Ecosystems 5.1

Vocabulary 5.1.1 Ecology – the study of relationships between organisms and between organisms and their environment http://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Blue_Linckia_Starfish.JPG/220px-Blue_Linckia_Starfish.JPG

Vocabulary 5.1.1 Species: organisms that can interbreed in the wild and produce viable offspring – share a gene pool Two species can mate and not produce fertile offspring – instead called interspecies hybridization Example: female horse and male donkey produce mules

Vocabulary 5.1.1 Habitat – environment in which an organism normally lives Includes abiotic factors Must provide food, shelter, water and space to live Examples: fast moving stream, temperate forest

Vocabulary 5.1.1 Niche – the role an organism occupies in its environment What its job is in the ecosystem? Predator of mule deer etc. What tolerance limits does it have? temperature, pH, light intensity Two organisms cannot occupy the same niche at the same time – competitive exclusion principle

Vocabulary 5.1.1 Population – all members of a single species living in a given area at a given time. All the mice in Palmer High School this year.

Vocabulary 5.1.1 Community – ALL of the populations of different species living and interacting in a given area at a given time All the humans, mice, spiders, cockroaches living in Palmer High School this year. http://0.tqn.com/d/exoticpets/1/0/D/9/1/mouse2angelo.jpg

Vocabulary 5.1.1 Ecosystem – a community interacting with its abiotic environment All the humans, mice, spiders, cockroaches living in Palmer High School this year with the heat, lights, water fountains, bathrooms, cafeteria, desks and lab equipment.

Environment Everything surrounding an organism Hydrosphere Atmosphere Lithosphere Biosphere

Troph = greek for nourishment Nutrition = how an organism obtains energy and a carbon source to build the organic molecules of cells

Vocabulary 5.1.2 Autotroph – synthesizes its organic molecules from simple inorganic substances Photoautotroph – light a source of energy for synthesis in most communities Explants, protists, prokaryotes http://www.ucmp.berkeley.edu/bacteria/oscillatoria2.jpg

Chemoautotroph 5.1.2 Use inorganic molecules as source of energy usually hydrogen sulfide, amonia or iron compounds prokaryotes found at hydrothermal vents (black smokers) Nitrogen fixing soil bacteria http://www.amnh.org/nationalcenter/expeditions/blacksmokers/black_smokers.html

Heterotroph 5.1.2 Organisms that obtain organic molecules from other organisms Ingest organisms to digest, ingest organic matter to digest, or digest outside and then absorb

Consumer 5.1.3 Ingest organisms that are living or recently killed and digest them internally http://clayruth.com/larvae.html http://www.animalorphanagekenya.org/photos/lion_eating_mara.jpg

Detritivores 5.1.3 Ingests non-living organic matter Dead plant and animal material Fill the decomposer niche Earthworms, crabs http://upload.wikimedia.org/wikipedia/commons/thumb/1/1f/Staphylinus.olens.vs.lumbricus.terrestris.jpg/220px-Staphylinus.olens.vs.lumbricus.terrestris.jpg

Saprotrophs 5.1.3 Lives on or in non-living organic matter Secretes digestive enzymes into the organic matter Absorbs the products of the digestive process Prokaryotes and fungi http://vanessavobis.com/wp-content/uploads/2009/01/Maine_Mushroom_(0).jpg

Decomposers 5.1.14 Saprotrophic bacteria and fungi Get nutrition from breaking down dead material Examples include saprotrophic bacteria and fungi Recycle nutrients by returning them to the environment in form of simple compounds such as carbon dioxide and nitrates (NO3), nitrites (NO2) ammonium (NH4)

Food Chain 5.1.4 Sequence of organisms each one feeds on the previous one Arrows point in the direction of energy flow ie towards the organism that is doing the eating Base of chain must be some form of autotroph Following steps are consumers No consumers feed on the last organism in the chain Decomposers are not included

CO2 CO2

Length of food chains Generally 2 to 5 organisms long Not longer because of inefficiency of conversion of energy from one organism to another

Trophic Levels 5.1.6 Categories reflect feeding relationships in food web or chain Producer, Primary Consumer, Secondary Consumer, Tertiary Consumer, Quaternary Consumer Carnivore, herbivore, omnivore – describe diet choices not trophic level – do not use them interchangeably

Food Web 5.1.5 Complex representation of feeding relationships within ecosystem more realistic than food chain Complex because most organisms feed on more than one species and are fed on by more than one species Some organisms feed at more than one trophic level Feeding preferences may change seasonally but are not shown in a food web

Because many animals eat more than one thing, tracing Because many animals eat more than one thing, tracing energy through the estuary can get messy. Relative Importance Of Food Web Linkages Primary (75-100% of Total) Secondary (50-74% of Total) Tertiary (25-49% of Total) Incidental (0-24% of Total) Sanderlings,Long & Short-billed Dowitchers, Greater Yellowlegs Whimbrel, Mallard, Northern Shoveler, Pintail, Western Sandpiper Great Blue Heron Snow Goose, Canada Goose, black Brant, American coot Penpoint Gunnel Padded Sculpin Chum Salmon (juv.) Crescent Gunnel Bay Pipefish Pacific Staghorn Sculpin Starry Flounder (juv.) Snake Prickleback Sharpnose Sculpin Saddleback Gunnel Tidepool Sculpin Shiner Perch Gastropod Molluscs Buffalo Sculpin English Sole (juv.) Nemerteans Small Fish (inc. herring, perch) Bivalve Molluscs Cumaceans Tubenose Poacher Polychaete Annelids Gammarid Amphipods Flabelliferan Isopods Tunicates Gastropod Molluscs Silverspotted Sculpin Harpacticoid Copepods Mysids Tanaids Hippolytid, Crangonid, And Penaeid Shrimp Saltmarsh Plants & Eelgrass Brachyuran Crabs Benthic Meiofauna Valviferan Isopods Macrophytic Algae Phytoplankton Microphytic Algae Anthozoans Detritus From Simenstad et al. 1979

Energy Required for Life Metabolism – sum total of all chemical reactions occurring in living organisms. Anabolic pathways – synthesize compounds, generally endergonic. (requires) Catabolic pathways – break down compounds, usually exergonic. (produces)

There are many kinds of energy that can interconvert from one form to another.

Sunlight Source of Energy for Most 5.1.9 Most ecosystems are based on producers using sunlight – photosynthesis Energy captured during photosynthesis is stored in the chemical bonds of the molecules synthesized during the process Some use chemical compounds – chemiosynthesis

Incoming Energy Many factors can affect amount of sun’s energy reaching the Earth’s surface Absorbed or Reflected Reflectivity of surface = albedo – can change with angle of light

Diagram of Earth's energy budget Diagram of Earth's energy budget. Credit: Image courtesy NASA's ERBE (Earth Radiation Budget Experiment) program

In Ecosystems, Energy Flows and Matter Cycles 5.1.13 Primary energy source for almost every ecosystem is sunlight Autotrophs convert radiant energy into chemical energy Primary production is the creation of new organic material from inorganic materials (Carbon dioxide and water yields sugar)

Energy Transfer 5.1.10 The stored chemical energy in the producer is available to the next trophic level Energy is transferred from one organism to the next when the carbohydrates, lipids, or proteins are digested If deer eats a clump of grass the energy goes to the deer if it dies without being grazed the decomposers will use the energy

Energy Use Chemical energy used for cellular respiration into ATP by producers, consumers and decomposers Organisms use energy for growth, reproduction, synthesis of molecules, cellular transport, movement Assimilation = ingestion – excretion (including waste heat from cell respiration)

Not all transfers are equally efficient Ectotherms (cold blooded organisms) have lower metabolic requirements than endotherms 80% assimilated energy used for metabolic needs 20% of assimilated energy for growth and reproduction Herbivores assimilate less energy from food than carnivores (plants have lots of indigestible fiber material)

1st Law Thermodynamics Energy cannot be created nor destroyed by ordinary means only converted from one form to another

2nd Law Thermodynamics 5.1.11 Energy transformations are never 100% efficient Energy exchanges in a closed system the potential energy of the final state will be less than the potential energy of the initial state Entropy increases in a system (entropy a measure of unavailable energy) Disorder increases since energy is needed to maintain order to compensate for energy loss

Ecological Pyramids The standing crop, productivity, number of organisms, etc. of an ecosystem can be conveniently depicted using “pyramids”, where the size of each compartment represents the amount of the item in each trophic level of a food chain. Note that the complexities of the interactions in a food web are not shown in a pyramid; but, pyramids are often useful conceptual devices--they give one a sense of the overall form of the trophic structure of an ecosystem. producers herbivores carnivores

Energy Pyramid A pyramid of energy depicts the energy flow, or productivity, of each trophic level. Due to the Laws of Thermodynamics, each higher level must be smaller than lower levels, due to loss of some energy as heat (via respiration) within each level. producers herbivores carnivores

Energy flow units How much moves from level to level and how quickly it moves Trophic level energy units are for energy per unit area per unit time Kilojoules per square meter per year kJm-2yr-1 Energy = ability to do work so Joules is unit

Energy Losses Only chemical energy can be used at next trophic level Only 10 to 20% of energy from an energy level is used by the next level

Why only 10% Not all parts eaten Not all foods swallowed are absorbed (owl pellets) feces Some organisms die without being eaten by organism at next level Heat loss from cellular respiration

Number Pyramids A pyramid of numbers indicates the number of individuals in each trophic level. Since the size of individuals may vary widely and may not indicate the productivity of that individual, pyramids of numbers say little or nothing about the amount of energy moving through the ecosystem. # of producers # of herbivores # of carnivores

Biomass Pyramid A pyramid of standing crop indicates how much biomass is present in each trophic level at any one time. As for pyramids of numbers, a pyramid of standing crop may not well reflect the flow of energy through the system, due to different sizes and growth rates of organisms. biomass of producers biomass of herbivores biomass of carnivores (at one point in time)

Inverted Pyramids A pyramid of standing crop (or of numbers) may be inverted, i.e., a higher trophic level may have a larger standing crop than a lower trophic level. This can occur if the lower trophic level has a high rate of turnover of small individuals (and high rate of productivity), such that the First and Second Laws of Thermodynamics are not violated. biomass of producers biomass of herbivores biomass of carnivores (at one point in time)

Points to remember Note that pyramids of energy can never be inverted, since this would violate the laws of thermodynamics. Pyramids of standing crop (biomass) and numbers can be inverted, since the amount of organisms at any one time does not indicate the amount of energy flowing through the system. For instance think about the amount of food you eat in a year compared to the amount on hand in your pantry.