ECOSYSTEMS

Ecosystem - all the organisms in a given area as well as the abiotic (= physical) factors with which they interact

Ecosystems Seen as systems which transform energy and process organic matter Detritivores Secondary consumers Primary consumers Detritus Primary producers

Ecosystems all photosynthetic organisms Who are each of the levels in these systems 1. Primary producers all photosynthetic organisms these are photoautrophs that fix carbon and allow it to be used at other levels Plants Algae Phytoplankton

Ecosystems all plant-eating organisms (= herbivores) Who are each of the levels in these systems 2. Primary consumers all plant-eating organisms (= herbivores)

Ecosystems all heterotrophic organisms predators Who are each of the levels in these systems 3. Secondary consumers all heterotrophic organisms predators

Ecosystems Who are each of the levels in these systems 4. Detritus - dead organic matter

Ecosystems Who are each of the levels in these systems 5. Detritivores/Decomposers -organisms that eat dead organic material

Ecosystems Seen as systems which transform energy and process organic matter = pathway for material (or carbon) Secondary consumers Detritivores Detritus Primary consumers Primary producers

Ecosystems Seen as systems which transform energy and process organic matter = pathway for energy = pathway for material (or carbon) Heat Heat Secondary consumers Detritivores Heat Heat Heat Detritus Primary consumers Heat Heat Heat Primary producers

From last lecture Heat Heat Heat Heat Heat Heat Heat = pathway for energy = pathway for material (or carbon) Heat Secondary consumers Detritivores Heat Heat Heat Detritus Primary consumers Heat Heat Heat Primary producers

Ecosystems We are looking at oversimplification The reality?? The Scotian Shelf Ecosystem

Production in Ecosystems - Starts with photosynthesis - fixes carbon Glucose Sunlight + O2 + Water + + H20 CO2 6 CO2 + 12H20 + light  C6H12O6 + 6H20 + 6O2

Production in Ecosystems The sum total of all carbon fixed by plants in any ecosystem is the GROSS PRIMARY PRODUCTION (GPP) But plants must use some of this fixed energy for in their own cellular respiration

Production in Ecosystems What is available to the next trophic (feeding) level is NET PRIMARY PRODUCTION (NPP) Gross primary Production (GPP) Energy used in respiration Net primary Production (NPP) - = Available to next level

FOOD CHAINS TRACE THE FATE OF NPP AT EACH LEVEL NET PRIMARY PRODUCTION Secondary consumers Detritivores FOOD CHAINS TRACE THE FATE OF NPP AT EACH LEVEL Detritus Primary consumers Primary producers

Production in Ecosystems Amount of NPP varies between ecosystems

Production in Ecosystems HOW EFFICIENT IS ALL THIS? Some available to detritivore level Unavailable Available to predators

Production in Ecosystems HOW EFFICIENT IS ALL THIS? It varies between ecosystems but 33 = 16.5% 200 This value is high generally assume 10% (varies from 5 to 20%)

Efficiencies in Ecosystems Prey production Exploitation efficiency Detritus Ingested energy Egestion Ecological (food chain) efficiency Assimilation efficiency Gross production efficiency Assimilated energy Respiration Excretion Net production efficiency Consumer production

Efficiencies in Ecosystems Ingestion of food Exploitation efficiency = Production of ‘prey’ Assimilation Assimilation efficiency = Ingestion Production (growth and reproduction) Net production efficiency = Assimilation Net production efficiency Production Gross Production efficiency = Assimilation efficiency X = Ingestion Net production efficiency Consumer production Ecological (food chain) efficiency Exploitation efficiency Assimilation efficiency = = X X Prey production

Production in Ecosystems What’s the result of this loss of material? At each trophic level - lose 90% energy taken in -not available to next level Production (or Trophic) (or Food) Pyramid

Production in Ecosystems - Standing Crop Standing Crop - total dry weight of all organisms at a trophic level in any ecosystem at a point in time Loss to next level Loss to respiration Total energy (=carbon) fixed Standing Crop

Production in Ecosystems - Standing Crop Generate Standing Crop or Biomass pyramids Secondary Consumer Primary Consumer Primary Producer Forest Ecosystem

Production in Ecosystems - Standing Crop Generate Standing Crop or Biomass pyramids Secondary Consumer Primary Consumer Primary Producer Coral Reef Forest Ecosystem Why the difference?

Production in Ecosystems - Standing Crop Turnover time = Standing crop biomass (mg/m2) Production (mg/m2/day) Translation: If standing crop is low and production is high, the turnover time is short

Production in Ecosystems - Standing Crop Why the difference? Primary production is very high Primary production is consumed very quickly Therefore, standing crop is low Coral Reef

Production in Ecosystems Also explains different numbers at each level A Numbers Pyramid

Food Webs – A Better Picture? Quaternary producers Tertiary producers Secondary producers Primary producers Detritivores

Fill in your answers here Last name first!!!! J o n e s J o e Fill in your answers here

NEXT WEEK’S LAB GET DRAWING PAPER AND PENCILS FROM THE BOOKSTORE LAB COATS ARE MANDATORY!!!!! IF YOU DON’T HAVE A LAB COAT …..

Food Webs – A Better Picture?

Cycling of Nutrients All the major nutrients cycle through the environment Often linked to the hydrological (or water) cycle

Cycling of Nutrients All the major nutrients cycle through the environment e.g. Carbon

Cycling of Nutrients All the major nutrients cycle through the environment e.g. Phosphorus

Cycling of Nutrients - 4 separate reservoirs of material Nutrient (chemical) cycles include more than just the biological world - 4 separate reservoirs of material Organic material available as nutrients Organic material unavailable as nutrients Living organisms, detritus Coal, oil, peat Inorganic material available as nutrients Inorganic material unavailable as nutrients Atmosphere, soil, water Minerals in rocks

Cycling of Nutrients Nutrient (chemical) cycles include more than just the biological world Organic material available as nutrients Living organisms, detritus

Cycling of Nutrients Nutrient (chemical) cycles include more than just the biological world Organic material available as nutrients Organic material unavailable as nutrients Fossilization Living organisms, detritus Coal, oil, peat

Cycling of Nutrients Nutrient (chemical) cycles include more than just the biological world Organic material available as nutrients Organic material unavailable as nutrients Fossilization Living organisms, detritus Coal, oil, peat Assimilation, Photosynthesis Respiration, Decomposition. Excretion Burning fossil fuels Inorganic material available as nutrients Atmosphere, soil, water

Cycling of Nutrients Nutrient (chemical) cycles include more than just the biological world Organic material available as nutrients Organic material unavailable as nutrients Fossilization Living organisms, detritus Coal, oil, peat Assimilation, Photosynthesis Respiration, Decomposition. Excretion Burning fossil fuels Weathering, erosion Inorganic material availiable as nutrients Inorganic material unavailable as nutrients Atmosphore, soil, water Minerals in rocks Formation of sedimentary rock