Ecosystem Interactions, Symbiotic Relationships, and Biogeochemical Cycles

Ecosystem Components: Biotic and Abiotic Factors

• Biotic Factors: The living components existing within an ecosystem.
  • Examples include humans, animals, plants, and microorganisms.
  • Microorganisms in the ecosystem consist of four major biological groups:
    • Protists
    • Bacteria
    • Fungi
    • Archaea
• Abiotic Factors: The nonliving physical and chemical components present in an ecosystem.
  • Examples include air, water, temperature, sunlight, soil type, salinity (salt level), pH level (acidity/basicity), minerals, humidity, and precipitation.
• Habitat: The environment where organisms find food, shelter, and other resources that they need to survive.
• Adaptation: A process in which an organism adjusts to the environment where it belongs to survive.

Biotic and Abiotic Interactions and Environmental Balance

• Influence of Abiotic Factors on Biotic Factors:
  • Terrestrial plants require soil, water, air, and sunlight to grow.
  • Living organisms in bodies of water require specific underwater conditions to survive, including proper temperature, salinity (salt level), and pH level (acidity/basicity).
  • Essential abiotic factors such as sunlight, air, and water are mostly used and are critical to the survival of many biotic factors.
  • When abiotic factors are not enough or become scarce, biotic factors tend to compete with one another for the limited abiotic factors around them (such as water).
• Influence of Biotic Factors on Abiotic Factors:
  • The daily activities and actions of biotic factors directly affect abiotic factors in the environment, bringing both good and harmful effects.
  • Humans throwing garbage in bodies of water affects the pH level of the water.
  • Humans throwing trash on land affects the pH level of the soil.
  • Using motor vehicles that produce smoke degrades the quality of the air, which negatively affects the health of biotic factors that breathe in the air.
• Ecosystem Regulation and Stability:
  • Limiting Factor: Factors that may affect the ecosystem by slowing and stopping it from growing. These factors regulate the number of organisms in an ecosystem.
    • Examples of abiotic limiting factors include space, food, oxygen, and water.
  • Carrying Capacity: The maximum number of organisms that can live and survive in an ecosystem. The presence of abiotic factors (such as water and oxygen) together with biotic factors determines how many organisms can survive.
  • Equilibrium: The stable state where living things and nonliving things exist in harmony in an ecosystem. The continuous interactions between biotic factors and abiotic factors maintain balance in the ecosystem.
• Field Investigation Procedure (Sci-Probe):
  • Objectives: Describe examples of biotic factors, discuss the interaction between biotic and abiotic factors, and give examples of these interactions.
  • Materials: Science book, magnifying glass.
  • Procedure Steps:
    1. Visit school grounds (such as a pond or designated field area).
    2. List all living things and nonliving things observed.
    3. From the list, select one living thing and one nonliving thing that are thought to interact.
    4. Identify and record the possible interactions occurring in the area using Table 5.2 (Data Sheet: List of Living Things, List of Nonliving Things).

Biogeochemical Cycles and Fundamental Ecosystem Processes

• Overview: Essential processes in the ecosystem involve continuous interactions between biotic factors and abiotic factors through biogeochemical cycles and photosynthesis.
• Photosynthesis:
  • Light energy from sunlight drives the process.
  • Inputs: Carbon dioxide enters the plant body from the air, and water is absorbed by roots.
  • Outputs: Oxygen gas is released out into the atmosphere. Carbon dioxide is also produced internally during plant processes, but stays inside the plant body.
• The Water Cycle (Simplified):
  • Evaporation: Liquid water absorbs heat and transforms into vapor, rising into the atmosphere.
  • Condensation: Water vapor cools and forms clouds.
  • Precipitation: Water falls back to Earth in forms such as rain, snow, and hail.
  • Collection: Precipitated water accumulates in soil and bodies of water.
• The Carbon Cycle:
  • Photosynthesis in plants absorbs atmospheric carbon dioxide using sunlight.
  • Animal respiration releases carbon dioxide back into the atmosphere.
  • Decomposers break down dead matter, returning carbon to the ecosystem.
  • Factory emissions and the combustion of fossil fuels release stored carbon back into the environment.
• The Nitrogen Cycle:
  • Atmospheric nitrogen gas ($N_2$) is converted into usable forms through various biological pathways.
  • Legumes with nitrogen-fixing bacteria and soil with nitrogen-fixing bacteria capture atmospheric nitrogen.
  • Nitrifying bacteria convert nitrogenous compounds through nitrification, producing nitrites ($NO_2^-$) and nitrates ($NO_3^-$).
  • Plants absorb nitrates ($NO_3^-$) through the process of assimilation.
  • Decomposers process organic waste through ammonification, producing ammonium ($NH_4^+$).
  • Denitrifying bacteria convert soil nitrogen compounds back into atmospheric nitrogen gas ($N_2$).

Symbiotic Relationships

• Definition of Symbiosis:
  • Refers to the close and prolonged interaction that occurs between two different organisms that exist in the ecosystem.
  • Also defined as the relationship among living things in an environment wherein one of them benefits, gets harmed, or is unaffected.
• Mutualism:
  • A type of symbiosis where both interacting organisms benefit from their relationship.
  • Example 1 (Sea Anemone and Clownfish): The sea anemone provides protection to the clownfish. In return, the clownfish provides multiple benefits to the sea anemone: cleaning the sea anemone, scaring away other fishes that may prey on the sea anemone, and providing nutrients from waste generated by the clownfish.
  • Example 2 (Bee and Flower): The bee gets nectar from the flower, while the flower gets pollinated.
• Commensalism:
  • A type of symbiosis where only one organism in the relationship benefits, while the other is left unharmed or unaffected.
  • Example 1 (Golden Jackal and Tiger): The golden jackal follows the tiger to feed on what is left over from the animal that the tiger has killed.
  • Example 2 (Barnacles and Whale): Barnacles attach to a whale to find food while traveling through water, while the whale is completely unaffected.
• Parasitism:
  • A type of symbiosis where the organism that benefits is called the parasite, and the harmed organism is called the host.
  • The parasite lives inside or outside the body of its host to get its nutrients, causing sickness or disease to the host.
  • Example (Tick and Cat): The tick acts as a parasite feeding on the cat's blood, while the cat is the host that gets skin irritation.

Predation and Competition Dynamics

• Predation Characteristics:
  • An interaction involving a predator and a prey.
  • The predator is usually the strongest living thing, whereas the prey is generally described as being small and weak.
  • The predator hunts and eats its prey.
• Predator-Prey Population Imbalance:
  • If there are more predators than prey in an ecosystem, it results in intense competition.
  • Predators fight over the remaining food in the ecosystem to survive.
  • This competition leads to a decrease in the number of predators as their food runs out.
• Definition of Species:
  • Refers to a group of organisms that are capable of reproduction among the members, producing viable offspring.
  • Example: All dogs belong to one single species, whereas cats and tigers are two different species.
• Intraspecific Competition:
  • Occurs in living things of the same species.
  • Organisms compete for the exact same biological needs: food, mates, breeding place, and territory.
  • Example: Male peacocks fighting for the same female peacock.
• Interspecific Competition:
  • Occurs in organisms of different species.
  • Organisms fight over shared environmental resources: food, shelter, and water.
  • Example: Snakes and eagles competing for the same food source.
• Management Practices and Applications (Sci-Value Builder):
  • Animals in the zoo are arranged and separated based on their kind (e.g., all birds in one area, wild animals in another area, and other animals having their own areas).
  • Animals are caged and separated to prevent competition in food, water, and space.
  • Following rules in the zoo helps maintain the safety of animals as well as the visiting public.
  • Giving animals unauthorized food may put the animals at risk.