Ecosystems 5.1

Vocabulary 5.1.1

Ecology – the study of relationships between organisms and between organisms and their environment

http://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Blue_Linckia_Starfish.JPG/220px-Blue_Linckia_Starfish.JPG

Vocabulary 5.1.1

Species: organisms that can interbreed in the wild and produce viable offspring – share a gene pool

Two species can mate and not produce fertile offspring – instead called interspecies hybridization

Example: female horse and male donkey produce mules

Vocabulary 5.1.1

Habitat – environment in which an organism normally lives

Includes abiotic factorsMust provide food, shelter, water and space to

liveExamples: fast moving stream, temperate forest

Vocabulary 5.1.1

Niche – the role an organism occupies in its environment

What its job is in the ecosystem?Predator of mule deer etc.What tolerance limits does it have?temperature, pH, light intensityTwo organisms cannot occupy the same niche at

the same time – competitive exclusion principle

Vocabulary 5.1.1

Population – all members of a single species living in a given area at a given time.

All the mice in Palmer High School this year.

Vocabulary 5.1.1

Community – ALL of the populations of different species living and interacting in a given area at a given time

All the humans, mice, spiders, cockroaches living in Palmer High School this year.

http://0.tqn.com/d/exoticpets/1/0/D/9/1/mouse2angelo.jpg

Vocabulary 5.1.1

Ecosystem – a community interacting with its abiotic environment

All the humans, mice, spiders, cockroaches living in Palmer High School this year with the heat, lights, water fountains, bathrooms, cafeteria, desks and lab equipment.

Environment

Everything surrounding an organism• Hydrosphere• Atmosphere• Lithosphere• Biosphere

Troph = greek for nourishment

Nutrition = how an organism obtains• energy and • a carbon source to build the organic molecules of

cells

Vocabulary 5.1.2 Autotroph – synthesizes its organic molecules

from simple inorganic substancesPhotoautotroph – light a source of energy for

synthesis in most communitiesExplants, protists, prokaryotes

http://www.ucmp.berkeley.edu/bacteria/oscillatoria2.jpg

Chemoautotroph 5.1.2

Use inorganic molecules as source of energy•usually hydrogen sulfide, amonia or iron compounds• prokaryotes found at hydrothermal vents(black smokers)•Nitrogen fixing soil bacteria

http://www.amnh.org/nationalcenter/expeditions/blacksmokers/black_smokers.html

Heterotroph 5.1.2

Organisms that obtain organic molecules from other organisms

Ingest organisms to digest, ingest organic matter to digest, or digest outside and then absorb

Consumer 5.1.3Ingest organisms that are living or recently killed

and digest them internally

http://clayruth.com/larvae.html

http://www.animalorphanagekenya.org/photos/lion_eating_mara.jpg

Detritivores 5.1.3

• Ingests non-living organic matter • Dead plant and animal material• Fill the decomposer niche• Earthworms, crabs

http://upload.wikimedia.org/wikipedia/commons/thumb/1/1f/Staphylinus.olens.vs.lumbricus.terrestris.jpg/220px-Staphylinus.olens.vs.lumbricus.terrestris.jpg

Saprotrophs 5.1.3

• Lives on or in non-living organic matter• Secretes digestive enzymes into the organic

matter• Absorbs the products of the digestive process• Prokaryotes and fungi

http://vanessavobis.com/wp-content/uploads/2009/01/Maine_Mushroom_(0).jpg

Decomposers 5.1.14

• Saprotrophic bacteria and fungi• Get nutrition from breaking down dead material• Examples include saprotrophic bacteria and fungi• Recycle nutrients by returning them to the

environment in form of simple compounds such as carbon dioxide and nitrates (NO3), nitrites (NO2) ammonium (NH4)

Food Chain 5.1.4• Sequence of organisms each one feeds on the

previous one• Arrows point in the direction of energy flow ie

towards the organism that is doing the eating• Base of chain must be some form of autotroph• Following steps are consumers• No consumers feed on the last organism in the

chain• Decomposers are not included

CO2CO2

Length of food chains

• Generally 2 to 5 organisms long• Not longer because of inefficiency of

conversion of energy from one organism to another

Trophic Levels 5.1.6

Categories reflect feeding relationships in food web or chain

Producer, Primary Consumer, Secondary Consumer, Tertiary Consumer, Quaternary ConsumerCarnivore, herbivore, omnivore – describe diet choices not trophic level – do not use them interchangeably

Food Web 5.1.5

Complex representation of feeding relationships within ecosystem more realistic than food chain

Complex because most organisms feed on more than one species and are fed on by more than one species

Some organisms feed at more than one trophic level

Feeding preferences may change seasonally but are not shown in a food web

Relative Importance Of Food Web LinkagesPrimary (75-100% of Total)Secondary (50-74% of Total)Tertiary (25-49% of Total)Incidental (0-24% of Total)

PacificStaghornSculpin

Great BlueHeron

PenpointGunnel

SharpnoseSculpin

Small Fish (inc.herring, perch)

BuffaloSculpin

ChumSalmon (juv.)

TubenosePoacher

Mysids

GammaridAmphipods

Detritus

Cumaceans

PaddedSculpin

Tunicates

StarryFlounder (juv.)

Sanderlings,Long & Short-billed

Dowitchers, Greater Yellowlegs

SaddlebackGunnel

BenthicMeiofauna

Hippolytid, Crangonid,

And PenaeidShrimp

PolychaeteAnnelids

GastropodMolluscs

SaltmarshPlants & Eelgrass

Phytoplankton

MicrophyticAlgae

Whimbrel, Mallard, Northern Shoveler, Pintail,

Western Sandpiper

EnglishSole (juv.)

CrescentGunnel

Nemerteans

TidepoolSculpin

ShinerPerch

BrachyuranCrabs

HarpacticoidCopepods

SnakePrickleback

GastropodMolluscs

Anthozoans

BivalveMolluscs

Snow Goose, Canada Goose,

black Brant, American coot

FlabelliferanIsopods

MacrophyticAlgae

SilverspottedSculpin

Tanaids

BayPipefish

ValviferanIsopods

From Simenstad et al. 1979

Because many animals eat more than one thing, tracing energy through the estuary can get messy.

Energy Required for Life

• Metabolism – sum total of all chemical reactions occurring in living organisms.

• Anabolic pathways – synthesize compounds, generally endergonic. (requires)

• Catabolic pathways – break down compounds, usually exergonic. (produces)

There are many kinds of energy that can interconvert from one form to another.

Sunlight Source of Energy for Most 5.1.9

• Most ecosystems are based on producers using sunlight – photosynthesis

• Energy captured during photosynthesis isstored in the chemical bonds of themolecules synthesized during the process

• Some use chemical compounds – chemiosynthesis

Incoming Energy

• Many factors can affect amount of sun’s energy reaching the Earth’s surface

• Absorbed or Reflected• Reflectivity of surface = albedo – can change

with angle of light

Diagram of Earth's energy budget.Credit: Image courtesy NASA's ERBE (Earth Radiation Budget Experiment) program

In Ecosystems, Energy Flows and Matter Cycles 5.1.13

• Primary energy source for almost every ecosystem is sunlight

• Autotrophs convert radiant energy into chemical energy

• Primary production is the creation of new organic material from inorganic materials

(Carbon dioxide and water yields sugar)

Energy Transfer 5.1.10

• The stored chemical energy in the producer is available to the next trophic level

• Energy is transferred from one organism to the next when the carbohydrates, lipids, or proteins are digested

• If deer eats a clump of grass the energy goes to the deer if it dies without being grazed the decomposers will use the energy

Energy Use

• Chemical energy used for cellular respiration into ATP by producers, consumers and decomposers

• Organisms use energy for growth, reproduction, synthesis of molecules, cellular transport, movement

• Assimilation = ingestion – excretion (including waste heat from cell respiration)

Not all transfers are equally efficient

Ectotherms (cold blooded organisms) have lower metabolic requirements than endotherms•80% assimilated energy used for metabolic needs •20% of assimilated energy for growth and reproduction

Herbivores assimilate less energy from food than carnivores (plants have lots of indigestible fiber material)

1st Law Thermodynamics

Energy cannot be created nor destroyed by ordinary means only converted from one form to another

2nd Law Thermodynamics 5.1.11

• Energy transformations are never 100% efficient

• Energy exchanges in a closed system the potential energy of the final state will be less than the potential energy of the initial state

• Entropy increases in a system (entropy a measure of unavailable energy)

• Disorder increases since energy is needed to maintain order to compensate for energy loss

Ecological Pyramids• The standing crop, productivity, number of organisms, etc. of an

ecosystem can be conveniently depicted using “pyramids”, where the size of each compartment represents the amount of the item in each trophic level of a food chain.

• Note that the complexities of the interactions in a food web are not shown in a pyramid; but, pyramids are often useful conceptual devices--they give one a sense of the overall form of the trophic structure of an ecosystem.

producersherbivorescarnivores

Energy Pyramid

• A pyramid of energy depicts the energy flow, or productivity, of each trophic level.

• Due to the Laws of Thermodynamics, each higher level must be smaller than lower levels, due to loss of some energy as heat (via respiration) within each level.

producersherbivorescarnivores

Energy flow units

• How much moves from level to level and how quickly it moves

• Trophic level energy units are for energy per unit area per unit time

• Kilojoules per square meter per year• kJm-2yr-1

• Energy = ability to do work so Joules is unit

Energy Losses

• Only chemical energy can be used at next trophic level

• Only 10 to 20% of energy from an energy level is used by the next level

Why only 10%

• Not all parts eaten• Not all foods swallowed are absorbed (owl

pellets) feces• Some organisms die without being eaten by

organism at next level• Heat loss from cellular respiration

Number Pyramids

• A pyramid of numbers indicates the number of individuals in each trophic level.

• Since the size of individuals may vary widely and may not indicate the productivity of that individual, pyramids of numbers say little or nothing about the amount of energy moving through the ecosystem.

# of producers# of herbivores# of carnivores

Biomass Pyramid

• A pyramid of standing crop indicates how much biomass is present in each trophic level at any one time.

• As for pyramids of numbers, a pyramid of standing crop may not well reflect the flow of energy through the system, due to different sizes and growth rates of organisms.

biomass of producersbiomass of herbivoresbiomass of carnivores

(at one point in time)

Inverted Pyramids• A pyramid of standing crop (or of numbers) may be inverted,

i.e., a higher trophic level may have a larger standing crop than a lower trophic level.

• This can occur if the lower trophic level has a high rate of turnover of small individuals (and high rate of productivity), such that the First and Second Laws of Thermodynamics are not violated.

biomass of producersbiomass of herbivoresbiomass of carnivores

(at one point in time)

Points to remember• Note that pyramids of energy can never be inverted, since

this would violate the laws of thermodynamics.

• Pyramids of standing crop (biomass) and numbers can be inverted, since the amount of organisms at any one time does not indicate the amount of energy flowing through the system.

• For instance think about the amount of food you eat in a year compared to the amount on hand in your pantry.