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Thermodynamic laws Law of conservation of mass ○ Mass can’t be created or destroyed(but can be rearranged) 1st law of thermodynamics ○ Energy can’t be created or destroyed(but can change forms yet again) 2nd law of thermodynam...

Thermodynamic laws Law of conservation of mass ○ Mass can’t be created or destroyed(but can be rearranged) 1st law of thermodynamics ○ Energy can’t be created or destroyed(but can change forms yet again) 2nd law of thermodynamics ○ Entropy increases over time (systems will reach thermodynamic equilibrium) How does each law apply to ecosystems? Trophic levels are the “steps” in a food web Autotroph, aka primary producers Heterotrophs: organisms that can’t make their own energy and consume others ○ Primary consumers: eat primary producers ○ Secondary consumers: eat primary consumers ○ Tertiary consumers: eat secondary consumers Who might we forget from our food webs? Other heterotrophs Omnivores: eat across multiple trophic levels Detritivores: consume dead organisms or tissues Energy flows one way through ecosystems Energy is first captured by primary producers Gross primary productivity.8% of the sun’s energy is captured by photosynthesis Why is photosynthesis important? What does it require? 45% of absorbed energy supports growth 55% lost due to cellular respiration 34% goes to decomposers Global patterns in Net Primary Productivity (gross primary productivity) - (cellular respiration) Not as much in deserts NPP is linked to an area’s climate About 25% of NPP is captured by herbivores. Herbivore net loss: 80.7% to cellular respiration, 1.6% used for growth and reproduction, 17.7% to decomposers Energy loss from each individual in a community limits the number of trophic levels. Trophic pyramids depict the change in energy (or mass) in an ecosystem Macronutrients: compose the vast majority of the organism Essential minerals: support biochemical processes and cell structure and function Phosphorus, Ca, K, S, etc. Trace minerals: enzyme cofactors in biochemical reactions 1. Primary producers: absorb nutrients from the environment 2. Consumers: move nutrients from one organism to the next 3. Decomposers: break down nutrients from waste and dead organisms and return it to the abiotic environment 9/26 Key nutrients in the ecosystem, Losing and adding nutrients, in aquatic ecosystems Why is carbon necessary for organisms? In all living things Reservoir: where a nutrient can be primarily be found Atmospheric CO2 levels regularly vary in a seasonal pattern known as the Keeling Curve Nitrogen: Why is it important for organisms? It is in lipids, proteins, and DNA Rubisco: carries out the 1st step of photosynthesis ○ 20-30% of plants nitrogen is in Rubisco Most common enzyme on the planet The nitrogen cycle: 74% of the atmosphere is N2 N2 is very stable (triple bond) Animals, plants, and fungi can’t obtain N from n2 Nitrogen-fixing bacteria convert N2 into ammonia and then into organic forms with oxygen ○ Bacteria turns it into nitrates and nitrites Crucial nitrogen reactions ○ 1. Fixation: atmospheric nitrogen>ammonium(NH4+) Carried out by lightning and some bacteria ○ 2. Nitrification: ammonium>organic nitrogen Organic forms: nitrite and nitrate, only done by bacteria and cyanobacteria Fungi and plants can use nitrate ○ Ammonification: organic nitrogen>ammonium (NH4+) Carried out by some bacteria and fungus ○ Denitrification: Nitrate>N2  Carried out by anaerobic bacteria Where is organic nitrogen found in terrestrial ecosystems? 1. In the tundra: Mass of nitrogen found in soil, and then roots, and then above ground 2. In the taiga: Evenly split between soil and the rest (more above ground plant) 3. In the grassland: Most of it in soil and above ground, less in soil 4. Deciduous forest: Similar to grassland 5. Savannah: Lots of nitrogen in above ground plant, some in roots, and very little in soil 6. Rainforest: Similar to savannah, even less nitrogen in the soil AKA: more nitrogen in living part of plant as weather is “better” for the plants Why is phosphorus important? Essential for making: ○ ATP ○ DNA ○ Phospholipids Relatively rare Weathering: release of phosphate from rock and sediments Plants can absorb inorganic phosphate and convert to an organic form Leaching: loss of phosphorous from an ecosystem via water (it can dissolve in water) How does eutrophication affect aquatic ecosystems? (adding extra nutrients) 1. Nitrogen and phosphorus leach 2. Algae growth quickly increases 3. Detritivores use lots of oxygen to consume the dead algae 4. Hypoxic areas (low oxygen ‘dead zones’) Wetland ecosystem absorb excess nutrients before they reach other aquatic ecosystems What happens to nutrients when an area is heavily disturbed? Nutrient loss increased 10 times SO, Plant roots decrease nutrient loss from erosion and leaching Nutrient availability changes during ecological succession: nitrogen raises in forest floor as trees get older Newer soils: nitrogen usually limiting Older soils: phosphorus usually limiting 10/1 Nutrients, biomes, and biodiversity Nutrients on islands: Foxes were introduced in the late 1700s for the fur trade to these islands ○ Introducing a new predator affected nutrient concentrations in the ecosystem ○ Foxes thus caused a decrease in biomass and richness of plants by predation of birds(less guano) Aquatic ecosystems: 1. Nutrient run-off (and erosion) from terrestrial ecosystems a. Dams impede the movement of nutrients through aquatic ecosystems i. Upstream: decreases water flow, sediments accumulate, pollutants accumulate, evaporation increases, light levels change, algae blooms ii. Downstream: less water volume, decreased nutrients, flow rate change, temperatures increase, riverbed physically degrades 2. Marine (saltwater) ecosystems also depends on upwellings to access nutrients a. Winds blow across coast b. Warmer surface water are blown away from shore c. Deep, cold, nutrient-rich water rises to replace the surface water that was pushed away i. Ocean zones are based on the amount of light and proximity to the continental shelf. 3. Lakes rely on turnover to move nutrients from the bottom of the lake to its surface a. Occurs twice per year (seasonal) i. Winter (stratified), autumn turnover, summer (stratified), Spring turnover What most affects terrestrial net primary productivity? Certain times of the year where the sun shines Bottom-up effects> Primary producers affect consumers in upper trophic levels (amphibian, avian, and mammalian species richness) Endemic species: species that are unique to a single, small geographic area Top-down effects: the effects of higher trophic levels on lower levels 10/3 hi cartee b hi pinkdoggie hi wackadoodle Islands often have high biodiversity Endemic species and relatively fast speciation (formation of new species) The theory of island biogeography: New species arriving on the island will have less competition and more resources Closer island has higher chance of introducing species Release from predators can result in gigantism &/or flightlessness (often on islands) Limited resources and increased competition on islands can result in dwarfism of species Isolation and newly available niches leads to faster rates of speciation on islands Patterns of increasing biodiversity: Greater NPP (bottom-up effects) Greater diversity of predators (top-down effects) Greater diversity of competitors, AKA resource partitioning Larger habitat area (patch size) Closer to source populations (recovery of sink populations) Regular and predictable disturbance regime (if applicable) Greater spatial diversity (heterogeneity) More stable environment (over evolutionary time) More evolutionary time for speciation Biodiversity increases ecosystem productivity and stability After a disturbance, a more biodiverse ecosystem has:  a. Greater resistance (lesser overall impact to the ecosystem’s NPP) b. Greater resilience (NPP rebounds more quickly) Humans often focus on the free services provided by biodiversity 1. Food 2. Raw materials 3. Nutrient cycling 4. Dispersal and breakdown of waste and dead organic material 5. Soil formation and maintenance 6. Pollination of crops 7. Control of crop pests and diseases 8. Genetic resources Biodiversity also has economic value Food New genes for domesticated species and agricultural crops Biological controls for “pest” species Natural products ○ Raw materials ○ Medicine ○ Natural pesticides Ecotourism Some value the aesthetics of biodiversity Preserving biodiversity may be considered an ethical and or spiritual responsibility The recent and rapid loss of species across the world is primarily due to: Habitat loss and degradation Climate Change Invasive species Pollution Overexploitation Diseases/pathogens Climate is not the same as weather Weather: atmospheric conditions at a particular place and time Climate: the average weather occurring across a region over an extended period Anthropogenic climate change: an additional change in climate caused by humans Many independent, credible sources confirm a significant rise in global temperatures How do we know global temperatures before thermometers? And before humans? Digging into ice, coral reefs, sediments, you can find atmosphere bits 10/8 Recap, how we know global temps before thermometers Concentrations of different atmospheric gasses Isotopes concentrations; C-13, C-14, H-2 (deuterium) Precipitation (snowfall) Volcanic eruptions Ocean volume Marine productivity Global ice and desert cover Temperatures correlate with deuterium and atmospheric co2 connection a. Deuterium (heavy hydrogen)>Proxy for temperature in that region b. Same air bubbles in the ice (same time)> atmospheric CO2 concentration What natural factors influence climate? Photosynthesis Cellular respiration and fermentation Volcanic activity Solar activity Milankovitch cycles (changes in earth's orbit and orientation) Global temps increasing exponentially Natural factors alone CAN’T account for recent temp changes Effects of greenhouse gasses are good but only in moderation, too much means the earth becomes too hot C-12 is the common variation of carbon, stable, never changes C-13 is rarer, but is also stable Relative C-13 comparison is lower, it means the CO2 we’re producing is C-12 CO2 can be “made” from Volcanic eruptions Gas-release from oceans These releases C-13 + C-12 so it can’t be these causing C-12 increase Plants DON’T use C-13 Atmospheric C-14 is NOT stable, it decays. Decays into N-14 Fossil fuels are result of atmospheric carbon because there is little C-14 in atmosphere, means that our atmospheric carbon source must be VERY OLD Another greenhouse gas: METHANE CH4 Last greenhouse gas: N2O Sources: 1. Carbon dioxide: 64%, fossil fuels and industry, highest in 3 mil years, breakdown: 100s-1000s yrs 2. Also CO2: 11%, land use and forestry 3. Methane: 18%, livestock, rice, fossil fuels, and burning biomass. Absorbs 20x more energy than CO2, 12 yr breakdown 4. Nitrous oxide: 4%, fertilizer and combustion, breakdown 115 to 120 yrs 5. F-gasses: 2%, replaced CFCs as a manufactured refrigerant, breakdown 1-1000yrs Climate Change An effect of climate change is: Warmer in summer, which when using AC Burning more fossil fuels means More greenhouse gasses which means Causes more climate change Positive feedback loop^. Effects of climate change that worsen the effects of climate change Negative feedback: effects of climate change that lessen the effects of climate change Examples of positive feedback: less ice (>less sunlight reflected;reduced albedo) Increased desertification Greater bacteria productivity (more methane produced0 More cell respiration More fires in the forests and tundras More evaporation (more GFG as atmospheric water vapor, but clouds may also increase reflection of sunlight) Warmer oceans More photosynthesis Negative feedback More clouds Forests replacing tundra More photosynthesis 10/10 Marine PP are decreasing Why aren’t marine PP doing better in warmer water? Upper surface is warmer than it usually is, which lessens the chance of upwelling. This causes increased stratification and less nutrients for PP Climate change has caused niches, ranges, and distributions to change. This is not beneficial for the species or the ecosystem typically, overshooting new habitat, pathogens, or wrong resources Phenology: the timing of the breeding seasons and other major life events Caterpillars are now growing and changing form a little quicker due to climates affecting their phenology NOT ALL SPECIES CAN CHANGE THEIR PHENOLOGY Increasing coral bleaching and mortality: Once coral starts dying and is bleached, it is going to die, no return. What causes bleaching: Increased temp of water, increased acidification, agricultural run-off and pollution, most sunscreens, pathogen infections, overexposure to sunlight, extremely low tides Higher atmospheric CO2 concentrations means higher CO2 concentrations in water When entering water, CO2 turns into carbonic acid, then it “steals” (reacts with) carbonate This takes carbonate away from calcium-carbonate using organisms (clams, mussels, corals, snails, urchins) Warmer & drier weather leads to more fires Fires can cause more greenhouse gasses Ecosystem interactions are being disrupted Fast-growing plants High nutrient availability leads to high-quality leaf litter, which leads to faster bacteria decomp Slow-growing plants Low nutrient availability, then low-quality leaf litter, which means slower bacteria decomp Predicted temperatures in 2060-2069: Obviously temperatures are higher, data based on current emission rates being projected through future Ocean levels will continue to rise from melting polar and glacial ice The influx of cold, freshwater from melting ice is also changing ocean current patterns + salinity Logging is a frequent cause of deforestation In 2022, we lost 10,100,000 acres of tropical forest in 2022 Loss and degradation of tropical forest effects ⅔ of the world’s species Common agriculture practices decrease soil quality and then thee area is used for livestock Wetlands are replaced with tree farms, aquaculture, and development 10/15: Fragmentation: Further degrades habitats Fragmentation increases edge effects (the degradation of habitat along the perimeter of a habitat patch Biomagnification is the accumulation of insoluble toxins in higher trophic levels DDT, small amount in water, greater amount in fish, greatest amount in birds Fishing practices that damage marine ecosystems Invasive species have been introduced by humans and detrimentally change the ecosystem: Fast reproduction Few predators or parasites Longevity Good at dispersing Generalists Pioneer species Many critically endangered species are negatively impacted by invasive species Conservation is an interdisciplinary field that focuses on biodiversity, threats, and how to best protect species and ecosystems. Priorities: Who? Where? What? How? 1. Who (species/ecosystems) should we focus on? a. Emphasis on rare, rapidly decreasing, and/or valuable b. What direct and indirect interactions are critical for ecosystem stability c. Might have to prioritize some over others 2. Where should we focus? a. What regions are most in need of conservation? b. Will this be a local, national, or international effort? 3. What threats, if mitigated, will result in the greatest benefit? 4. How should we help? a. What conservation measures should we apply? b. How will they be quantified and evaluated?  c. How do we determine the value of a species? How do we determine the value of a species? Role in the ecosystem? Economic? Unique qualities? Irreplaceable? Attract attention?