Goals of This Course Understand ecosystem structure and function Understand how ecosystems can be disrupted Understand local ecological issues Understand the basic methods of experimental design and analysis

Ecology and Ecosystems Ecology – Study of the interactions of living organisms with one another and with their non-living environment of matter and energy. Ecology is basically the study of why we find living organisms where we do!

Levels of Ecological Study Population – distinct group of individuals of a species that live, interbreed, and interact in the same geographic area. Community – includes all of the populations of organisms that live and interact with one another in a given area at a given time.

Levels of Ecological Study Ecosystem – consists of a self-sustaining, self-regulating community of organisms interacting with the physical (abiotic) environment within a defined geographical environment. Biosphere – Earth. Bayousphere – Research Lab, 303 Gouaux Hall

Sub cellular Organelles Molecules Atoms Realm of Ecology Universe Galaxies Planets Earth Biosphere Landscapes Ecosystems Communities Species Populations Individual Organisms Organ Systems Organs Tissues Cells Sub cellular Organelles Molecules Atoms Biosphere Ecosystems Communities Populations Organisms Realm of Ecology

One of the main goals of this course is to grasp a detailed understanding of what ecosystem function is and what mechanisms affect ecosystem structure and function. Timbalier Island 7/2/2005, photo’s by Gary Lafleur

Types of Ecosystems Terrestrial Fresh Water Marine Coastal Chaparral and Scrub Coniferous Forest Desert Prairie Grassland Deciduous Forest Fresh Water Lakes Rivers Streams Marine Estuaries Coastlines Coral Reefs Deep Ocean

Ecosystem Boundaries? It is easy to picture ecosystems as having distinct boundaries. The area of transition from one ecosystem to another is considered to be an ecotone. Ecotones have a mixture of species from both ecosystems. A marsh between a freshwater lake and dry land. Zone of grasses, shrubs, and scattered small trees between forests and grasslands.

Where does one ecosystem end and the other begin? Two examples of ecotones.

Species Overlap in Ecotones Land zone Transition zone Aquatic zone Number of species Species in land zone Species in aquatic zone Species in transition zone only

Major Components of Ecosystems Abiotic - nonliving Energy, nutrients, water and air Biotic - living Plants, animals, and microorganisms (biota)

Energy Flow in Ecosystems Producers Consumers Decomposers

Two Laws of Thermodynamics First Law: Energy cannot be created or destroyed, but it can be changed from one form to another. Second Law: Energy cannot be changed from one form to another without loss of usable energy.

Solar radiation Energy in = Energy out Reflected by atmosphere (34%) UV radiation Absorbed by ozone by the earth Visible light Lower Stratosphere (ozone layer) Troposphere Heat Greenhouse effect Radiated by atmosphere as heat (66%) Earth Heat radiated

One Way Flow of Energy First law Second law When energy transformations occur, energy is neither created nor destroyed (1st Law) but there is always loss of usable energy, usually as heat (2nd Law).

Heat in the environment While energy has a unidirectional flow through ecosystems, nutrients are cycled. All nutrients are already here. They are cycled from one organism to another and may have a long abiotic existence. Some nutrients are lost from ecosystems due to runoff. Biosphere Carbon cycle Phosphorus Nitrogen Water Oxygen Heat in the environment Heat

How Do Ecosystems Gain Lost Nutrients? Carbon – Photosynthetic fixation Nitrogen – nitrogen fixing bacteria and atmosphere Phosphorous – original deposits on land and shallow ocean sediments (artificial fertilizers) Oxygen – Photosynthesis Water – Precipitation

Biotic Components of Ecosystems: Producers (autotrophs) -photosynthesis Consumers (heterotrophs) -respiration Decomposers Heat Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Producers (plants) Decomposers (bacteria, fungus) Consumers (herbivores, carnivores) Solar energy

Trophic Levels Producers (autotroph) Primary Consumer (herbivore) Secondary Consumer (carnivore) Tertiary Consumer Omnivore Detritivores and Scavengers Decomposers

Food Webs (chain) and Energy Flow Heat First Trophic Level Second Trophic Third Trophic Fourth Trophic Solar energy Producers (plants) Primary consumers (herbivores) Tertiary (top carnivores) Secondary (carnivores) Detritvores (decomposers and detritus feeders)

Ecological Pyramid Heat 10 100 1,000 10,000 Usable energy Available at Each tropic level (in kilocalories) Producers (phytoplankton) Primary consumers (zooplankton) Secondary (perch) Tertiary (human) Decomposers Generally, only about 10% of usable energy is passed on to the next trophic level. Biomass follows a similar pattern.

Net Primary Production (measure of produced energy) Estuaries Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland and shrubland Temperate grassland Lakes and streams Continental shelf Open ocean Tundra (arctic and alpine) Desert scrub Extreme desert 800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600 Average net primary productivity (kcal/m2/yr)

What Factors Limit a Species Abundance and/or Distribution?

Law of Tolerance – The existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by that species Limiting Factor Principle - Too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimum range of tolerance.

Tolerance limits – the range of conditions at which a species is able to survive. A particular species may have a wide tolerance for some variables, but a very narrow tolerance for other variables. Highly tolerant species can live in a variety of habitats with widely different conditions.

Abiotic Limiting Factors Temperature Law of Tolerance Population size Low High Temperature Zone of intolerance physiological stress Optimum range No organisms Few Lower limit of tolerance Abundance of organisms Upper limit If temperature is optimum, but dissolved oxygen is too low, there will be no fish!

Select Key Factors Affecting Ecosystems Terrestrial Sunlight Temperature Precipitation Wind Latitude (distance from equator) Altitude (distance above sea level) Fire Frequency Soil Aquatic Light Penetration Water Currents Dissolved Oxygen Salinity Dissolved Nutrient Concentrations (especially N and P) Suspended Solids

What is Ecosystem Structure ?

What is Ecosystem Function ?

Local Issues You Should Understand Assignment 1 Subsidence Global Warming Sea Level Rise Wetland Loss Invasive Species Eutrophication Human Population Growth Pick one of these subjects and write a two page (12 pt font double spaced) synopsis that explains how that issue may affect Louisiana.

Scientific Method Observation Hypothesis Experiment Conclusion Theory What is the question? Designed to answer the question? Correct interpretation?

Experimental Design Will this design answer my question? Treatment / Control – what is the question? Randomization – assignment of treatments to experimental units so as to reduce bias Bias – a unidirectional shift in error Replication – assigning of more than one experimental unit to a treatment combination What is the experimental unit?

Experimental Unit The basic unit of study used for replication Examples…..