Ecological Energetics I full slide set

Ecological Energetics I full slide set - Henry John-Alder...

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Unformatted text preview: Henry John-Alder Henry Department of Ecology, Evolution, and Natural Resources 14 College Farm Road, Room 152 [email protected] Phone: 732-932-1064 Henry John-Alder Henry Ecological Energetics Energy Budgets Metabolic Rate Calorimetry: Measurement of Metabolic Rate Background Background Biological systems are constrained by the laws of thermodynamics. Biological systems are highly ordered, thus thermodynamically improbable. Continuous input of energy is required to maintain the structural and functional integrity of biological systems. Second Law of Thermodynamics - Increased Entropy Second The Second Law of Thermodynamics is commonly known as the Law of Increased Entropy. While quantity remains the same (First Law), the quality Usable Usable energy is inevitably used for productivity, growth and repair. In the process, usable energy is converted into unusable energy. Thus, usable energy is irretrievably lost in the form of unusable energy. of matter/energy deteriorates gradually over time. How so? "Entropy" is defined as a measure of unusable energy within a closed or isolated system (the universe for example). As usable energy decreases and unusable energy increases, "entropy" increases. unusable Entropy is also a gauge of randomness or chaos within a closed system. As usable energy is irretrievably lost, disorganization, randomness and chaos increase. Second Law of Thermodynamics Second Heat cannot be transfered from a colder to a hotter body. As a result natural processes that involve energy transfer must have one direction, and all natural processes are irreversible. This law also predicts of this fact of thermodynamics, that the entropy of an isolated system always increases with time. Entropy is the measure of the disorder or randomness of energy and matter in a system. The following five slides present The a pictoral outline of my lectures. Ice + Heat (i.e., thermal energy) = Hot Water Iceberg Geyser Body Size Energy Requirements Chevy Tahoe is about 3X heavier than Smart car. How much more energy is required to propel a Tahoe than a Smart? Allometric estimate: ~ 2.28X (2.28 = 30.75) (EPA estimates: 15/21 versus 33/41 mpg) (33 ÷ 15 = 2.2) Rate of Heat Loss This guy has higher “thermal conductance” than the guys wearing fur coats. In other words, his rate of heat loss is high compared to theirs. Energy Requirement Activity Level Couch potatoes expend energy at a lower rate than runners. Energy Requirement Rate of Energy Input What is the relationship between speed and the energy required to transport a unit mass over a unit distance? Speed of Transport Earth Radiation Balance – Global Energy Budget Earth 342 W/m2 170 W/m2 2.7 x 1024 J/y Page 34 in V. Smil, 2008. Energy in Nature and Society, MIT Press Energy 342 W/m2 170 W/m2 170 2.7 x 1024 J/y See http://eosweb.larc.nasa.gov/EDDOCS/radiation_facts.html Solar energy gives rise to Solar Atmospheric currents (see http://rst.gsfc.nasa.gov/Sect14/Sect14_1c.html) Atmospheric http://rst.gsfc.nasa.gov/Sect14/Sect14_1c.html The hydrologic cycle (http://ga.water.usgs.gov/edu/watercycle.html) Solar energy gives rise to atmospheric currents (see Solar http://rst.gsfc.nasa.gov/Sect14/Sect14_1c.html) http://rst.gsfc.nasa.gov/Sect14/Sect14_1c.html Atmospheric currents give rise to broad climatic patterns and thus are key determinants of the distribution of life on earth. It is fair to say that the distribution of life on earth is ultimately dependent on solar energy. Solar energy gives rise to the hydrologic cycle Solar (http://ga.water.usgs.gov/edu/watercycle.html) “Greenhouse effect” warms the earth’s mean surface temperature by 33 K to about 15 °C. It has allowed the evolution and diversification of life. With the exception of chemoautotrophs, which oxidize H2S, the whole pyramid of life is supported by photosynthetic conversion of solar energy into phytomass. Net photosynthetic efficiency of the whole biosphere averages <0.2%. Only 1/500th of the energy in photons that reaches ice-free surface gets converted into phytomass. Photosynthesis in plants supports all of heterotrophic life and nearly all of the energy needs of human civilization. Almost all of life on earth is fueled by energy Almost from the sun. But life forms do not capture energy for eternity. Life simply “borrows” a small fraction of solar energy on its path to be radiated back into space. Energy “flows through” biological systems, not to be recycled. Trophic relationships provide insight into the diversity of feeding mechanisms. Aquatic Habitats Carbohydrates are not locked in structural polysaccharides. Suspension feeding is common in aquatic animals. Terrestrial Habitats Lots of energy in structural carbohydrate (i.e., cellulose) is inaccessible to animals. The use of microorganisms for digestion of plants was the most important nutritional adaptation to terrestrial life. Lots of energy in structural carbohydrate (i.e., cellulose) is inaccessible to animals. Symbiotic Relationships with Microorganisms Require Fermentation Chambers: Omnivorous Dog vs. Herbivorous, Ruminant Goat A Conceptual Energy Budget Energy Budget of an Organism (Termite) Energy Page 4 in Karasov and Martínez del Rio, 2007. Page Karasov and Mart del Physiological Ecology, Princeton University Press Physiological Energy Budget of a Termite Energy A budget is a detailed accounting of input and output. Budgets allow the identification of factors that limit the flux of energy and materials through organisms. Budgets allow us to construct models that link mass and energy flow in individuals to populations, communities, ecosystems, and the entire biosphere. 4000 termites per square meter consume 77g of wood per meter per year (15% of woody litter) and produce 48 mmol of methane per meter per year. Termites may account for 15% of total worldwide methane. Idealized Idealized Energy Budget: C=P+R+U+F Production: Growth, Storage, Reproduction Consumed Food Respiration Urine Feces Assimilated Energy: Digested & Absorbed A More Explicit Idealized Energy Budget F C R U P A More Explicit Idealized Energy Budget F C R U P Specific Dynamic Action, SDA A Conceptual Energy Budget Toward a Metabolic Theory of Ecology Brown et al., 2004. Ecology. 85:1771-1789. Metabolism: biological processing of energy and materials C F Metabolism determines the demands that organisms place on their environment for all resources. R U Metabolic rate – the overall rate of the processes of P metabolism – sets the rate of uptake of resources. Specific Dynamic Action, SDA Thus, metabolic rate controls ecological processes at all levels of organization – from individuals to the biosphere – including population growth rate, carrying capacity, and ecosystem processes such as trophic dynamics. Metabolic Rate Defined as the rate at which an animal consumes energy. 1. MR determines food requirements 2. MR provides a quantitative measure of the total activity of all physiological processes 3. MR measures how much useful energy an animal removes from its ecosystem Metabolic Rate Basal Metabolic Rate Minimal rate of energy metabolism of an endotherm Fasting adult At rest Thermal neutral zone Standard Metabolic Rate Minimal rate of energy metabolism of an ectotherm at a given body temperature Metabolic Rate Basal Metabolic Rate Minimal rate of energy metabolism of an endotherm Endotherms are organisms that use internal heat produced by metabolism for temperature regulation. Standard Metabolic Rate Minimal rate of energy metabolism of an ectotherm Minimal ectotherm Ectotherms are organisms that utilize external sources of heat for temperature regulation. Measurement of Metabolic Rate Substrate + O2 ↔ CO2 + H2O + Heat For example: C6H12O6 + 6O2 ↔ 6CO2 + 6H2O + 2874 kJ mole-1 Note stoichiometric relationships between O2 consumption, CO2 production, and heat production. Measurement of the “Fire of Life” Substrate + O2 ↔ CO2 + H2O + Heat C6H12O6 + 6O2 ↔ 6CO2 + 6H2O + 2874 kJ mole-1 Note stoichiometric relationships between O2 consumption, CO2 production, and heat production. Measurement of Metabolic Rate Direct Calorimetry Substrate + O2 ↔ CO2 + H2O + Heat C6H12O6 + 6O2 ↔ 6CO2 + 6H2O + 2874 kJ mole-1 Note stoichiometric relationships between O2 consumption, CO2 production, and heat production. Indirect Calorimetry Field Metabolic Rate Isotope exchange can be used to measure metabolic rate in unrestrained, free-living animals. Recall stoichiometry: Substrate + O2 ↔ CO2 + H2O + Heat Doubly-labeled water: D218O or 3H218O is used to “label” total body water. 18O is lost as CO2 and H2O D (or 3H) is lost only as H2O The difference between the rate of loss of oxygen and the rate of loss of the hydrogen label is a measure of the rate of CO2 production, which is a measure of metabolic rate. ...
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This note was uploaded on 08/18/2011 for the course ECOLOGY 351 taught by Professor Staff during the Spring '11 term at Rutgers.

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