Ecology and Invasive Species

Astronomy Lessons

  • Next lessons will cover astronomy, focusing on the solar system, planets, comets, meteorites, and asteroids.

  • Discussions on Earth's motions, seasons, and the reasons behind years.

Limiting Factors

  • Abiotic and biotic factors determine a population's survival in an environment.

  • Carrying capacity affects the maximum number of individuals in a population.

  • Carrying capacity can be altered by human or natural activities.

Introduction of Non-Native Species

  • Introductions of non-native species often fail due to the inability to adapt to new environments.

  • When non-native species prevail, they can become invasive, outcompeting the native species due to lack of predators or diseases in the new environment.

Invasive Species Definition

  • Invasive species are non-native species introduced to an ecosystem that cause negative impacts.

Ecological Consequences of Invasive Species

  • Invasive species compete with native species for food, altering food webs.

  • Example: Carp in the Great Lakes compete with native fish like lake trout and wild salmon, affecting their populations.

Economic Problems due to Invasive Species

  • Invasive species damage forests and livestock, affecting the economy.

  • They can introduce diseases to crops, leading to economic losses.

  • Tourism can be affected by harm to natural parks and reduced water quality.

Health impacts of Invasive Species

  • Invasive species can impact the health of organisms, including humans.

  • Example: Mosquito larvae carrying malaria being transported to new regions.

Control Measures for Invasive Species

  • Pesticides: Kill invasive insects but can also harm native species and pollute water systems.

  • Mechanical Control: Physical barriers or removal of species, including controlled fires and cutting down infected trees.

  • Biological Control: Introducing organisms to control invasive species populations, though rarely eradicates them completely.

Examples of Invasive Species

  • Zebra Mussels: Arrived in the Great Lakes through ballast water and attach to native species, limiting movement. They overeat algae causing native species that rely on it to dwindle.

  • Goldfish: Released as unwanted pets, they tolerate poor water quality, outcompete native species for food, carry exotic diseases, and stir up mud, increasing water cloudiness.

Pests and Pest Control

  • Difference between Pests and Invasive species: Pests are something that can disrupt an ecosystem and, unlike invasive species, they might be native to the ecosystem.

  • Pesticides are chemicals used to kill, repel, or control pests.

Drawbacks of Pesticides

  • Cause water and air pollution.

  • Kill non-target species, including beneficial organisms.

  • Species can become resistant to pesticides over time, requiring new ones.

Persistent Organic Pollutants (POPs)

  • Toxic chemicals that do not break down easily in the environment.

  • Stored in fat stores, making them hard to eliminate from the body.

  • Examples: DDT and mercury.

Bioaccumulation

  • Accumulation of toxic substances in an organism over time.

  • Organisms may suffer side effects or die from toxic exposure.

Bioamplification/Biomagnification

  • Toxins stored in fats and oils are passed on to the next trophic level.

  • The higher up the food chain, the more concentrated the POPs become.

  • Example: DDT in plants eaten by grasshoppers, then birds, and finally concentrated in eagles, causing thin eggshells.

Organic Farming

  • Avoids synthetic pesticides and fertilizers.

  • Relies on ecologically sustainable techniques.

  • More work-intensive and expensive.

Techniques Used in Organic Farming

  • Biological control (introducing predatory insects).

  • Altered timing of planting and harvesting to avoid pest populations.

  • Crop rotation and mixed planting instead of monocultures.

  • Baiting pests using pheromones.