Question

identify all the trophic levels in the food web above and then complete the table below.
table: columns - cause, population (phytoplankton, krill, leopard seals, killer whale, seagull), effect on population, why?; cause row: \a significant oil spill has caused a layer of oil to sit on the ocean’s surface, blocking sunlight from the organisms below.\; phytoplankton row: effect (handwritten: \theyll decrease\), why (handwritten: \theres no sun light\)

Explanation:

To solve this, we analyze the food web and the effect of the oil spill (blocking sunlight) on each population:

Krill

• Effect on Population: Decrease
• Why?: Krill feed on phytoplankton. If phytoplankton (their food source) decreases due to lack of sunlight for photosynthesis, krill will have less food, so their population decreases.

Leopard Seals

• Effect on Population: Decrease
• Why?: Leopard Seals feed on krill. If krill population decreases, leopard seals will have less food, leading to a decrease in their population.

Killer Whale

• Effect on Population: Decrease
• Why?: Killer Whales feed on leopard seals (and other prey like seals). If leopard seals’ population decreases, killer whales will have less food, so their population decreases.

Seagull

• Effect on Population: Decrease (or change depending on diet, but if their prey in the web (like small fish that depend on phytoplankton/krill) decreases, seagulls’ food source is affected, leading to population decrease).
• Why?: Seagulls feed on organisms in the marine food web. If lower trophic levels (phytoplankton, krill, etc.) decrease, their prey (e.g., small fish, krill) becomes scarce, reducing seagulls’ population.

Completed Table:

Population	Effect on Population	Why?
Krill	Decrease	Depends on phytoplankton for food; less phytoplankton means less food.
Leopard Seals	Decrease	Depends on krill for food; less krill means less food.
Killer Whale	Decrease	Depends on leopard seals (and others) for food; less prey means less food.
Seagull	Decrease	Depends on marine organisms (prey) that are affected by the food web disruption.

This follows the trophic cascade: a change in the producer (phytoplankton) affects all higher trophic levels.

Answer:

To solve this, we analyze the food web and the effect of the oil spill (blocking sunlight) on each population:

Krill

• Effect on Population: Decrease
• Why?: Krill feed on phytoplankton. If phytoplankton (their food source) decreases due to lack of sunlight for photosynthesis, krill will have less food, so their population decreases.

Leopard Seals

• Effect on Population: Decrease
• Why?: Leopard Seals feed on krill. If krill population decreases, leopard seals will have less food, leading to a decrease in their population.

Killer Whale

• Effect on Population: Decrease
• Why?: Killer Whales feed on leopard seals (and other prey like seals). If leopard seals’ population decreases, killer whales will have less food, so their population decreases.

Seagull

• Effect on Population: Decrease (or change depending on diet, but if their prey in the web (like small fish that depend on phytoplankton/krill) decreases, seagulls’ food source is affected, leading to population decrease).
• Why?: Seagulls feed on organisms in the marine food web. If lower trophic levels (phytoplankton, krill, etc.) decrease, their prey (e.g., small fish, krill) becomes scarce, reducing seagulls’ population.

Completed Table:

Population	Effect on Population	Why?
Krill	Decrease	Depends on phytoplankton for food; less phytoplankton means less food.
Leopard Seals	Decrease	Depends on krill for food; less krill means less food.
Killer Whale	Decrease	Depends on leopard seals (and others) for food; less prey means less food.
Seagull	Decrease	Depends on marine organisms (prey) that are affected by the food web disruption.

This follows the trophic cascade: a change in the producer (phytoplankton) affects all higher trophic levels.