MOD 4 BIO (AT1)

• Ecosystem


  Dynamics - Constant shift of ways interactions occur
• Ecosystem Dynamics


  Processes working in the environment that is subject to change
• Population


  The number of organisms of one species living in an area of one habitat
• Distribution


  The way these organisms are spread out in the area/habitat
• Abundance


  The population size of the organism in the habitats
• Factors affecting population dynamics

  • Biotic factors (living organisms)
  • Abiotic factors (non-living)
• Biotic factors


  • Food organisms
  • Predators
  • Diseases organisms
  • Competitors
• Abiotic factors


  • Availability of water
  • Availability of oxygen
  • Light intensity
  • Temperature change
  • Soil characteristics
• All living things can: Reproduce, Grow, Repair, Respire
• Abiotic factors


  Physical rather than biological in that they are not derived from living organisms
• Abiotic factors


  • pH (acidity)
  • Sunlight
  • Temperature
  • Salinity
  • Water
  • CO2
  • O2 (DO) → Dissolved oxygen
• Biotic factors


  Related to living organisms
• Types of symbiosis


  • Mutualism - Mutual benefit for both organisms
  • Commensalism - One organism benefits, other is neither helped nor harmed
  • Parasitism - One organism is harmed whilst the other benefits from its resources
• Carrying capacity


  The maximum number of individuals of a particular species that can live in a certain ecosystem or ecosystem niche without causing harm to the ecosystem in the long term
• Ecological niche


  The specific role and position of a species within its ecosystem, including its interactions with both biotic and abiotic factors
• Components of an ecological niche

  • Habitat
  • Resources e.g food, water, shelter, mates etc…
  • Interactions e.g. competition, predation and symbiosis
• Bald Eagle in a Coastal Ecosystem

  • Habitat - Coastal regions, including shorelines, estuaries, and wetlands
  • Resources - Fish, waterfowl, and carrion
  • Interactions - Predation on fish and waterfowl, competition with other raptors, scavenging on carrion
  • Niche Differentiation - Eagles may specialise in hunting specific fish species or utilise different foraging strategies to minimise competition
  • Role - Apex predator regulating prey populations, scavenger contributing to nutrient cycling, and indicator species reflecting ecosystem health
• Habitat of the Amazon Rainforest

  • Location - Located in South America, spanning nine countries
  • Characteristics - Dense, biodiverse tropical forest with high levels of rainfall and humidity
  • Vegetation - Towering trees, dense undergrowth, and a wide variety of plant species
  • Wildlife - Home to an incredibly diverse array of plant and animal species
  • Importance - Considered the "lungs of the Earth" for its role in global carbon sequestration and oxygen production
  • Threats - Facing threats from deforestation, habitat fragmentation, and climate change, leading to loss of biodiversity and ecological degradation
• Predator


  An animal that hunts, kills and consumes other animals
• Prey


  An animal that is killed and consumed by another animal
• Intraspecific competition


  Competition for resources between individuals of the same species
• Interspecific competition


  Competition for resources between individuals of different species
• Key processes all living organisms perform

  • Movement
  • Respiration
  • Sensation
  • Growth
  • Reproduction
  • Excretion
  • Nutrition
• Infectious disease


  Caused by pathogens (bacteria, virus, protozoan, prion, fungal) and can be transferred between individuals
• Non-infectious disease


  Either environmental, genetic or nutritional and can not be transferred between individuals
• Pathogen


  An infectious disease causing agent
• Infectious disease impact on population: When the pathogen is introduced the overall health and wellbeing of the species is impaired and the species population will drop. Typically doesn't cause extinction due to outliers such as numbers that are able to fight off the disease or deal with it better than others. The pathogen will continue to spread through the population until it is isolated or a vaccine is developed.
• Abundance


  The number of organisms in the study area
• Distribution


  The spread of the organisms within the study area
• Sampling techniques


  • Random quadrats (abundance)
  • Transects (distribution and abundance)
  • Capture-recapture (abundance)
• Sampling techniques are used to determine distribution and abundance of a species when direct counts are not possible.
• Random Quadrats


  Abundance → Area quadrats
• Line Transects


  1. Measure distribution of plants or immobile animals

  2. Involves drawing a random straight line through study area

  3. Presence of species along transect recorded at set intervals
• Belt Transects


  1. Measures both distribution and abundance

  2. Presence of species recorded at set intervals

  3. Numbers of species counted on both sides of the line for a set distance
• Capture-recapture


  Used to measure the abundance and distribution of highly mobile and/or difficult to observe animals through tagging and sampling
• Formula used for capture-recapture calculation: S1 x S2 / M2 (S = Sections, M = Marked)
• Extinction is the reduction in a population to zero
• Capture a number of individuals and mark them by tagging them as S1

  1. Return them to the wild population

  2. Recapture second sample of the population S2

  3. Record number of individuals in S2 that are 'marked' M2
• If the total area of the study site is known

  A total count of the species can be estimated
• Prior to fishing season, a capture - recapture sample is used to determine that adequate numbers of a species are available