AI assignment threats to biodiversity

We often think of "habitat loss" as cutting down forests to build cities or shopping malls. However, there is a different human activity that is actually the #1 cause of habitat destruction worldwide.

1. Habitat Removal and Alteration
   • Human Activity:
     • Clearing land for agriculture (farming/ranching), forestry (logging), and urban development (housing/roads).
     • Damming rivers, which alters aquatic habitats.
   • Why it is a problem:
     • It directly removes the food, shelter, and breeding grounds species need.
     • Fragmentation: It breaks large habitats into small, isolated "islands," making it hard for animals to find mates or migrate.
   • What can be done:
     • Preservation: Creating protected parks and reserves.
     • Restoration: Replanting forests and restoring wetlands.

Sustainable Agriculture: Farming in ways that leave space for nature (like leaving hedgerows between fields).

• Human activity can damage habitats.
• This damages local ecosystems and removes necessary ressources for the local animals
• Fragmentation can break large habitats into smaller ones, this makes it harder for animals to mate or migrate
• We can stop this by protecting parks and reserves, replanting forests and restoring wetlands. We can also farm in ways that leave space for nature

• Habitat Loss, the Dynamics of Biodiversity, and a Conservation Challenge
• Author: Ilkka Hanski (et al.)
• Publication: Philosophical Transactions of the Royal Society B (2011)
• https://pmc.ncbi.nlm.nih.gov/articles/PMC3357798/

If the climate changes too quickly for a species to evolve or adapt, what are the only two options left for that species to survive? (Think about what you would do if your house suddenly became too hot to live in.)

You identified the two main survival strategies!

• Migrate: Move toward the poles or higher up mountains to find cooler air.
• Adapt: Change their behavior (e.g., hunting at night) or physical traits over time.

Here is the catch: Because climate change is happening so fast right now, most species cannot evolve quickly enough to adapt. And many cannot migrate (like a Polar Bear running out of ice, or a fish in a warming lake). If they fail to do either, they face extinction.

• Human Activity:
  • Burning fossil fuels (coal, oil, gas) for energy and transportation releases Carbon Dioxide (CO2​) and Methane.
  • Deforestation (trees absorb CO2​, so cutting them down releases it back into the air).
• Why it is a problem:
  • Speed: Temperatures are rising faster than species can adapt.
  • Habitat Loss: Melting sea ice (affects polar bears), rising sea levels (floods coastal habitats), and warming oceans (kills coral reefs).
• What can be done:
  • Reduce Emissions: Walk/bike/bus instead of driving, use energy-efficient appliances.
  • Renewable Energy: Switch to wind, solar, or hydro power.
  • Reforestation: Planting trees to absorb carbon.

• Combustion releases CO₂ and Methane
• Deforestation removes a major carbon sink
• Temperatures are rising extremely fast
• Sea levels are rising and many aquatic habitats are being destroyed
• We can try to prevent this by staying efficient with our energy usage
• We can also switch to renewable energy sources
• We can replant trees to absorb more carbon

Today, the biggest overharvesting problem isn't on land; it is in the oceans. Why is "overfishing" considered a threat to the entire ocean ecosystem, rather than just a problem for the specific fish we are eating (like Tuna or Cod)?

You nailed it again. You have correctly identified the three main reasons why overfishing destroys more than just the fish on our dinner plates.

Here is the breakdown of the concepts you just described (these are excellent terms to use in a Grade 9 assignment):

• "Other fish rely on them" (Food Webs): This is called a Trophic Cascade. If you take too many Tuna (predators) out of the ocean, the population of the fish they eat (prey) explodes, which can eat up all the plankton, causing the whole system to crash.
• "Other ones are caught in the way" (Bycatch): This is the technical term for when nets accidentally catch animals we didn't mean to, like sea turtles, dolphins, and baby fish. They are usually thrown back dead.
• "Giant net fishing" (Bottom Trawling): This is when massive weighted nets are dragged along the sea floor. As you noted, this destroys the habitat (corals and sponges) that baby fish need to hide and grow.

Here is your summary for Topic 3:

• Overharvesting and Exploitation
  • Human Activity:
    • Overfishing: Taking fish faster than they can reproduce.
    • Poaching: Illegal hunting of animals for trophies (e.g., elephant ivory) or traditional medicine.
    • Bottom Trawling: Dragging heavy nets across the sea floor.
  • Why it is a problem:
    • Population Collapse: Species like Cod or Tuna can be wiped out commercially.
    • Bycatch: Killing non-target species (turtles, dolphins) disrupts the ecosystem.
    • Ghost Fishing: Abandoned fishing gear continues to trap and kill animals for years.
  • What can be done:
    • Quotas: Laws that limit how many fish can be caught.
    • Marine Protected Areas (MPAs): Zones where fishing is banned so fish can breed.
    • Consumer Choice: Buying "Sustainably Certified" seafood (look for the blue MSC label).

• Killing small fish kills the food source for the predators and killing big fish causes the population of the prey to rise
• We sometimes catch animals we dont mean to and then throw them out
• Bottom trawling destroys habitats
• We can prevent this by limiting how much fish can be caught, creating areas where fishing is banned, and buying sustainably certified seafood.

• https://www.longdom.org/open-access/the-impact-of-overfishing-on-marine-ecosystems-99707.html
• Author: L. Wright
• The Impact of Overfishing on Marine Ecosystems
• Published: Poultry, Fish & Wildlife Sciences (2023)

Question 4: Imagine a factory dumps a small amount of mercury (a toxic metal) into a lake.

• The algae absorb a tiny bit.
• The tiny bugs eat lots of algae.
• The small fish eat lots of bugs.
• The big fish (like Pike or Trout) eat lots of small fish.

Exactly! You’ve described the process of Biomagnification perfectly. In a food chain, energy is lost as you go up (the 10% rule), but certain toxins—like mercury or the pesticide DDT—don't disappear. Because a big fish must eat hundreds of small fish to survive, it ends up absorbing all the poison those small fish ever ate.

Here is your summary for Topic 4: Pollution

1. Human Activity:
   • Chemical Runoff: Pesticides and fertilizers from farms wash into rivers.
   • Industrial Waste: Factories releasing heavy metals (mercury, lead) or plastics into the air and water.
   • Litter: Plastics that break down into "microplastics" and enter the food chain.
2. Why it is a problem:
   • Biomagnification: Toxins become more concentrated at the top of the food chain, poisoning top predators (and humans!).
   • Eutrophication: Fertilizer runoff causes "algal blooms" that suck all the oxygen out of the water, creating "dead zones" where fish suffocate.
3. What can be done:
   • Regulation: Governments passing laws to limit what factories can dump.
   • Organic Farming: Reducing the use of synthetic pesticides.
   • Proper Disposal: Never pouring chemicals (like paint or oil) down the drain.

• Humans cause pollution
• Pollutant levels are more concentrated at the top of food chains
• Fertilizer runoff causes "algal blooms" from that suck oxygen from water and suffocate fish(see: Denitrification)

When a non-native "Invasive Species" arrives in a new place, why do they often take over so quickly and wipe out the local species? (Hint: Think about what they are missing in their new home.)

Exactly! Since they have no natural predators to hunt them and no natural diseases to slow them down, their population explodes. They are like a team playing a sports match where the other side doesn't show up—they win every time.

Here is your summary for Topic 5:

• Human Activity:
  • Accidental: Species "hitchhiking" in the ballast water of ships, on the bottom of hiking boots, or in shipping crates.
  • Intentional: Releasing pets (like goldfish or pythons) into the wild, or bringing in plants for gardens that later escape into the forest.
• Why it is a problem:
  • Competition: They take the food, water, and space that native species need to survive.
  • Predation: They may eat native species that have no way to defend themselves.
  • No "Checks and Balances": Without predators to regulate them, they can take over an entire ecosystem, leading to a loss of biodiversity.
• What can be done:
  • Prevention: Cleaning boats and boots before moving to new areas and never releasing pets into the wild.
  • Management: Physically removing the species (pulling invasive weeds) or using "biological controls" (introducing a predator from their home country, though this is very risky!).

• Invasive species increase competition and eat defenseless native species.
• There are no predators to regulate them, so they can dominate ecosystems
• We can stop this by preventing invasive species from coming to areas and removing invasive species

Your Final Challenge: Think about your own school or neighborhood. Based on the five threats we just discussed (Habitat, Climate, Overharvesting, Pollution, Invasives)…

What is one specific "Stewardship Action" you could take this week to help reduce one of these threats? (For example: "I will use a reusable water bottle to reduce Pollution.")

When you choose to bike or walk, you are directly reducing the amount of CO2​ entering the atmosphere. When you turn off lights, you reduce the demand for power plants to burn coal or gas. These small individual choices, when multiplied by millions of people, are exactly how we begin to solve these large global problems.