Chapter 1 Energy Transfer in the Biosphere

ENERGY AND THE BIOSPHERE Energy enters the biosphere by photosynthesis. For some organisms, energy enters their part of the biosphere through the process of chemosynthesis.

CELLULAR RESPIRATION AND PHOTOSYNTHESIS Cellular respiration and photosynthesis (and chemosynthesis) are related processes. Photosynthetic producers capture the Sun’s energy and convert it to chemical energy (glucose). Chemosynthetic producers capture the chemical energy stored in chemical bonds and convert it to chemical energy (glucose).

LAWS OF THERMODYNAMICS 1st Law of Thermodynamics: Energy cannot be created or destroyed, only transformed from one form to another. 2nd Law of Thermodynamics: In any energy conversion, some energy is always lost as waste (heat). No energy transformation is completely efficient, much of it is lost as heat.

FOOD CHAIN A food chain shows the linear pathway through which food is transferred from producers to primary consumers and to progressively higher feeding levels.

FOOD WEB A food web shows energy transfer among several food chains.

TROPHIC LEVELS PRODUCERS – Organisms that can photosynthesize (convert light energy into sugars) or chemosynthesize (convert inorganic chemicals into sugars) Photosynthesis CO2 + H2O -> C6H12O6 + O2 Chemosynthesis NH3 + CO2 -> C6H12O6 + NO3 CO2 + H2O + O2 + H2S -> > C6H12O6 + H2SO4

TROPHIC LEVELS

Deep sea vent ecosystems https://www.youtube.com/watch?v=D69hGvCsWgA Check it out!

CONSUMERS PRIMARY CONSUMERS – are herbivores (eat only plants)

CONSUMERS SECONDARY CONSUMERS – eat primary consumers (herbivores) and producers (plants)

CONSUMERS TERIARY CONSUMERS – eat secondary consumers, primary consumers and producers

DECOMPOSERS Decomposers obtain energy by eating dead organisms or waste matter from organisms (eg feces) Examples of decomposers: earthworms, fungi, bacteria, beetles, centipedes, other insects.

AQUATIC FOOD WEBS (Marine)

Food Webs http://www.youtube.com/watch?v=3Bn7wdCP2v4 (grasslands/savannah food web) http://www.kevinflint.org/ppt/chap5/Animations/rainforest_anim.html (rainforest animation) http://www.youtube.com/watch?v=roRQQZlGIvM (aquatic food webs and human effects on them)

ENERGY LOST AT EACH TROPHIC LEVEL Only part of the available energy from one trophic level can be transferred to the next. Assume that 10% of the energy available at a particular trophic level is transferred to the next. 10%

ECOLOGICAL PYRAMIDS describe quantitative relationships between trophic levels. Pyramids of: • numbers • biomass • energy

ECOLOGICAL PYRAMIDS: pyramid of numbers A pyramid of numbers is based on the number of organisms in each trophic level. Numbers of organisms are counted and recorded – but size of organism isn’t dealt with

INVERTED PYRAMID OF NUMBERS sometimes occur – when a forest of a few trees supports thousands or even millions of insects

A pyramid of biomass is based on the biomass (dry weight) of organisms in each trophic level (g/m3).

Inverted Pyramid of Biomass – marine ecosystems WHY?

Inverted Pyramid of Biomass – marine ecosystems Consumer biomass (copepods, krill, shrimp, fish) is larger than producer biomass (tiny phytoplankton) because the phytoplankton grow and reproduce so rapidly, that a small mass can have a fast rate of production, supporting larger animals.

In contrast, terrestrial producers are plants which grow and reproduce slowly (ie. Herbs, shrubs, trees).

ECOLOGICAL PYRAMIDS A pyramid of energy is based on the total amount of energy in each trophic level.

HOW MUCH ENERGY (KJ) IS AVAILABLE TO THE OWL IN THIS FOOD WEB IF THE SUNFLOWER HAS 80 000 KJ OF ENERGY?

HOW MUCH ENERGY IS AVAILABLE TO THE HAWK IF THE ALGAE CONTAINS 125 000 KJ OF ENERGY?

HUMAN IMPACT ON ECOSYSTEMS MONOCULTURES – a habitat that contains primarily one species of plant (eg) – farmer’s field, lawn, apple orchard Monocultures lack biodiversity – very few species of consumers can be supported – therefore unhealthy food web

BIOMAGNIFICATION Biomagnification: toxic chemicals (eg – DDT, PCBs, lead, mercury, etc) accumulate in the soft tissues of organisms and concentrate up the food chain

BIOMAGNIFICATION Higher level consumers are the most severely affected Since humans are often higher on the food chain these toxins accumulate in us!

more concentrated further up the food chain In this food chain, DDT becomes more concentrated further up the food chain The osprey in this food chain is the most affected by the toxin in the water

Crash Course: Ecology Here is a quick review of the concepts covered in Chapters 1,2,3. https://search.yahoo.com/yhs/search?p=you+tube+crash+course+ecology&ei=UTF-8&hspart=mozilla&hsimp=yhs-001

Complexities of ecosystems – natural and human effects Thought Lab pg. 20 – How do we use energy in the ecosystem responsibly? Biomagnification pg. 28 – methylmercury – a human toxin, what is our responsibility – see question #4

Complexities of ecosystems – natural and human effects Thought Lab pg. 25 – How do we trace the complexities in an ecosystem to figure out what is happening in a changing population? You thought the ideas above are complex – try this! https://www.youtube.com/watch?v=ysa5OBhXz-Q