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It involves understanding bioticand abiotic factors influencingthe distribution and abundanceof living things.

Biotic Factors• Competitors

• Disease

• Predators

• Food availability

• Habitat availability

• Symbiotic relationships

Abiotic Factors• pH

• Temperature

• Weather conditions

• Water availability

• Chemical composition ofenvironment

• nitrates, phosphates,ammonia, O2, pollution

• population growth• competition between species• symbiotic relationships• trophic (=feeding) relationships• origin of biological diversity• interaction with the physical environment

Energy Flow & Nutrient Cycle

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Food Chains

• Artificial devices toillustrate energy flowfrom one trophic levelto another

• Trophic Levels:groups of organismsthat obtain theirenergy in a similarmanner

• Total number of levels in a food chaindepends upon locality and number ofspecies

• Highest trophic levels occupied by adultanimals with no predators of their own

• Secondary Production: total amount ofbiomass produced in all higher trophiclevels

Food Chains

Nutrients• Inorganic nutrients incorporated

into cells during photosynthesis- e.g. N, P, C, S

• Cyclic flow in food chains

• Decomposers release inorganicforms that become available toautotrophs again

Energy• Non-cyclic, unidirectional flow• Losses at each transfer from one

trophic level to another- Losses as heat from respiration- Inefficiencies in processing

• Total energy declines from one transferto another- Limits number of trophic levels

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Energy Flow

PrimaryProducer Primary

Consumer SecondaryConsumer

TertiaryConsumer

Food Chain

Decomposer

zooplankton larval fishfish

fungi

Energy Flow through an Ecosystem

heat heatheat

phytoplankton

sun

water

Nutrients

Transfer Efficiencies• Efficiency of energy transfer called

transfer efficiency

• Units are energy or biomass

Et = PtPt-1

Pt = annual production atlevel t

Pt-1 = annual productionat t-1

Transfer Efficiency Example• Net primary production = 150 g C/m2/yr• Herbivorous copepod production = 25 g C/m2/yr

• Typical transfer efficiency ranges*Level 1-2 ~20%*Levels 2-3, …: ~10%

Et = PtPt-1

= Pcopepods

Pphytoplankton

= 25 = 0.17150

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Primaryproducers

Tertiaryconsumers

Secondaryconsumers

Primaryconsumers

1,000 J

10% efficiency

Deposit feeders, filter feeders, grazers

1,000,000 J sunlight

10,000 Jalgae, seagrass, cyanobacteria, phytoplankton

100 J1st order carnivores

10 J2nd order carnivores

Feces

Growth

CellularRespiration

Food Webs• Food chains don’t exist in real

ecosystems

• Almost all organisms are eaten bymore than one predator

• Food webs reflect these multipleand shifting interactions

Antarctic Food Web

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Some Feeding TypesSome Feeding TypesMany species don’t fit into convenient categories

• Algal Grazers and Browsers• Suspension Feeding• Filter Feeding• Deposit Feeding• Benthic Animal Predators• Plankton Pickers• Corallivores• Piscivores• Omnivores• Detritivores• Scavengers• Parasites• Cannibals• Ontogenetic dietary shifts

Recycling: The Microbial Loop• All organisms leak and excrete

dissolved organic carbon (DOC)• Bacteria can utilize DOC• Bacteria abundant in the euphotic

zone (~5 million/ml)• Numbers controlled by grazing due to

nanoplankton• Increases food web efficiency

SolarEnergy

Microbial Loop

CO2nutrients

Phytoplankton

Herbivores

Planktivores

Piscivores

DOC

Bacteria Nanoplankton(protozoans)

Keystone Species

A species whose presence inthe community exerts asignificant influence on thestructure of that community.

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Keystone predator hypothesis -predation by certain keystone predatorsis important in maintaining communitydiversity.

Paine’s study on Pisaster and blue mussels

Kelp ForestsKeystone SpeciesKeystone Species

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Keystone SpeciesKeystone Species

Algal turf farming bythe Pacific Gregory(Stegastes fasciolatus)

An Ecological Mystery

An Ecological Mystery• Long-term study of sea otter populations

along the Aleutians and Western Alaska• 1970s: sea otter populations healthy and

expanding• 1990s: some populations of sea otters

were declining• Possibly due to migration rather than

mortality• 1993: 800km area in Aleutians surveyed

- Sea otter population reduced by 50%

Vanishing Sea Otters

• 1997: surveys repeated• Sea otter populations had declines by 90%

- 1970: ~53,000 sea otters in survey area- 1997: ~6,000 sea otters

• Why?- Reproductive failure?- Starvation, pollution disease?

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Cause of the Decline• 1991: one researcher observed an orca

eating a sea otter• Sea lions and seals are normal prey for

orcas• Clam Lagoon inaccessible to orcas- no

decline• Decline in usual prey led to a switch to sea

otters• As few as 4 orcas feeding on otters could

account on the impact- Single orca could consume 1,825otters/year

Ecological Succession

The progressivechange in the speciescomposition of anecosystem.

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Ecological Succession

Climax Stage

New Bare Substrate

Colonizing Stage

Successionist Stage

PRIMARY SECONDARY

Growth occurs onnewly exposedsurfaces where nosoil exists

Ex. Surfaces ofvolcanic eruptions

Growth occurringafter a disturbancechanges acommunity withoutremoving the soil

2 types of succession

• For example, new land created by a volcaniceruption is colonized by various livingorganisms

• Disturbances responsible can includecleared and plowed land, burnedwoodlands

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Mount St. Helens

prior 1980

Mount St. Helens

May 18, 1980

Sep. 24, 1980

Mount St. Helens

Fireweed 1980 aftereruption 2004

2012Hanauma Bay Tuff Ring

(shield volcano)

Succession after Volcanic Eruption

What organisms would appear first?

How do organisms arrive, i.e., methods for dispersal?

Volcanic eruption createssterile environment

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Mechanisms of SuccessionFacilitation

Inhibition

Tolerance

Early species improve habitat.Ex. Early marine colonists provide a substrateconducive for settling of later arriving species.

As resources become scarce due to depletion andcompetition, species capable of tolerating the lowestresource levels will survive.

Competition for space, nutrients and light; allopathicchemicals.

First arrivals take precedence.

r & K Selected Species

Pioneer species- 1st species to colonize a newly disturbed arear selected

Late successional speciesK selected

low competitive abilityshort life spanhigh growth rate

higher maternal investment per offspringlow reproductive output

high reproductive output

slow growth ratelong life spanhigh competitive ability

r & K refer toparameters inlogistic growth

equation

Ecological Succession on a CoralReef

Successional Models and theirImpacts

Case 1: No Disturbance(Competitive Exclusion Model)

Case 2: Occasional Strong Disturbance(Intermediate Disturbance Model)

Case 3: Constant Strong Disturbance(Colonial Model)

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Case 1: No Disturbance(Competitive Exclusion Model)

• As the reef becomes complex, organismscompete for space.

• Dominant organism outcompetes otherspecies.

• Occurs in stable environments.• Results in low species diversity.• Highly protected patch reefs withinlagoons or protected bays

• Deeper water

Case 2: Occasional Strong Disturbance(Intermediate Disturbance Model)

• Storms and hurricanes allow for otherspecies to move in

• Dominant species would not beallowed to reach competitive exclusion

• After each disturbance have a recoveryperiod

• Area of high diversity

Case 3: Constant Strong Disturbance(Colonial Model)

• Constant exposure to disturbance• Shallow environment• High turnover of species• r-selected species

Case 3

Case 2

Case 1Deep reef slope

Reef slope beneathreef crest

Near reef crest

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Ecological Succession on a Coral ReefThe Big Island Ecological Succession on a Coral Reef

Ecological Succession on a Coral Reef Ecological Succession on a Coral Reef

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Ecological Succession on a Coral Reef Ecological Succession on a Coral Reef

Ecological Succession on a Coral Reef Ecological Succession on a Coral Reef

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Successional Models and theirImpacts

Successional Models and theirImpacts Aliran Energi dan

daur ulang nutrient diekosistem pantai

berbatu

• Semua organisme yang hidup dalam komunitas pantai berbatumembutuhkan energi untuk bertahan hidup.

• Bagaimana energi ini diperoleh dan berapa banyak yangditeruskan?

• Bagaimana organisme ini mendapatkan atom dan molekul untukpertumbuhan dan perbaikan?

• dan bagaimana nutrisi ini diteruskan?Jawab Pertanyaan tersebut dalam bentuk MAKALAH

TUGAS 3