Energy Flow
Food web Diagram that shows how food chains are linked together in a complex feeding relationship The food web has a number of advantages over a food chains including: More than one producer supporting a community A single producer being a food source for a number of primary consumers A consumer may have a number of different food sources on the same or different trophic levels A consumer can be an omnivore, feeding as a primary consumer and as a consumer at higher trophic levels
Matter is recycled Decomposition: process by which organic matter is broken down into simpler forms. Allows for the formation of soil, the recycling of nutrients stored in the organic materials Saprotrophs: secrete digestive enzymes into dead organism, which hydrolyze biological molecules of which the dead organism is composed Saprotrophs are essential in the flow of nutrients through ecosystem, which would otherwise accumulate in debris
Energy transformations Aquatic and terrestrial communities rely on sunlight as source of energy Light energy is converted to chemical energy in carbon compounds by photosynthesis Chemical energy in carbon compounds flow through food chains by feeding. The transfer of energy from one trophic level to the next is inefficient Producers convert only about 1% of solar energy available to them to organic matter 10-20 % of the energy on one trophic level will be assimilated at the next higher trophic level Energy is used to run cell activities (to make ATP via cellular respiration) Energy mostly lost via heat
Energy flow in a food chain Energy is also lost: Not consumed Not absorbed/assimilated I=input, A=assimilation, R=respiration, NU=not utilized, P=production, B=biomass
Pyramids of energy Units = energy/ area/unit time e.g. kj m -2 yr -1 Pyramid should be stepped, not triangular Labels: producer, first consumer, second consumer, etc.
Construct a pyramid of energy, given appropriate information Trophic level and energy flow e.g. freshwater spring in Florida, USA. Each trophic level is plotted with equal thickness on the vertical scale, but horizontal scale indicates the size of each bar. Original data are halved for the purposes of plotting
Construct a pyramid of energy, given appropriate information flipped and the two sides stuck together as follows
Today Data base question: A simple food web (p. 219 of Ecology notes) Finish bottle biology
Energy Flow
Gross production vs. Net production Energy is not entirely lost; organisms do trap some of the energy in the form of biomass Gross production (GP) = total amount of energy trapped in organic matter produced by plants in an ecosystem Net production (NP) = GP energy lost through respiration Amount of biomass that is available to the next trophic level
Biomass Biomass = total dry mass of organic matter in organisms of ecosystems Organic matter = carbon compounds such as carbohydrates, lipids and proteins Most matter usually includes water (not organic) so the matter has to be dried Units = energy/area/unit time e.g. g m -2 yr -1
Feed conversion ratio (FCR) Measure of the efficiency of an animal s ability to convert feed mass into increased body mass Mass of food eaten / body of mass gain 8 kg of food / 1 kg of weight gain = 8 Low FCR efficient use of food High FCR inefficient use of food
Pyramids of Energy from different ecosystems
Gersmehl nutrient cycle diagrams Model of nutrient storage and flow for terrestrial ecosystems Three storage compartments: biomass, litter, soil Arrows represent nutrient flows Thickness of arrow represent rates of nutrient flow Input: nitrogen, carbon, and minerals from weathered rock Output: leaching and runoff Flows: leaf and needle fall from biomass to litter, and uptake of nutrients from soil by plants
Example 1: Tropical rainforest Biomass is the main store of nutrients and has tall, dense vegetation with many layers Precipitation: high rainfall Litter: very small store because of high rate of decomposition Soil: very small store because of leaching and low soil fertility Weathering is rapid because of high heat and humidity Leaching is high because of high rainfall Runoff is high because of large amount of rain
Litter is the largest store of nutrients because of low rate of decomposition Run off is high. Ground is frozen when snow is melting Biomass is low. Transfer from biomass to litter is high because of constant supply of needles from coniferous trees Soil stores are small. Low soil fertility Weathering of rocks is slow because of cold. Example 2: Taiga
Biomagnification
Biomagnification Process in which chemical substances become more concentrated at each trophic level As each individual eats contaminated food, it builds up these chemical substances When large number of contaminated individuals are eaten, they pass on a high concentration of chemicals to the predator
Minamata Disease (1956) Methylmercury in industrial wastewater from Chisso Corporation s chemical factory (nitrogenous fertilizer) Bioaccumulation in fish and shellfish in Minamata Bay Neurological disorder: general weakness of muscles, coordination disturbance, narrow visual field, insanity, coma death Mercury Poisoning
DDT Poisoning DDT is an insecticide used in 20 th century DDT cause thin shelled eggs of birds and unable to reproduce successfully Human effects: reduced fertility, genital birth defect, cancer World Health Organization endorses use of DDT because it helps to protect people from malaria
Oil refining: purify crude oil into petroleum products (diesel, gasoline) Curacao: Oil refining Up to 100 pollutants emitted from the stacks Land is polluted by the large amount of harmful waste from refineries which needs to be dumped Water is polluted by the fallout from air pollution and by refineries discharging chemical pollutants into waterways
Series of changes to an ecosystem Succession Caused by complex interactions between the community of living organisms and the abiotic environment Primary: Colonization of region where there is no pre-existing community Secondary: Occurs where an existing community has been cleared by a disturbance that does not involve complete soil loss Begins with no life No soil New area e.g. volcanic island Lichen and mosses are first plants Follows a disturbance of the primary succession Soil is present Old area e.g. following a forest fire Seeds and roots already present
Primary succession
Secondary succession
Change in species diversity and production Few species many species Pioneer species species that compete with others for nutrients Little diversity high diversity Simple relationships complex relationships of mutualism, competition, predation More and more biomass (dry mass of organic matter) at each stage of succession
Interactions with organism and the environment Soils become deeper as a result of decay of plants Allows well-draining soil Organic matter (humus) in soil increases as a result of decay of plants Organic matter quickly absorbs and releases water so is a good medium for plant growth Mineral recycling increases bacteria and fungi become more active in soils that have high organic matter Soil erosion reduces plant roots that stabilize the sand Minerals added Alder plants fix atmospheric nitrogen which leads to increase of nitrogen in the soil
Greenhouses How warming affects Soil nutrient availability, microbial biomass, Plant community structure, time of flowering Fertilized plots Caribou exclosures Tara s research: caribou-plant-soil interactions in the context of climate change
Seed quality of small plants and large plants in a population
Separating seeds from plants Seeds in coin envelopes
G1.10 Measurement of different biomass of trophic levels in an ecosystem E.g. An ecologist wants to compare the amount of organisms in each trophic level of an ecosystem Method: 1. Representative samples of organisms collected, such as random quadrats 2. Organisms sorted into trophic levels 3. Organisms dried in oven at (60 80 degree C) 4. Mass organism of each trophic level is measured using electronic balance
TODAY 1. Try energy pyramid modeling! http://glencoe.mcgrawhill.com/sites/dl/free/0078757134/383926/bl_02. html 2. Energy flow worksheet 3. Continue to update your LL 4. Next class: Quiz on niches, matter/energy flow