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IB Biology Option G: Ecology
 

IB Biology Option G: Ecology

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  • … However, there is some disagreement among scientists about how many biomes there should be. Some argue that there are as few as five and others that there are as many as thirteen or more. For our purposes, we will focus only on the terrestrial (land) biomes. If we included aquatic, there would be even more. The eight biomes represented here are pretty standard, but they are relatively generic. It is possible to divide these into smaller biomes. For example, we could break the tundra into arctic tundra and alpine tundra.

IB Biology Option G: Ecology IB Biology Option G: Ecology Presentation Transcript

  • IB Biology Option G: Ecology
  • Option G Ecology Ecology is the study of ecosystems
    • Biosphere
    • Ecosystem is a compilation of both biotic and abiotic factors, how organisms interact with their environment.
    • Community of different species in the same area which are interacting
    • Population group of organisms of the same species who live in the same area at the same time
    • Individuals species
    Habitat is the environment in which a species normally lives or the location of a living organism
  •  
  • Distinguish between autotroph and heterotroph .
    • Autotrophs are capable of making their own organic molecules from inorganic molecules as a food source (a.k.a. producers); Examples?
    • Heterotrophs – cannot make their own food and must obtain organic molecules from other organisms (a.k.a. consumers); Examples?
  •  
  • Consumers ingest organic matter which is living or recently killed food chains show the flow of energy through the trophic levels of a feeding relationship .
  • Decomposers
    • Two Types
    • Detritivores (Ingest, then digest) ingests non-living organic matter
    • Saprotrophs (Digest first, then absorb) live in or on non-living matter, secreting digestive enzymes into it and absorbing digestive products
    Saprotrophs Detritivores
  • Trophic Levels of Feeding Groups
      • Ecologists divide the species in a community or ecosystem into trophic levels based on their main source of nutrition.
      • Primary producers- autotrophs- produce their own energy source.
          • Photoautotrophs - derive energy via photosynthesis- plants
          • Chemoautotrophs- use energy stored in chemical bonds- Sulfur
  • Trophic Levels
    • Consumers - heterotrophs- derive energy from consuming other organisms
      • 1  consumer- eat producers
      • 2  consumer- eats herbivores- 1  consumer
      • 3  consumer- eats 2  and 1  consumers
    • Decomposers - consume dead material- recycle nutrients back to the environment- Saprotroph
  • Trophic Levels
  • Trophic Levels
    • Secondary Productivity- the rate as which an ecosystem ’ s consumers convert the chemical energy of the food they eat into their own new biomass
    • The efficiency of energy transfer between trophic levels is usually < 20% (≈10%)
  • Trophic Levels Notice that only 10% is moved to the next level. Where does the rest go?
  • THE 10% RULE and ECOLOGICAL PYRAMID
  •  
  • Energy Flow Through Ecosystems
    • Shows more complex interactions between species within a community/ ecosystem
    • More than one producer supporting a community
    • A consumer may have a number of different food sources on the same or different trophic levels
    Food web
  • Food web
  • Food web
  • What are the factors that effect
    • Abiotic (nutrients and energy)
    • Biotic individual organisms that live in that ecosystem
  • Factors controlling and ecosystem
    • Nutrients (Closed System)
    • Energy (Open System)
    • Interactions between species
  • I. Nutrient Cycles Through Ecosystems
    • Biogeochemical cycles are cycles of matter between the abiotic and the biotic components of the environment
      • The carbon, nitrogen , phosphorus, and water cycles are central to life on Earth
      • Carbon, nitrogen, and water cycles have atmospheric components, and cycle on a global scale
      • Phosphorus has no atmospheric component, and cycles on a local scale
  • Very few types of organism play a role in the cycling of nutrients Saprotrophic Bacteria cycle Nitrogen Fungi Cycle Carbon
  • Carbon Cycle
    • Is exchanged of the element carbon among the biosphere. Or geosphere, hydrosphere, and atmosphere of the Earth.
    • Carbon interconnected by pathways of exchange with these reservoirs is mainly through plants .
  • Carbon Cycle
  • Carboniferous
    • Extended from 359 million years ago, to the about 299.
    • A time of glaciation, low sea level and mountain building. With many beds of coal were laid down all over the world during this period.
  • Carboniferous period
    • The world’s large coal deposits occurred during this time period.
    • Two factors
    • 1. The appearance of bark-bearing trees
    • (containing bark fiber lignin ).
    • 2. Lower sea levels
    • Development of extensive lowland swamps and forests .
    • Large quantities of wood were buried during this period.
    • Animals and decomposing bacteria had not yet evolved that could effectively digest the new lignin.
  • Basidiomycetes (fungi)
    • Appear 290 million years ago . They can degrade it Lignin . The substance is insoluble, to heterogeneous because of specific enzymes, and toxic, they are one of the few organisms that can.
  • II. Energy (Open system on Earth)
  • Hubbard Brook Experimental Forest
  • Hubbard Brook Experimental
    • Found that 1,200,000 of kcal of energy hit the Earth from the Sun per sq. meter (or about enough energy to light a 150watt light bulb continuously).
    • Photosynthetic plants were only absorbing about 10,000 kcal per sq. meter and converting in organic material sometimes called the primary production. (or enough energy to power a 1.5 watt light bulb continuously).
  • Sunlight is the initial energy source for almost all communities
    • Energy flows through the food chain, being lost at each stage due to respiration.
  • Pyramids of energy
    • Show the flow of energy between trophic levels
    • Measured in units of energy per unit area per unit time. KJ m -2 y -1
    • The transfer of energy is never 100% efficient
  • Energy Flow through the Ecosystem
    • The conversion of light energy into energy stored in chemical bonds within plant tissue. Primary production results in the addition of new plant biomass to the system.
    • Two types
            • Net Primary Production
            • Gross Primary Production .
    Primary Production
  • Primary Productivity
    • The most productive terrestrial areas are tropical rain forests; least productive are deserts
  • NPP = GPP - R
    • Gross Primary Production (GPP) is the amount of light energy that is converted to chemical energy by photosynthesis per unit time.
    • Net Primary Production (NPP) is equal to gross primary production minus the energy used by the primary producers for respiration (R). Which will be the total energy available to all the other living things in that ecosystem
  •  
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  • Biomass
    • Biomass is the total dry mass of organic matter in the organisms or ecosystem.
    • By measuring biomass of an ecosystem we can see how productive it is and compare this to other ecosystems of past data
  • Pyramids of Biomass
  •  
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  • The movement to a stable ecosystem
  • Succession
    • Ecosystems are not fixed, but constantly
    • change with time. This change is called
    • succession . Imagine a lifeless area of bare
    • rock. What will happen to it as time passes?
  • What Occurs during Succession?
    • Soil
      • Produced by detritivores (worms) following death of other plants and animals
      • Detritivores and bacteria fix nitrogen and other inorganic nutrients into the soil
    • Plant roots
      • Bind the soil, preventing erosion
      • Support larger plans
      • Uptake, filter and recycle massive amounts of water.
  • Primary succession
    • starts with bare rock or sand, such as behind a retreating glacier, after a  volcanic eruption, following the silting of a shallow lake or seashore, on a new sand dune, or on rock scree from erosion and weathering of a mountain.
  • Primary Succesion
    • Gross production increases
    • First colonizers are lichens on rock surfaces
    • Soil builds up following death of smaller lichens
    • Productivity plateaus as soils carrying capacity is reached
    • Species diversity increases
    • More soil allows for burrowers, worms and detritivores
    • More plants take root and provide mew niches
    • More deaths leads to more soil and nutrient recycling
  • Colonizers
    • Very few species can live on bare rock since it stores
    • little water and has few available nutrients. The first
    • colonizers are usually lichens. Colonizers start to erode
    • the rock and so form a thin soil.
    • .
    Lichen
    • G rasses and ferns grow in the thin soil and their roots accelerate soil formation. They have a larger photosynthetic area, so they grow faster
    • Pioneer species
    Ferns
  • Herbaceous Plants
    • Dandelion, goosegrass “weeds” have small wind-dispersed seeds and rapid growth, so they become established before larger plants.
    goosegrass
  • Larger plants ( Small trees and large shrubs)
    • bramble, gorse, hawthorn, broom and rhododendron can now grow in the good soil. These grow faster and so out-compete the slower-growing pioneers.
    Hawthorn
  • Large Trees
    • Trees grow slowly, but eventually shade and out-compete the shrubs, which are replaced by shade-tolerant forest-floor species. A complex food web is now established with many trophic levels and interactions. This is called the climax community .
    Beech Tree
  • Secondary succession
    • • Starts with soil, but no (or only a few) species, such as in a forest clearing, following a forest fire, or when soil is deposited by a meandering river
    Picture right after a forest fire One year later Five years later
  • Primary vs. Secondary Succesion
  • Soil creation
  • The Biosphere
    • Is made up of all the world’s biomes. Biomes are simply component of the larger unified ecological system, the biosphere
  • Biomes
    • Climatically and geographically defined areas of ecologically similar characteristics. Temperature and rainfall are key abiotic features of each biome and plant and animal species are adapted to survive in the available niches.
  • Rainfall and Temperature Affect the Distribution of Biomes.
  • Biomes of the World
  • How many biomes are there?
    • Tropical Rainforest
    • Desert
    • Shrubland (Chaparral)
    • Grassland
    • Temperate Deciduous Forest
    • Tundra
    Although there is some disagreement among scientists on how to divide up the Earth’s biomes, most can agree on the following six:
  • Tundra
    • Means treeless or marshy plain
    • Characterized by permafrost – permanently frozen soil starting as high as a few centimeters below the surface – which severely limits plant growth
    • Low temperature , winter temperatures average –34 o C while summer temperatures usually average below 10 o C
    • Low precipitation (15–25 cm per year) but ground is usually wet because of low evaporation
  • Desert
    • Typically found between 25 o and 40 o latitude
    • Receives less than 25 cm of rain each year
    • Temperatures typically range between 20 o C and 25 o C but some extreme deserts can reach temperatures higher than 38 o C and lower than –15 o C
  • Shrubland (Chaparral)
    • Found between 32 o and 40 o latitude on the west coast of continents
    • Receives between 35 and 70 cm of rain, usually in the winter
    • Extremely resistant to drought and weather events
  • Grassland
    • Because of the dry climate, trees are found only near water sources such as streams
    • Usually receives between 50 and 90 cm of rainfall each year
    • Summer temperatures can reach up to 38 o C, and winter temperatures can fall to –40 o C
  • Temperate Deciduous Forest
    • Moderate climate
    • Most trees will lose their leaves in the winter
    • Temperatures range between –30 o C and 30 o C
    • Averages from 75 to 150 cm of precipitation
    • Well developed understory
  • Tropical Rainforest
    • Typically found near the equator
    • Receives more than 200 cm of rain annually
    • Temperatures typically fall between 20 o C and 25 o C for the entire year
    • As many as 50% of all the world’s animal species may be found here
  • III. Interactions between species
  • G 1.2a Explain the factors that affect the distribution of animal species, including temperature, water, breeding sites, food supply and territory.
  • G 1.1a Outline the factors that affect the distribution of plant species, including temperature, water, light, soil pH, salinity and mineral nutrients.
  • G 1.2b Explain the factors that affect the distribution of animal species, including temperature, water, breeding sites, food supply and territory.
  • G 1.2c Explain the factors that affect the distribution of animal species, including temperature, water, breeding sites, food supply and territory.
  • G 1.2c Explain the factors that affect the distribution of animal species, including temperature, water, breeding sites, food supply and territory.
  • Interactions Between Species
    • Competition is when two species need the same resource such as a breeding site or food. It will result in the removal of one of the species. There are two major types of competition
  • I. Intraspecific competition
    • A form of competition in which individuals of the same species compete for the same resource in an ecosystem. This tends to have a stabilizing influence on population size. If the population gets too big, intraspecific population increases, so the population falls again.
  • II. Interspecific competition
    • A form of competition in which individuals of different species compete for the same resource in an ecosystem.
    • A. Predation is the relation between the predator, which is usually bigger, and the prey, which is usually smaller. An example would be a fox and a rabbit
    Anteater Ant
    • B. Parasitism is the relation between the host and the parasite. The parasite causes harm to the host to get food and other resources. Examples of parasites are some viruses, fungi, worms, bacteria, and protazoa.
    Bass Lamprey
  • C. Mutualism is where two members of different species benefit and neither suffers. Examples include rumen termite/protazoa that digest cellulose
  • D. Herbivory
    • Primary Consumers that feed only on plant material. Considered predators of plants. Ladybug and a caterpillar are examples of herbivories
  • Reproductive strategies
    • Organisms devised methods of reproduction to deal with species interactions
        • r-strategies
        • k-strategies
  • r-strategies “real lot”
    • An r-strategy involves investing more resources into producing many offspring, having a short life span, early maturity, reproducing only once and having a small body size.
  • Frog Eggs Frogs lay many eggs & leave them in the water to hatch into tadpoles, some get eaten, some become tadpoles.
  • Tadpole Some tadpoles are eaten, some tadpoles become frogs
  • Frog Many animals are waiting on shore for frogs: raccoons, foxes, and many other small predators. If 1 frog from a 100 eggs lives to be a parent, his/her survival is really outstanding
  • K-strategies “caring”
    • A K-strategy involves investing more resources into development and long-term survival. This involves a longer life span and late maturity, and is more likely to involve parental care, the production of few offspring, and reproducing more than once.
  • K-strategies
  •  
  •  
  • Where does a species fit on the r-k spectrum?
    • Exceptions :
    • Some organisms have both r and K stages or characteristics, such as large trees, sea turtles and many other reptiles
    • Some species, such as Drosophila, change strategies depending on environmental conditions
  • r and K strategists favor different enviromental conditions
    • Unstable, changing environments provide opportunities for fast reproducing organisms.
    • Early primary or secondary secession provide opportunities for these species
    • In stable, predictable environments it is more effective to invest resources in becoming more competitive.
    • Macrofauna and flora are more abundant in stable, long established ecosystems and havitats after much of succession of species.
  • Niche Concept
    • A population’s niche refers to its role in its ecosystem .
    • This usually means its feeding role in the food chain .
    • A description of a niche should really include many different aspects such as its food, its habitat, its reproduction method and the organisms it interacts with.
    • Identifying the different niches in an ecosystem helps us to understand the interactions between populations. Members of the same population always have the same niche, and will be well-adapted to that niche.
  • Competitive Exclusion
    • No two species in a community can occupy the same niche
    Species A niche Species B niche
  • Principle of Competitive Exclusion
    • Where two species need the same resources and will compete until one species is removed.
    • One would be more capable of gathering more resources or reproducing more rapidly until the other was run out of existence.
    • Experiments with paramecium populations in the lab of Ecologist G.F. Gause demonstrated this concept scientifically.
  • The niche concept was investigated in some classic experiments in the 1930s by Gause . He used flasks of different species of the protozoan Paramecium , which eats bacteria and yeast .
    • Conclusion: These two species of Paramecium share the same niche, so they compete. P. aurelia is faster-growing, so it out-competes P. caudatum .
    Experiment 1
  • P. aurelia P. caudatum
    • In the second experiment he took P. caudatum and had it compete with a second type of Paramecia. It is important to understand the distribution in experiment 2.
    • P. caudatum lives in the upper part of the flask because only it is adapted to that niche and it has no competition. In the lower part of the flask both species could survive, but only P. bursaria is found because it out-competes P. caudatum .
    Experiment 2
  • Experiment 2
    • Conclusion : These two species of Paramecium have slightly different niches, so they don't compete and can coexist.
  • Fundamental vs. Realized Niche
    • Fundamental Niche : the potential mode of existence, given the adaptation of the species
    • Realized Niche : the actual mode of existence, which results from its adaptations and competition with other species
    Competition II Competition I Competition III Realized Niche
  • Populations
    • The total number of individuals of a species in a given area.
    • Populations are affected by four main factors
  • Four Factors Influence the Size of a Population:
    • Natality: Birth Rate (offspring produced and added to population)
    Babies!
  • Mortality: Death Rate (individuals that die)
  • Immigration: Movement of members of the species into the area
  • Emigration: Movement of members of the species out of area to live elsewhere.
  • Population Changes
  •  
    • 3 Phases:
    • Exponential growth Phase
    • Transitional Phase
    • Plateau Phase
    Limited Growth Sigmoid (S-Shaped)
  • 1. Exponential Growth Phase
    • Population increases exponentially.
    • Resources are abundant.
    • Predators and disease are rare .
  • 2. Transitional Phase
    • As a result of intra-specific competition
      • for food, shelter, nesting space, etc.,
      • and the build up of waste.
    • The growth rate slows down.
      • Birth rates decline and death rate increases
  • 3. Plateau Phase
    • Natality and mortality are equal so population size is constant.
    • When the number of individuals in the population have reached the maximum which can be supported by the environment.
    The number is called the CARRYING CAPACITY
  • Population size oscillates around the carrying capacity ( K) Time N K overshoot oscillations
    • Density Dependent Limits
      • Food
      • Water
      • Shelter
      • Disease
    • Density Independent Limits
      • Natural Disasters
      • Humans (logging, mining, farming )
    Water and shelter are critical limiting factors in the desert. Fire is an example of a Density independent Limiting factor. Limits on Population Growth
  •  
  • How did we get here?
    • When I graduated
    • high school there were
    • 4 billion people.
    • Today there are
    • almost 7 billion people
  • About 5 million years ago Hunter-gathers 1 million people
  • Neolithic Period (6000 B.C.) No longer a Natural Setting 100 million people
  • Common area 2000 years ago 300 million people
  • 1800’s (Carbon cycle control) Steam engine 1 billion people
  • London between 1800 to 1880
    • 1800 pop. 1 million
    • 1880 pop. 4.5 million
    • Improvements in medicine and public health
  • Life Expectance
    • Neolithic it was 20
    • 1900 it was 30
    • 1950 it was 47
    • Current world average is 67
  • 1800-2000?
    • From 1 billion to 6 billion? How???
  • 1908 Control of the Nitrogen Cycle
    • Up until 1908 farms were dependent on organic sources for nitrogen (manure)
    • Haber figured out how to convert N 2 into NH 3 and then into NH 4 + of NO 3 -
    • Commercial fertilizers are born
    Fritz Haber
  • 1944 Plant Breeding
    • Improves yields
    • Disease resistance improvements
    • Less day-length sensitive
    • Improve sharing of ideas on plant breeding
  • What’s Behind Population Growth
    • Three Factors
      • Fertility
      • Infant Mortality
      • Longevity
    • Animal Domestication and Agriculture
      • Provided for a few to feed many
    • Industrial Revolution
      • Growth of Cities and Infrastructure
        • Water
        • Energy
        • Transportation
      • Increased Productivity
      • Nutrition
      • Sanitation
      • Medicine
  • Exponential growth of the human population Human population growth does not currently show density effects that typically characterize natural populations. Limited resources eventually will cause human population growth to slow, but global human carrying capacity is not known.
  • Population Predictions
    • Most predictions: 9-12B by 2050 10-15B by 2100
    • Large uncertainties
  • Resource Limits
    • Land
      • Deforesting to acquire more arable land
      • Would run out in next century at current yields
    • Water
      • In 1950 people used half of accessible water
      • Are now dependent on dams
      • Pollution loses 33% of potential water
      • Getting close to limits
    • Energy
      • growth very high last fifty years
      • Mostly hydrocarbon fuels
      • Nonrenewable resource consumption
      • Climate change issues
  •  
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    • Why monitor populations ?
    • Determine current status of a population
    • Determine habitat requirements of a species
    • Evaluate effects of management
    • *Complete “census” of natural populations is often very difficult!
    Population Sampling
  • Population vs. Sample Sample True Population
  • RANDOM SAMPLING
    • A sampling procedure that assures that each element in the population has an equal chance of being selected
    • Sampled population should be representative of target population
  • Sample Methods
    • Quadrat
    • Mark-Recapture
    • There are MANY more…
  • Quadrat Sampling
    • A square frame is placed in a habitat
    • All the individuals in the quadrat are counted
    • The process is repeated until the sample size is large enough
    • Useful for small organisms or for organisms that do not move
  • Converting a population study into a graph
  • MARK-RECAPTURE (Lincoln Index)
    • Capture and mark known number of individuals
    • 2 nd round of captures soon after
      • Time for mixing, but not mortality
    • Fraction of marked individuals in recapture sample is estimate of the proportion of population marked in first capture
  • Marking methods
    • Paint or dye
    • Color band
      • birds
    • Unique markings
      • Large mammals; keep photo record
    • Toe clipping
      • Reptiles, amphibians, rodents
    • Radio Collars
    • Micro chips
    (NPS 2000)
  • Lincoln Index
    • Using mark-recapture sampling to estimate animal populations
    • Population Size P =( # initially marked) x (total 2 nd catch)
    • (# of marked recaptures)
    • Or
    • N 1 x N 2
    • N 3
  • Mark Recapture Lincoln Index N 1 = 4 N 2 = 5 N 3 = 2 N 1 = first capture N 2 = second capture N 3 = #’s of marked in second capture
  • Survey 1: N 1 = 12 Survey 2: N 2 = 15 N 3 = 4
    • You capture and mark 150 fish in a lake. (This must be a random, representative sample.)
    • You release them back into the lake, allowing enough time for them to remix with the population.
    • You trap another 220 fish, of which 25 are recaptures (i.e., marked from the initial trapping.
    • What is your estimate of the total population of fish in the lake?
    Example:
    • N 1 = 150
    • N 2 = 220
    • N 3 = 25
    • P = [(220)(150)] / 25
        • = 1320 FISH
    Example:
  • Example:
    • Use the Lincoln Index to monitor this mountain gorilla population over time
  •  
  • Human Effect on the World Fish Population
    • Overexploitation of species affects the loss of
    • genetic diversity and the loss in the relative
    • species abundance of both individual and/or groups of interacting species.  Overexploitation may include over fishing and over harvesting
    • Historically, humans have fished the oceans, which never seemed to pose a problem due to their abundant resources.  Gear (fish trap, gill nets, electro-fishing) and vessel efficiency modifications have caused a significant decrease in fish populations.
  • A case study: The Peruvian Anchovy ( Engraulis ringens ) Universidad de La Serena
  • The Peruvian Anchovy
    • This is a small (12-20cm), short-lived species maturing in 1 year
    • Anchovy live in the surface waters in large shoals off the coast of Peru and northern Chile
    • Here there are cold currents up-welling from the sea bed bringing nutrients for phytoplankton
    • Plankton is at the base of the food chain.
  • The Peruvian Anchovy
    • The harvest of this fish doubled every year from 1955 to 1961
    • Experts estimated the maximum harvestable yield ( MSY ) at 10 to 11 million tonnes per year
    • Through the 1960s the harvest was about this level
    • The biggest fishing harvest in the world
    • Some of the anchovy were used for human food
    • But a lot was ground into fishmeal for animal feed
  • The collapse of the anchovy fishery
    • In 1972 there was an El Ni ñ o event that brought warm tropical water into the area
    • The up-welling stopped,
    • the phytoplankton growth decreased
    • the anchovy numbers fell and concentrated further south
    • The concentrated shoals of anchovy were easy targets for fishing boat eager to recuperate their harvest
    • The political will was not there to impose reduced quotas
    • Larger catches were made
    • No young fish were entering the population (no recruitment)
    • No reproduction was taking place
    • The fish stocks collapsed and did not recover
  • Population dynamics of fisheries
    • A fishery is an area with an associated fish population which is harvested for its commercial or recreational value. Fisheries can be wild or farmed.
    • Population dynamics describes the ways in which a given population grows and shrinks over time, as controlled by birth , death , and emigration or immigration . It is the basis for understanding changing fishery patterns and issues such as habitat destruction , predation and optimal harvesting rates .
    • The population dynamics of fisheries is used by fisheries scientists to determine sustainable yields
  • Estimating Fish populations
    • Fish Catch Data The total volume of the catch (in tons). The catch rate (number of times fishing). The catch rate by age of the fish.
    • Technology The use of echolocation and satellite images can be used to track and estimate populations
    • Lincoln Index (Capture-Mark-Recapture ) day one, mark and release the fish. The next day, repeat the sequential sampling and also records the total number of fish marked and unmarked so we can use to estimate of fish population density
  • The overall catch has decreased fish stocks in many areas of the United States, as catches in each area exceed the maximum number of fish that these fishermen are allowed to take.
  • Maximum Sustainable Yield (MSY)
    • Based upon:
    • the harvest rate
    • the recruitment rate of new (young) fish into the population
        • a population can be harvested at the point in their population growth rate where it is highest (the exponential phase)
        • Harvesting (output) balances recruitment (input)
        • Fixed fishing quotas will produce a constant harvesting rate (i.e. a constant number of individuals fished in a given period of time)
  • Maximum Sustainable Yield (MSY) K
      • Numbers
    Time 1 2 3
  • Maximum Sustainable Yield
    • The Largest possible catch without adversely affecting the ability of the population to recover.
  • Problems with MSY
    • Age structure : If all the age groups are harvested recruitment of young fish into the reproductive group will be reduced. The answer is to use a net with a big enough mesh size that lets the young fish escape
    • Limiting factors : If the limiting factors in the environment change so does the population growth rate
        • Limiting factors set the carrying capacity (K) of an environment
        • Increasing limiting factors will cause K to drop
        • Fixed quotas cannot cope with this
        • Data: For MSY to work accurate data in fish populations is needed (population size, age structure, recruitment rates)
        • Usually these are not well known
  • What is required?
    • Nets with bigger mesh size
    • Regulated fishing methods
    • More data on fish populations (e.g. by fish tagging investigations – mark and recapture)
    • Constant monitoring to observe changes in environmental factors (e.g.El Ni ñ o events
    • Policing of fishing industry – respect of quotas
    • International agreements
    • Greater exploitation of fish farming
    • But this is not without its own problems (space, diseases and pollution are all associated with intensive fish culture)
  • 4 Serious Environmental Issues
    • Reduction in Biodiversity
    • Biomagnification
    • Ozone Depletion
    • Greenhouse Effect (Global Warming)
  • 1. Reduction in Biodiversity
  • Simpson diversity index
    • The index of diversity is used as a measure of the range and numbers of species in an area.  It usually takes into account the number of species present and the number of individuals of each species.  It can be calculated by the following formulae:
    • D = N(N-1) ∑n(n-1)
    • D= Diversity index
    • n = number of individuals of a each species found in an area.
    • N = total # of organisms of all species found in an area.
    • The simpson diversity index is a measure of species richness.
    • A high value of D suggests a stable and ancient site.
    • Example :
    • Crested newt 8
    • Stickleback 20
    • Leech 15
    • Great pond snail 20
    • Dragon fly larva 2
    • Stonefly larva 10
    • Water boatman 6
    • Caddisfly larva 30
    • N = 111
    • N(N-1) = 111(111-1) = 12,210
    • ∑ n(n-1) = (8x7) + (20x19) + (20x19) + (15x14) + (20x19) +
    • (2x1) + (10x9) + (6x5) + ( 30x29) = 2018
    • D = 12,210 = 6.05
    • 2018
    • Example: In another pond there were:
    • Crested newt 45
    • Stickleback 4
    • Leech 18
    • Great pond snail 10
    • N=77
    • D = 2.6
    • Comparing both indices, 6.05 is an indicator of greater
    • diversity.  The higher number indicates greater diversity
  • Abiotic factors for Biodiversity
    • In extreme environments the diversity of organisms is usually low (has a low index number).  This may result in an unstable ecosystem in which populations are usually dominated by abiotic factors .  The abiotic factor(s) are extreme and few species have adaptations allowing them to survive.  Therefore food webs are relatively simple, with few food chains, or connections between them – because few producers survive. 
  • Abiotic factors for Biodiversity
    • In less hostile environments the
    • Diversity of organisms is usually high
    • (high index number).  This may
    • result in a stable ecosystem in which
    • populations are usually dominated by
    • biotic factors , and abiotic factors are
    • not extreme.  Many species have
    • adaptations that allow them to
    • survive, including many
    • plants/producers.  Therefore
    • food webs are complex, with many
    • inter-connected food chains. 
  • The use of biotic indicator for monitoring environmental change
      • Are a good indicator of change
      • Highly sensitive to environmental changes
      • Highly sensitive to population increases or decreases.
      • The numbers of organisms in the indicator species populations, can be measured directly so they are easy to keep track of larger changes that maybe occurring.
  • American Dipper
    • Feeds on aquatic insects and their larvae, including dragonfly, nymphs and caddisfly larvae. It may also take tiny fish.
    • The presence of this indicator species shows good water quality; it has vanished from some locations due to pollution or increased silt load in streams
  • Humans Contribute to Declining Biological Diversity
    • Introduction of exotic species harms native species due to competition, predation, or interbreeding
      • The zebra mussel from the Caspian, introduced into the American Great Lakes These mussels not only cause billions of
    • dollars of damage but have displaced the native clams and mussels
    Invasive Species
  • Asian long-horned beetle
    • Discovered in the US in 1996 on several hardwood trees (destroying the hardwood tree) in Brooklyn, NY. The wood-boring beetle is believed to have been introduced on wood pallets and wood packing material in cargo shipments from Asia. The infestation quickly spread to Long Island, Manhattan and Queens
  • Phragmites
    • A wetland plant species found in every U.S. state (crowding out the native species). 
    • It can grow up to 6 meters high in dense stands and is long lived. The species is invasive particularly in the eastern states along the Atlantic Coast and increasingly across much of the Midwest and in parts of the Pacific Northwest.
  • Rabbits as an invasive species
    • Rabbits were brought to New Zealand and released for both food and sport at various sites as early as the 1830s
    • Once rabbits became established, their population increased to plague proportions
    • Their impact has been little short of an ecological disaster, as the vegetation grazed off by rabbits may never recovered.
  • Example of a biological control of invasive species.
    • Example : RHDV (rabiit haemmorragic disease virus) has been introduced to in order to control the population of rabbits.
    • Solution : Introduce RHDV, a virus specific to the rabbits. Tested under quarantine first (to ensure safety), then released into the wild populations. Adult rabbit contract spreads the virus, but it does not affect any other species.
    • Effectiveness : Very effective, though some evidence of RHDV resistance in rabbits is starting to become apparent.
  • The Conservation of Biodiversity
    • Biodiversity is highest in the Tropical Rainforest
    • Four Reason for conservation of the tropical rainforest
    • Ethical reasons for conserving biodiversity are that all species have a right to live on this planet.
    • Ecological reasons are that species live with great interaction and dependence on each other. If one species dies out, a food chain is disrupted, therefore disrupting all of the other species as well.
    • Economic reasons are that the rainforest is a source of materials important to human life. Medicinal substances can be taken from a variety of plants in the rain forest, and ecotourism offers a new source of funds for the many impoverished nations these forests exist in .
    • IV. Aesthetic reasons are that the tropical rain forest is one of the most beautiful attractions on this planet. There is variety everywhere in the rainforest.
  • 2. Biomagnification
  • The cause and the consequences of biomagnification
    • A process in which chemical substances become more concentrated at each trophic level.
    • As each individual eats contaminated food or filters contaminated water, it is building up these substances.
    • When a large number of contaminated individuals are eaten, they pass on a high concentration of chemicals to the predator.
  • An example of biomagnification
    • Biomagnification of DDT
    • Cause: DDT is a synthetic pesticide sprayed on crops and can be used against malaria mosquitoes. It is washed into waterways in low concentrations, where it is biomagnified up the food chain. It is highly toxic at high concentrations.
    • Consequences: Stored in fats and accumulates quickly. Very high concentrations in large fish and seabirds. It is responsible for reduced reproductive function and shell thinning in birds, which has impacted populations of large birds of prey heavily. In humans, it has been linked with cancers, fertility and developmental problems.
  • An example of biomagnification
  • 3. The ozone layer in the stratosphere absorbs UV radiation
  • Ultraviolet Radiation and the Ozone Layer
    • With a depleted ozone layer, more UV radiation will reach the surface of Earth
    • This will cause an increase in many problems, including cancer, will affect crops, damage phytoplankton and zooplankton
    Ozone Depletion
  • Chlorofluorocarbons ( CFCs)
    • Certain chemicals destroy stratospheric ozone
      • Chlorofluorocarbons ( CFCs) are broken down by UV in the stratosphere and react with ozone, forming molecular oxygen
      • CFCs are not used up in this reaction, and are able to break down many thousands of ozone molecules
  • Ozone Depletion Is Harmful
    • Ozone depletion harms living organisms
      • Exposure to UV is linked to disorders in humans, including cataracts, skin cancer, and weakened immune systems
      • Exposure to increasing UV is linked to declines in phytoplankton productivity
  • Basal Cell Skin Cancer
  • 6% Declines in phytoplankton over the last 10 years map right: Satellites Many of the areas showing an increasing trend appear along the coasts, in red, while most of the dark blue areas indicate a decreasing trend. Units for the top two panels are milligrams of chlorophyll per cubic meter.
  • 4. Greenhouse Effect ( Global Warming)
  • Carbon Cycle
  • The Greenhouse Effect
  • The Greenhouse Gases
    • How the greenhouse effect works
      • Sunlight enters Earth’s atmosphere b/c the gases of the atmosphere are transparent to light
      • Most is reflected off surface
      • Some is transferred into heat energy and warms the planet which in turn radiates much back to the atmosphere
      • Greenhouse gases trap heat in atmosphere
  • The Greenhouse Effect
    • The molecules of some gases in the atmosphere absorb heat energy and retain it
    • This can be a good thing
    • Without an atmosphere the Earth would have same temperature as the moon
    • Moon mean surface temperature -46°C
    • Moon temperature range: -233 to +123°C
    • Earth is undergoing global warming b/c human-generated greenhouse gases are causing the atmosphere to retain more and more heat
    • Carbon, methane, and oxides of nitrogen are main culprits
    • Oxides of nitrogen:
      • Burning fossil fuels
      • Organic and commercial fertilizers
      • Industrial processes
    • Methane:
      • Cattle ranching
      • Waste disposal in landfills
      • Production and distribution of natural gas
    The Greenhouse Gases
  • The Greenhouse Gases
    • H 2 O vapor
    • CO 2
    • CH 4
    • NO x
    • CFC
  • Mauna Loa Observatory © Mauna Loa Observatory Site © Earth System Research Laboratory © Earth System Research Laboratory
  • Carbon dioxide a greenhouse gas
  • South Pole Data
  • Samoa data
  • The consequences of a global temperature rise on arctic ecosystems
    • More and more ice is melting every year
    • Less snow and more frozen rain in the winter
    • Some regions which never had them before are now populated with mosquitoes
    • Certain woody shrubs are proliferating on warmer soils where once there were only mosses and lichens on tundra
    • Bird species such as robins have moved into areas where they are so foreign to the local people that a name for them does not exist in their language
  • Is it really getting warmer © NASA 1979 2003
  • Knock-on effects
    • Increased temperature melts the permafrost
    • Frozen plant remains decompose
    • More methane released
    • Similarly soils will lose organic carbon (humus) more rapidly in a warmer climate
    • Ice caps melt more sea exposed
    • Snow reflects light (high albedo)
    • Water absorbs light, increases warming
    • More CO 2 dissolving in water lowers pH
    • Currently this is buffered and remains stable
    • Eventually pH will drop sea life will die CO 2 produced as organisms decompose
  • The precautionary principle
    • An ethical theory which says that action should be take to prevent harm even if there is not sufficient data to prove that the activity will have severe negative consequences
  • Response to the threats posed by the enhanced greenhouse effect
    • Preventative action should be taken now to reduce carbon emissions and greenhouse gases before it’s too late
    • Those who wish to continue producing excess greenhouse gases should prove that there are no harmful effects before continuing
    • Concerned scientists say that money spend now on preventative measures is not money wasted
    • Prevention is better than cure
  • Species can be used as an indicator of environmental health.
    • Some species are not tolerant of pollution, so will not be present in water or an environment which is polluted.
    • Other species can tolerated pollution or environment al stress and will thrive under these conditions
    • Indicator species are those which can be used to identify areas as clean or polluted, by their presence or absence.
    • Lichen are a good indicator species for air pollution
  • Extinction
    • The end of a species.
    • Extinction has always been a part of evolution. Those species that are best adapted to their environment will survive and reproduce. Those which are die.
    • Although many species have gone extinct due to natural processes and phenomena, the impacts of humans on the ecosystems has greatly accelerated the rate of species extinction in the world
    • Human factors
        • Habitat destruction
        • Pollution
        • Overfishing or hunting
        • Climate change
        • Invasive species
  • Example of the extinction
    • Habitat : Mauritus
    • Why did it die out so quickly?
        • Flightless
        • Short legs
        • No behavioral adaptation for avoiding predators
    • Cause :
        • Deforestation and habitat loss
        • Hunting for food
        • Invasive species
          • Rats, dogs, cats on ships
  • Should we let the Komodo Dragon go Extinct?
    • The Komodo dragon is a large species of lizard found in the Indonesian.
    • There may presently be only 350 breeding females left in the world.
    • To address these concerns, the Komodo National Park was founded in 1980 to protect Komodo dragon populations.
  • Nature Reserves
    • Aquatic or terrestrial ecosystems that have been protected in order to conserve biodiversity, heritage or are home to unique species.
    • Reserves can have huge benefits
      • Control of invasive species
      • Control of human exploitation
      • Legal protection for endangered species
    • Examples in Inonesia :
      • Ujunkulon, West Java
      • Komodo Island, Lombok
      • Bunaken, Marine Reserve
  • Nature Reserves
    • Bigger Reserves are better
      • Larger habitats
      • More resources more niches
      • Some migration
      • More biodiversity established ecosystems
      • Larger species can hide
    Javan Rhino the rarest large mammal on earth. A population of at least 40–50 live in a National Park in Indonesia
  • Active management techniques in conservation
    • It may be enough to create a national park and leave it to its natural state
    • If active management did not occur, the habitat may continue to decline or recover too slowly.
      • Techniques
        • Culling alien or damaging species
        • Fire clearing areas to kill invasive species
        • Replanting or reintroducing endangered species
        • Legal meaures against human impact
  • In situ Ex situ
    • In situ :
    • Conservation of species in their natural habitat
    • E.g. natural parks, nature reserves
    • Ex situ :
    • Conserving species in isolation of their natural habitat
    • E.g. zoos, botanical gardens, seed banks
  • The advantages of in situ (conservation in original habitat )
    • The species will have all the resources that it is adapted too
    • The species will continue to evolve in their environment
    • The species have more space
    • Bigger breeding populations can be kept
    • It is cheaper to keep an organism in its natural habitat
  • terrestrial and aquatic in situ habitats
    • Animal Examples
      • GPS tagging whales and turtles
      • Protecting a habitat
    • Plant Examples
      • Replanting damaged ecosystems
      • Protecting habitats
  • However there are problems
    • It is difficult to control illegal exploitation (e.g. poaching)
    • The environment may need restoring and alien species are difficult to control
    Sciencemuseum.org
  • Ex situ (outside original habitat)
    • Represents the last chance for survival
    • Species may be too rare to be left in the wild
    • Habitat may have been lost
    • Carefully controlled conditions
  • Ex situ conservation
    • Captive breeding of endangered species is a last resort
    • These species have already reached the point where their populations would not recover in the wild
    • It works well for species that are easily bred in captivity but more specialised animals are difficult to keep (aye aye)
    • Isolated in captivity they do not evolve with their environment
  • Ex situ conservation : Captive breeding
    • The Hawaiian goose was practically extinct in the wild
    • 12 birds were taken into captivity
    • A population of 9000 was released back into the wild
    • The experiment failed because the original cause rats had not been eliminated.
    • The rats eat the eggs and the nestlings of the geese
    State Symbols USA
  • Zoos: The land of the living dead?
    • They have a very small gene pool in which to mix their genes
    • Inbreeding is a serious problem
    • Zoos and parks try to solve this by exchanging specimens or by artificial insemination where it is possible
    • In vitro fertilization and fostering by a closely related species has even been tried (Indian Guar – large species of cattle - cloned)
    • Even if it is possible to restore a population in captivity the natural habitat may have disappeared in the wild
    • Species that rely on this much help are often considered to be “the living dead”
  • Botanical gardens
    • Botanical gardens show the same problems as captive breeding of animals
    • Originally the role of botanical gardens was economic, pharmaceutical and aesthetic
    • There range of species collected was limited
    • The distribution of botanical gardens reflects the distribution of colonial powers
    • Most are found in Europe and North America
    • But plant diversity is greatest in the tropics
  • Seed banks
    • Seeds can be maintained for decades or even centuries if the conditions are controlled
    • <5% humidity and –20°C
    • Not all species are suited to this treatment
    • Seeds need to be regularly germinated to renew stock or the seeds will eventually loose their viability
    • Seed banks are at risk from power failure, natural disasters and war
    • Duplicate stocks can be maintained
    • Seeds kept in seed banks do not evolve with changes in the environment
  • The doomsday vault - Spitzbergen Bergen Nat Acc of Arts BBC
  • International agencies
    • CITES (The Convention in International Trade in Endangered Species)
    • Set up in 1988 to control and encourage the sustainable exploitation of species
    • The CITES conferences determine the status of a species and whether or not its exploitation requires regulation
    • Species are placed into different appendices depending on their status
    CITES
  • The bottom line
    • Two factors will ultimately govern what happens:
    • 1. Human population growth
    • More people means greater demand for non-renewable resources
    • 2. The ecological footprint of each individual human
    • Higher standards of living usually means higher consumption of fossil fuels
        • The planet will look after itself in the end
        • There are plenty of examples where human communities have disappeared because they outstripped the environmental resources
  • The planet will look after itself in the end
    • Easter Island (Rapanui) in the Pacific
    • Settled between AD900 and 1200
    • Community in severe decline AD 1700
    • Cause: excessive deforestation
  • The planet will look after itself in the end
    • Chaco Canyon, New Mexico
    • Anasazi culture
    • AD 850 – 1250
    • Cause: Deforestation combined with a decline in rainfall
  • The planet will look after itself in the end
    • Mesopotamia
    • Sumerian civilization
    • 3100 – 1200 BC
    • Increased salt levels in soil due to irrigation systems & arid environment
    • Reduced food yield
    © Asociación Cultural Nueva Acrópolis en Barcelona
  • The planet will look after itself in the end
    • Greenland
    • Viking colony
    • AD982 – 1350
    • Cause: Deforestation, soil degradation & cooling of the climate
    © Emporia State University