fuels

4000

fossil fu elburning

The Global Carbon Cycle

Burial 0.1

Ocean 38,000

9092

Atmospheric Pool

Soils 1500

Pools (10 1 5 g C)

Fluxes (10 15 g C/yr)

Net destruction of vegetation Rocks

81,000,000 Fossil Fuels

4000

Rivers 0.8

120 60

GP P

R p 60

6

Land s

560 plant

fossil fu elburning

+3.2/yr

750

Measured changes in CO2 dissolved on the surface of the Atlantic ocean.

Adapted from: Schlesinger, 1997 (Figure 9.10)

Adapted from Krebs, Fig. 28.13 Adapted from Krebs, Fig. 28.11

Trees from Arizon, North Carolina and Italy

Concentration of CO2 at Mauna Loa Observatory Long-term variation in global temperature In Hawaii. Adapted from Krebs Fig 28.9. and atmospheric CO2 concentration determined from the Vostok Ice Core,

Antarctica. Adapted from Krebs. Fig. 28.15

Temperatures Relative to Millenial Average*. Adapted from Mann et.al., 1999

It’s not just CO2

Fuels, fertilizer,

deforestation62300.20.31Nitrous

oxide

Wetlands, rice,

livestock, fossil fuels

122511.675Methane

Foams, aerosols, solvents,

refrigeration

2515 00050.00225CFC’s

Fossil fuels, deforestation

5710.4351Carbon dioxide

Principal sources of

gas

Current Greenhouse Contribution

(%)

Relative greenhouse efficiency (CO2 = 1)

Annual Concentration

Increase (%)

Atmospheric Concentration

(ppm)Gas

Fuels, fertilizer,

deforestation62300.20.31Nitrous

oxide

Wetlands, rice,

livestock, fossil fuels

122511.675Methane

Foams, aerosols, solvents,

refrigeration

2515 00050.00225CFC’s

Fossil fuels, deforestation

5710.4351Carbon dioxide

Principal sources of

gas

Current Greenhouse Contribution

(%)

Relative greenhouse efficiency (CO2 = 1)

Annual Concentration

Increase (%)

Atmospheric Concentration

(ppm)Gas

Source: Schlesinger, 1997

Effects of increased CO2 on Phytoplankton: Time variation of Larval weight Riebesell U., et. al. “Reduced calcification of (adapted from Krebs Fig. 28.17) Marine phytoplankton in response to increased Atmospheric CO2. Nature 407:364 (2000).

Read:

ZKA BISKUP, “GET THE OCEANS SOME TUMS”

tudy questions est C reservoirs and fluxes in the environment?

g” carbon likely to be?

AGNIESPublished on October 7, 2003, Boston Globe, Page C2 Col 2 S• What are the larg• What do we mean by the “missing carbon”? Where is this “missin• How do temperate forests respond to elevated CO2 after 1-5 years? 30 years? • How can stable isotopes be used to determine temperature 1000s of years ago?• By what mechanism do oceans primarily absorb CO2?


Global Climate Change Discussion – 10/16/03

The dramatic increase in atmospheric CO2 concentrations is alarming to many people. While reduction in emissions is the obvious solution, some people are proposing more immediate actions to reduce the amount of CO2 in the atmosphere. Some proposed ideas are iron-fertilization, deep-sea injection of CO2 and carbon sequestration in terrestrial plants. There is also a lot of debate about whether increasing CO2 concentrations will lead to greater terrestrial and aquatic productivity, which could serve as a feedback mechanism to absorb some of the extra atmospheric CO2.

We’re going to spend a lecture evaluating these topics. To make the discussion more informative, I’ve assigned some readings pertinent to each topic. Each person is responsible for reading one set of articles. You should be prepared to talk about the answers to the questions below, drawing on the major points of the below articles and any other information you find (these articles were some that I found briefly searching through Nature & Science).

When you get to class, you will break into groups, share your answers to the questions, and prepare to explain your topic to the class.

As you read these articles, keep the following questions in mind: • What is the rationale behind each approach? How will this approach work to reduce

atmospheric CO2? • In which compartment of the environment will the C be stored? What is the MRT? • Can it work in the short-run? In the long-run? • What are other effects besides decreasing atmospheric CO2? • What are the major uncertainties? • Overall, do you think it’s a good idea? Would your answer be different if you lived in Holland

or on a tiny island barely above sea level?

Everyone (focus on pages 422-426A)

Betts KS. 2000. Engineering maintainable development. Environmental Science and Technology. 34:422A.

1. Ecological responses to high CO2 concentrations (Adrienne, April, Ayse, Ben, Candace, Cynthia)

Norby R. 1997. Inside the black box. Nature. 388:522.

Sarmiento J. 2000. That sinking feeling. Nature. 408:155.

Schlesinger WH and JH Lichter. 2001. Limited carbon storage in soil and litter of experimental forest plots under increased atmospheric CO2. Nature. 411:466.

DeLucia EH. 1999. Net primary productivity of a forest ecosystem with experimental CO2

enrichment. Science. 284:1177.

Gill RA et al. 2002. Nonlinear grassland responses to past and future atmospheric CO2. Nature. 417:279.

2. Deep-Sea or Mineral Injection of CO2 (Genevieve, Helen, Jason, Jennifer, Jessie, Jonathon, Katie)

Dalton R. 1999. US warms to carbon sequestration research. Nature. 401:315.

Kaiser J. 1998. A way to make CO2 go away: Deep-six it. Science. 281:505.

Seibel BA and PJ Walsh. 2001. Potential impacts of CO2 injection on deep-sea biota. Science. 294:319.

Celia MA. 2001. How hydrogeology can save the world. Ground Water.

Caldeira K and ME Wickett. 2003. Anthropogenic carbon and ocean pH. Nature. 425:365.

Lackner KS. 2003. A guide to CO2 sequestration. Science. 300:1677.

3. C sequestration in terrestrial systems (Kelly, Ling, Liz, Lynn, Marion, Maywa, Melissa)

Smaglik P. 2000. United States backs soil strategy in fight against global warming. Nature. 406:549.

Körner C. 2003. Slow in, rapid out – carbon flux studies and Kyoto targets. Science. 300:1242.

Goodale CL and EA Davidson. 2002. Uncertain sinks in the shrubs. Nature. 418:593.

Betts RA. 2000. Offset of the potential carbon sink from boreal forestation by decreases in surface albedo. Nature. 408:187.

Fang J et al. 2001. Changes in forest biomass carbon storage in China between 1949 and 1998. Science. 292:2320.

4. Iron Fertilization of Open Oceans (Michael, Nicole, Nina, Priya, Schuyler, Tom)

Buesseler KO and PW Boyd. 2003. Will ocean fertilization work? Science. 300:67.

Chisholm SW, PG Falkowski, and JJ Cullen. 2001. Dis-crediting ocean fertilization. Science. 294:309.

Watson AJ et al. 2000. Effect of iron supply on Southern Ocean CO2 uptake and implications forglacial atmospheric CO2. Nature. 407:730.

Lawrence MG. 2002. Side effect of oceanic iron fertilization. Science. 297:1993.

Lam PJ and SW Chisholm. 2002. Iron fertilization of the oceans: Reconciling commercial claims with published models. http://web.mit.edu/chisholm/www/Fefert.pdf. accessed 10/8/03.

Ecology

Populations

Communities

Ecosystems


Population Ecology

How do populations grow?

Most widely used branch of ecology •Endangered species •Invasive species •Agricultural Pests •Disease dynamics

Major Problem: People vs. Elephants

•Park is too small for the elephants. •People are settling outside the park •Elephants like farm food•Elephants and cows both need water

Task: Make a model of elephant population dynamics to ask “what-if” questions about purchasing more land.

w/ Sandy Andelman Data from (2001) Moss, CJ. J Zool. 255: 145-156

How will the elephant population grow?

dN/dt = B - D + I - E

B = Births

D = Deaths

I = Immigration

E = Emigration

Continuous Exponential Growth

Births = bNt Ignore I and E for nowDeaths = dNt

dN/dt = bNt - dNt = (b - d) Nt = r Nt

Integrate to get Nt =

r = “Intrinsic rate of growth”

Discrete Exponential Growth

Nt = Nt-1 + bNt-1 - dNt-1 + I - E

Ignoring I and E, we get

Nt = (b - d) Nt-1

= r Nt - 1

Try this equation in a spreadsheet.

Density Dependence

Nt = rNt-1 (1 - N / K)

“Logistic Growth Equation”

K = Carrying capacity

Try r of different values and graph

Digression: Chaos

Digression: Growth rate vs. Population Size

This graph is the basis of population management and harvesting. For instance, the cod fishery might be managed using a graph like this.

Measuring this turns out to be very hard

Age at First Reproduction Nt = bNt-a - dNt-1

Try changing these and see how it affects doubling time

0 2 4 6 8 10 12 14 16 18 20 22-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Age at first known birth

Cu

mu

lati

ve p

rop

ort

ion

Probability of first birth occurring at eachage for known-age females.

Digression: Why wait to reproduce?

Obviously, you will have more offspring faster if you reproduce sooner. Why doesn’t everything reproduce as soon as its born?

R-selected species: reproduce very at young age and small size / resources.

K-selected species: reproduce at older age and larger size / resources

Environmental Stochasticity

Demographic Stochasticity

What happens when population is small?

Small numbers means that probability comes into play.

Allee effect

When population is small, some things may get harder (like finding mates)

If so, fecundity could actually decrease at low population size.

Some Terms

•Intrinsic rate of growth: maximum offspring / individual / time •Doubling time: Amount of time for population to double •Carrying capacity: The maximum population that the environment can sustain •Discrete vs. continuous: Do events happen continuously or once per some unit of time (such as once per year). •Density-dependent/ independent: Are the parameters like b and d dependent on the density of the population •Demographic stochasticity: When populations are low enough, chance events matter to the population size. •Alee effect: Fecundity decreasing at low population size

Recap

Basic Population Dynamics Eqn dN/dt = B - D + I - E

Continuous Exponential growth dN/dt = rN

Discrete Exponential growth N(t) = N(t-1) + rN(t-1)

Discrete Logistic growth N(t) = N(t-1) + rN(t-1)[(K-N(t-1))/K]


Digression: Why wait to reproduce?

Obviously, you will have more offspring faster if you reproduce sooner. Why doesn’t everything reproduce as soon as its born?

R-selected species: reproduce at young age and small size or resources.

K-selected species: reproduce at older age and larger size or resources

Demographic Stochasticity

What happens when population is small?

Small numbers means that probability comes into play.

Allee effect

When population is small, some things may get harder (like finding mates)

If so, fecundity could actually decrease at low population size.

Estimating Population Size With luck, you can count (like elephants)

Normally, you must sample. Sampling, and analyzing samples, is 90% of most ecologists’ job.

Some sampling techniques

Estimating Model Parameters

1. Plot data 2. Select a growth equation 3. Select parameters for that growth equation 4. Plot the equation over the data 5. Measure the distance of the equation plot from the data

points6. Change the parameters and repeat 7. Select the parameters that give the “best-fit” to the data 8. You can repeat this with a different equation and see

which one fits better - if equations have different numbers of parameters, must take into account that its easier to fit data with more parameters.

Split Data Into Ages or Stages

birth rate death rate

Juvenile 0 0.02

Adult 0.2 0.01

Ancient 0.05 0.05

N(juvenile, t) = 0.98 * N(juvenile, t-1) + 0.2 * N(adult, t-1) + 0.05 * N(ancient, t-1)

N(adult, t) = 0.99 * N(adult, t-1) + prop_age_14 * N(juvenile, t-1)

N(ancient, t) = 0.95 * N(ancient,t-1) + prop_age_55 * N(adult,t-1)

Life Tables Just using matrices to organize data on birth and death rates at different ages / stages.

N(juvenile, t) = 0.98 * N(juvenile, t-1) + 0.2 * N(adult, t-1) + 0.05 * N(ancient, t-1)

N(adult, t) = 0.99 * N(adult, t-1) + prop_age_14 * N(juvenile, t-1)

N(ancient, t) = 0.95 * N(ancient,t-1) + prop_age_55 * N(adult,t-1)

juv |0.91 0.2 0.05 | juv adult = |0.02 0.99 0 | * adult Ancient |0 0.06 0.95 | ancient

Life Tables are just Matrices

Eigenvector = “Stable age distribution”

Eigenvalue = “Growth rate”


In general, population dynamics is not useful for making accurate quantitative predictions.

It’s useful for making qualitative predictions comparing different scenarios.

Individual-based Models

“EcoBeaker”-style

Follow individual creatures. Each creature can have its own Variables

Pluses • Can have infinite stages, ages, etc. • Can account for space, interactions between individuals

Minuses• Often lots of parameters • Limits on number of creatures • Hard to make general conclusions

Some Terms

•Intrinsic rate of growth: maximum offspring / individual / time •Doubling time: Amount of time for population to double •Carrying capacity: The maximum population that the environment can sustain •Discrete vs. continuous: Do events happen continuously or once per some unit of time (such as once per year). •Density-dependent/ independent: Are the parameters like b and d dependent on the density of the population •Demographic stochasticity: When populations are low enough, chance events matter to the population size. •Alee effect: Fecundity decreasing at low population size •Stable age/stage distribution - the eigenvector for the life table matrix


Lecture 15 – Human Population Growth

Krebs Chapter 11: “Population Growth”

Krebs Chapter 10: “Demographic Techniques: Vital Statistics” Krebs Chapter 9: “Population Parameters” Krebs Chapter 28: Pages 583-590.

READINGS FOR NEXT LECTURE: (some of these are from last week’s lectures) Outline for today:

1. Historical population growth 2. Carrying capacity and ecological footprints 3. Life tables 4. Guest speaker: David Greene

Study Questions:

• Describe the concept of carrying capacity. Why is it hard to define the carrying capacity of a country?

• Doubling times for human population have decreased significantly over the past 2000

years. What does this imply about the rate of growth? (Use an equation)

• Define the concept of ecological footprint, and what is involved with calculating one. Compare the ecological footprint of N. America and Asia.

• Compare stable and expansive populations, and explain the idea of population

momentum.

• How do life tables help you predict future population growth?

1

Life table nx = number of individuals in age group qx = mortality rate for individuals in age group bx = number of babies born per person (or female) over time interval 1. Fill in boldly-outlined boxes. 2. Is this an expansive or stable population? 3. Which of the above numbers would change if:

(a) teenage pregnancy rates went down?

(b) all women delayed having births by 10 years?

(c) infant mortality rates increased?

(d) a new drug is introduced which lowers heart attacks in 40-49 year olds?

..

1990 pop’n

(millions)

...........00.0545550-5900.0428640-49

0.050.02711930-390.30.01513220-290.10.00916710-1900.0052150-9

2000pop’n

(millions)

Birth rate(bx)

Mortality rate(qx)

1980 pop’n(millions)

(nx)

Age group

..

1990 pop’n

(millions)

...........00.0545550-5900.0428640-49

0.050.02711930-390.30.01513220-290.10.00916710-1900.0052150-9

2000pop’n

(millions)

Birth rate(bx)

Mortality rate(qx)


(nx)

Age group

in this case, bx is based on number born per person (not per female)

2

Human Population Growth

Krebs, 2001 (Figure 28.1)

Doubling times

Year (AD) Population (billions)0 0.25

1650 0.5

1850 1.0

1930 2.0

1975 4.0

1650 years

200 years

80 years

45 years

Pop

ulat

ion

(mill

ions

)Carrying capacity = 197 million

logistic curve

In 1924, Pearl and Reed fit U.S. population data for 1790-1910 using the logistic equation.

Joel E. Cohen, How Many People Can the Earth Support? Norton 1995

In 1990, the population of the U.S. was 250 millionJoel E. Cohen, How Many People Can the Earth Support? Norton 1995

Pop

ulat

ion

(mill

ions

)


Ecological Footprint

Ecological footprint by region, 1996

North America Latin America & CaribbeanWestern Europe Asia / PacificCentral and Eastern Europe AfricaMiddle East and Central Asia

299384

343307

484 3222 710

Population (millions)

Are

a un

its p

er p

erso

n

12

10

8

6

4

2

0

OECD average

non-OECD average

Adapted from: WWF, UNEP World Conservation Monitoring Centre, et al. 2000.Living Planet Report 2000. Gland, Switzerland: WWF.

9 hectares / person= 90,000 m2 / person

300 m

Manhattan has 1.5 million peopleon 21.8 square miles

at 9 ha/person (1 ha=104 m2),what is Manhattan’s ecological footprint?

Manhattan’s ecological footprint =54,000 square miles

Estimates of Earth’s Carrying Capacity


“Expansive” population distribution

Source: www.wri.org

“Stable” population distribution

Source: www.wri.org

Adapted from: www.wri.org

Fertility Decline 1950 - 1998


Hypothetical Survivorship Curves

Source: Krebs, 2001(Figure 10.2)

Life Tables

Agegroup


(nx)

Mortalityrate(qx)

Birth rate(bx)

1990pop’n

(millions)

2000pop’n

(millions)

0-9 215 0.005 0

..

10-19 167 0.009 0.1

20-29 132 0.015 0.3

30-39 119 0.027 0.05

40-49 86 0.042 0

50-59 55 0.054 0

.. .. .. .. ..


Lecture 16 – Competition

O I. II.

S •

• •

•

•

Krebs Chapter 22 pages 447-448. Krebs Chapter 12: Species Interactions: Competition

READINGS:

utline for today:

Life tables (from last class) Competition

a. Resource vs interference competition b. Lotka-Volterra equations c. Tilman’s approach d. Niches

tudy questions

Explain the difference between resource and interference competition. Give an example of each.

What do α and β in the Lotka-Volterra equations represent?

For the 4 general cases of the Lotka-Volterra equations, will in > or < in the following inequalities, and describe whether inter- or intraspecific competition is more important for species 1 and 2

K1 ___ K2/β K2 ___ K1/α

What were Tilman’s criticisms of the Lotka-Volterra approach? Describe Tilman’s approach to determining the outcome of competition between two species.

Suppose the densities of two species A and B are 60 and 30 organisms per acre. Their carrying capacities are 65 and 80 organisms per acre, respectively. Can you say whether or not these species could be in stable coexistence as described by the Lotka-Volterra Equations? Why or why not? What if the densities of the two species are 20 and 20 organisms per acre, respectively. What can you say now?


Lecture 17 – Competition and Niches

Krebs Chapter 13: Species Interactions: Predation

READINGS: Outline for today: I. Finish competition

a. Tilman’s approach b. Competitive exclusion principle c. Character displacement and resource partitioning d. Fundamental and Realized Niches

Study questions • Explain the difference between a fundamental and a realized niche. • Explain character displacement and provide and example • Explain the significance of Gause’s experiments with paramecium. Gause’s paramecium experiments

Fundemental vs. realized niche

Independent vs. inter-dependent niches(a) (c)(b)

A

A

A

AA

A

B

BB

BB

B

Two species, A and B

(a) Niches are independent(b) and (c) Niches are partially dependent

Independent vs. inter-dependent niches(a) (c)(b)

A

A

A

AA

A

B

BB

BB

B



Macarthur’s Warblers: See Krebs 12.15

2

Supplement to class (11/6):

Clarifying Tilman’s approach:

Consider the graph for one species, Species A:

Suppose that Species A uses Resources 1

R2

R1

Zone 1

Zone 2

and 2 in the ratio of 2:1 (shown by the dotted line)

If the supply point falls in Zone 1 (above the line), then R1 will be limiting. In other words, if Species A uses up the resources at a constant 2:1 ratio, and the supply point ratio of R1:R2 is less than 2:1, then Species A will run out of R1 first.

Below the line, in Zone 2, R2 will be limiting.

For Species A, because the usage ratio of R1:R2 is greater than 1, Species A is more efficient at using R2, and it is generally considered to be limited by R1. Whether or not it will actually be limited by R1 depends on conditions in the environment (whether your starting point is in Zone 1 or 2).

Consider the graph for Species B: Now let’s consider the case for Species B.

R2

Zone 1 Zone 2 Again in Zone 1 (above the dotted line),

Species B will be limited by R1, and below the line will be limited by R2.

Generally speaking, Species B will be more limited by R2, and is considered more efficient at using R1.

R1

Species A and B together:

CB1 Species A and B both lose

3 2 Species B wins over Species AR2 2 4 CA

3 Falls within Zone 1 for both Species A and B. Hence, R1 will be limiting for both. Since Species B is more efficient

5 at using R1, it will predominate.

B 4 Here, A will be limited by R1 and B will 6 A be limited by R2. Since B is generally1

more limited by R2 and A is generally R1 limited by R1, neither species will have a

competitive advantage over the other and both will be limited. This is the zone of coexistence. The stable equilibrium point will occur at the intersection of the two lines (since dN/dt=0 for both species here).

5 Falls within Zone 2 for both Species, meaning that R2 will be limiting for both species. Since Species A is more efficient at using R2, Species A will be able to outcompete Species B in this region.

6 Species A wins over Species B

Independent vs. inter-dependent niches

The axes in graphs on right represent availability of two resources. The arrows show the range of availabilities that will permit the growth of Species A and B.

Let’s consider the shape of the niche for just Species A, in two dimensions. There are three general shapes for the two-dimensional niche.

(1) No interdependence of niches. At high availability of R1, any level of R2 will permit growth.


(a) (c)(b)

A

A

A

A A

A

B

BB

BB

B


(a) Niches are independent (b) and (c) Niches are partially dependent


(a) (c)(b)

A

A

A

AA

A

B

BB

BB

B



(2) Interdependent niche. At high availability of R1 (e.g. bright sunlight for a plant), Species A requires high availability of R2 (e.g. high water availability) in order to grow.

(3) Interdependent niche. This time, high availability of R1 permits Species A to grow only if availability of R2 is low.

(1) (2) (3) R2 R2 R2

A AA A

R1 R1R1

CA


Lecture 18 – Predation READINGS:

Gilg O, I Hanski and B Sittler. 2003. Cyclic dynamics in a simple vertebrate predator-prey community. Science. 302:866.

Turchin P, L Oksanen, et al. 2000. Are lemmings prey or predators? Nature. 405:562.

Tilman D. 2000. Causes, consequences and ethics of biodiversity. Nature. 405:208.

Ranta E. 2003. Making sense of complex population cycles. Science. 301:171.

Outline for today: I. Predation

a. Lotka-Volterra b. Rosenweig-MacArthur c. Functional Response Curves -- Holling

II. Guest Speaker, Aladdine Joroff (’00) Lemmings: Predator or Prey? Study Questions • What is unrealistic about Lotka-Volterra’s approach to modeling predator-prey

interactions? What other shapes can the isoclines assume? • What situations are stable and unstable in Rosenweig-MacArthur’s approach? What

changes might make stable interactions unstable? • Sketch the Type I, II and III Functional Response Curves and describe what the shapes of

the curves mean. • According to Tilman, how does competition among members of a single trophic level

serve to stabilize communities? What are the requirements for coexistence? • Compare the findings of Gilg et al. and Turchin et al. Are their findings compatible with

each other? • In the Gilg et al. paper, what type of function response curves do the predators exhibit

with respect to lemming density?

abgupt

Rectangle

Creating Stable Oscillations in Lab Settings Adapted from Krebs Fig. 13.2


2

Huffaker Adapted from Krebs Fig. 13.8

Oscillations in Natural Settings

3

Functional Responses: Type II Adapted from Krebs Fig. 13.17

4

Conservation Examples

Population Viability Analysis - Butterflies and Restoration

Indicator Species - Good idea?

Hotspots

Endangered Species

Part of declaring a species endangered involves doing a Population Viability Analysis (PVA)

A population is not considered endangered if it has 95% chance of persisting for 100 years.

Once a species is declared endangered, it gets a “recovery plan” •What will be done to help it •When is it considered “recovered”

1


Fender’s Blue Butterfly

Pretty butterfly that lives in western Oregon

Lays eggs on Kincaid’s Lupine

Kincaid’s Lupine only grows in “old growth” prairies

Prairies are prime land for farms, suburbs, shopping malls, universities…

Both Kincaid’s Lupine and Fender’s Blue Butterfly were recently listed as endangered species.

Sources: Schultz and Hammond (2003) Conservation Biology 17:1372-1385. Schultz (1998) Conservation Biology 12: 284-298 E. Crone, pers. comm.

2

Population Viability for Fender’s Blue

Data: •Yearly population census in different patches

Assume: •Density independent growth •No observer error •No exceptional years

Use exponential growth equation

N(t+1) = N(t) + (r + ε) N(t)

ε = error term

3

Growth rate and variance for Fender’s Blue Site Ownership Protected

statusNumber ofcensuses

Average population sizec

Population growth rate ( )

Variance in population growth rate ( 2)

Butterfly Meadowsd

Private Unprotected 8 412 1.06 0.122

Fern Ridge – Eaton Lane

Public Protected 9 5 2.66 1.461

Fern Ridge – Spires Lane

Public Protected 9 22 1.92 1.338

Fir Butte Public Protected 8 54 1.61 0.861 Willow Creek-Bailey Hill

Private Protected 9 77 1.34 0.692

Willow Creek-Main Area


Willow Creek-North Area


Basket Butte Public Protected 8 589 1.12 0.436 Gopher Valley Private Unprotected 8 10 0.99 0.468 McTimmonds Valley

Public Unprotectede 9 11 2.02 1.715

Mill Creek Public Unprotectede 10 17 1.31 0.607 Oak Ridge Private Unprotected 9 149 1.21 0.448

Avg. growth rate = 1.49 Avg. variance = 0.79 (for sites with > 25 butterflies = 0.54)

Chance of Persistence

4

Multiple Patches = Metapopulation

Chance of survival with no colonization is:

survival anywhere = 1 - Π (1 - survivali)i

Chance of survival WITH colonization will be higher

Metapopulation can survive even when all patches will Individually go extinct

5

Prairie Restoration Measure •Flight paths •Chance to leave lupine area •Daily time budget •Lifespan

Model different habitat configurations and ask which increases survival the most.

Fender’s Blue Butterflies:

Live ~ 10 days Fly ~ 2.3 hours / day Disperse within lupine ~ 3 m2/sDisperse outside lupine ~ 15 m2/s

Weakly bias flight towards lupine patches

Butterfly might go 0.75 km within lupine 2 km outside of lupine

Historically, patches ~ 0.5 km apart

Now patches 3 - 30 km apart

6

Other Examples of Recommendations

Spotted Owls Save old growth trees

Sea Turtles Protect the adults, forget the eggs

Sea Otters Based PVA on risks of oil spills, recommend number and area for recovery

Problem

Fender’s Blue study: •8 years dedicated study by grad student, TNC personnel •Undergraduate field assistants •Lots of volunteers

Impossible to do for very many species

7

Indicator Species

A well-studied species whose protection will also protect many other less weel-studied species.

What makes a good indicator?

8

Hot Spots

Places with high biodiversity, especially many endemic species

9

Brooks et al., (2002) Habitat loss and extinction in the hotspots of biodiversity. Conservation Biology 16: 909-924.

Save Hotspots to Save Diversity?

Myers et. al. claim that 1.4% of land area contains 44% of vascular plants and 35% of vertebrates

Save 1.4% and you save a good bit of world’s biodiversity

Myers et al., (2000) Biodiversity hotspots for conservation priorities. Nature 403: 853-858.

10

Looks good, but…

Conclusions

Tools of ecology help guide small, local decisions

At large scale, tools of ecology also offer guidance, but no easy answers.

11

Manter Fire Sequoia National Forest California (http://www.nifc.gov/gallery/manter.html

A presentation about giving a presentation

Laurel Schaider 1.018/7.30J Final Lecture

November 20, 2003

Outline for today

• Components of an effective talk

• Visual guidelines

• Review

• Conclusions

Components of presentation Setting the stage

• Set the stage • You can have bullet points

• Background • to tell the audience what

• State the question/hypothesis • you’re going to talk about

• Describe your approach • but what might be better

• Sample data • is a picture to really

• Conclusions • set the stage

Picture of a fire along the side of a road.Removed for copyright restriction.See: http://www.nifc.gov/gallery/manter.html

1

Manter Fire Sequoia National Forest California (http://www.nifc.gov/gallery/manter.htmlManter Fire Sequoia National Forest California (http://www.nifc.gov/gallery/manter.html

How can this be prevented?

www.nifc.gov -Sequoia National Forest California

http://www.n fc.gov ga ery manter.htmli / ll /

What are we doing to rangeland genetic diversity?

http://www.nau.edu/~envsci/sisk/courses/env440/SCBS/andy.htm

Are we being affected by

environmental estrogens?

news.bbc.co.uk/hi/english/business/newsid_610000/610046.stm

www.njeit.org/examples.htm

http://www.ecology.com/dr-jacks-natural-world/most-important-organism/

Introduction

• Why is your topic significant?

• What have other people studied about it?

• What is not known?

2

State the Question/Hypothesis

• What is the major question or hypothesis you are testing?

• You can have 1 or 2 or 3, but not too many What role do chelated metals

play in total metal uptake?

Approach & methods

• Discuss approach

• Briefly include important methods

– Site selection

– Novel experimental techniques

– Unfamiliar concepts

• Pictures are very helpful here! Pi l

DNA

Cells

Laser

Forward light scatter detector

gment f uorescence detector

Flo w Cyto metry

per cell

Prof. Chisholm

Methods

• Grow plants 4-6 weeks

• 2-3 days exposure metal-EDTAsolutions

total metal – GFAAS

FeEDTA- & total EDTA HPLC, Nowack et al., 1996

Me-EDTA2- – HPLC Bedsworth & Sedlak, 2001

Hypothesized results

• Graphs are really helpful

• Tables can be hard to read

• Just one or two examples...You don’t have time to share all your hypothesized data

3

% black % with

bubbles

% with colors in

mud

Meat 100 100 50

No Meat 0 80 60

Wi Wi

0

20

40

60

80

100

les l i

l

nogradsky data nogradsky data

black bubb co ors n mud

% s

amp

es

Meat No meat

a b659 -4000

CO2 f

Potential further global emissions from fossil fuels (GtC)

Storage Option Southern Ocean Fe-Fertilisation

Deep Ocean Injection or Diffusion

c50 - 200

i CO2

($/ i j

85k

m

n

Residence t me of in the

atmosphere (yr)

Approx. Global Capacity (GtC)

Total Cost tC)

152 1-15

> 1,000 >300 (4.1)

d3.3 ± 0.2

2

g, h

o

Atmospheric CO accumulation rate (GtC/yr)

Residence Time (years) Varies with durati on of

ocean fertilisation 100-1000

eApprox. 850

2

l

Target reduction in atmospheric CO over next 100 years (GtC)

Sequestration Rate (GtC/yr)

Ecological Risks

1.52 (100 year average)

Hypoxia, HABs, change in species composition

3.5 + [rise in emissions]

Gl l 2obal annua CO avoidance & capture target (GtC/yr)

Other Benefits

Stimulates fish production?

None

Deployment Status IRONEX I & II, SO IREE, and CARUSO field experiments DOE Testing off Kona Island in 2001-2002?

Commercial pilot at Sleipner in North Sea.

Ocean Aquifers

Depleted Oil & Gas Reservoirs

(About 290 Mha suitable globally

m q

s

u

100 -220

180

50 - 100 (Depends on land & water

s

r

10v i

50-60m,r

(4.7)

(8.2)

- 80 (Depends on management

m

s

Si te specific

Up to 1,000,000

> 100 / w(2.2tC ha-yr)

t

s

Optimal rate to be determined

> 0.001 (not yet maximized)

Site specific

1.2 alien species, monoculturing,

p

Ecos yst em disruption due to CO2 acidity Groundwater impact, leakage to bent hic zone

None

Groundwater impact, land absidence, subsidence

Extends value of reservoir site

Introduction of Biofuels and ot her product s, wildlife habitat, x

olel Te, exico . Farm

JI project in ScM

Agro-forestry

Enhanced Oil Recovery

for this practice)

s>16.6

cost, & valuof products)

s

e

40-60

strategy)

s Up to

1,000,000

s (3.9–7.7tC/ha

-yr) s0.4

s land/water use conflicts Groundwater impact, land absidence,

watershed management. Increased oil recovery

2. anagement in

USA for CO m

Commercial use in North Sea &

4Coal-bed CH (a) 1.4 - 4.1 (b)18 - 22

y(c) 40

-(a) 55 (!) (b) 50

s(c) 350-450

s Up to

1,000,000 Site specific Low risk

subsidence Recovery of methane

Commercial pilots in New

s .West Texas

Mexico and Australia.

0

0.02

0.04

0.06

0.08

0.1

l µM

500 µM 500 µM 80

85

90

95

**

**

**

*

***

Effects of excess EDTA

contro (45 excess EDTA)

excess EDTA

excess EDTA +

Cu, Fe, Mn, Zn

Roo

t or

shoo

t dry

wei

ght (

g)

Sho

ot w

ater

con

tent

(%

)

roots

% water

shoots

0

0.02

0.04

0.06

0.08

0.1

l µM

500 µM 500 µM 80

85

90

95

**

**

*

l i ions

• l l

• i

l

Effects of excess EDTA

contro (45 excess EDTA)

excess EDTA

excess EDTA +

Cu, Fe, Mn, Zn

Roo

t or

shoo

t dry

wei

ght (

g)

Sho

ot w

ater

con

tent

(%

)

roots

% water

shoots

Conc usions & Impl cat

Te them what you to d them

Re-iterate why t matters

4

Planning content

• Consider knowledge of audience

• Consider what makes an interesting story

• Ask rhetorical questions

• You can’t say everything that’s in your proposal!

General hints on effective visuals

• Don’t use more words than are necessary

• Choose a font style and size that will allow your audience to see the words clearly

• While colors can be very useful, choose carefully and don’t over-do it.

Bullet points

• W atch out for alignment of bullets

• There should be a space between bullet and first word

• And second line should be aligned

• And there should be space between points

• This will make the words easier to read

• But you shouldn’t have this many words in the first place, this is more as an example

General hints on effective visuals

• Concise

• Font

• Color

Bullet points •W atch out for alignment of bullets

•There should be a space between bullet and first word

•And second line should be aligned •And there should be space between points

•This will make the words easier to read

•But you shouldn’t have this many words in the first place, this is more as an example

Beware the flying bullet

• Some people like the bullet points

• To come flying in one-by-one

• This can interesting and amusing

• But sometimes is distracting

• Plus people sometimes like to have time to read over all the points at their leisure

5

This is in size 40 font








Fonts without serifs are easier to read than fonts with serifs. Serifs are those little lines like you have in Times New Roman font. This is in Arial Font size 20.

Fonts without serifs are easier to read than fonts with serifs. Serifs are those little lines like you have in Times New Roman font. This is in Comic Sans M S Fo nt size 20 .

Fonts without serifs are easier to read than fonts with serifs. Serifs are those little lines like you have in Times New Ro man font. This is in Tahoma Font size 20.

Fonts without serifs are easier to read than fonts with serifs. Serifs are those little lines like you have in Times New Roman font. This is in Times New Roman Font size 20.

Fonts without serifs are easier to read than fonts with serifs. Serifs are those little lines like you have in Times New Roman font. This is in Palatino Font size 20.

Colors can be used very effectively. Of course, color choice depends on your background.

Contrasting colors make a more dramatic effect than Contrasting colors make a more dramatic effect than

really similar colors, which might not show up as really similar colors, which might not show up as different. different.

Some colors show up better than others. Some colors show up better than others.

Too many colors, well, are just too many colors. Too many colors, well, are just too many colors.

Speaking of backgrounds

• Dark backgrounds with light writing can be really nice

• Problems:

– Sometimes harder to make handouts

– W astes a lot of ink if you want to photocopy

– Can darken a room

ll

i i

l

Beware of rea y busy or textured backgrounds

These can be d stract ng

And a so make the text harder to read

6

There are many pre-set options

� Some are interesting

� Some are distracting

� Choose carefully

There are many pre-set options Engaging the audience

� Some are interesting • Eye contact

� Some are distracting • Pace � Choose carefully

• Content – Who’s your audience?

PRACTICE!

biosphere

ecosystem

community

population

organism

Organism

Metabolisms: sources of C, energy, e -

heterotrophs

photoautotrophs and chemolithoautotrophs

nutrients light

grass

Population

Population growth

Intraspecific competition

nutrients light

7

wolf

deer moose

wolf

moose deer

grass

Community Ecosystem

Interspecific competition Productivity

Predation Limiting nutrients

Food webs Life �� Surroundings

grass

moose

wolf

deer moose

wo

deer

lf

nutrients light nutrients light

grass

Biosphere

Biogeochemical cycles

Climate change

CO2 NO2

algae

shrimp

fish

copepod

nutrients light

algae

shrimp

fish

copepod

nutrients light

Ocean

moss

mouse

fox

ferr et

nutrients light

Tundra

grass

moose

wolf

deer

nutrients light

grass

moose

wolf

deer

nutrients light

Grassland What else is ecology?

• Different biomes

– Tropical ecology, marine ecology, etc.

• Different organisms

– Plants, microbes, animals

• Population & community ecology

• Evolutionary ecology

Want to learn more?

Department of Organismic & Evolutionary Biology

Evolution of Plant Life in Geologic Time

Biological Oceanography

Tropical Insect Systematics

Global Change Biology

Topics in Marine Biology

Nature and Regulation of Marine Ecosystems

Forest Ecology

Ecology is a science

8

Ecology is a science ...but ecological principles can be applied

to other aspects of our lives

Thanks Sagol Gracias Shukriya Merci Tashakkur Danke Takk Salamat Arigato Komapsumnida Xie xie Spasibo Tack Khawpkhun Vinaka Köszönöm Asante Nandri Ngiyabonga Cám ón Dakujem Tapadh leat Dhannvaad Kongoi Gratia Makasih Dankie Shukran

9

fundamentals of ecology

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