Ecology NOTES

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Modes of Nutritions

POPULATION AND SPECIES

Species: group of organisms with similar characteristics, which can potentially interbreed and produce fertile offspring

Population: group of organisms of the same species, who live in the same area at the same time

-member of a species may be reproductively isolated in separate isolations

-as long as they could interbreed

AUTOTROPHS AND HETEROTROPHS

2 Main Modes of Nutrition

1. Autotrophic

-make their own food

-absorb CO2, water and inorganic nutrients i.e. nitrates

-use them to synthesize all the carbon compounds

-external energy source such as light is needed

Examples:

2. Heterotrophic

-cannot make all the carbon compounds they need

-obtain energy from other organisms

-many carbon compounds including proteins and starch must be digested before they can absorb it

Examples:

MODES OF HETEROTROPHIC NUTRITIONS

-3 Main Modes of Heterotrophic Nutrition

1. Saprotrophs

obtain organic nutrients from dead organisms

external digestion of protein, cellulose and other carbon compounds

secrete digestive enzymes into materials

aka "decomposers"

most are fungi and bacteria

Examples: dead leaves, wood, dead animals and feces

2. Consumers

feed on living organisms by ingestion

take other organisms into their digestive system for digestion and absorption

organism may be swallowed whole or in parts

alive or recently killed

Examples:

3. Detritivores

obtain organic nutrients from detritus

internal digestion

Detritus: dead material from living organisms

-includes dead leaves or roots, parts of decomposing animals and feces

Example:

HETEROTROPHIC PLANTS AND ALGAE

-most plants + algae are autotrophs

-some exceptional species that no longer make food by photosynthesis

Examples:

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Communities and Ecosystems

ECOSYSTEMS

-soil, air, water that surrounds organisms

-Abiotic Environment ==> non-living surroundings of a community

-community forms an ecosystem by its interactions with abiotic environment

-many interactions

-transfers o chemical elements between populations in the community and the abiotic environment

-essential part of nutrient recycling

MESOCOSMS

-small experimental ea set up in an ecological research programme

-ecosystems have the potential to be sustainable over long periods of time

What is Required?

1. nutrients recycling

2. supply of energy ; usually in the form of light

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Energy Flow

ENERGY SOURCES

Producers

-absorb light energy

-converts into chemical energy (help of photosynthesis)

Consumers, Detritivores and Saprotrophs

-obtain energy from the food

-chemical energy in carbon compounds

-carbon compounds + chemical energy passed from one organism to the next

-passed along the food chain

-light is required as an energy source

ENERGY LOSSES

-food containing energy is passed on

-each trophic level less food and chemical energy is available

-loss of energy between stages

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Food Chains and Energy Pyramids

TROPHIC LEVELS AND FOOD CHAINS

-each species in a food chain feeds on the previous one

-linear sequence of organisms through which nutrients and energy are passed on

-each organism occupies a different trophic level

-except producer

-Producer, primary consumer, secondary consumer, tertiary consumer

-position of an organism in the food chain

-commonly contain 3 or 4 levels

ENERGY PYRAMIDS

-diagrams that show how much energy flows through each trophic level in a community

-Units : KJm-2y-1 per square metre of area occupied by the community and per year

-always pyramid shape

-each level is smaller than the one below (big to small)

-energy is lost at each trophic level ; less remains for the next level

-biomass lost as well ==> energy content per gram of the tissues is not lower

-biomass lost when carbon compounds are broken down by cellular respiration and CO2 produced is excreted

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Nutrient Cycles

NUTRIENT RECYCLING IN ECOSYSTEMS

CARBON SOURCES IN AIR AND WATER

DRAWING THE CARBON CYCLE

METHANE IN THE CARBON CYCLE

COMBUSTION IN THE CARBON CYCLE

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Carbon Cycle

ATMOSPHERIC MONITORING

-air monitoring stations

-measure concentrations of carbon dioxide, methane, other gases

-measurements are as accurate as possible

-reliable data is available to scientists

-CO2 concentrations show annual fluctuation

-drop from May to October

-rise through to the next May

-drop occurs cause of excess photosynthesis over cell respiration globally and vice versa for the rise

-changes follow northern hemisphere seasons

-area of land is greater and CO2 concentrations are greater on land than on sea

-rising trend in atmospheric CO2 concentrations due to human activities

CARBON FLUXES IN THE CARBON CYCLE

-NOT possible to measure global carbon fluxes preceisely

-scntists have produced estimates

-based on many measurements in natural ecosystems and in mesocosms

-global fluxes are very large

-estimates are in gigatonnes

-ocean uptake is CO2 from the atmosphere dissolved in sea water

-ocean loss is the opposite

Process Flux / Gigatonnes year-1

Photosynthesis -120

Cell Respiration +119.6

Ocean Uptake -92.2

Ocean Loss +90.6

Deforestation + Land Use Changes +1.6

Combustion of Fossil Fuels +6.4

THE BIOGEOCHEMICAL CARBON CYCLE

LIMESTONE IN THE CARBON CYCLE

-a rock that consists mainly of calcium carbonate (CaCO3)

-often contains many fossils i.e. mollusc shells, skeletons of hard corals

-absorb calcium and carbonate ions

-secrete them as calcium carbonate

FORMATION OF FOSSIL FUELS

1. Peat and Coal

Peat: brown material consisting of partly decomposed plant matter found in bogs and swamps

-Coal: a combustible black or dark brown rock consisting chiefly of carbonized plant matter, found mainly in underground seams and used as fuel

-past geological eras peat was crushed and converted into coal

2. Oil and Gas

-silt deposited on the bed of some shallow seas

-remains of dead marine organisms

-organic matter is only partially decomposed ==> anaerobic conditions

-process occured in past geological areas

-silt on the sea bed converted to shale with compounds from organic matter

-produces oil or gas trapped in pores in the rock

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Global Warming and the Greenhouse Effect

THE GREENHOUSE EFFECT

GREENHOUSE GASES

GLOBAL WARMING AND CLIMATE CHANGE

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Rising Carbon Dioxide Concentrations

GLOBAL TEMPERATURES AND CARBON DIOXIDE CONCENTRATIONS

CARBON EMISSIONS AND GLOBAL WARMING

CORAL REEFS AND CARBON DIOXIDE