BIO 373 1st Edition Lecture 24 Outline of Last Lecture I. Energy in Ecosystemsa. Primary productioni. Gross primary productionii. Net primary production1. Variations in NPPb. Secondary productionc. Energy flowi. Trophic levels1. detritusOutline of Current LectureI. Energy in Ecosystems contda. Efficiencyi. Trophic efficiencyii. Assimilation eggiciencyiii. Production efficiencyiv. Energy efficiencyv. Consumption efficienciesb. Trophic cascadesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c. Biogeochemistryi. Nutrients1. Lithosphere2. Atmosphere3. Biosphereii. Nutrient storageCurrent LectureEnergy in Ecosystems- Efficiencyo Trophic efficiency Proportion of available biomass that is consumeso Assimilation efficiency Proportion of ingested biomass that consumer can assimilate with digestion- What can the consumer use and what can’t it use- What can be assimilated goes towards production efficiencyo Production efficiency Proportion of assimilated biomass used to produce new consumer biomass/maintain tissueso NPP—energy can be consumed and not consumed Not consumed becomes detritus Consumed energy can be assimilated or not assimilated- Not assimilated becomes feces which becomes detritus- Assimilated energy can go towards biomass or noto Energy not going towards biomass is used for respirationo Energy towards biomass goes to the growth (biomass) and maintenance of secondary producerso Energy efficiency The percentage of energy transferred from one trophic level to the next- 10%- energy to next trophic level- 50%- metabolism- 40%- detrituso Consumption efficiencies Tend to be higher for carnivores than herbivores- Consumption efficiency is higher in aquatic ecosystems than terrestrialo Production efficiency is strongly related to thermal physiology and size of consumer Size affects energy usage- Smaller organisms have greater surface area to volume ration so they lose a lot of energy to the envornment Top-down—like trophic cascades- Rates of consumption at high trophic levels determines species competition Bottom-up—high availability of NPP- Greater availability of limiting resources increases NPPo Trophic cascades Series of trophic interactions that result in changes in biomass and species competition at lower trophic levels Cascades can change- Ex: escessive fishing decreased food for sea lions decrease in sea lions decrease in food for whales whales begin to eat sea otterso – a top-down energy transfer (higher trophic levels determine competition)- Biogeochemistryo Physical, chemical, and biological factors that influence movement and transformation of elements How nutrients are moving across atmosphere, lithosphere, and biosphereo Nutrients= required for metabolism (maintenance) and growth Different organisms use different amounts of different inorganic and organic compounds depending on evolutionary history and cellular/metabolic needs Lithosphere- Rock sedimentation is the common way for organisms to obtain nutrients because rocks contain lots of mineralso They can sediment by icing over, land slides, physical fragmentation of any sorto Can also sediment by chemical weathering via rain watero Need to fragment so minerals have greater surface areao Important to soil formation Soil texture affects water availability for plants- Smallest particles (clay) capture more water but don’t release much to the plant and very good for holding nutrients- Large particles (sand) can’t hold much but releases a lot of what it does have to the plant- Need intermediate mix of sand and clay particles for best water and nutrient captureand release Atmosphere- Carbon in atmosphere from CO2 (cellular respiration)- Nitrogen as N2 (strong, high energy bond N=N)o Symbiotic relationship: microbes fix nitrogen to make a form that can be uptaken by plants and the energy neededfor microbes to fix nitrogen comes from plants- Delivers and transports nutrients with winds Biosphere- Decomposition= makes nutrients in detritus available and provides energy to decomposerso Breakdown into simpler molecules, now more soluble in water in soil, now available for plants Done by decomposers (fungi, microbes)o Soil stores nutrients and is site of transformationo Climate controls activity of decomposers Low soil moisture limits decomposer activity via desiccation (they need water) Decomposition is most rapid at warm temperatures High moisture results in decreased oxygen concentration, lowering the activity of decomposers (need oxygen)o Lignin Decreased rate of decomposition- Low lignin to nitrogen ratio leads to increased decomposition rate Decomposition rates are higher in warmer soil if lignin to nitrogen ratio is similar Increased secondary compounds lead to decreased decomposition rateso Some nutrients released are used by the decomposers themselves High carbon to nitrogen ration will have low net release of nutrients because are limited by nitrogenavailability Nutrient storage- Plants uptake and store inorganic (most) or soluble organic forms of nitrogen as nutrients- Plants recycle nutrients within their